[mob17]

I have a 2008 E92 335D which is tuned to 420bhp/620ft.lbs torque, and need to stiffen the rear a bit.

So i am looking to replace my front and rear control arms with m3 ones in a few weeks (tension struts, wishbone, upper link and guide rods). I will also be asking the shop to replace the standard 335 subframe bushes with solid AKG 75D ones.

My question is, will i save a lot on labour costs by upgrading the diff bushes at the same time, or will it not make much of a difference? Seeing as i'm going solid for the subframe, i gather going softer for the diff is recommended, such as powerflex yellow/purple?

[feuer]

Originally Posted by mob17

I have a 2008 E92 335D which is tuned to 420bhp/620ft.lbs torque, and need to stiffen the rear a bit.

So i am looking to replace my front and rear control arms with m3 ones in a few weeks (tension struts, wishbone, upper link and guide rods). I will also be asking the shop to replace the standard 335 subframe bushes with solid AKG 75D ones.

My question is, will i save a lot on labour costs by upgrading the diff bushes at the same time, or will it not make much of a difference? Seeing as i'm going solid for the subframe, i gather going softer for the diff is recommended, such as powerflex yellow/purple?

Leave the diff bushes alone and instead get a lockdown kit and install it yourself.
Photo borrowed from vwetish on n54tech

[justpete]

Originally Posted by mob17

I have a 2008 E92 335D which is tuned to 420bhp/620ft.lbs torque, and need to stiffen the rear a bit.

So i am looking to replace my front and rear control arms with m3 ones in a few weeks (tension struts, wishbone, upper link and guide rods). I will also be asking the shop to replace the standard 335 subframe bushes with solid AKG 75D ones.

My question is, will i save a lot on labour costs by upgrading the diff bushes at the same time, or will it not make much of a difference? Seeing as i'm going solid for the subframe, i gather going softer for the diff is recommended, such as powerflex yellow/purple?

With that much torque you might consider spherical bearings instead of bushings on the trailing links as well to keep the rear caster more constant.

[mob17]

Feuer: I have seen those around and was thinking to do the lockdown kit, as it's quite an easy job. But does it negate the need to do anything to the OEM bushes, ie once the lockdown kit is fitted, does it matter what diff bushes i have?

Originally Posted by justpete

With that much torque you might consider spherical bearings instead of bushings on the trailing links as well to keep the rear caster more constant.

Do you have any links/part numbers for the spherical bearings you mention?

[feuer]

Originally Posted by mob17

Feuer: I have seen those around and was thinking to do the lockdown kit, as it's quite an easy job. But does it negate the need to do anything to the OEM bushes, ie once the lockdown kit is fitted, does it matter what diff bushes i have?

Even if you install solid diff bushing the diff will continue twisting because there are only 3 mounting points. You could upgrade the bushes but I don't think you will have to if you have a lockdown kit. Solid bushes on top of cost will also add vibrations and harshness.

[justpete]

Originally Posted by mob17

Do you have any links/part numbers for the spherical bearings you mention?

http://www.bimmerworld.com/Suspensio...aring-Set.html

[mob17]

Originally Posted by feuer

Even if you install solid diff bushing the diff will continue twisting because there are only 3 mounting points. You could upgrade the bushes but I don't think you will have to if you have a lockdown kit. Solid bushes on top of cost will also add vibrations and harshness.

Thanks feuer. I think i will leave the diff bushes then, and evaluate after the install if i still feel i need some improvements. If so then i will go for the lockdown kit

Originally Posted by justpete

http://www.bimmerworld.com/Suspensio...aring-Set.html

Thanks, they are unfortunately out of stock. I had a search and found your build thread. Very impressive! Also found the OEM part number: 33326775551

If i have understood what i've read, the oem part above needs to be machined down to 48mm?

Should i go for the genuine part, or will TRW branded be ok? And i am assuming i'll need 4 to replace them all?

[mweisdorfer]

Originally Posted by feuer

Leave the diff bushes alone and instead get a lockdown kit and install it yourself.
Photo borrowed from vwetish on n54tech

Do you have a link for this tool?

[feuer]

Originally Posted by mweisdorfer

Do you have a link for this tool?

here it is:
http://www.n54tech.com/forums/showth...t=28937&page=6

[justpete]

Originally Posted by mob17

Thanks, they are unfortunately out of stock. I had a search and found your build thread. Very impressive! Also found the OEM part number: 33326775551

If i have understood what i've read, the oem part above needs to be machined down to 48mm?

Should i go for the genuine part, or will TRW branded be ok? And i am assuming i'll need 4 to replace them all?

Didn't notice that, bummer. Good find on the OEM P/N and yes, 48mm sounds right. Pretty sure genuine or TRW parts are fine, if not identical. And yes, you'll need four. If I'm not mistaken I think these may fit the stock toe arms as well but couldn't swear to it.

[mob17]

Originally Posted by justpete

Didn't notice that, bummer. Good find on the OEM P/N and yes, 48mm sounds right. Pretty sure genuine or TRW parts are fine, if not identical. And yes, you'll need four. If I'm not mistaken I think these may fit the stock toe arms as well but couldn't swear to it.

Thanks Pete. I'll see if i can get them in time and if the shop can machine them. I don't suppose you know exactly what has to be machined? Is it just the top and bottom of the length of the bearing to enable fitment?

[justpete]

Originally Posted by mob17

Thanks Pete. I'll see if i can get them in time and if the shop can machine them. I don't suppose you know exactly what has to be machined? Is it just the top and bottom of the length of the bearing to enable fitment?

That's what I recall, yes. The shop should be able to figure it out if they have machining experience, it seems to me.

[Phil325i]

Another one here:

[feuer]

Originally Posted by Phil325i

Another one here

That will not fit on all e9x as some do not have the holes in the subframe and one would have to drill. Is OK product but VWETISH is far superior.

[mob17]

For alignment i currently have:

Front camber -1
Front toe 0.06
Rear camber -1.5
Rear toe 0.07

After the m3 arms i should have more front camber and hopefully will keep toe close to 0.05. But for the rear, what camber and toe is suggested?

[justpete]

Originally Posted by mob17

For alignment i currently have:

Front camber -1
Front toe 0.06
Rear camber -1.5
Rear toe 0.07

After the m3 arms i should have more front camber and hopefully will keep toe close to 0.05. But for the rear, what camber and toe is suggested?

You'll need to put the front toe at zero once you have both M3 arms installed. Rear camber and toe should be in spec for your car.

[mmmnot]

Originally Posted by feuer

Leave the diff bushes alone and instead get a lockdown kit and install it yourself.
Photo borrowed from vwetish on n54tech

I am going to have to respectfully disagree. Doing subframe and diff bushings (solid) drastically improved rear end stability and a much more planted feel over dips/bumps on a track.

Now, take that with a grain of salt as I just have a 328 with little power to 'lock down'

[feuer]

Originally Posted by mmmnot

I am going to have to respectfully disagree. Doing subframe and diff bushings (solid) drastically improved rear end stability and a much more planted feel over dips/bumps on a track.

Now, take that with a grain of salt as I just have a 328 with little power to 'lock down'

I'm assuming you had them done at the same time, correct? If yes it is impossible to determine which contributed and which did not.
Also, is your car MT or AT ?
328i AT with 255tq will cause very little diff twisting, MT would do more but a lot less than FBO 335i with double the torque!
Rear end stability and planted feel over dips and bumps is most definitely improved by the subframe bushings not the diff bushings.
The solid diff bushings would excel only during hard launches and gear shifts where the soft OEM bushes would smush and allow the diff to twist.
But, like I previously stated, there is only 3 mounting point so it will still continue to twist even with solid bushings because there is only 1 bushing in the rear which is also not centered like the fronts are.
That is why the wheels hop, well usually only one, and lockdown kit is the remedy for that.

[mob17]

Originally Posted by justpete

You'll need to put the front toe at zero once you have both M3 arms installed. Rear camber and toe should be in spec for your car.

I did wonder whether i should use zero toe last time i had it aligned. I think i will go for zero this time. If im on -1 camber now, how much do you think i'll gain with the m3 arms?

[mmmnot]

Originally Posted by feuer

I'm assuming you had them done at the same time, correct? If yes it is impossible to determine which contributed and which did not.
Also, is your car MT or AT ?
328i AT with 255tq will cause very little diff twisting, MT would do more but a lot less than FBO 335i with double the torque!
Rear end stability and planted feel over dips and bumps is most definitely improved by the subframe bushings not the diff bushings.
The solid diff bushings would excel only during hard launches and gear shifts where the soft OEM bushes would smush and allow the diff to twist.
But, like I previously stated, there is only 3 mounting point so it will still continue to twist even with solid bushings because there is only 1 bushing in the rear which is also not centered like the fronts are.
That is why the wheels hop, well usually only one, and lockdown kit is the remedy for that.

Correct - both at the same time - AT. Honest to God - my most favorite and noticeable upgrade thus far. Plus, I like the stiffer/harsher ride.

[justpete]

Originally Posted by mob17

I did wonder whether i should use zero toe last time i had it aligned. I think i will go for zero this time. If im on -1 camber now, how much do you think i'll gain with the m3 arms?

I think the lower control arm adds 0.7* but don't quote me...

Pretty sure zero toe is the M3 alignment spec. But I'm running with toe out so probably best to listen to the experts.

[mob17]

Cheers pete.

Anything else i should be looking at while the rear subframe is down...?