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For the rally car build of a 2002, i am looking at options for the final drive. Gearing is paramount for small NA engines and 3.9 is just not enough. Hoping for something in the 4.88 on up range. 

 

Is there aftermarket options?

 

I might have to consider exchanging the differential for something more apt to have gears (and LSD). 

 

That said, what is the ring diameter of the 2002?

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For the rally car build of a 2002, i am looking at options for the final drive. Gearing is paramount for small NA engines and 3.9 is just not enough. Hoping for something in the 4.88 on up range.

 

That said, what is the ring diameter of the 2002?

 

Ring gear diameter is 168mm.

There was a 4.75 ring/pinion available (email - I might sell mine), and something over 5.0 (5.15?). -KB

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33 12 3 610 005

I=35:8=4,375

Production discontinued

 

X

4.000 kg / 8.818 lb

 

33 12 3 610 009

I=38:9=4,22

Production discontinued

 

X

4.100 kg / 9.039 lb

 

33 12 3 610 010

I=37:9=4,111

Production discontinued

 

X

4.100 kg / 9.039 lb

 

33 12 3 610 013

I=38:8=4,75

Production discontinued

 

X

4.250 kg / 9.37 lb

 

33 12 3 610 014

I=35:8=4,375 HD

Production discontinued

 

X

4.200 kg / 9.259 lb

 

33 12 3 610 015

I=41:7=5,86

Production discontinued

 

X

4.400 kg / 9.7 lb

 

33 12 3 610 016

I=37:7=5,29

Production discontinued

 

X

4.175 kg / 9.204 lb

 

33 12 3 710 000

I=39:10=3,90 HD

Production discontinued

 

X

4.250 kg / 9.37 lb

 

33 12 3 710 002

I=41:10=4,10 HD

Production discontinued

Can be replaced by the part in the next line

 

X

4.300 kg / 9.48 lb

 

33 12 0 413 446

I=41:10=4,10 HD

Production discontinued

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did you read this in your search of the faq?

http://www.bmw2002faq.com/_/technical-articles/engine-and-drivetrain/bmw-2002-differentials-guide-r36

 

 

small case e30 diffs use the same R&P size and it can be swapped.  a 4.44 was avail for that car, although not common.

 

is there a thread regarding the E30 differential swap? i believe the 318ic had 4.27? 

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i was refering to swapping the R&P into a 2002 or E21 case.  details in my build thread.  i just put a 4.44 into an E21 case.  also look in faq under construction for aceandrew's diff build thread. lots of detail.

 

the extreme is to use the e30 diff in its entirety, but the requires massive subframe modifications or buying one of 02haus's custom rear subframes.  you should know whether the class you intend to rally in allows that kind of thing.

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rally is essentially unlimited for Group2/5. That is why i was looking at "any" IRS if i had too. 1200 bucks for a ring and pinion is just a lot. 

 

the 8" toyota diff has been done (in a 318Ti) and ring and pinion options are about 150 bucks in whatever ration ya want. The 4.44 might work out if i went with an M10 turbo, but being naturally aspirated... not sure it will be enough.

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The 4.44's easy to find-  an emailing search on ebay usually gets you one for less than $200 in less than a month...

put it into a late 320 housing, and it's pretty darned stout.

 

The 4.27 was in the 91- 92 318ic, but not all came that way.  Those are also not so hard to find.

 

I found that a 4.44 was as tall as I could use, even at Mission,

even with the OD trans.  But you're leaving out a few things:

 

What's your power band?  Redline?

 

What's your tire circumference?

 

What transmission do you plan to use?

 

If it was me, I'd start with a 4.44 and see if it worked,

since it's an order of magnatude easier than any

other option you have at this point.

 

t

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