bmwe21.net forums

Hi guys, anybody know of any "off the shelf" half shaft upgrades for an e21? I ask as I'm about to start building another car this year with an sr20det motor and wanna know if any of you guys have an upgrade for the rear axle apart from the e12 diff which still leaves you with the driveshaft problem? Failing this ill be modifying an e30 325 rear axle.

Can't you chop the ends off of an e30 rear beam and narrow it slightly? Or is that a bit too simplistic? I'm sure I read it somewhere?

Lol that's my backup plan mark lol

M15KYY,

I started this thread last year to discuss the limits of the standard rear end of our cars, may be of some use:

http://www.bmwe21.net/forum/viewtopic.p ... =rear+axle

Personally I'd already gone for an E12 diff but rather than using the weak std shafts/cv's that most people use I went for new custom shafts with new GKN CV's. See my build thread for pictures of the shafts(near the bottom of page 12), these shafts won't break but the cv's will wear over time and need to be replaced. But they are now a std easy to obtain GKN joint rather than the unobtainable original. There are motorsport versions of these CV's as well which are stronger again. Hold up to my S54 ok at the moment with a few trips down the Pod which is probably the harshest test for the rear axle.

What are your plans for the SR20, if it stays fairly std then the standard rear axle should be ok.

Ben

PS. E30 driveshaft CV's are not much stronger than the E21's its just they are younger and have had less use.

I think it was 2 E30's at the Pod this year breaking CV's, I know one was an M52B30 but won't be like the torque an SR20DET can put out.

Ben

Mmm didn't see that thread before Ben thanks, some interesting reading on there, I'm only going to stage1 with the sr20 so intercooler and exhaust. I think the best course of action is to rebuild the shafts with new cv's and boots, and run the standard setup, diff will be welded as the car is going to be drifted, might take on the idea of an oil cooler though that can't hurt

I'm sorta in the same predicament. I want to turbo my m52 and run about 350/400hp.

I'm going to do something like what Ben did with uprated shafts and joints on my e12 LSD.

I know I am always constantly banging this drum butiI noticed people who snap shafts and joints a lot more than usual are those with welded diffs.. its the constant opposing forces when you are turning that does it I think (with my limited engineering knowledge)

Kudos to you though Misky the sr20det is an awesome engine really.. the turbo manifold is on the opposite side as well. I bet it will fit real nice in there.

I thought about going the same way but just like BMW to have their own engines. No denying the bang for buck though and multiple megafonzie cool rating.

Hopefully nas, wouldn't mind some power steering in it so might try and mount an s14 rack to it also. Well if it goes bang it goes bang, 316 diffs aren't hard to come by and I'm pretty sure someone would hunt me down if I welded an e12 diff ha ha

Only BMW diff I've broken was a 2002 one and that was after several full right lock, rev to the max, select 2nd gear and dump the clutch wheelspins. (I was only young/stupid). It just went BANG! and lost all drive.

What torque rating is the OE Datsun diff?

God knows mark, they take a fair bit of shit though, even welded they're still pretty strong, about the same physical size as an e36 medium case.

Where can I buy gkn cv joints guys?

Don't think they do them for the standard BMW driveshafts. I asked GKN direct to try and locate/make some (had contact with one of the their motorsport technical guys as well) and had no joy. Which is why I had new shafts made up to suit a standard joint (easily available).

As far as I know new std CV's are only available from BMW as complete driveshafts. I think Topcat (spl?) bought a pair from BMW last year for his E21.

Ben

Ahhh ok thanks Ben, seems as though I won't be building the SR21 now as when I got called into work this morning I was informed that I am being made redundant so it seems I must draw in the purse strings now, sucks eh?