[tryffis]

So i managed to blow my stock diff, thanks to the wheelhop issues and now found m3 salvage parts for reasonable price. So im going for the rear subframe+driveline swap along with brakes etc. and already checked that only lower spring pads and bump stops on the struts differ on misc parts, since oem suspension has been removed on the salvage car.

I could also fit front knuckles along brakes, so i could fit full m3 coilover or spring+shock set. Now the question is that how does 335 tie rods fit to m3 knuckle? I did found something related to swapping m3 steering rack with 335 knuckles u have to use inner 335 and outer m3, so does that mean that in my case its otherway round, use 335 outers with m3 inners

Edit: managed to solve my issue already, outer piece has same oe number on both cars, and found out that the diffrence in the inner one is caused by diffrence in the knuckle, not the rack. So m3 rod works for me.

[slowcar]

you should swap an m3 rack while youre in there. night and day difference in feel. feels like racecar now.

[tryffis]

Originally Posted by slowcar

you should swap an m3 rack while youre in there. night and day difference in feel. feels like racecar now.

I might do that in the future, salvage car owner just sold his rack already. Just wondering how is the steering stiffness after? Mine is a DD so does it get annoying around city corners?

[feuer]

Originally Posted by tryffis

So i managed to blow my stock diff, thanks to the wheelhop issues

Get a diff brace / lockdown kit.

[tryffis]

Originally Posted by feuer

Get a diff brace / lockdown kit.

Yeah i think that is the solution to be sure. Although only kit you can buy for m3 is defiv, wich is quite expensive piece of metal..

Just wondering that when im swapping the subframe, should i swap poly bushings to the m3 one? I know m3 bushes are quite good and less than 20k miles on parts, but will there be any difference compared to 90sha? My mate doing the work, wont take much extra from it since just pop them off under a press. Could also go solid but i think they are quite overkill for DD, and some casual trackdays.

[feuer]

Originally Posted by tryffis

Yeah i think that is the solution to be sure. Although only kit you can buy for m3 is defiv, wich is quite expensive piece of metal..

Just wondering that when im swapping the subframe, should i swap poly bushings to the m3 one? I know m3 bushes are quite good and less than 20k miles on parts, but will there be any difference compared to 90sha? My mate doing the work, wont take much extra from it since just pop them off under a press. Could also go solid but i think they are quite overkill for DD, and some casual trackdays.

Not only Defiv. I have connection in EU that makes diff lockdown for e9x m3. I can put you in touch if needed.

[iqraceworks]

If you have solid bushings in the rear subframe.... and the rear subframe is what all of the suspension components are mounted to......what does locking the diff down get you? Even if it moves around a little bit, the rear suspension parts are all mounted to the subframe, so they won't move .....right?

What am I missing??

[feuer]

Originally Posted by iqraceworks

If you have solid bushings in the rear subframe.... and the rear subframe is what all of the suspension components are mounted to......what does locking the diff down get you? Even if it moves around a little bit, the rear suspension parts are all mounted to the subframe, so they won't move .....right?

What am I missing??

The diff isn't mounted solid. Even if you have solid diff mounts they are only 3 so diff would still flex which can cause wheel hop, which can cause broken half axle, and etc...

[iqraceworks]

Originally Posted by feuer

The diff isn't mounted solid. Even if you have solid diff mounts they are only 3 so diff would still flex which can cause wheel hop, which can cause broken half axle, and etc...

I know....but that's what I don't understand. Since the diff is isolated from the rest of the suspension via the axle shafts.... why does it really matter if it moves around a little? If it was a solid rear axle I would understand, but with the IRS type suspension, the diff moving around doesn't apply any force to the rest of the suspension components......right?

Wheel hop will transfer added force to the diff gears, but I don't see how stiffening up the diff is going to lessen when hop.

Just trying to figure out the physics behind it all...

[feuer]

Originally Posted by iqraceworks

I know....but that's what I don't understand. Since the diff is isolated from the rest of the suspension via the axle shafts.... why does it really matter if it moves around a little? If it was a solid rear axle I would understand, but with the IRS type suspension, the diff moving around doesn't apply any force to the rest of the suspension components......right?

Wheel hop will transfer added force to the diff gears, but I don't see how stiffening up the diff is going to lessen when hop.

Just trying to figure out the physics behind it all...

It does. The half axle is rotating. When diff is moving around the axle rotations will have similar effect of axle that is out of balance, it will cause vibrations, wheel hop, can damage the axle, can damage the diff, can break mounts. That is why people brace the diff. If we follow the logic that it would not have effect because of independent suspension then why balance the wheels right? They won't shake the vehicle because the suspension is independent.

[tryffis]

Originally Posted by feuer

Not only Defiv. I have connection in EU that makes diff lockdown for e9x m3. I can put you in touch if needed.

Ill send you a pm.

I think im going to install those 90sha subframe bushes, just dont wanna get any regrets hence the subframe was already on the floor.
Keeping the stock at the diff and leaving option to lock it up after.