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WTB: LSD for e30 (4.10, 3.73, 4.27): FOUND!


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Looking for a medium case LSD for the e30 racecar. Something went in my 4.10 yesterday at the track and rear end is making sounds like putting metal bits down a garbage disposal. I'll be opening things up to get a sense of the carnage but in the meantime I could use a diff. A medium case 4.10, 3.73, or 4.27 would all work. Thanks!

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  • Boris3 changed the title to WTB: LSD for e30 (4.10, 3.73, 4.27): FOUND!

Exploring an alternative explanation first.

I had found a 50mm bolt in the paddock grass after coming in early from qualifying when the issues started. I couldn’t figure out where it came from or if it was mine. I was focused on a prior issue of rolling resistance from passenger front which was a brake pad sticking. Fixed that, drove it around the paddock and all seemed fine.

Went out for the race and as soon as I was going around 40 on the out lap the issues started again. Fought the car for about 7 laps and said this is stupid and came in. 

Watching my race video I can’t hear the noises from the rear I was hearing in the race. So not sure. Still kept looking for a diff just in case

Meanwhile I went through the car at home looking for other possible sources of the driveline vibration / noise.  Motor mounts were fine, trans mounts slightly loose, wheel bearings no play, diff noise no different than usual, driveshaft, CSB, all good.

But when turning the driveshaft I discovered I was missing a guibo bolt. Best guess is that it had come loose, got hammered a bit and had fallen out when I jacked up the front end to check the brakes. Helps to explain why the vibration seemed to come on all of sudden during qual.

All the other bolts were tight and guibo looked fine. Replaced the bolt and the lock nut with BMW parts and I guess we’ll see. No real place to test it except for on track in a few weeks. 🤷‍♂️



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  • 1 month later...

Realized I never updated this. The vibration issue was the missing guibo bolt. Did a test day and a race earlier in July and all good...except someone got over enthusiastic and hit me on the first lap of the race in the driver's rear quarter, spun me 180 degrees and into the gators on the exit of T4 at Blackhawk. Car was fine after shaking loose the gravel and able to finish. One more aerodynamic "dimple".  Ain't racing grand!   

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