'88 325is M30 street car-->S54 -->S50 -->M54 Enduro Race car

[jink0619]

Just read the entire thread over again, nice job! I just picked up my motor today, super excited. I'll have it on the engine stand to start the cleaning process.

[zumjosh]

Sorry if this has already been answered... but what are your spring rates currently? I noticed you have GC coilover kit.

[Jb325is]

550/750 and it is too soft for what I want to do.

Did some autocross testing today at work and I'm glad I did before the start of the season, I ended up destroying the clutches in the diff about 3 minutes in. Just got the car back home and am about to start pulling the diff, I think I'm going to go with 4 clutches and a taller gear

GEDC2024 by braswell.jonathan, on Flickr

[MX339]

You're going to have that diff rebuild by next weekend for Roebling, right? Right!?

The weather is going to be ridiculously good though, 70's and sunny.

On a serious note, what ratio are you currently running? And I don't recall, but do you have a 5 or 6 speed in it?

[Jb325is]

20141115_181454 by braswell.jonathan, on Flickr

You're going to have that diff rebuild by next weekend for Roebling, right? Right!?

The weather is going to be ridiculously good though, 70's and sunny.

On a serious note, what ratio are you currently running? And I don't recall, but do you have a 5 or 6 speed in it?

I doubt I will make it to Roebling, too much going on. It has a 3.73 with a 5 speed, which is not usable, I think I'm going to go with a 3.25 but I don't know what I want to do about clutches yet.

[Good & Tight]

Got it running correctly last night, finally. I tried to take it to the dyno, but they were closed. Long story short I had the pre-cat o2 sensors swapped. I did one short pull last night on the street because it's still too loud, and it was immediately obvious that its running correctly. Videos coming this weekend, before I put another muffler on it!

Did I miss the 8k video....? Nice to hear you got the issue sorted.

[WannaBe30]

Welcome back and glad you got your issues sorted good luck with the diff. I could not imagine driving 3.73 in your setup

3.46 would be the max for me

With the headers you went with did you have to modify them to fit besides shaving the transmission down? I'm not a welder and if those gorgeous things will avoid me having to learn or pay I want to get the same ones

[Jb325is]

Did I miss the 8k video....? Nice to hear you got the issue sorted.

We were about to get the GoPro out on Saturday, then I roasted the diff and that was that, so only videos are the ones I posted from the dyno for now.

Welcome back and glad you got your issues sorted good luck with the diff. I could not imagine driving 3.73 in your setup

3.46 would be the max for me

With the headers you went with did you have to modify them to fit besides shaving the transmission down? I'm not a welder and if those gorgeous things will avoid me having to learn or pay I want to get the same ones

Yeah the 3.73 is terrible for street use. It was next on my list anways, but I was going to run it at the first couple auto-x events of the year because it's decent for that. I might go 3.46 if I can find one but I think 3.25 or 3.38 is the way to go, working on sourcing some clutches right now. I really want to build a 4 clutch but I don't know if I have enough time/money to get it done before Dec. 7

And no, they fit pretty well, but I think you need Treehouse CAB's for them to work and I don't know if they would clear the stock subframe. They also hang a little lower than I would like

[Jb325is]

Took the diff apart last night, the bolts to the clutch housing in the carrier were coming out, they were all hand tight and the housing cover was not flush on the carrier. I think this was probably causing my lack of lock-up, just not quite sure how it happened. Ordering 2 new clutches/wear plates for the diff and got a 3.23 LSD from an e36 m3 for the gear set. I haven't decided if I am going to re-use one clutch or two. There is a spacer inside the clutch housing that is the exact width of a clutch/wear plate, so adding one more clutch is easy. If I want to do a 4 clutch diff I will need to machine the thickness of another clutch/wear plate from the clutch housing cover.

Me and two friends are planning on running pretty much a full SCCA autocross schedule this year in SM, all in e30's. The first big event of the year is on the 7th like I mentioned before, and 2 of the 3 cars are in pieces at the moment.. Gonna be a busy couple of weeks!

[WannaBe30]

Good luck putting them together. Do you think they came loose because of vibration or not torqued properly to begin with? Stuff like that makes me paranoid especially buying used which is mainly what I do

Thanks for the feedback on the headers I do have the treehouse control arm bushings sitting in my glove box but I don't want to swap my stock subframe so I'll prolly get some cheapo headers and modify them.

[Jb325is]

Good luck putting them together. Do you think they came loose because of vibration or not torqued properly to begin with? Stuff like that makes me paranoid especially buying used which is mainly what I do

Thanks for the feedback on the headers I do have the treehouse control arm bushings sitting in my glove box but I don't want to swap my stock subframe so I'll prolly get some cheapo headers and modify them.

I don't know, I have owned this car for like 12 years and never did anything with the diff, so it's probably original. Not sure what happened

You could probably notch or hammer the subframe enough to get the headers to clear

[iwantspeed]

before you finish your diff rebuild i would recommend you pick up some of these bolts for your ring gear.
its common problem for e36's and e46's to have these bolts get loose and back out.

This is a factory bmw part and is serrated on the bottom to provide a little bit more grip, this with loctite and proper torque will be helpful.
photo from Andrew at Ireland enginnering

[MatRacer]

Your E30 is just perfect to me!

Will you rebuild your diff yourself? (bearing preload, contact, backlash...) Would be interested to get feedback on the process. Will tackle this job this winter... 3.73 to 3.25. I did a lot of research and got some nice DIY finds but haven't really started serious reading on it and planning my work.

[Jb325is]

Thanks for the info on the bolts! I'll look into it. I think I am going to replace the socket heads that were loose also, don't know if they stretched or what but I don't want to take a chance with them.

I am going to do the diff myself. There is a lot of info out there and I don't really care to pay someone else to do it, so I'll figure it out one way or the other. I'll try to take some pics as I go.

Here are some pics of the diff as it sits now

20141118_190926 by braswell.jonathan, on Flickr

Clutches not looking so hot, note the grooves on the top one

20141118_191026 by braswell.jonathan, on Flickr

Check out the wear/big lip on the conical spring/plate, this was the cover side where the bolts were backing out
20141118_191101 by braswell.jonathan, on Flickr

[MX339]

Ouch, those dog-eared discs look like they've just about had it as well.

Here's a great Diff write-up on the FAQ for anyone who's curious about the process. It's for a small-case diff, but the principle is similar for the medium cases.

http://www.bmw2002faq.com/_/technical-articles/engine-and-drivetrain/strongest-2002-limited-slip-differential-build-r74