bolt pattern for g260/5 trans

E28 technical advice asked and given! Troubleshooting, modifications and more.
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ROSSI1
Posts: 9
Joined: Aug 10, 2021 2:18 PM
Location: illinois

bolt pattern for g260/5 trans

Post by ROSSI1 »

Does anyone have pictures of the bellhousing bolt pattern for the M20 and M30 bolt patterns? I got a 535is that came with a manual trans conversion but am not sure if its for the M20 or M30. Its definitely a 260/5 due to not having the finned case but i dont know what it came out of and the previous owner didnt know either. If its for an M20 i dont want to take my car apart just to find out.
demetk
Posts: 8431
Joined: Aug 09, 2007 8:58 AM
Location: CT, USA

Re: bolt pattern for g260/5 trans

Post by demetk »

post a pic.
ROSSI1
Posts: 9
Joined: Aug 10, 2021 2:18 PM
Location: illinois

Re: bolt pattern for g260/5 trans

Post by ROSSI1 »

Im not near where the car is stored at the moment so cant get a pic of the trans I got. I was just wondering how one can distinguish between the m30 or m20 version
Mike W.
Posts: 26872
Joined: Feb 12, 2006 12:00 PM
Location: California Whine Country

Re: bolt pattern for g260/5 trans

Post by Mike W. »

I believe M20s use all 12MM mounting bolts but M30s use a mix of 8 and 10MM bolts. I'm sure on M30s. Realoem bears me out on M20s, but I've never pulled one.
tn535i
Posts: 5585
Joined: Jul 14, 2006 1:30 PM
Location: Middle Tennessee

Re: bolt pattern for g260/5 trans

Post by tn535i »

Is the OP asking about manual trans conversion parts that have NOT yet been installed?

I have saved a pair of bell housings from both an M20 and M10/M30 automatic trans and iirc it is pretty easy to tell the difference just by the width where it meets the block below the head or the width between those two bolt locations. If I remember when I get home I will measure.
tn535i
Posts: 5585
Joined: Jul 14, 2006 1:30 PM
Location: Middle Tennessee

Re: bolt pattern for g260/5 trans

Post by tn535i »

I can confirm the two are quite different. If you can measure across the raised rectangle section just under the head one is about 12cm and the other 14cm bolt spacing. It might be opposite of what I had in my head, big block is smaller bolt spacing and small block is wider. And yes the M20 appears to use larger bolts all around and the M10/30 smaller and mixed in size.
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austin8753
Posts: 1444
Joined: May 16, 2010 1:37 AM
Location: Portland, Oregon, USA

Re: bolt pattern for g260/5 trans

Post by austin8753 »

M20 uses four 12mm bolts at the block and two 10mm bolts at the starter.

M30 uses 4 10mm bolts at the block and two 10mm bolts at the starter. seems like i recall there being a "V" notch near the starter, that i never saw on an M20 bell housing, only the M30.

hope this helps!
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