First off, I installed a Yoshi-rebuilt (shiboujin) 3.73 LSD diff that I bought from Dave (jalopi). Our old 3.73 LSD whined like a spoiled child on the highway. Hell, it made a fair amount of noise cruising at 10 mph, and just got louder from there. Here are the specs from Yoshi on the new diff:
"3 clutch 0.2mm over shimmed 3.73 lsd using bimmer world clutches. The dog ear plates are Porsche."
Dave was extremely generous and basically did the whole install for me in his garage since he has plenty of tools and experience doing diffs. Aside from the hassle of removing my stupid 3" exhaust and swapping diff covers and axle flanges (it came off his E30), everything went smoothly, and I was pleasantly surprised driving home that I no longer had to listen to that constant high-pitched whine....just my obnoxious exhaust....hooray! I haven't tested the lock up characteristics yet, but I'm confidant it will help me put down power a little bit better in the dirt.
The new diff
Getting ready to swap parts
The next day, I went over to Josh's house and he helped me cut my rear E34 springs! I don't have anything to cut with, and he knows suspension stuff, plus he has a garage, so another win. We started with cutting one rear coil, and after reassembling it, that's where we left it. I forgot to measure the ride height before, but it looks like it dropped the rear down about an inch. Using his camber gauge, it looks like we added about -1* of camber to the rear, from about 0* before. So between the increased spring rate from cutting, the lower center of gravity, and the better camber, I'm expecting good things from this.
When we cut the rear springs, we cut from the top, as the upper coils didn't get as close to the coils below as the bottom ones get to the ones above them.
Top:
Bottom:
To answer the question that I kept asking earlier, it looks like the rear springs are not considered "square" as they won't stand up by themselves:
So in my opinion, while not perfectly tangential, they are closer to that than to square, and are safe to cut (to an extent). With only one coil cut, they were under compression with the top mount installed, so no need for tender springs or limit straps. I'm curious to see if I could get away with cutting another coil, but that would require me getting another set of E34 rear springs in case it's too much and they won't stay seated/under compression.
Josh smoothing out the edges:
Sorry, but I don't have any after pics yet, but I will soon.
In related news, I bumped up the stiffness of the FSB from the middle position to the full stiff position, and the front end seems a bit tighter, but I haven't really pushed it hard yet. Still, I'm hopeful this will balance out any additional oversteer I created with the stiffer rear end.
We then decided it would be interesting to do Josh's ghetto car weighing using four bathroom scales placed under each wheel with the other side on wood blocks to even out the ride height. It's not super accurate, but it's good enough for a rough idea. Josh's 318 with an M42 weighed about 2200 pounds when he weighted it, and mine came out to just over 2900, which is where I thought it would be, so that's good enough confirmation for me. Still though, it's not great to know that my car weighs a full 30% more than his car, when I know it doesn't make 30% more power.
Anyway, I'll post up my impressions of all the new stuff when I drive the car a bit more, but I'm feeling pretty good about where the car is right now! Big thanks to Dave and Josh for all of their help. I don't think I could have done all this without them!