Replacing my M3 E46 Diff with an E36 EVO unit
Discussion
My diff clunks when turning from one side to the other, you can hear this when exting roundabouts or sharp changes in direction or when parking. It has been diagnosed by various people as slack in the backlash on the driver side. Apprently the diff shaft on this side is very short and this causes play in the seat with the drive cup. This is super common and affects loads on E46 M3s..been told this by BMS, Hardy Gearboxes and JC Racing. Odd as although these diffs are known to be noisy I've not read that much about this particular issue.
Anyhow, apparently the only way to cure it permanently is to replace the diff with aftermarket or to have JC Racing take the internals from an E36 EVO unit and swap them to my diff box. So this is what i'll be doing. I'll keep the thread updated on progress, in the maentime am looking for a second hand E36 Evo diff so if anyone hears of one please Pm me, condition does not matter so the cheaper the better.
Anyhow, apparently the only way to cure it permanently is to replace the diff with aftermarket or to have JC Racing take the internals from an E36 EVO unit and swap them to my diff box. So this is what i'll be doing. I'll keep the thread updated on progress, in the maentime am looking for a second hand E36 Evo diff so if anyone hears of one please Pm me, condition does not matter so the cheaper the better.
jackpe said:
My diff clunks when turning from one side to the other, you can hear this when exting roundabouts or sharp changes in direction or when parking. It has been diagnosed by various people as slack in the backlash on the driver side. Apprently the diff shaft on this side is very short and this causes play in the seat with the drive cup. This is super common and affects loads on E46 M3s..been told this by BMS, Hardy Gearboxes and JC Racing. Odd as although these diffs are known to be noisy I've not read that much about this particular issue.
Anyhow, apparently the only way to cure it permanently is to replace the diff with aftermarket or to have JC Racing take the internals from an E36 EVO unit and swap them to my diff box. So this is what i'll be doing. I'll keep the thread updated on progress, in the maentime am looking for a second hand E36 Evo diff so if anyone hears of one please Pm me, condition does not matter so the cheaper the better.
JC Racing did this with my E92 M3 and converted it to a 4 plate diff and it has been superb so far and has done a few hundred laps of the ring since it was installed without any issues just a few oil changes.I also run a diff cooler because all it gets used for is track.Anyhow, apparently the only way to cure it permanently is to replace the diff with aftermarket or to have JC Racing take the internals from an E36 EVO unit and swap them to my diff box. So this is what i'll be doing. I'll keep the thread updated on progress, in the maentime am looking for a second hand E36 Evo diff so if anyone hears of one please Pm me, condition does not matter so the cheaper the better.
Andy
griff7 said:
JC Racing did this with my E92 M3 and converted it to a 4 plate diff and it has been superb so far and has done a few hundred laps of the ring since it was installed without any issues just a few oil changes.I also run a diff cooler because all it gets used for is track.
Andy
Yep, E90s are also known for the same issueAndy
Beedub said:
i haven't heard this being a common issue tbh??
Strange.. on the forums i've not run across it massively but all the professional people I speak to say that loads of cars are affected. One thing is that the clunk is not terribly noticeable so many people may just be living with it.. I have been told the diff will continue working with no issues despite the noise.There is possibly more than one issue being discussed.
Diff output shaft play is normal on one side, to a degree; the cause is insufficient support from the casing due to the offset of the diff. From memory it's the RHS. The M3 was like this from the factory and many diffs were mistakenly replaced under warranty (one can forgive the mechanics for that if BMW didn't release sufficient training info!). It's not really a problem unless the car has either 1) done a fair amount of work i.e. fair wear and tear, 2) been abused, or 3) not had a running in service and follow up Inspection IIs with the diff oil change (the annual service regardless of mileage is a load of crap, but the car must be serviced according to mileage).
A worn gearbox (generally only higher mileages), engine/gearbox/diff/subframe mounts, prop CVs, prop bearing, or diff input bearing will lead to a clunk. I've read on other forums people describing an 'M clunk’, which is nonsense IMO. The cars don't so that if they are in good condition and driven correctly. SMG clunks in S5 or S6 if you are heavy handed, but that’s not a problem per-se.
A JC racing rebuilt standard diff should serve another 60k+ miles, or (lots) more if looked after.
Diff output shaft play is normal on one side, to a degree; the cause is insufficient support from the casing due to the offset of the diff. From memory it's the RHS. The M3 was like this from the factory and many diffs were mistakenly replaced under warranty (one can forgive the mechanics for that if BMW didn't release sufficient training info!). It's not really a problem unless the car has either 1) done a fair amount of work i.e. fair wear and tear, 2) been abused, or 3) not had a running in service and follow up Inspection IIs with the diff oil change (the annual service regardless of mileage is a load of crap, but the car must be serviced according to mileage).
A worn gearbox (generally only higher mileages), engine/gearbox/diff/subframe mounts, prop CVs, prop bearing, or diff input bearing will lead to a clunk. I've read on other forums people describing an 'M clunk’, which is nonsense IMO. The cars don't so that if they are in good condition and driven correctly. SMG clunks in S5 or S6 if you are heavy handed, but that’s not a problem per-se.
A JC racing rebuilt standard diff should serve another 60k+ miles, or (lots) more if looked after.
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