E21 Differentials and Driveshafts (The weak Point?)

[Duracel79]

Looks like we've had the first pictures of a broken differential (the LSD parts anyway). Went whilst Problemchild was on a trackday with an M52 doing the damage.

I'm guessing with the M50 inlet it was pushing about 220bhp and 210lbft, obviously I don't know if there was a remap involved or other spec, so may be off the mark here.

Hopefully Problemchild will post his pics up here as well with some more details

Regards

Ben

[problemchild75]

m52, remap m50 inlet so probably a smidge over 200bhp. 3.9 e21 lsd with fresh oil and vey quiet. 6 fast but not hard ie not snatching gears and using lots of engine breaking shakedown laps of Anglesey circuit ended in the following pics. the 168mm is not up to the job IMO some say its the oil getting to hot that's the problem but after six sensible laps I doubt it. E12 lsd conversion underway.

[croma_man]

ouch !

so a tuned M20 stroker is over the limit ?

[Jeroen]

I am wondering what happened because I've seen enough E21 diffs take over 200 BHP. Bearing that broke into pieces and ruined the rest on its way?

[problemchild75]

The bearings are all still ok. Somthing has given up and wiped everything else out though. I think it was one ot the side gears but that's just a best guess. I'm happy to test another if anyone wants to sponser the diffs

[croma_man]

so next stop is a E12 sideloader?

you made me a very worried owner of a small diff

[problemchild75]

Yes side loader on way. Don't worry about your diff I might have been unlucky. But if your going to drive it hard a side loader might be worth thinking about whilst you still have a expensive small diff to sell.

[J.K.jr.bad.]

Probably that diff simply was too old to keep that tension. We all get old and then we die.

[M15KYY]

i had an e12 diff in the back of my m60 v8 e21 and didnt have any problems with the diff. the driveshafts however..... 7 destroyed in 6 months, inner joints every time apart from one.... complete waste of time. the only good thing to come of this was it stopped the underside of the car from rusting when it threw cv grease everywhere. i have now fitted an e36 m3 evo rear axle but as i can appreciate not everyone can/ wants to do this to their e21. i think the best solution would be to get a medium case diff from an e36 6 cylinder grafted onto either an e21/e30 rear axle with some half decent custom shafts. you'd never have to worry about it ever again. i have another e21 shell coming soon so i might look into creating a "bullet proof" bolt on e21 rear axle solution for those who want to chase big power. if i do i will make a jig and offer this on the the forum providing i have enough interest.

[Duracel79]

i had an e12 diff in the back of my m60 v8 e21 and didnt have any problems with the diff. the driveshafts however..... 7 destroyed in 6 months, inner joints every time apart from one.... complete waste of time. the only good thing to come of this was it stopped the underside of the car from rusting when it threw cv grease everywhere. i have now fitted an e36 m3 evo rear axle but as i can appreciate not everyone can/ wants to do this to their e21. i think the best solution would be to get a medium case diff from an e36 6 cylinder grafted onto either an e21/e30 rear axle with some half decent custom shafts. you'd never have to worry about it ever again. i have another e21 shell coming soon so i might look into creating a "bullet proof" bolt on e21 rear axle solution for those who want to chase big power. if i do i will make a jig and offer this on the the forum providing i have enough interest.

E12 diff with custom shafts and GKN Motorsport joints on my car. No issues so far with over 330bhp. But not a cheap solution (doubt there is a cheap solution).

Ben

[e21-Mark]

i had an e12 diff in the back of my m60 v8 e21 and didnt have any problems with the diff. the driveshafts however..... 7 destroyed in 6 months, inner joints every time apart from one.... complete waste of time. the only good thing to come of this was it stopped the underside of the car from rusting when it threw cv grease everywhere. i have now fitted an e36 m3 evo rear axle but as i can appreciate not everyone can/ wants to do this to their e21. i think the best solution would be to get a medium case diff from an e36 6 cylinder grafted onto either an e21/e30 rear axle with some half decent custom shafts. you'd never have to worry about it ever again. i have another e21 shell coming soon so i might look into creating a "bullet proof" bolt on e21 rear axle solution for those who want to chase big power. if i do i will make a jig and offer this on the the forum providing i have enough interest.

E12 diff with custom shafts and GKN Motorsport joints on my car. No issues so far with over 330bhp. But not a cheap solution (doubt there is a cheap solution).

Ben

What is a ballpark figure on the custom shafts & GKN joints, for those folk with sideloaders fitted?

[Duracel79]

£270 + VAT - Custom Shafts the correct length each (F1 grade material)
£168.67 + VAT - GKN Motorsport CV's each
£103.22 incl VAT - GKN Fast boots set of 4
Plus delivery from 3 suppliers

I don't really want to add it up, its a bit scary

Not sure how that compares to the costs of an M3 rear end like M15KYY's

Ben

[nas80]

Those prices are for 2x or are they EACH.

[Duracel79]

shafts and CV's are each, only the boots is for the set.

[e21-Mark]