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Wow. I would’ve hoped they would be in better condition at that mileage. Did the car get a lot of high RPM use?

Here in the US, we can’t get much over 75mph without going to a track. So I’d imagine a Euro M5 will see more total RPM over the same mileage.
 

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Discussion Starter #124 (Edited)
Wow. I would’ve hoped they would be in better condition at that mileage. Did the car get a lot of high RPM use?
Yes, static sustained high engine load as well as dynamic high engine load:

- Circa 100 laps on the Nurburgring North loop (2002-2006) => high dynamic load
- Frequent use on the German autoban (1999-onwards) => high dynamic and sustained high static load (>30% of the 100k km has been covered in these conditions)
- Many trips to the Alps with high dynamic load on the mountain passes (1999-2008)

Please note that aggressive redlining into the limiter has been avoided on most times, but could not be avoided in some occasions. Sustained high static load means >6500RPM in fifth gear.

For the rest, frequent oil changes and regular Used Oil Analysis to obtain an early detection. The trigger for the project to commence was based on facts (elevated copper and lead wear reported by Blackstone)
 

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Discussion Starter #125 (Edited)
It has been a while since I last shared an update; to date, I have added 1345km this year, totalling 3253km since the conrod bearings have been replaced. Most of the mileage this year has been added during a driving-event with friends to the Eiffel and Rhineland Palatinate just recently. This trip was completed uneventfully. This was also because of the preparational works that have been performed during the preceding months.

• Replaced the output seal and the gear-selector seal from the Gearbox
• Replaced the gearbox shift-knob with the original M-Technik version.
• Replaced the rubber bearings and rubber boot-seal of the shifter mechanism.
• Replaced the exhaust mounts and suspension brackets with OEM parts
• Replaced the gearbox mounts with OEM ($$$ nowadays).
• Replaced the right front wheel bearing with a New Old Stock part
• Replaced the front brake pads with OEM parts
• Replaced the worn-out front (Michelin PS2) tires with fresh Michelin PS4’s (235/45ZR17 / 97Y)
• Engine oil service (Motul Competition 300V 15W50)
• Replaced the steering tie-rods with new OEM parts
• Full BMW-KDS alignment by an official dealer.
• Replaced the battery (now 12V/95Ah)

For the parts strategy, I try to apply New Old Stock as much as possible, however this will be increasingly more difficult when stocks are exhausted. Coincidentally I had a NOS front wheel bearing on stock, which ensured production quality and that it is the same part as originally fitted.



The technical work was straightforward and executed in compliance with the factory repair instructions. All the work had a very positive impact to the cars overall handling and balance. In 2017, BK02837 started to understeer on the typical Eiffel roads at around 70km/h forcing the car outwards. With the new PS4 tires and the suspension and steering geometries on-spec, the car could be positioned with pin-point precision in all circumstances. As a direct result, the nervous handling disappeared completely in favour of completely neutral behaviour which increased confidence levels significantly. This allowed the overall pace to be increased with 40 to 50km/h in corners and 20-30km/h overall before a mild progressive understeer appeared..



The rebuild of the steering gearbox eliminated the excessive play in the straight-line position and groaning noises from the steering gearbox when cold. The insensitivity around the centre position remained, yet this is a known anomaly for this type (recirculating ball) of gearboxes. Another small issue that remains is a slight audible ‘click’ when changing steering direction. The replacement of the tie-rods as time-saving measure for the KDS alignment did not resolve this issue, reducing the number of options to three (1) centre tie-rod, (2) universal joint between steering shaft and steering gearbox or (3) steering gearbox itself.



Lessons learnt from 3152643 (E32 735i) with the servotronic system learnt that this system can offer more precision when manoeuvring at lower speed and more tactile feedback at higher speeds. An E34S M5 specific steering gearbox with that system is available and can be retrofitted at some point when the auxiliary material (wiring loom and E34S M5 specific control unit) become available.

It is without a doubt that the fresh Michelin PS4 tires have grip-levels that are comparable with the old Michelin PS2 (when new). The impact of the KDS alignment is positive, yet whether this has the same tangible impact as the change in tire type remains to be seen. From a scientific perspective this is interesting question; in the end just academic one as the objective from this project, a significantly better handling car, has been achieved.



As far as the alignment procedure itself; the adjusting procedure itself does not differ between the std. four-point alignment from the wheel/tire specialist and the KDS alignment from BMW. However, the KDS-procedure calibrates against a wider scope (quality attributes) and tighter quality-criteria. Although the std. four-point alignment can return good results and fully satisfy the owner/driver, only the full scope and the SMART criteria from the KDS procedure are referenced against the original concept from the manufacturer. As such the probability that a car handles to the original concept after performing the alignment to the KDS procedure is significantly higher than any other alignment method.



With completion of all this work, the overall issue list of BK02837 is small and apart from the A/C system reduced to normal maintenance. The A/C system needs a refill and conversion to R134a. For 3152643, we had to rebuild the A/C pump itself which allowed replacement of the seals to R134a and synthetic PACH oil compliant types. Overall cost when compared to placing a new pump from BMW themselves is competitive but not negligible.



Fact is that this is a brilliant car. As a matter of fact, next April, it has been twenty years ago when I bought this magnificent beast from her first owner in Switzerland.



How time can fly?!
 
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