Bericht: Motoruberhohlung E28S M5

At 2113km, I drained the mineral oil and replaced it with Castrol TWS 10W60. Although I have applied the Castrol TWS 10W60 and its predecessor, the RS 10W60 for my E34 M5 for almost ten years; I considered the use of TWS for the M88/3. But in the end I could not find a suitable replacement with a lower viscosity so why change?

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I have been told that many Dutch dealers terminated or did not extend the exclusivity contract with Castrol for some reason and may discontinue stocking Castrol products in the future. My dealer still stocks TWS so a healthy supply is guaranteed for the time being. After the oil-exchange, I drove about ten kilometers to pump around the oil and clear the ramp to make room for the E32 that is being prepared for late summer and autumn use.

A few days later, I started the #231 for the second time after which I heard a ticking sound coming from the cylinder head. It lasted for about one minute after which it disappeared. One normally would associate the sound with contaminated hydraulic valve-buckets, but since the M88/3 only has mechanical buckets, the cause of the sound must be related to a recent change. I consulted member BillieS38 who came up with a plausible theory that is hard to ignore.

During the oil-change, Castrol TWS that was poured into the engine has a much higher film-strength then the drained mineral running in oil from Eurol. However, remnants of the mineral oil that cannot be drained are mixed with the synthetic oil. This leads to a non-homogenous oil film between some components. The result is an adhesive force that is related to the difference of the film-strength of the two oils. After some time, the existing oil film is pushed away by the new oil after which adhesive force is negligible.

There are two locations were this is a concern. (1) The oil film between the valve-shim and the valve-bucket and; (2) the oil film between the valve bucket and the camshaft housing. Since the valve bucket and the valve-shim in the bucket can move freely within the valve clearance, the resulting force can cause the bucket and or the shim to move upwards against the cam lobe before the valve is being opened again. I realize that this theory will be difficult to prove, so I will look for industry experts to ask for their opinion.

During the third attempt two days later, this problem didn’t appear and #231 was idling smoothly directly from the start. I then added 158km to test the engine thoroughly. I have a nice route for this purposes that includes a part of the Oberhausen straight (A31) in Germany. This loop can be done in just one hour, but I extended the loop with a small detour over the B213 between Lingen and Nordhorn so it was about one-and a halve hour. Since I follow a strict protocol before lifting the full throttle constraints, I only applied part load up until 5000RPM, which equates to about 210km/h.

The E28 is a joy to drive. The suspension is tight and responsive and #231 feels very stable at speed. With its lower weight, it is more agile then my E34 M5, but the latter has a more neutral handling that makes it easier to drive. This is not so much a concern on long distance autobahn trips, but I suspect that it will be difficult to keep track with a well-driven E34S M5 on twisty roads.

With 2319km driven, I am closing in on completing the third phase. I checked the valve clearances last week and compared them with the results taken at 1514km. They have reached stability within 0,02mm, which is excellent.

The fuel consumption over the last 650km has been calculated at 15,6 liters for every 100km. This is a bit more then my E34 M5, but that car runs in closed loop with a lambda-probe.

I checked the new and old 91C switches by partially emerging them in boiling water and both tripped within two seconds. The 99C switches cannot be checked by this method as their trip-temp is too close to the boiling temp of water. But given the test-results of the 91C switches, I don't doubt them anymore.

With other words, it appears that my radiator isn't 100% anymore and a new one is needed.

Edit: A new radiator is 315 Euro ex VAT and stocked at the factory in Munich. It takes a week to deliver.

The new radiator arrived just in time for the sharknose meeting that I will attend tomorrow. Before I installed the new radiator, I compared it with the old one. Please check the following pictures.

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[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img670.jpg]

Clearly visible is the difference in distance between two adjacent water galleries. With other words, the new radiator has more water galleries (45 versus 30) and thus has fifty percent more capacity then the old radiator. This explains the raised coolant temperature at high ambient temperatures.

I suspect that the radiator needed replacement in the past and that some mechanic actually ordered the radiator for a garden variety M30 version for some reason. Since I already drained the coolant system in the previous week, I only had to replace the radiator and reconnect the hoses.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img672.jpg]

Next to the radiator, the thermostatic switches were replaced as well. The rest of the work was straight forward.#231 is now ready to attend the sharknose meeting in Wezepe (Holland) tomorrow.

With the recent trip to the Ardennes, 1296km were added to the rebuild engine of #231. All regular checks like oil and coolant and valve-clearances indicated that the engine is functioning to my expectations, but final proof can only be given with a compression test so I made an appointment with engine rebuilder “Twentse Motoren Revisie” in Almelo for Friday morning the first of October.

Since for a compression test, the spark plugs need to be removed as well, also the spark plug image could be checked to verify that the enrichment of the A/F mixture in May of this year at 1514km, did increase the margin against a lean running engine condition under high load conditions (see a previous contribution in this thread).

Upon arrival at TMR’s workshop, we allowed the engine to cool down before performing the actual test. Unfortunately they don’t have a fully calibrated compression tester, so the measurement results may not be seen as absolute values.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img682.jpg]

The test was carried out in accordance with the procedure that can be found in the M88/3 engine description. This document can be found on the World Wide Web with some searching.

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I actually carried out the test myself with the shop owner witnessing the test. This was important for me as when something was wrong (which I did not expect) he was present to see that first hand. In that respect, the lack of a traceable calibration of the equipment that was used is not relevant. The rejection criterion are:

1: The variance between the individual cylinders compression is such that individual cylinders achieve lower-and higher pressures then the criteria (10-12bar)

2: A compression significantly lower or higher then the criteria. With a 1,5bar accuracy margin (±5% of full scale assumed), this would be anything more then 13,5bar or less then 8,5bar. If this would be the case, a second test is required with other test-equipment to determine the accuracy. This would also be the case for any result between 8,5bar and 10bar.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img683.jpg]

The actual results were recorded after two measurements to verify their reproducibility with the same test equipment.

Cylinder #1: 12,0bar
Cylinder #2: 12,2bar
Cylinder #3: 12,5bar
Cylinder #4: 12,5bar
Cylinder #5: 12,8bar
Cylinder #6: 12,5bar

Although the difference between the results appear to be large, they only differ between –4% to +2,4% from their median. This is not bad for a test that is just indicative. Since all the results are on the high side, but still within the assumed accuracy of the test equipment by quite some margin, the results can be used to determine the health of the rebuild engine after 3862km.

Based on the results and their analysis, there is no reason to assume that the engine shows a hidden defect that may be the cause of a material defect or human error during its assembly.

During the first spark plug image check, the conclusion was drawn that cylinders #2 and #5 were running a tad to lean, hence why the AFR was lowered from 14,7 (AFRstoich) to 14,0. With this setup, 2348km were added and the spark plug image rechecked.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img684.jpg]

The spark plugs are placed in sequence, cylinder #1 left and cylinder #6 to the right. The picture clearly shows that all spark plugs have an identical image. An idle that is a tad too rich, but with all six insulators showing a nice brown tint, the combustion is not far from the optimum under load. It could be a tad richer if high engine stress is required (e.g Nordschleife and Alps usage at a large WOT percentage), but given the expected use of #231, there is no reason to readjust.

Also visible is the complete lack of oil fouling. This confirms the outcome of the regular oil-dip stick inspections that indicate that the oil consumption of #231 is negligible.

With these two tests, it is possible to make a preliminary conclusion that the engine is functioning correctly and is in perfect health. The following steps will be adjusting the valves followed by a throttle body synchronization and an under pressure synchronization before the WOT restrictions can be lifted. The specifications shall be confirmed on a dyno-jet.

To be continued!

Sometime ago, I replaced the radiator with a new part. However, just prior to its installation, I discovered a small white stripe just above the connection for the lower thermostatic switch.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img680.jpg]

However, the part was new and the stripe didn’t extend to the threaded-insert of the thermostatic switch. As the part was new, I gave it the benefit of the doubt but documented the artifact just in case and decided to monitor the stripe at every trip.

Although the radiator performed excellent, one of the inspections on the return from my trip to the Ardennes revealed that this stripe had developed into a small crack when the system was fully pressurized. On light to medium-load trips, one can adapt driving style, but for high load trips such as the Alps, this won’t hold.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img685.jpg]

I contacted the supplier (main BMW dealer) and they decided to put a warranty claim. Within a day, I got the confirmation that they got the clearance from the warranty claims department to replace the radiator with a new part.

I picked it up this morning and replaced the old radiator in a spare hour this afternoon.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img686.jpg]

I still have to recheck its installation and tighten the bolts, clamps and switches to spec. I need another spare hour for that; maybe this weekend.

On the first full weekend of November, another 570km were added to #231 for a meeting with fellow board members with E39 and E34 M5’s, the most of who also participated in the international M5 meeting of May 2010 on the Nurburgring in Germany.

The reason why E39 and E34 M5 owners in North Western Europe are combining their meetings more often is caused by a shared enthusiasm of BMW’s finest products whilst sharing the same ideas about driving fun.

The reason that I didn’t mention the E28 M5 is the fact that it is very rare due to its historical value and as such is regarded as ‘classic car’. This is not the case for the later versions that may be classified as a ‘youngtimer’ (E34 M5) and ‘newtimer’ (E39 M5). In that respect, the E34 and E39 owners share more then they differ. As I also own (an E34 M5, I am consistently balancing between both worlds, hence why I also attend events that are not primarily aimed at the sharknose era of BMW (Paul Bracq).

The idea behind the November 2007 meeting was rather simple. A simple get together to close the 2010 season and to strengthen the network. The location was set to be the ‘Moeder de Gans’ restaurant in Teuven (Belgium), in the close vicinity of Maastricht and Aachen (Germany). This is a popular establishment and as such, requires advance booking. Members ‘Tiauguinho’ and ‘Martijn M5T’ planned and organized this meeting. More information and pictures can be found here.

Since this meeting was so late in the season, I doubted about using #231, but the weather forecast was just good enough (depressions moving to the south with clearing weather in the north) to use her for this meet. Although I could have driven over Germany, the shortest route would be roughly 310km before reaching the south of Limburg. This is 60km more then the shortest route over Arnhem (A50) and Venlo (A73). This is too much to benefit from the speed-unrestricted A31 between Ochtrup and Bottrop.

The journey towards Teuven didn’t go entirely uneventful as shortly after entering highway A1, some sort of Seat appeared in my rearview mirror; normally no big deal, but as I was driving 30km/h over the limit and was passing slower traffic, I didn’t feel the need to let him pass. This annoyed him and he flashed his lights; this triggered the devil inside me so I decided to play the game. At some point shortly before Deventer, there was a gap of a few hundred meters that I could have used. I consistently delayed my move to the right for a second; since the Seat driver was very inpatient, he moved to the right in a futile attempt to pass on the right. By doing so, he entered my carefully planned trap.

To avoid stressing the engine, I already had shifted back from fifth to forth gear shortly before that. I waited for his nose to come in front of #231’s nose and floored it. The rear-of #231 went down, its Michelin Pilot Sports seeking and finding grip and the fresh M88/3 created an exhaust-tone that must have been rather intimidating. Needless to say that the Seat didn’t have any chance and #231 created a healthy gap in seconds. He tried again one more time, but then gave up. Needless to say that he was not amused.

We arrived in Teuven at around 0.45PM and most of the crowd had already arrived. Apart from the seven E39 M5’s, there were two E34 M5’s (one 1995 touring and one very late 3.6 limousine from 1992), one E28 M5 (mine), one Alpina B8 4.6 touring (from member ‘chrislux’), one E24 M635CSI from member ‘Frits’ and last but not least member ‘Kleintje’ with his daily E23 732i.

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We all know that BMW Classic is perfectly able to get all M5 generations, but what are the chances that you see three M5 generations in the wild in a single moment. This is a very rare occasion indeed.

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After finishing lunch and the usual petrol talk, we left restaurant ‘Moeder the Gans’ in a large convoy for a small drive through the countryside in Belgium and the Netherlands.

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The organizers of the driving tour took the lead and maintained a healthy pace that allowed the large group to stay in one convoy. Granted, at some points, the group got separated, but it was never difficult to keep track with the front group. During the drive, we stopped for a few times to take pictures and talk about the cars.

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We closed the meeting with a hot cup of chocolade in the Vijlenerbos. Since there was no place for such a large group inside the establishment, we had to resort to the terrace outside forcing us to endure the chilly conditions after sundown.

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During the various petrol talks, the drivers of the E39’s admitted that they had floored it on some occasions. Some of them redlined it into the rev limiter that could be heard from time to time. From a pure performance perspective they are impossible to beat. I didn’t pursue that for my E28 M5, nor did Robert pursue that for his E34 M5 as well. We had to endure the pain of maintaining these classic M5’s more then once whereas many of the E39 M5 drivers are in a different phase of their lives and most likely didn’t have to experience the hardship of owning these cars (yet). However, we all shared the essence of owning one of these cars, driving throughout the splendor of a lovely countryside and sharing experiences.

One thing is for certain; despite the differences between the first three M5 generations, they share more then we might think. By maintaining these contacts and sharing our experiences we not only can enjoy ownership of these cars, but also motivate and help each other with the upkeep of these cars.

The drivetrain of #231 performed flawlessly and with a modest 11ltr/100km, the fuel consumption was rather pleasant as well. At the end of the day, the trip-meter indicated 4562km since the rebuild. With other words, I am close on finishing 438km before completing the running-in phase. With winter approaching soon, it is time for #231's winter-sleep during which she will be prepared for the 2011 season.

ABS issue

Already in 2007, I observed the failure of the ABS system at speeds above 220km/h during road trips through Germany. Then still on a German temporary registration (5-days KKE), there was no need to comply with any vehicle inspection such as MOT, APK or TuV.

When I decided to register #231 on a Dutch registration I had to resolve the Dutch APK relevant issues for which we performed a pre-registration check up in the winter of 2008. During those inspections, I discovered that the impulse sending wheels of the rear-wheel drive flanges were corroded as can be seen on the following picture.

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This explains for the ABS failure at very high road speeds. However, for obtaining a Dutch registration in May 2008, this was a non-issue, as the RDW institute would not test the car under such extreme conditions. Since #231’s ABS system was fully functional within the legal speed limits in the Netherlands with a margin of 100km/h, this wasn’t a critical issue hence why I placed this issue on the back-log and planned to solve it in the winter of 2009/2010.

Then in June 2008, the engine failure came in between. With the following engine rebuild between March and September 2009, addressing the ABS issue was not important at all and remained low on the priorities list. Granted, I could have combined this the installation of the rebuild engine, but decided against that to obtain focus to the main objectives for that time.

With the running-in phase almost completed, solving the ABS issue is placed higher on the priorities list, especially since the speed at which the ABS warning light illuminates has lowered to about 190km/h on the speedo-meter. This reduces the margin to less then 70km/h from the legal limit. Although this still is more then enough to have my drivers license being put through the ‘shredder’, but with the expected decay, it can become a relevant issue sooner or later and I’d rather resolve it in my own time and not with a fixed time-table to meet the criteria for obtaining the next road-worthy certificate.

I have just received the parts quotation from my dealer and although the drive flanges are just Euro 42,87 each, their status is backorder from factory. With other words, delivery time cannot be confirmed at the moment.

Appearance of the differential

Another issue that bugged me for a long time is the corroded diff-housing that deteriorates the otherwise very clean bottom of #231. Just like the ABS issue, this issue was placed on hold following the earlier mentioned engine failure.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20101117/img003.JPG]

Since the drive-shafts need to be removed for resolving the ABS issue, this is a good opportunity to improve the differential at the same time, therefore I plan to remove it as well according to the following scheme.

1: Remove drive shafts, inspect them and replace the boots of the universal joints if necessary.
2: Replace drive flanges and solve the ABS issue
3: Remove differential from car
3: Disassembly of the LSD, but leave the pignon-shaft in place because of the required pre-tension
4: Remove the rust and clean the housing.
5: Paint the housing with black POR15
6: Reassemble the differential, use new parts where necessary.

Front shimmy

I already have ordered two new lower control arms for the front suspension to solve the shimmy that I have experienced during recent road-trips. I have decided against after market such as Meyle HD or Lemforder for two reasons.

1: Orginality
2: I am not convinced on Meyle HD on my fathers A6 quattro were I preferred these over OEM. The ride still is a bit deteriorated by mild vibrations, even when new OEM shock absorbers with all the associated parts were installed soon after to eliminate other sources.

Front wheel arch liners

Following the experiences of member BMWWGN’s experiences with his recently acquired South African E28 M5, I decided to check the cover liners of the front wheel arches as well. This resulted in the decision to replace them on #231 as well, including the rubber seals. Fortunately, #231 doesn’t suffer from corrosion in the enclosed area behind these liners so there is no need to do some bodywork there.

All the required parts have been ordered; some of them already have arrived. The ABS flanges require the most time as they have been confirmed for Wk06/2011.

I will update this thread from time to time and report the progress.

I picked up the largest part of the required parts for the overhaul of the differential this afternoon. After disassembly, cleaning and finishing the cast iron differential housing, the differential will be reassembled with new seals.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img696.jpg]

Although the output shafts of the E28 and E34 are very robust, the rubber boots will perish sooner or later exposing the expensive constant velocity joints to the hostile environment of the outside world we live in. After twenty-five years, it is wise to replace the boots and give the constant velocity joints a proper clean and a fresh supply of grease. BMW offers a complete revision set including the required grease and hylomar adhesive. The set costs 42,75 Euro ex VAT per piece; four are needed for both outputs shafts. Rest assured that a new output shaft is much more expensive then that.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img697.jpg]

BMW also listed a sealing set for the differential, but my parts catalogue indicated that only the single parts could be ordered. The following picture shows the seal and the circular clip for the output shaft.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img698.jpg]

I plan the tackle this job between Christmas and Boxing Day as I need to finish the E32 first that returned from a week stay at the body shop to repair the sill damage that I discovered some time ago. The rust is the result of poor craftsmanship during a previous repair before we even bought the car (1998.

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After I removed the filling that at some spots was over 5mm thick, the true extent of the damage appeared.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img701.jpg]

Repairing such damage goes beyond my capabilities so I outsourced the work to the bodyshop of my brother in law. The final result looks very nice; bear in mind that the sills are covered by plastic liners; oops these need replacement as well, which is $$$ for seven series parts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img702.jpg]

Last week, I have finished the E32 by installing the new ill-covers, after which the lift was free for the E28. The E32 has some issues left, but none that can be solved off the ramp. As the snow that has fallen last month, hasn’t melted due to the low ambient temperatures, there is a nice layer of ice in front of my workshop, due to which it was quite a hassle to get the E28 on the lift. When driving on the lift with the front wheels, the rear wheels were still outside and spinned on the centimeter thick layer of ice during which the car’s rear jumped sideways. Eventually, I took a rolling start to get some momentum and that did the trick.

I started with removing both driveshaft’s These will be overhauled with new boots and a new filling of grease for the coupling joints.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img705.jpg]

With both driveshaft’s out of the way, I was able to remove the final drive. This is rather easy, but the four 19mm bolts with which the final drive is bolted on the rear sub-frame were tight and I needed a breaker bar to loosen them. Eventually, the bugger came loose, but with a heavy cast iron house, lowering the damn thing didn’t came without protest from my back.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img703.jpg]

The plan is to get it back in a visual excellent condition to match the rest of the drivetrains excellent visual condition. The bearings themselves don’t need replacement, so I will just remove the rust and treat it with POR15 before reassembly with new seals.

With the differential out of the way, I have a better position to inspect the cars underside. There is only some surface rust on the sub-frame that will be removed and treated with POR15. There is no need to replace the sub-frame’s bushings; these were all replaced just 7000km ago by a main dealer and are all in excellent condition.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img704.jpg]

To diagnose the front wheel shimmy, I have removed the front wheels so I can remove the strut assembly. The plan is to replace the lower control and thrust arms and have the struts themselves sandblasted and powder coated. This also allows me to replace the protective covers of the shock-cylinder and inspect the strut mounts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img706.jpg]

Yesterday evening, I removed the right-front strut assembly. Although this is relatively straightforward, bear in mind that unbolting the various nuts and bolts require a significant amount of force and thus your cars should be safely positioned on a ramp. Never, ever try to do this from underneath a car.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img707.jpg]

I have yet to disassemble the strut-assembly for which I need spring-compressors. Again, never ever remove the top not holding the upper strut-mount without these. This will cause serious injuries due to the energy stored in the compressed spring.

A first analysis revealed a significant amount of play in the rotational part, both in axial and longitudinal directions. This could be the cause of the shimmy under braking, but for a comparison, I have to remove the left-strut assembly first. Anyhow, these parts will be replaced, together with all the associated parts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img708.jpg]

Unbolting the ball-joint nuts from the strut-base is rather straight forwards, but even with a ball-joint depressor, I wasn’t able to remove them. Therefore, I will remove the entire base-plate with the thrust arms and lower control arms as well and move them to the bench were it is safer to apply a lot more force.

My first thoughts is that the ball joints have lost their stiffness significantly, but for a comparison with the new part, I have to wait until I have removed the old part.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img709.jpg]

Apart from some surface corrosion, the strut towers are in fine condition. They will be cleaned and treated with Caprotec RX5 before installing the reassembled struts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img710.jpg]

After having driven roughly 4800km, I drove #231 on the ramp and removed the engine’s under-tray to inspect the drivetrain from below. Apart from a small drip of oil underneath the A/C connection-pipe to the A/C compressor, the engine is dry. This oil-drip is unrelated to the engine though as the entire engine including the chain-tensioner is dry.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img711.jpg]

This also applies to the gearbox; with no dirt or smear on the gearbox mounts and its subframe, it is safe to conclude that the propeller-shaft seal and gear-lever seal are dry. Both have been replaced in the spring of 2008, just a few months prior to the engine failure.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img712.jpg]

As I like to keep #231 in this condition, I will continue to avoid using her in poor weather conditions (rain) and decommission her during the winter-period in order to preserve her for fun-drives. I am thinking about travelling to the Mille Miglia in May 2011 for which I have to sort #231’s front suspension issues first.

Last week, I have removed the left strut, and both strut-base plates with attached control arms. The removal of the strut itself only requires half an hour. Disconnect the ABS sensors, guide their wiring through the inner fender, unbolt the brake caliper from the strut and remove the brake-hose from the strut as well. Then loosen the three 17mm bolts with which the strut is connected to the base plate and loosen the three 13mm nuts that hold the upper strut-mount to the strut-tower.

One word of warning though; unbolting the three 17mm bolts requires a significant amount of force. Make sure that your car is safely jacked up with the appropriate means. I cannot emphasize this hard enough as no car is worth risking your life for.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img713.jpg]

To remove both thrust arms, I removed the front stabilizer bar and one strengthening bar. This is required to gain access to the 22mm bolt and nut with which the thrust arm is bolted to the front beams.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img714.jpg]

On the right side, I also needed to remove a heat-shield, this is rather straight forward and therefore, I didn’t make a picture.

I already had bought the lower control arms as a possible suspect of the shimmy, but decided against ordering the thrust arms as I wanted to analyze the individual parts first. As can be seen on the following picture, the left thrust arm is made in 1989, and thus most likely installed in the same or following year. Clearly visible are the cracks in the rubber vulcanization of the bushing.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img715.jpg]

The right thrust arm is of a more recent date (see following picture), but without any OE or manufacturers markings visible, I can only conclude that this is an after-market part of unknown origin. As a corrective measure, I will replace both thrust arms and bushings with new OE parts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img717.jpg]

The next step is the disassembly of the struts, To remove the springs, a special tool is required to secure the springs when the strut mount is removed. Without this tool, the compressed spring will release its energy to the strut mount launching it into the air with a force that is enough to cause serious injuries.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img718.jpg]

Ideally, the three compressors are placed at an angle of 120 degrees from each other, allowing for an evenly compression of the spring. The spring can be compressed by turning the screws with a wrench or ratchet until the spring is compressed enough to loosen the top nut with which the upper strut mount is bolted to the shock absorber. The following picture shows the deteriorated seal of the strut-mounts bearing exposing its ball-bearings.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img720.jpg]

As both spring mounts show a similar sort of damage and have ~1mm of radial play and some axial play, it is safe to conclude that this is the main cause of the shimmy. Both parts will be replaced with factory OE parts. Another discovery was the missing lower-spring pad on the left strut indicating a poor quality repair in the past. The following picture shows the lower spring pad of the right front strut still on the spring.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img722.jpg]

With both springs removed from the strut, I have access to the nut that secures the shock-absorber in the spring.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img723.jpg]

My first impression is that both shock absorbers are in fine condition. They have a similar resistance to the new shocks that I installed in my E34S M5 a few years ago. But a final analysis can only be made after I have removed the inserts., something that is scheduled for next week.

This evening, I spend an hour in removing the shock absorber inserts from both struts to answer the questions that I asked in my reply to Davidoli. The removal of both collar nuts was rather straightforward and I was helped by their excellent condition with only a slight corrosion on the upper thread. A few whacks with the hammer and screw driver was enough to release them after which I could manually turn them out of the strut.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img724.jpg]

I was stunned by the depth of the color of the inserts; I know that Bilstein paints its products yellow, but a 25 year old product with over 150k km of usage could not look cannot look that good.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img728.jpg]

The markings on both struts indicate that the inserts were manufactured by Bilstein as OE-parts for BMW. A cross reference search of this part number in the parts catalogue didn’t reveal anything; however that doesn’t really surprise me as I bought #231 in 2001 and my latest parts database is many years younger (2008). I don’t think that all supersession of the parts is listed. With other words, I cannot determine the application for the shock inserts at the moment. Maybe with the older parts catalogue of which I still have a copy.
The currently listed part for the ECE and SA E28 M5 is exactly the same with exception of the last three numbers; the parts catalogue indicate 016 rather than 017.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img727.jpg]

I couldn’t find date codes either so I cannot determine their age, but given their condition, I doubt that these have much mileage on them. The only other markings that I have found are shown on the following picture. I think this is a track/trace code from manufacturer Bilstein.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img726.jpg]

Given their visual condition and the sealing between the cylinder and shaft, I think that these inserts will live another ten years with my usage and if I can confirm this part number to be correct for the DC91 model variant, I will reuse them.

The following picture shows the hub that contains the bearing of the left strut. The allen-bolt that secures the brake disk to the hub went off rather easy.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img729.jpg]

That did not apply for the right brake disk. Its allen bolt is so tight that I could not remove it with the right tools. I need a grip-nut to loosen it. That is something for next week.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img730.jpg]

I picked up another stash of parts today; all for the front suspension including strut mounts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img731.jpg]

I decided against using OE thrust arms as the installed bushing is identical to the 520. Instead, I followed Stevie’s advice and ordered the Meyle HD replacements. These exceed OEM specifications and will not only last longer, but in theory also improve the steering-feel by tightening the play in the suspension.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img733.jpg]

I checked the mounting holes of the new top-mounts for axial and radial play and found that none was present. This conforms that the old top-mounts have lived their lives. At around 46 Euro/each, these may be considered a bargain compared to those of its successor that retail for more than 100 Euro/each.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img736.jpg]

As I was sick last week, I didn’t do much work on #231 other then about half an hour for the disassembly of the final drive on last Thursday evening . I removed the output flanges and the alloy back-cover. I drained the oil in a bucket whilst doing so.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img734.jpg]

The LSD itself is huge and made from a high grade steel; it is designed to take a beating without wearing down.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img735.jpg]

Although difficult to see on the preceding picture (#1), the LSD-drive sprocket shows a healthy running pattern with a correct play between the pinion-and LSD sprockets (see following chart for reference).

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img737.jpg]

This means that no adjustments are necessary and that the slight whining noise is caused by the output bearings. I will ask for quotes for their replacement. Before removing the LSD, bearing-caps need to be removed. I didn’t have the time for that.

Note #1: The camera I use for these pictures is a seven year old Sony DSC-F717. Although this still is a fine camera with much better optics then the bulk of today's point-shoot cameras, its optical and digital abilities is not sufficient to capture all the fine details compared to modern (DSLR) camera technology.

Due to other commitments, I didn’t spend much time on the E28S in the past few weeks until yesterday. I did find the time for a few days of skiing with five of my brother in laws though. The weather in Austria was excellent with clear blue skies and visibility of more then 100km as can be seen on the following picture. The following picture shows the Dachstein massive in the background; that with a few meters shy of 3000mtr, this group hosts the most eastern located glacier in the Alps.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img740.jpg]

Yesterday, I started removing the paint from both struts. Originally, I wanted to sandblast and powder coat them; but that forced me to remove the bearings, something that would make them unusable. As I hate to waste perfect functioning bearings for just a preferred method, I decided for another solution; the good old trusted RX5 rust primer coat and black body paint from Innotec, a professional product that cannot be bought in the regular stores.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img742.jpg]

Removing and sanding each strut requires about 60-70minutes with machine tools. As I use RX5 rust converter, I do not care about the residual corrosion as long as it is solid.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img741.jpg]

Caprotec RX5 is not only a rust converter but also a primer coat; it just requires 24hrs of curing after which the final coat of paint can be applied. RX5 is a very low viscosity helping it to reach narrow cavities as well.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img743.jpg]

After the required curing time, I applied the first layer of black coating. As mentioned, I used a product from Innotec as it is highly resistant to the hardship of outdoor use.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img744.jpg]

I applied just two thin layers of coat in order to keep the thermal resistance between shock absorber and ambient as low as possible. I will allow another 24hrs for curing before deciding weather or not a third layer is required.

I also removed both bearing houses of the LSD. These need to be driven out from the cast-iron final drive enclosure. The following picture clearly shows the spacer ring. When replacing these, one has to order a complete set of varying thickness as this parameter alone determines the clearance of the LSD its needle bearings.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img745.jpg]

The removed bearing houses directly after their separation from the final-drive enclosure. Note that the oil-retaining seals are still installed.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img748.jpg]

With both needle bearing-houses removed, the heavy LSD can be taken out as well. Clearly visible are its needle bearings. Directly after its removal, I packed the LSD in a plastic bag and sealed it to prevent contamination.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img746.jpg]

The hypoid pinion wheel; The exact position of this part is the reference of the final drive; therefore, when there is no need to replace the bearing, leave it as is. Reinstalling this part requires special expensive tooling and is a specialist job. When the clearance isn’t tight, you’ll risk a noisy final drive.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img747.jpg]

Now, I can prepare the enclosure from sanding to remove the existing rust. I have yet to decide about the finish of the cast-iron enclosure. I want a durable finish; POR15 can be applied, but also adds a thick layer, increasing the thermal resistance to the ambient. Some research is required in this field.

After a few days, the’ innotec’ paint has cured into a nice black finish that has a very high resistance to scratching and protrusion.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img749.jpg]

Normally, the struts need to be filled with oil before inserting the shock-inserts; however, the outlined section in BMW’s repair instructions clearly prohibit this for gas-filled shock absorbers such as the Bilstein’s as used on the E28 M5.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img750.jpg]

With other words; simply dry-insert the yellow Bilstein’s.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img751.jpg]

As can be seen on the following picture, the seal of the old threaded ring is completely worn, hence the 25 Euro per threaded ring is worth the effort.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img752.jpg]

Compared to the threaded ring for the (Sachs) shock absorber as used on the E34 M54, the Bilstein threaded ring is hideously expensive. However, the Bilstein threaded ring contains a seal providing for a double protection for the shock absorber’s internal parts. The specified fastening torque is 130Nm to fully secure the position of the insert in the strut.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img753.jpg]

The new strut-mounts and spring plates with the associated spacer rings and protective covers.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img755.jpg]

The springs for the E28S M5 are stiff and cannot e compressed without using spring compressors.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img754.jpg]

Whilst turning-in the M14-nut to secure the top-mount to the piston of the shock-absorber, the new protective boot around the piston was twisted. I’ll correct that once the struts are refitted to #231 in a later stage and I can tighten it to the specified 80Nm.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img756.jpg]

One strut done; one to go!

I assembled the right strut earlier today. Its assembly went uneventful so no specifics here. For more details, please see the earlier report from 12 February 2011.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img757.jpg]

The removal of the control arms wasn’t that easy. We recently replaced the left-front control arm of my W203 and that one snapped off quite easily with the with tie-rod lever still attached to the strut. No such luck with #231 though, so I removed the tie-rod levers with the control arms attached some time ago. But now the ball joints wouldn’t move, not even when properly fixed on a bench. Sometimes they need a whack from a claw-hammer, but to not avail. Eventually, we resorted to using a 20ton hydraulic press, which worked. One by one, the arms gave up. For the other side, we didn’t even try using less forceful methods and directly went for the power tool.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img758.jpg]

Unlike the ball-joint of the left-front thrust arm of my W203 two months ago, #231’s ball-joints didn’t have any play. This concurs with the handling of #231 that apart from hard braking from above 80-90km/h was little to complain about.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img759.jpg]

The tie-rod levers will be cleaned, sanded, coated with RX5 and finished with black paint from ‘Innotec’ before reassembly.

Although the ball-joints of the thrust arms have no play and no significant crack in the bushings could be detected, I decided to replace the four thrust arms as well. This raises the question: “to be or not to be original”. Member Stevie highly recommended the Meyle HD thrust arms based on his own experiences with a vast variety cars. His reasoning for the E28 M5 to use the Meyle HD arms as well was that the OE-arms for the E28S M5 is the same part as for the E28 520i. Given the fact that the suspension of an E28S M5 is much more stressed then the garden variety of its E28 sisters, his rationale makes sense.

On the other hand; there is member ‘Trompert’ on the Dutch E34 forum with an E34 525i (M50) who uses his car for roughly 40k km per year and maintains a detailed weblog with his experiences. He also tried the Meyle HD arms, but wasn’t pleased with them as they failed after having covered 45k km. Another member reported a similar result (40km with a 520i (M50).

Then, there is member ‘Robert Kiel’, whose GD55450 I know well. He had all the arms replaced with OE parts by an official dealer in 2007, but they failed after less than two years. He had them replaced with Meyle HD parts by an well-known BMW specialist in the North off Holland and didn’t report problems ever since. However, he didn’t add 40k km with them.

So what caused the discrepancies in the experiences with the Meyle HD arms ? To understand that, one has to consider the type of use of the cars and the source of where the parts have been obtained. Member ‘Trompert’ uses his E34 as a daily driver and frequently makes long distance trips into Eastern Europe. Member Stevie also makes many long distance trips, but also uses the cars on the track. The distinct difference may be explained by (1) the quality of the roads and (2) the hardship of usage. The dynamic stresses at an E34S will be much higher than with its E34 siblings, but only when appropriate usage. Another difference is that most E34 M5’s are being kept as enthusiast cars by now and see selective usage. Generally, poor quality roads and dirt roads are out of the question.
For the E28S M5, I have decided to perform a test; for the (lower) control arms, I will apply OE parts. For the (upper) control arms I will try the Meyle HD parts.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img732.jpg]

Compared to the old arms, the bushings of the new parts are much stiffer. The ball-joints of the Meyle HD arms are much stiffer then the OE arms, which is a good thing as it will improve the cars steering. The quality of the materials is excellent as well. I will evaluate them throughout 2011, but I expect them to perform fine as #231 won’t be used for >5k km per year and won’t be used as hard as my E34S M5 throughout many years. I have sourced them through an official distributor and NOT the internet. There is has a cost-penalty of as much as 50%, but I want parts that are not that old and have been stored and handled well. With your garden variety Internet supplier, this is not that obvious. If they fail, I can always resort to the OE arms or even the E31 arms that supposedly fit as well.

Prior to reusing the tie-rod levers, I gave them a new appearance. I used a three step process; (1) cleaning and degreasing, (2) primer coat with Caprotec RX5, (3) 24hrs of curing and last but not least (3) a few layers of Innotec Black body paint.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img760.jpg]

Yesterday, evening, I started with the assembly of the four control arms to the tie-rod levers. The M14 nuts of the lower control arms need to be tightened to 80Nm prior to their assembly to the struts as otherwise, they cannot be reached anymore.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img761.jpg]

I then installed both control arm assemblies onto the car. Please note that I didn’t tighten the M14 nut for the thrust arms yet as these can be reached from underneath and it is wiser to that later when the car is standing on its own feet.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img762.jpg]

I then installed both struts to the car without tightening the three M8 nuts to the specified 22Nm. That has to be done later when the car is standing on its own feet.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img763.jpg]

Please note the nut that is indicated by the red-arrow. This is the same M14-nut that secure the control arms to the tie-rod levers. Although I ordered six of them, I only found four. I will have to investigate as the bill mentions that the delivery should contain six of them.

The tie-rod levers are bolted with three M10x20 bolts to the struts. I couldn’t find the exact fastening spec in the repair information, so I asked a friend who quickly gave the correct information (Thanks Serge); these bolts are of 10.9 quality and should be tightened to 65Nm and secured with Loctite 270 or equivalent

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img764.jpg]

As can be seen on the following picture, the ball-joint of the right tie-rod is damaged. I discovered that only yesterday evening when I wanted to secure its position with an M10 nut. I disassembled them from the tie-rod lever with appropriate tooling so the damage must have occurred during a past repair. Anyhow, these parts will be replaced as well.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img765.jpg]

I will retain the anchor-plates for the front brake-disks as is. I will give them a good clean, but that will be it. There is no gain in removing them as that can be done as part of a bearing replacement which at the moment is not necessary at all. And spending more than 150 Euro per side for a new hub-with bearing when the existing bearings are still excellent is not my cup-off tea.

I also cleaned the lower part of the wheel-arches. There are some cavities down there in which dirt is collected after some time. I used brake-cleaner for removal of the collected dirt. Unlike water, brake cleaner quickly vaporizes without leaving a residue.

[Blockierte Grafik: http://rwoe.150m.com/tmp/20080301/img766.jpg]

Clearly visible is the surface corrosion underneath the trapped dirt. This requires treatment with POR15.
New issues:

1: order the left and right ball-joints for the tie-rods.
2: Order a few M14 nuts (same as used on the tie-rod levers).
3: Treat affected areas of the wheel arches with PRO15.