Bericht: Motoruberhohlung E28S M5

Last Thursday, I started with the removal of the coating on the lower wheel arches to uncover the true extent of the corrosion. I will use the same procedure as member BMWWGN as described in
post 68 of his blog on this board. After degreasing and cleaning of the metalwork, I treated the exposed metal with Caprotec RX5, which is a rust converter and primer.

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In the mean-time, the new tie-rod end s and associated small material arrived as well.

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As I experienced difficulty with the removal of the old tie-rod ends on the car, I removed both tie-rods and placed them on a bench, but even there with lots of WD40 applied and a few whacks from the claw-hammer onto the affected tie-rod ends, they wouldn’t move. A commonly used method is to heat them up, but as this is not allowed I have no other choice then placing an order for new tie-rods. Until they arrive, I can continue working on the front suspension.

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I also started working on the left drive-shaft by removing the cover of its coupling joint. The plan is to replace the boots and replace the lubricant. This is no luxury as the 25-year old lubricant lost its viscosity and was concentrated in small clogs with no even distribution on the balls of the coupling joint anymore.

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The next step is the removal of the driveshaft from the coupling joint after which I can clean the coupling joints themselves. Please note that it is not allowed the disassemble the joints in single parts.
Due to the work on the front suspension, there was little progress on the refurbishment of the differential until now. To apply a coating of RX5, the surface must be slightly corroded so blasting won’t be required, however there is lots of rust that needs to be removed first.

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In order to remove that rust, I started with covering the case its openings for which I use simple carton-board.

To replace the boots of the driveshaft’s universal joints, one has to push out the driveshaft from both coupling joints. Basically, this is rather simple. It first starts with the removal of the cover. This cover is made from simple sheet metal, but is glued to the coupling joint with Curil K2; hence why some gentle force may be required from a screw driver and a hammer. With the cover removed, the universal joint is exposed.

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The next step is to push the shaft from the U- joint, for which the cir-clip needs to be removed first. It is wise to remove most of the grease first in order to spot the opening in the cir-clip in between the depressor tool can be placed.

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The next step is to remove the inner cover from the U-joint. Like the rear-cover, this one is sealed with curil so some force from a screwdriver and a hammer is required.

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It is now possible to separate the shaft from the U-joint. Although the splines contain Loctite 270, this went easier than expected, but bear in mind that it is not allowed to disassemble the U-joint so be careful in here.

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After the opening the clam that secures the boot to the shaft, the boot can be removed. Please note the absence of ample-grease in the boot; this is IMHO not normal.

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The removal of the other U-joint is just the same. Please note the presence of an ample supply of grease that also hasn’t lost its viscosity. This is normal.

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The next step is clean and label both U-joints and clean and mark the shaft so it is known what U-joint was placed on one side. The splines and the U-joints must be closely inspected for wear and damages. This requires a thorough clean with brake fluid/degreaser.

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The splines appear to be in excellent condition. The paint could be more shiny, but I think that after another good clean, they will look much better; therefore I have decided not to repaint them.

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Since I like a clean working environment, I replaced the newspaper with a new one.

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Although I wrote in an earlier post that I didn’t want to paint the drive-shafts, I reversed that decision as on a closer inspection, the paint on the right drive-shaft has faded away more than the left driveshaft. After sanding away the existing layer of paint to flatten the surface, I sprayed three thin layers of ‘Innotec’ paint.

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The paint requires some time to cure into a scratch free finish, after which the U-joints can be reinstalled with the OEM revision sets. These revision kit contain all the required parts for the re-installation of the U-joints, including the factory approved grease in the correct volume. The kit also contains a replacement for the original specified Curil-K2 for sealing the cover plates to the U-joint. Only the Loctite 270 that has to be applied to the splines is not supplied, but that can easily be sourced from a hardware store.

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I gave the anchor plates a mild clean instead of re-spraying them. This would have required their removal which is not possible without pulling and thus destroying the bearings.

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Originally I wanted just to replace the tie-rod ends to the tie-rod lever, but as it was impossible to remove the old ends without damaging the tie-rods, this is the better (albeit expensive) solution.

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With new ball-joints and bushings all over the place, I expect nothing else then a significant improvement in handling, braking and steering.

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The next picture will answer Davidoli’s question about the bushings of the thrust arms. Clearly visible is the Meyle inscription (see red arrow). With other words, these are not originated from the M70 powered E32. However, it is possible that Meyle got the same idea and just installs more rugged bushings then the OEM variant.

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Last but not least, the first reassembled U-joint for the left driveshaft. I will describe the process in more detail later, but this is a real PTA job, but the result is promising.

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Later more!

Gents,

During the past week, I found some time to work on #231; she is now standing in her own feet again. Some minor points remain such as tightening the steering-nuts to spec and the reinstallation of the stabilizer bar, but that is about it.

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I also cleaned the lower wheel arches a little further by removing all the dirt to until the A-pillar after which I sand-blasted the narrow gaps. After a thorough clean I added the RX5 primer paints.

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I allowed 48 hours of curing before applying the final coat of Silver POR15 paint. This matches the original 203 color very closely, but bear in mind
that there I have new liners to cover the gaping hole so no one will see.

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With the front-suspension almost finished, I can focus fully on the drive-train for which I am considering to outsource the overhaul of the differential to a specialized company. This will not only speed-up the process, but will also allow a thorough investigation in the diff’s actual condition.

A quick survey on the www learnt that there aren’t that many specialists for differential overhaul in the Netherlands; to find some, I enquired at a few Dutch forum’s. The members of driving-fun and the BMW E21 network added five leads to the shortlist. One of the respondents actually works for one of these companies and already gave some interesting information about the longevity of the LSD.

Due too personal obligations in the past few weeks, progress on #231 isn’t what I expected it to be. The front suspension is almost complete; only the stabilizer bar needs to be installed. The differential however still is untouched and with the spring of 2011 already in ‘motion’, I do not want to wait much longer so I have decided to postpone the diff-rebuild to the winter of 2011/2012.

Revision of the driveshafts

This job isn’t really rocket science; but there are some things to consider, hence why I have documented the process below in a few single steps.
Nothing is so nasty as components that look aged; so when possible start with refurbishing individual parts. This costs a little bit more time, but the reward will be fresh looking parts.

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Before starting the assembly process, it is essential to clean the splines at both end with for instance brake cleaner. This will remove contaminations sufficiently enough to Loctite 270 later in the process.

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Be prepared to make your hands dirty and remove the old grease from the U-joints as far as possible. I also used brake-cleaner and degreasing solvent before checking them for play and movability. Please note that these U-joints cannot be bought separate parts, so treat them with care to avoid buying new driveshafts.

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The revision set contains almost all the required parts for overhauling one U-joint. Only the earlier mentioned Loctite 270 is not included and has to be sourced separately.

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After cleaning the shaft-ends, the new boot can be pushed over the shaft. Wait with the hose-clamp; to avoid losing it, this part has to be installed just before placing the second boot.

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Add a small amount of Loctite 270 over the splines, but prevent spilling it as it may not be mixed with the Molycote grease to avoid damage to the U-joint.

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The next step is the U-joint that has to be pushed over the splines until the seat for the spring-clip is visible. Push it in with for instance a 30mm socket when needed.

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The spring-clip is part of the revision set and secures the position of the ‘U-joint’ on the driveshaft shaft.

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With the ‘U-joint’ well seated in position, the U’-joint’ lubricant can be injected into the protective boot. It is not possible to inject all of the 120 grams, so save some for……

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The ‘U-joint’ itself. Please note that the following picture also shows the liquid hylomar that seals the protective covers.

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Last but not least, rotate the protective covers in a position that allows the bolt to move freely though each hole without resistance.

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All this work results in a nicely refurbished driveshaft that not only looks well, but also functions a lot better.

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Differential

During the past few weeks, I have exchanged Emails with Hardemann Motorsport for the overhaul of the differential. Based on the information exchanged, I am confident that they can rebuild my differential to my requirements and satisfaction. However, I have decided to postpone that until the next Winter season:

1: Hardemann Motorsport estimates that they need 20-30days before returning the LSD.
2: The delivery of the drive flanges with impulse sending wheel has been postponed by BMW without giving a new estimate.

Since the spring season of 2011 has already started, I do not want to wait any longer . With the 20-30 days of turnaround time for the LSD, it will be well into May before #231 is drivable. At least when the drive flanges are supplied and that is highly uncertain at the moment. Therefore, I have decided to put that issue in the fridge until BMW supplies the new drive flanges. Since that requires the removal of the driveshafts, I can combine the rebuild of the LSD . These issues have not been cancelled, but just postponed as it is better to drive #231 with a compromise then wait for perfection to achieve.

M.H,

Der E28 ist jetzt fertig fur das neue Saison; allerdings ist der ausflug nach London morgen noch etwas zu fruh. Das wird sehr wahrscheinlich mit einem F10 funfer geschehen.

As I wrote in an earlier post, I have separated the overhaul of the differential into three phases (1) research, (2) requirements and specifications and (3) actual rebuild. In order to use #231, I have reassembled the differential using new seals for the output shafts and a new gasket set for the rear-cover. Since the pinion seal is dry and a real PITA to replace, I decided not to replace that one.

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The new output shafts alone give the rear a complete fresh appearance, so I am quite happy with that. The differential itself can wait when the drive flanges with the ABS-tooth’s arrive. Originally these were confirmed for delivery in the fifth week of 2011, however BMW postponed their delivery for indefinite time. I just hope that BMW will supply them sometime this year.

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The next step is to fill the differential with lubricant that is suitable for LSD’s with preloaded friction-clutches. Replacing this oil is essential for longevity of the differential as the friction plates do wear in time because of aging and usage. Depending on the type of usage, this should not be postponed beyond any second inspection II service as otherwise, the diff will be lubed in its own dirt, which will result in premature wear of the internal bearings, especially the pinion bearing.

I have decided for the 75W140 viscosity rated Castrol SAX-XJ, which is BMW approved for LSD- differentials with preloaded friction-plates. Given its hefty price-tag, it almost is a waste for using one just one season, but things are what they are.

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Filling the diff is rather straightforward and easy and can be done without making a mess.

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After the last checks, #231 was submitted to the annual Dutch safety inspection for which an emission test is mandatory. Although the CO limit for #231 is such that it will pass it nonetheless, the four-gas (CO, CO2, hc and O2) test-results give valuable information about the health of the engine. Although it was subject to a full rebuild some time ago and I expected nothing was wrong, analyzing the emission results gives an early warning . The next picture shows the operating AFR as a function of time. The samples were taken with a digital camera and the time tag’s derived from the EXIF information. The samples are equidistant within one second, not bad.

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I have similar graphs of the other parameters and confirmed that #231’s combustion is about the same as in May 2010. This confirms the stability of the petrol-injection and ignition.

The last step is a full alignment of the front-suspension, but that cannot be done before the sixth of May as capable shops have a busy agenda and are always fully booked.

During the second week of April, I completed the last issues on #231 to prepare her for the 2011 season. This was just the week before the meeting at the Goat in Hertford that I attended with Stevie. Without proper testing beforehand, this 1160km round trip would be too risky to undertake with #231, hence why we used an F10 520d instead.

One of the remaining issues is a proper alignment, but there aren’t that many capable shops in my vicinity so there is little too choose and the first opportunity within my agenda and that of van Aalderen tires in Vriezenveen is the sixth of May. Despite that, I took #231 for a small spin the day before the meeting at ‘the Goat’ and it tracked rather well. This 25km trip, confirmed that the front suspension overhaul project of last winter was carried out successfully. The shimmy disappeared completely and the front felt much more stable at the relatively twisty and rough Klokkendijk road between Rijssen and Nijverdal.

My appointment with member RobertK to assist him in measuring the valve lash of the S38B36 engine of his E34 M5 was a great opportunity to kick-off the 2011 season for #231. During the test-drive, I noticed that #231 tracked rather well without an alignment so the current setup isn’t that far-off from the

As expected, the 135km trip to Almere went flawlessly and from time to time I played with the throttle and confusing other road-users with a screaming M88/3 from a boxy old-beemer.

The strength of the E28 M5 lies in its midrange acceleration. Throttle response is imminent and linear without being overtly present, hence why its acceleration feels effortless and almost goes unnoticed until looking at the speedometer. And when combined with full throttle, one is rewarded with a combined fortissimo from engine-and exhaust that the later M-cars including the E34 M5 simply cannot match as these were subject to exhaust fine-tuning during their development. The E28 M5’s exhaust system simply does without these tricks giving it a dr. Jackal in a disguise of Mr. Hyde character.

Suspension wise, there is little to complain. The combination of a stiff suspension and relative high profile tires makes it easy to live with under almost any circumstances. The shimmy disappeared completely confirming the outcome of the first test-drive the week before. Although it doesn’t track completely straight, it isn’t that far off; the alignment that is scheduled for the 6th of May will solve that issue.

The rest of the trip went uneventful and I arrived at Roberts premises in Almere around noon. He already did the preparations on his E34 M5 so we could start with the measurements straight away. The valve-lash on his car turned out to be the same as last year with only four shims needing replacement. The work was completed around 5:00PM and a after a discussion of the results, I left Almere at around 6:00PM. For my return trip, I choose the route through the Flevopolder allowing a short social visit to Jeroen (member bmwe21.net) as well.

At Harderwijk, at the last stoplights before highway A28 a Golf six drove next to on the left lane. Judging the character behind the wheel (a typical Golf driver), he wanted to out accelerate thye old beemer. This suspicion turned out to be true as when green light came, the Golf spinned its front tires for a moment before taking advantage of the inner lane in the left corner. This was the right moment to trigger dr. jackal passing the Golf on the outer lane and gaining distance quickly. By the time I entered the A28, the Golf was lagging more than one-hundred meters behind.

Despite that the front-wheels haven’t been aligned properly yet, the front suspension has improved a lot. The drivetrain performed flawlessly as well and didn’t even miss a beat. With this trip, another 257km were added to the odometer that now indicates 4865km being driven since the rebuild. The new season looks promising.

On Saturday 7th May, we had the first S38/M88 conference at my premises. This idea started some time ago when member Stoffie wanted to see my car. During the offline mail conversations that followed, it appeared that we have similar objectives, albeit follow a different approach to achieve them.

Parallel to that, I assisted member RobertK in the valve adjustment on his 1992 E34 M5 3.6 some weeks ago. The next step was the synchronization by Jeroen (member bmwe21.net). As this was scheduled for the same day as the meeting with member Stoffie, Jeroen proposed combining this, creating the first M88 S38 conference for which we also invited another S38 Guru, member Billie-S38.

The day started with the vacuum sync on Roberts car. Since Jeroen’s vacuum meters are only for four cylinders, we had to separate the measurements in two sections, one for cylinders 1-4 and one for cylinders 3-6.

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Since the conditions for performing the intake-vacuum sync were already met (mechanical TB-sync and a proper valve adjustment), adjusting the intake vacuum worked like a charm. Including the replacement of the O-rings of the bypass-screws, Jeroen needed less than one hour. As we scheduled two hours for this (experience based), we had some time to measure the intake vacuum on member Stoffie’s E24 M635CSI.

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The conclusion is that the intake vacuum varied between the six cylinders slightly, but not that much. On Robert’s car this variance was the reason to readjust, but without known data about the valve-lash (which was done 14000km ago) and TB-sync, we decided against the fine-adjustment

The next step was the emission measurement on Stoffie’s car according to the four-gas method (O2, CO2, hc and CO). The reason we wanted to do this test was that the data that he provided us, could not be explained and we wanted to reproduce the measurement data with a factory new Capellec emission tester from my neighbor.

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The outcome of the measurement was that the emissions didn’t reproduce and that the AFR was close to stoichiometric, which is too high for an M88/3 without closed loop emissions control. Furthermore, the value for not-combusted hydrocarbons was too high as well, which we could only reduce by lowering the AFR. Despite the new injectors, the CO adjustment didn’t go as expected so there is an outstanding issue, possibly the air-bypass that doesn’t work correctly. But as there was not enough time to investigate and diagnose, we just concluded that this needs further investigation.

After lunch at my house, we drove out for a small photo-session in a neighboring forest.

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Jeroen used his E30 320iS for this trip. Don’t get confused by the modest four-door looks of this car as it includes a full house S14B20 engine that has been specifically designed for the Italian market for fiscal reasons. This two-liter variant produces 192hp, which is just three horsepower less than the S14B23 it was derived from. According to road tests from the German AMS magazine in 1986, this car was faster than the E30 M3’s from the same model year!

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Member RobertK’s E34 M5 is one of the last 3.6 liter models and was first registered in 1992 a few months later then the first 3.8 liter models. With 280k km, this particular car has some experience, but it is maintained meticulously and handles and performs like a car with 200k km less.

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Member Stoffie drove the ~300km from Belgium with his lovely E24 M635CSI. I didn’t really know this car, but this is a fine example and despite the years looks much better than many of the E24’s that I have seen thus far.

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I used my E28 M5 for this little drive-out. We managed to drive through the village in one convoy, which must be quite an impressive sight. When waiting for the stop-lights out of the village, an old Opel Monza drove next to us. If I would have a fully warmed up engine, I would have answered to his challenge, but I gave him the pleasure of outperforming an M5 to preserve my costly engine rebuild.

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Two M88/3 powered cars and one S38B36 powered car on one location.

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At the end of the day, I also drove In Stoffie’s car. Despite sharing the drivetrain, the E24 M635CSI doesn’t feel like an E28 M5. The E24 is larger and feels a bit roomier and holds the middle between the E28 M5 and the later E34 M5. The engine noise is a bit different than mine, probably because of the different sound insulation. The E28 M5 is a little more agile and responds a bit brisker to the steering input because of its smaller size and weight, but also is little less refined then the E24 M635CSI. The E28 M5 is more of a sports car then the E24 M635CSI is, but the latter is a much better gran-tourismo with a staggering performance that even today is capable to outperform the vast majority of modern cars.

Gents

Last night, # 231 underwent its first high speed test on the German A31 highway. This test is part of my acceptance test upon completion of the running-in phase at 5000km. At the time of departure, the trip odometer indicated 4954km, but the distance to the A31, including a brief stopover in Gronau is around 60km which is used as warming-up time to achieve a thermal equilibrium in the drivetrain.

The stopover in Gronau was required to refill the petrol tank with Shell V-Power Racing, which octane is rated at 100RON. Next to BP Ultimate 102, this is the only type of gasoline that I trust for driving at high engine loads as Super Plus is no longer available petrol stations that distribute A-brands. Unlike the S38B36 the M88/3 requires gasoline with a minimum octane rating of 98RON (according to EN228 standard). Therefore, I take the much higher price of V-Power Racing 100RON of Euro 1.809 per liter for granted.

After a few easy kilometers on the B54, I took entered the A31 towards Emden because the northbound highway usually is not as congested as the southbound highway to Oberhausen. At entering the A31, the playful ease with which #231 accelerates was a true pleasure. The front-suspension is also much more stable and quieter than during a similar session last year in July with a cruising speed of 180km/h and a few short splurges to 210km / h.

The objective for this time was to maintain a sustained speed of over 200km/h for a prolonged period of time. At first I settled for 210km/h on the speedometer which corresponds to ~5300RPM. This is still 1200RPM below the point where the M88/3 delivers maximum power. At that time, the ABS light went on, but that is a known issue and will be solved once the new drive-flanges with ABS-toothing arrive.

During this test I had to slow down twice for slower moving traffic. The first time was when I approached a VW Tiguan with around 210km/h. I applied a little more throttle to shorten the distance. The driver in the Tiguan must have spotted that in his rearview mirror and move to the right. This allowed me to go to full throttle and pass the Tiguan at little over 240km/h and slightly less than 6000RPM. According to the math this indicates a true speed of 232km/h (@ 5900RPM). It was tempting to push to 6500RPM which would be sufficient to reach a true speed of 252km/ h, but to achieve that, full throttle during a much longer time was required which is too risky without performing additional checks. Given that at 6000RPM, the engine still had enough reserve to accelerate further, I believe that for now.

Up until the exit to Lingen / Wietmarschen I varied the engine speed between the 4500RPM and 6000rpm. There was another nice moment when a new W212 tried to pass me to the right when I was driving behind slower traffic. At that time, the slower car in front of way moved to the right, allowing me to select fourth gear. With a free A31 in front of me, I accelerated fully and just saw the appearance of the W212 becoming smaller and smaller in my rearview mirror. AT Lingen, I took the exit and entered the A31 again, this time towards Oberhausen. The highway-junction at Shüttdorf came much too soon, but in the end, the test-run was close to 70km/h which doesn’t differ that much from my original test-plan.

Once driving on the highway A30 towards Oldenzaal and Hengelo, there was no room for ‘spielerei’ due to the road constructions that lasted up until the border with my home country. With normal road-going speeds I followed the highways A1 and A35 and drove back home. On the last strech of country-roads, I tested acceleration in second gear up until 6000RPM, something that I haven’t tried before.

Unlike the exhaust system of the E34 M5, the E28 M5 doesn’t attenuate the sharp-tones of the engine, making the experience much more intense. The orchestra of the mechanical interaction leads to a beautiful symphony for which you want your radio shut-down.

Overall I am very satisfied. The next step is to measure the valve clearance to the verify the stability of the valve seats. When required, these will be adjusted. The required valve adjustment hook (11 3150) differs from the S38 and already has been ordered from BMW. If the valve clearance are set correctly, it is time to verify the basic throttle body and-intake vacuum synchronization.

Zitat von compactdriver

Guten Abend Raimond,

könntest du mir deinen Fahrbericht über den E24 im Vergleich zum E28 "ausdeutschen".

Hallo Stefan,

Danke für deine PN. Ich habe mich entschlossen mein Antwort in mein Thema zu fügen weil deine Frage auch durch anderen gestellt werden wird.

Laut der 1986 M3/M5/M635 Katalog hat der M5 ein Leergewicht von 1430kg und der M635 von 1500kg. Da hinzu kommt das meiner ohne schiebe-hebe Dach und ohne elektrisch verstellbare sitze eine der leichteste M5'er überhaupt ist.

Während meinem Fahrt mit Kristof deinen M635CSI (August 1984, BMW-Schwarz mit Zierstreifen) ist das Mehrgewicht zu spuren. Der E28 M5 ist etwas handlicher in die kurze kurven und die Motorgeräusche sind mehr zu spüren als beim M635CSI was die fahr-belebung etwas intensiver macht. Diese kleine Unterschied macht das der M635 mehr ein Gran-Turismo als ein Sportwagen ist. Es halt das mitten zwischen E28 und E34 wobei der sitz Position im E24 M635CSI wie beim E34 spürbar niedriger ist als im E28. Der sitz Position im E28 ist ohnehin komisch. Mann sitzt fast senkrecht und schaut gegen ein Frontscheibe der auch fast eine senkrechte Winkel hat. Der M635CSI wirkt dadurch moderner.

Das ist nach meiner Einsicht auch der strake des E28. Man erwartet kein handliches Fahrzeug, aber es verfuhrt den Fahrer mit eine purer Fahrerlebnis und ist das Gegenteil. Nach meiner Einsicht ist es mehr Sportauto dann der E24 M635CSI oder sogar der E34 M5.

Ich hab den Fahrt im Kristof seinen E24 M635CSI sehr genossen. Ich hab es mich Uber bekannte Landstraßen gefahren um ein gutes Gefühl für das Fahrwerk zu bekommen en der ist gut. Kristof seinen Fahrwerk ist original, aber mit neue Stoßdämpfer. Das Auto ist frei von Vibrationen und Nebengeräusche was bemerkenswert ist für ein 27 Jahr altes Höchstleistung Coupé ohne B-Säule. Der Motor hangt gut am Gas, allerdings hab ich es nicht über 4000RPM gedreht weil der hc-Wert viel zu hoch ist und der 2,2% CO erst beim vollen Anschlag der einstellschraube erreicht wurde. Der LMM ist neu, genau wie die Injektoren und allen Sensoren. Weitere untersuch ist notwendig um diesen Fehler zu beheben.

Das Coupé lasst sich gut-und präzise in Kurven einlenken, allerdings beim kurven Ausgang ist es ein bisschen untersteuert. Mein E28 M5 lasst sich auf die gleiche stelle mit eine kürzere Radius fahren. Um das mit dem Großen Coupé zu erreichen muss aggressiver eingelenkt werden was mit einem Verlust an Moment um geht. Weil Radstand und Spurbreite identisch sind kann dies nur an das höhere Fahrzeug Gewicht des Coupé liegen.

Nach eine kurze Pause habe ich über ein normaler Landstraße zurück gefahren um ein Gefühl für der Motor und antrieb zu bekommen. Auch der führte über ein bekannte Landstraße mit dem ich mir gut auskenne. Auch hier bin ich nicht weit oberhalb 4000RPM gefahren, dies reichte durchaus für eine rasche Einhol-Manöver von ein Ford Focus. Dabei war auch Robert der mit seinem E34 M5 3.6er hinterher fuhr auch in der Lage um kurz bevor die Rechtskurve ein zu hohlen. Allerdings brauchte Robert ein erheblich höhere Motordrehzahl um dies zu erreichen. Die kurven in diese Straße sind mehr geeignet für das Coupé und darin wirkte es auch Präzise.

Was mich daneben bei meinem E28 M5 und auch bei Kristof seinen M635CSO auffalte war die Komplette Abwesenheit von Lenkrad spiel in der Mitte, etwas was viel jüngere E34 M5er nicht sagen können.

Insofern hat der Kurze ausfahrt in Kristof seinen Coupé mir viel Spaß gemacht. Ich versstehe jetzt besser die Unterschiede und Übereinstimmungen von beide M88/3-auto’s. Derjenige der beide besitzt soll ein glücklicher Mann/Frau sein.

I have been lurking after E39 530i Touring’s recently to replace our current daily (MB W203). In that process, I found a nice example (on paper) on mobile, but its location in the far east of Germany just a few kilometers shy from the border with Poland meant a nice continental trip had to be made to examine it.

considerations
Normally, I would avoid to use #231 for such demanding trips; I consider the E28S as a luxury that needs to be used appropriately. But due to the current high-pressure zone over the continent, the ambient temperatures hover around the 25°C mark with very low humidity; making ideal driving conditions for #231 to add up some miles on some unrestricted German autobahns.

route
The distance to Trebendorf according to the Michelin route-guide is little more than 660km, most of which on the highways, consecutively the A1 (A30), A2, A10, A13, A15. As I was early, there was hardly any traffic on the four lane A30 from the Dutch border towards Bad Oeynhausen. The following A2 towards Hannover and Potsdam has been extended fully into a six lane highway, the cruising speed ranged between 160km/h and 230km/h on the speedometer only reducing speed for slower traffic. Traffic would easily allow more, especially between Hannover and Magdeburg, but this would be contra-productive as more refueling-stops would be needed.

Engine
The engine runs smooth and is flexible; the rebuild engine pulls already pulls strong and linear from the low-range in the highest gear up until very high speeds. The engine doesn’t feel that fast, but that is misleading; I was repeatedly surprised after I looked at the speedometer. When accelerating from 100-120km/h (most of the time in fifth gear), the speedometer indicated more than 180km/h when I expected no more than 160km/h. Granted, 286hp was impressive twenty five years ago and now there are heaps of cars producing output in that range, but there will be very few that are capable of doing so in the same way. It delivers its power effortlessly and smoothly without hiding its racing origin.

For example, I was really impressed with the ease of maintain high speed on the highway between Bad Oeynhausen towards Stadthagen in Germany. As some of you may know, this section is located in a mid-sized mountain range (Porta Westfalica). The typical incline is between four and five percent. Combined with the road-layout, this is a serious challenge for any car and driver. From time to time, I had to reduce speed to about 120km/ for slower traffic. After the road cleared, the flexibility of the engine allowed me to quickly accelerate to my cruising speed of about 180km/h without even stressing the engine (no WOT usage). This is something that an E34 M5 simply is not capable of without selecting a lower (fourth) gear.

Results of throttle body synchronization
I just managed to complete the basic mechanical throttle body synchronization the day before. The first impressions in around town looked promising. Idle is smooth and stable and the transition from ‘no-load’ to ‘part-load’ is smooth and swift. The slight shock that could be felt prior to the engine management transiting from ‘load’ to ‘no-load’ when lifting throttle disappeared completely. With other words, a significant improvement compared to the previous attempt (July 2011).

During the throttle body synchronization, the Throttle Position Sensor’s WOT switch engaged about five degrees before reaching the maximum opening of the butterfly valves, allowing for some margin against operation at Wide Open Throttle (WOT). However, most of the acceleration was done with the throttle-pedal depressed at no more than 70%. On some occasions though engine was deliberately operated at WOT to test the transition from ‘part-load’ to ‘full load’, which also is fluent.

Since the synchronization of the three push-roads in ‘idle’ is done with 0,01mm accuracy, it is impossible to compensate for the tolerances in the butterfly system mechanically. That is only possible by synchronizing the intake-vacuum of the six intake ports, something that can now be scheduled.

Fuel consumption
Throughout the day, I had to refuel four times (!). Generally, I prefer to buy the highest octane rating as possible, but I had to settle for Total Excellium 98 on one occasion between Magdeburg and Potsdam. Although Total’s premium products octane rating meets the M88/3 requirements, I rate it as crap compared to for instance Shell’s V-Power Racing (100RON) or BP (Aral) Ultimate (102RON). Generally, I’d say that the higher the octane rating the better the M88/3 runs and reacts to throttle commands.

In average, #231 needed between 12-13ltrs/100km (21,8-23,6mpg), which IMHO is very acceptable on a high speed long distance continental trip like this.

Comfort
Better than expected; although the German autobahns generally are very good, some parts are in dire need of refurbishment and offer a bumpy ride; but the E28’s suspension copes with those very well. The combination of a stiff suspension and high profile tires provide for very good contact with the road and decent absorbance capabilities. As a result, the car doesn’t dribble on the older tarmac and therefore is easy to drive.

Also bear in mind that with exception of the ‘Porta Westfalica’ and the Braunschweig regions, the entire route was located on what is called the German lowlands, i.e. not that much height difference and long straight sections. Rather boring actually and certainly not challenging from a drivers point of view. Since the unification of Eastern and Western Germany, the entire A2 highway has been upgraded to six lanes according to modern standards. This was certainly not the case when I last drove to Berlin sixteen years ago when this highway was still a simple four lane highway according to the original pre-WWII design. As a result, it is easy to maintain very high speeds limited only by the cars capabilities.

Although the E28’s interior actually feels a little cramped inside, the seats are excellent. For example, my father underwent surgery about seven weeks ago and I gave him the choice; E28 M5 or his more spacious and more comfortable (A6) diesel workhorse? Granted, he needed a few more stops to walk a little bit, but he didn’t complain at all and actually enjoyed the drive.

Noise
The longer differential (3,73:1) lowers the engine speed when driving normal road speeds, and thus also reduces the sound. I have said before that the E28 M5 is one of the last cars which sound-track wasn’t tuned by acoustic engineers to achieve a certain brand-idenity spectrum. Therefore, it resembles a normal M30 in the low-to mid- range and is unrestricted in the mid to-high range. The E34 M5 is already a different animal; its soundtrack is more pronounced in the low range and is attenuated in the high-range. Both are very nice to listen too, even when they are too loud for the environment by today’s standards. But IMHO, the M88/3 and S38’s sound-spectrum are the ‘right sound’ and therefore very pleasant to listen to; unlike those modern four-pot engines with a forced induction, especially those irritating four-pot diesel engines from the VAG-group (sorry can’t help).

In fact, your M635CSI filters external sounds better from the interior then my E28 M5, but my Michelin Pilot Sport tires have remained silent throughout their lifetime that now is 9+ years and approximately 9k km, limiting road noise to the minimum allowing an unfiltered sound-track of the twenty-four singing valves in an engine which origins are in racing.

Steering
One would not expect from a recirculating ball steering to have some vagueness around the center-position forcing continuous steering corrections in the straight line; at least that is my experience with most E34’s. The E28 M5 shares the same recirculating ball steering box, but in the case of my car, there is no center vagueness. In fact, it is precise and tight in any angle, not least thanks to the new rubber and ball-joints in the front-suspension and steering.

Handling
The handling on the autobahn is just excellent. It’s more agile then an E34 M5, but the E28 M5 has a tendency to under-steer in fast autobahn-corners in situations where the E34 M5 remains neutral until reaching even much higher speeds. Nevertheless, a cruising speed of around 190km/h in the Porta-Westfalica hills is very respectable for a twenty-six year old car; this is a territory that the vast majority of modern cars cannot even dream about.

Suspension
The OE setup with Bilstein gas-filled dampers and stiff springs is brilliant. As I wrote before, the suspension is tout and firm and the high profile tires provide for excellent absorbing capabilities on rough roads. Some may not like the looks of them and fit larger rims and even wider (low profile) tires for that reason, but they also pass on more energy to the chassis. Not only does this result in a bumpy ride, but also weakens the E28/E24 chassis that in itself is not really rigid. A front strut-bar would certainly reduce that.

Long distance capabilities
The E28 M5 has much better long-distance capabilities then I previously thought. But it depends on the situation. Last year when driving to the southern Ardennes, I was much more tired after arriving in our hotel, but as you know, the poor roads in Wallonia are partially to blame.

Conclusion
This was the first cross-continental trip with #231 since the engine rebuild and she didn’t disappoint. In fact, I am very happy with her now I have had an opportunity to stretch her legs and get a good idea about her long-distance travelling capabilities. The recent throttle-body synchronization has been a success and thus an important milestone in the re-commissioning phase has been reached, allowing to proceed with the next step, adjusting the intake vacuum.

Although the basic throttle adjustment was carried out in July of this year, I was not really happy with the outcome. I had some issues with a rising engine idle-speed when the engine was in the warming-up phase, and also the transition from ‘part-load’ to ‘no’load’ was not really smooth. I suspected two causes; (1) a malfunctioning auxiliary air-slide and/or (2) one or more throttle bodies that are not correctly adjusted.

In the past, I always had good results with the simple adjustment method on various E34 M5’s; but that only works if the basics are correct. However, the current throttle bodies were bought new in 2005 and thus may not be aligned properly. In order to avoid adjusting for errors, I replaced the auxiliary air-slide some time ago (see an earlier post) and bought the full-measuring set with a dial-gauge and extensions. These are currently still available from BMW, albeit come at a hefty price tag.

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One of the main checks that often is overlooked is the axial play of the spindle shafts. This is required to compensate for thermal expansion.

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It goes beyond the purpose of this post to cover all the details, but the dial-gauge allows me to correctly measure the idle-setting of the butterfly valves, which I think is much more critical for the M88/3 then for the later S38 and S50 engines.

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The paper sheet method allows you to check the idle-setting, but only when the basic adjustment of the spindle-shafts are correct. When this is not the case, the results of the TB basic-sync will be poor. When this is the case, only a full-Monty of the synchronization procedure gives satisfying results.

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The dial-gauge also allows an exact synchronization between the operation of the spindles of the three throttle bodies.

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Please note that the mechanical TB-sync was carried out with the TPS removed; it can be left in place if the basic settings are OK, but the two Philips-head screws have to be slackened to prevent interference of the TPS with the adjustment of the idle-stops.

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Also important is the verification of the TPS contacts in the relevant states of operation; after re-checking all connections underneath the throttle bodies, electrically and mechanically, the intake plenum was reinstalled and the engine was started to adjust the engine idle-speed.

My first impressions are very good; the transition from ‘part-load’ to ‘no-load’ is smooth and without delay and throttle response has improved significantly. I also checked the exhaust emissions to verify the safe operating area. AFR is close to 13,7, which is a little richer than before, but that is OK.

Tomorrow, #231 will be used for a trip into the ‘Heimat’ which will rack up another 1500km to the odo. This allows me to test my work more thoroughly. If no more issues emerge, a major milestone of the engine-re-commissioning phase is completed.

With the recent valve-adjustment and this TB-sync the two conditions are met to carry out the adjustment of the intake vacuum. This will further improve the idle smoothness and pick-up.

Introduction:
Even though the vast majority of cars don’t use carburetors anymore, tools for synchronization are widely available as the vast majority of motorcycles still rely on (multiple) carburetors instead of sequential fuel injection. During the first M88-S38 conference of May 2011, we used a set of vacuum-meters for balancing the throttle bodies of the 1992 E34 M5 from member Robert Kiel. At that time #231 was not ready to do the same as the valve adjustment and basic (mechanical) throttle body synchronization were still due.

Reference measurement:
Member JeroenE21 was so kind to borrow me his set of vacuum-meters allowing me to synchronize the intake vacuum last Saturday. I started with a benchmark measurement to obtain the pressure values prior to their synchronization. This resulted in a variance of 22.2mbar and an average of 321.7mbar measured over all six tapping points. According to the six-sigma method, the throttle bodies are allowed to be within 310mbar to 333mbar for this measurement. This turned out to be the case, hence it is safe to assume that the actual throttle body synchronization is within production tolerances of the mechanical assembly.

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Preparations to synchronization
A requirement that is often overlooked is that there may be no vacuum-leaks as otherwise, you are looking at calibration for errors. With individual throttle bodies, this goes much further than just replacing some hoses. Especially the O-rings in the bypasses between the three throttle bodies is often overlooked. These can only be checked by removing and disassembly of the entire throttle bodies, something that should be scheduled once in every 10-15years as rubber parts age, even when not used.

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I removed the bypass adjustment screws for inspection and cleaning. As can be seen on the following picture, there are some deposits visible that has developed since 2005 when I installed the new throttle bodies on #231.

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Please note the condition of the O-rings. Although far from bad, these have dried up and will damage when the bypass-screws are adjusted. This can result in an erroneous air-leak around the bypasses. If these occur, you are looking at synchronizing away the error without being aware of its presence. Therefore, always replace the O-rings prior to turning the bypass-adjustment screws.

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I then carried out a second measurement with the bypass screws fully turned in. This resulted in a variance of just 20,1mbar and an average of 310,8mbar. Although this is slightly lower than the benchmark measurement, but as far as I am concerned still in compliance as the benchmark measurement was carried out with each bypass screw relaxed by one turn.

synchronization:
The actual synchronization was carried out with a set-point of 320mbar, which is the rounded down figure calculated from the average of the benchmark measurement. With just four meters available, cylinders #1 till #4 was alternated with #3 till #6 whilst iteratively adjusting the bypasses to a variance of 0mbar.

results:
I already wrote about my positive experiences during a recent cross-continental trip to Trebendorf and the impact of the basic throttle body synchronization. This was confirmed during a country-drive from my workshop to my home that was necessary to avoid last-weeks traffic-infarct in my town. This allowed me to exploit its midrange performance which impressed me a lot; accelerating in third gear from 50km/h till 140km/h is done effortlessly in a way that an E34 M5, even ‘three point eight’ liter models can only dream off.

This has improved even more after synchronization of the intake vacuum. After refueling with 52liters of Shell’s finest in Gronau, I exploited #231’s full-welly behavior on the A31 between Ochtrup and Schuttdorf. The transition between the three load-states (no-load, part-load and full-load) is even smoother then before with a clear improvement of midrange and a slight improvement in the full-throttle range.

Before placing the tamper-proof plugs on the bypass-screws, I verified last week’s measurements of the intake vacuum.

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Before commencing with the verification, the vacuum meters were calibrated against each other to obtain the correction values for each meter. This allows me to correct the readings in order to obtain a more accurate measurement before analyzing the results.

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After correcting for the meter-errors, the values of the intake vacuum were determined as follows:

TB #1 = 322mbar (+0,31% from average)
TB #2 = 319mbar (-0,62% from average)
TB #3 = 322mbar (+0,31% from average)
TB #4 = 319mbar (-0,62% from average)
TB #5 = 322mbar (+0,31% from average)
TB #6 = 322mbar (+0,31% from average)

The statistical variance is a mere 1,7mbar, which 14% from the benchmark measurement (11,7mbar). With other words an idle improvement of 86% is achieved. More equality is hard to achieve without using electronic measurement gear. Biketec has one in program, but it is questionable if the inter-channel accuracy is better than 1%.

The question arises how meticulously synchronized intake-vacuum will affect the mid-and full-range performance. Although the benchmark result was far from bad, a larger percentage of error means a much larger absolute difference between the throttle bodies when the engine speed rises. With other words, the better the synchronization at idle actually is, the better the inter-cylinder balance will be, improving the throttle response.

Next to #231, I also measured the intake vacuum of my other M5; an E34 M5 with the later S38B36 engine.

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The results are as follows (after correction). Please note that I did not replace any parts, nor did I make any adjustments to the throttle body setup.

TB #1 = 300mbar (-0,28% from average)
TB #2 = 305mbar (+1,39% from average)
TB #3 = 295mbar (-0,94% from average)
TB #4 = 300mbar (-0,28% from average)
TB #5 = 300mbar (-0,28% from average)
TB #6 = 305mbar (+1,39% from average)

Although the differences are relatively small, the variance is 10,1mbar, which is close to the benchmark measurement of #231. However, as my E34 M5 has never seen a full disassembly of the throttle bodies for inspection, crucial O-rings in the throttle body system may have deteriorated causing small erroneous air-leaks. Keep that in mind when synchronizing the intake-vacuum without adhering to the primary conditions (valve-clearances correct and no air-leaks).

However, if everything is correct, your rewards will be the placement of the tamper-proof plugs. Some may argue about the purpose of these, but they prevent messing around with the bypass screws by unauthorized persons. After all, I’d hate to lose the meticulously achieved settings that took many months to achieve when I have to bring her in for the annual (Dutch) MOT.

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With all six tamper-proof plugs in place, the throttle body synchronization is now formally completed, marking another milestone of the running-in scheme.

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Vor kurzen habe ich neue OEM Bilsteins fur die vorderachse gekauft. Ich hatte dies letzte Jahr bei der uberhohlung der VA tun sollen, allerdings waren due alten damals noch i.o

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Ein paar bilder von ein Treffen in den Belgische Ardennen in September 2010.

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