e36 m3 to m20 gearbox swap

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professormatt
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Location: scotland

Post Mon Jun 19, 2006 5:12 pm

what is needed to fit a e36 5sp m3 box on to a 325i?

cheers matt
jmc330i
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Post Mon Jun 19, 2006 6:13 pm

A new diff.

The 3.91 diff on the 325i will be too short for the E36 M3 box - 50mph at about 3k rpm in 5th 8O The E30 M3 diff will work.

You will also need an E30 M3 prop to fit to the output flange of the E36 M3 box (or a custom made prop with E30 rear and E36 M3 front section).

Other than that, assuming you want to fit the E36 box to the M20, the gearbox will rotate slightly in one direction, meaning the gearstick will also have moved off centre.
James
'91 325i Sport
'93 318i touring 16v
professormatt
E30 Zone Newbie
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Location: scotland

Post Mon Jun 19, 2006 11:07 pm

when you say off center,will it make it difficult to change gears?

cheers matt
jmc330i
Engaged to the E30 Zone
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Location: Somerset

Post Tue Jun 20, 2006 10:23 am

I couldnt tell you.

I do know that in the USA, the M50/S50 engine conversions are often fitted with the M20 gearbox and that rotates the gearbox in the opposite direction - about 10 degrees to the right from its normal position. From what Ive read on some US forums, it just takes a bit of getting used to.

One problem you may have is, as the E36 M3 gearbox rotates to the left, you may have trouble selecting reverse gear because of the position of the gearstick in the tunnel. Until you get the gearbox in there, you wont know how much out of position it will be.
You could ask on some of the US forums how people have re-centred the gearstick on the M20 gearbox and the do the opposite for the E36 box??

Another thing I guess you will need is a custom mounting bracket for the gearbox, as the standard mount wont work with the rotation.
James
'91 325i Sport
'93 318i touring 16v