Mid Case Diffs and Early 6 Suspensions in E9s

lafngrvy

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One of the issues with vintage racing my car is a lack of ratios for the diff in the car. There seem to be 2 possible solutions.

1] Using the mid case diff from E30 M3 & E36 M3's. My sources say that putting one of these in an E9 chassis can be time consuming.

2] Using the diff & rear suspension from an early 6 series. Easier to install and offers advantages of adjustability and strength.

Anybody have experience with these options? Anybody have thoughts about these options?

Thanks,
Steve
 

shanon

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What ratio are you looking for?
Or, what tracks and tranny will you be running?

You can take/rebuild a side loader and change the ring to whatever ratio you want.
A 3:91 to 4:27 is about all you'll need for most west coast tracks.

Also, are trying be period correct? Some clubs may have issue with adapting later model items.

Try Ireland Engineering regarding LSD options, Jeff is also a VARA club tech.
they might have some ring options/ideas.

HTH and come on down to CA next season and join the circus!

-shanon
 

Bill Riblett

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2] Using the diff & rear suspension from an early 6 series. Easier to install and offers advantages of adjustability and strength.
"Early" 6 series can be either E12 chassis or E28 chassis. Although they are all called E24s, the 76-82 cars use the E12 chassis and the 83-89 cars use the E28 chassis.

The E12 chassis cars use the same diff as E9s, so don't help your diff problem.

The E28 chassis rear suspension will be a lot more complicated to swap, although it has been done.
 

M5dCS

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late model diff conversion

Metric Mechanic used to offer a modified trailing arm mount and different diff cover that would let you use the later diffs in the early chassis, as I remember, they were fairly spendy and required a trade-in of your trailing arm crossmember. Check with Jim Rowe and see if it is a viable alternative for you. Best of luck, Leroy
 

lafngrvy

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Shannon,

Thanks for the invite south of the border. I raced at Infineon year before last at the Fall Vintage SCCA race. It was a blast. HMSA is planning a march race at THill which I hope to come down for.

Do you ever 'slum' it north of the Siskyous? We have a new track in eastern OR that will be holding SCCA and ICSCC races next summer that is a REAL challenge. Check it out:

http://oregonraceway.com/

Steve
 

lafngrvy

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"Early" 6 series can be either E12 chassis or E28 chassis. Although they are all called E24s, the 76-82 cars use the E12 chassis and the 83-89 cars use the E28 chassis.

The E12 chassis cars use the same diff as E9s, so don't help your diff problem.

The E28 chassis rear suspension will be a lot more complicated to swap, although it has been done.

Bill,

Very helpful, thank you.

What was suggested was to use the entire rear subframe from an E28 car so that we don't have to make custom axels, etc. This would also provide the opportunity to tie-in the roll cage to the new mounting points for the subframe.

I haven't looked under an E28 to see how close it is to the E9 subframe, and how much work is involved.

Steve
 
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