M3 3.0l diff advice

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jac-in-a-box
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M3 3.0l diff advice

Post by jac-in-a-box » Thu Dec 27, 2012 6:18 pm

Kid has my M3 and appears to have bust the diff...I'm not anywhere near the car so can't confirm the actual facts. It seems that the diff casing has failed and one of the securing brackets/lugs where it bolts to the diff carrier has fractured - it's definately not the diff carrier at fault but the actual diff casing that's given up.

It appears that 3.0 LSD versions of the diff are thin on the ground and those that are available seem to be somewhat costly.

To get the car on the road and running, he's considering fitting the diff from another E36 - 320/325/328. I'm certain the ratio on these models will be incorrect but it will do as a stop-gap measure until he can sort out a replacement/repair of the current diff.

The proposal to fit a non M3 diff - will they physically fit and will input/output drive flanges need changing? I understand the 4 pot E36's use a small case diff; the 320-328 & M3 3.0 use a medium case diff and the 3.2l M3 use's a large case diff.

IF it is the case the diff casing is damaged, I don't imagine a weld repair of the bust lug will work - or will it if properly done?
Can the internals of the his duff diff be swapped into a medium case diff from another variant? If yes,will it need special tools and setting up...pre-load etc? (never worked on a diff before)
Any other options to consider - just need to get the car mobile and work on the correct repair/replacement later

Info is vague and I aplologise - but he is adamant that it is the diff case that's failed so I'm having to work on that info'! I anyone knows of a used 3.0 LSD for sale I'd be grateful for a heads up.

Thanks and HNY to all!

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Mitch2.0
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Re: M3 3.0l diff advice

Post by Mitch2.0 » Thu Dec 27, 2012 11:16 pm

The cheapest way to get it back on the road would be to get a 328 or 323 (2.93:1 ratio) or get a 325 diff (3.15:1 ratio, same as your 3.0l M3) and then change the 4 bolt input flange for your M3 diff's 6 bolt output flange. Any of these diffs can be picked up for £20 or so.

HOWEVER, I wouldn't do this, if I had to get it back on the road asap for little money I'd spend an extra £40 or so and get a 328 propshaft too, that way you don't have to fiddle about taking diffs apart just yet, you can just get your 3.0l diff fixed with a new casing at your own pleasure. And yes you can fit the internals from your 3.0l diff into a new 188 casing.

Depends how quickly he needs the car up and running.

jac-in-a-box
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Re: M3 3.0l diff advice

Post by jac-in-a-box » Fri Dec 28, 2012 10:04 am

Thanks for the reply Mitch - just the sort of info' I needed:)

To clarify, you said "change the 4 bolt input flange for your M3 diff's 6 bolt output flange"...I'm scratching my head over the input and output and on what diff. If he sources a 328 propshaft is he simply looking at dropping in one of the diff's you mention without having to mess around swapping flanges? If yes, that sounds the perfect get on the road quick fix!

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Mitch2.0
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Re: M3 3.0l diff advice

Post by Mitch2.0 » Fri Dec 28, 2012 5:26 pm

Yup - if he gets a 328/323 or 325 diff then he just needs a 328 prop and both and go in - no mods required.

LEE
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Re: M3 3.0l diff advice

Post by LEE » Sat Dec 29, 2012 8:44 am

Output flanges are different but the simply lever out with a bar or screwdriver

jac-in-a-box
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Re: M3 3.0l diff advice

Post by jac-in-a-box » Sat Dec 29, 2012 10:49 am

Thanks all - good advice and much appreciated:)

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Mitch2.0
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Re: M3 3.0l diff advice

Post by Mitch2.0 » Sat Dec 29, 2012 5:41 pm

LEE wrote:Output flanges are different but the simply lever out with a bar or screwdriver
I thought the output flanges were the same, I had a 3.0l M3 diff in my 328 - the only thing that was changed was the input flange for a 6-bolt to a 4-bolt.

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