Large 210mm Diff into E30...

[3rotore30]

I am trying to track down some info about fitting a large 210mm diff into my e30.

I have noticed that they are available from the M5 and most of the V8 5 and 7 series BMWs.

Has anyone done this before? Is it even possible? I will consider buying a complete rear end and modifying to suit but need to know what's involved.

thanks

[lolcantturn]

Why?

[Tico Frank]

Why?

[3rotore30]

Not that it should matter but I am putting a 20b rotary in it with a gtx47 turbo. The mediums case diffs are only rated to 500 ft/lb torque, this motor will destroy that...

[VinniE30]

Because lots of torque

[e30leigh]

anything is possible with the right amount of money, know how, know who, and dedication and drive

[3rotore30]

anything is possible with the right amount of money, know how, know who, and dedication and drive

and that's the exact type of info i am after. you've solved all my problems, thank you!

[yert315]

As far as I know the large case and medium case are interchangeable.

[Wanganstyle]

Not that it should matter but I am putting a 20b rotary in it with a gtx47 turbo. The mediums case diffs are only rated to 500 ft/lb torque, this motor will destroy that...

not really. There are a few LS7 (7,000cc 520rwhp NA) e30's and e36's in the SF bay area running stock diffs built up for the power.
we have some very serious power engines in local BMW's.


another local proved running a 188mm stock gearset and built up stock LSD can take 9's and 1,000rwhp. (built s52+GTX42R). ran about 30 passes on a standard un-treated BMW 188mm Gearset, the 5 disc high locking LSD unit wore out before the gears died.

make sure the axels and stubs are up to par (driveshaft shop). Then you can put down 20B power.

Even the BMW torsen LSD unit can take 1K rwhp. the Mazada units cannot.

As far as I know the large case and medium case are interchangeable.

Incorrect, the small 168mm and medium 188mm can be interchanged- the 210mm units use a completely different style of mounting in the rear.

[yert315]

Sorry you're right. They are, in fact, interchangeable on the large chassis cars (e28,e24,e23,etc).

Carry on.

[3rotore30]

thanks Wanganstyle, it looks like it will be the go. thanks for the reply in the other topic too. i've been looking at a norway forum and they all seem to be using the medium case centres too. i guess if it does let go then i will look at replacing it then.

[Wanganstyle]

The halfshaft is the fuse on the e30 setup; 86mm cv standard.

One could fit an e28 rear suspension setup and shorten the axels (or wide body the e30). The e28/23 3500cc cars have 96mm cv's and corresponding axel shafts. Those are ok for m102, s38b35, m90 power.

The most easy option would be to fit the rear hubs/trailing arms and axels of the mz3 e36/7 and it's 96mm cv axels. Those are Pnp to an e30 chassis. The diff would need 96mm stub axels installed.

20b 3 rotor setup with a gtx47 should be in the 1000-1400hp range??

what is this beast for? How are you going to keep the rear end stable at 150mph traps??

The ls7 e30m here is getting some serious body changes to handle the power on street/hpde conditions. Dss axels /stub inners would be suggested for over 400rwhp and abusive conditions. The diff units and years will handle the power if setup correctly, obviously the wear rate will be pretty high. 210mm from e28m5 would be a nice reliability modification but then at that point a ford 9" or c4 corvette rear or viper rear end (or Nissan r200) would be more economical. Espicially if cutting up the floor for the rear mounting is required.

[Wanganstyle]

The halfshaft is the fuse on the e30 setup; 86mm cv standard.

One could fit an e28 rear suspension setup and shorten the axels (or wide body the e30). The e28/23 3500cc cars have 96mm cv's and corresponding axel shafts. Those are ok for m102, s38b35, m90 power.

The most easy option would be to fit the rear hubs/trailing arms and axels of the mz3 e36/7 and it's 96mm cv axels. Those are Pnp to an e30 chassis. The diff would need 96mm stub axels installed.

20b 3 rotor setup with a gtx47 should be in the 1000-1400hp range??

what is this beast for? How are you going to keep the rear end stable at 150mph ++traps??

The ls7 e30m here is getting some serious body changes to handle the power on street/hpde conditions. Dss axels /stub inners would be suggested for over 400rwhp and abusive conditions. The diff units and years will handle the power if setup correctly, obviously the wear rate will be pretty high. 210mm from e28m5 would be a nice reliability modification but then at that point a ford 9" or c4 corvette rear or viper rear end (or Nissan r200) would be more economical. Espicially if cutting up the floor for the rear mounting is required.

[3rotore30]

cbf replying anymore. i'll figure something out. i just don't see the point in using something that isn't rated to the capability of the engine despite what other people might be doing. just doesn't make any sense to me.