Cutch Help!! I'm in desperate need.

[V8<turbo4]

so i recently replaced the clutch with the following

ACT unsprung clutch kit
ACT street light single mass fly wheel

The gear rattle is so bad i can't stand it.

put 20 miles on the car and need to change something.

one tech at ACT says that using their sprung disk will help significantly with the rattle!

another tech at ACT says that using a sprung disk will barley help with the gear rattle...

ITs currently really really bad!

I'm thinking of going in there and changing out the SMFW and putting the stock DMFW in.

is this DMFW still good?

Please let me know if anyone is running a SMFW with a sprung disk and how bad the gear rattle is.

Id like to use the SMFW but its really only a 4 pound savings over stock...probably not worth it.

Car will be FBO so nothing crazy clutch i got is good for 520 torque

im not excited about the 12 hour job to change it out again so id like to make this the last time.

thanks in advance

[Ric in RVA]

Did you try the redline anti rattle gear lube mix?

http://www.uucmotorwerks.com/html_te...nny_rattle.htm

"Make: BMW
Models: All BMW models including E46, E39, E36, Z3, and Z4


BMW Transmission Rattle / Gear rattle / Gear lash noise

With most any lightened flywheel, everyone sees the benefits immediately due to the reduction of the rotation weight. However, if there is a downside, it's the possibility of a rattle sound that may be evident at idle/low rpm. Note that this particular effect is only evident at idle with the clutch let out.

For details on what actually causes the sound, click here.

Heavier weight transmission fluid will damp the rattle effect, but may not be suitable for cold climates or high-mileage transmissions. The goal, then, would be to find a fluid that would have the high-temp heavy viscosity to damp the rattle but retain the low-temp thin viscosity and synchro additives to ensure all-condition smooth operation.

After experimenting with different weight transmission lubricants, we have come up with a formula that eliminates the gear rattle in the majority of test cars.

The recipe:

1 quart bottle of Redline 75W140NS Gear Oil. ( click here to order ) The "NS" oils have no friction modifiers, thus does not increase shifting effort. From the Redline information about the gear oil: "a GL-5 which does not contain the friction modifiers for limited-slip hypoid differentials. This makes the transmission synchronizers come to equal speeds more quickly, allowing faster shifting and much easier low-temperature shifting."

and...

1 quart bottle of Redline D4 Synthetic ATF. ( click here to order ) "D4 ATF is designed to satisfy the improved low-temperature requirements which will be in the new Dexron IV specification, and the improved shear-stability requirements which will be part of the new Mercon specifications. The balanced frictional characteristics provide smooth and consistent shifts for extended drain intervals. Provides improved shifting in cold weather."

How to use:

Drain the transmission (preferably when warm so as to allow as much of the original fluid to drain). Put in the full bottle of 75W140NS, then fill the remainder with the D4 ATF. Note that the majority of BMW transmissions will not take 2 complete quarts, so you will be left with approximately 1/5th of the bottle of D4.

HOT CLIMATE MIX

If you live in an area that is normally hotter than average (California or any Southern or SouthWestern state) then the ambient temps might make your transmission run hotter. In turn, this lowers the viscosity of the transmission fluid, which lessens it's ability to damp the gearbox rattle. Such being the case, we suggest substituting Redline MT-90 for the D4 ATF. So the mix is 1 bottle 75W140NS and the remainder of 1 bottle of MT-90.

MT-90: "MT-90 Manual Transmission Lubricant; a 75W90 GL-4 gear oil designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting." ( click here to order )"



Probably help some and easier than a flywheel swap.

[V8<turbo4]

thanks for the suggestion but i think this rattle is to much for fluid to fix I'm sure it will help but i think some parts need to change

[bNks334]

Originally Posted by Ric in RVA

Did you try the redline anti rattle gear lube mix?

I can't see this as being good for the transmission... You are mixing fluid with 100c viscosity of 6.x (D4) with a fluid with 100c viscosity of 25.x (75-140NS)... BMW calls for a fluid with a 100c viscosity of 6.x... which means you should be using straight D4.

That mixture produces a significantly thicker fluid. How would that NOT negatively impact the transmission? I know the N55 specifically uses low friction synchros that need the thinner viscosity fluid. Gear rattle is gear rattle and fluid shouldn't be used to dampen noise, in my opinion.

OP, raise your idle. That's about the only real solution. Or, go back to a DMFW which dampens the vibrations.

[MightyMouseTech]

I use MTL which has a 100 C vis of 10.4. Trans likes it, but would not use in below freezing. But even with my stock clutch and flywheel, still have rattle when warm.

The only real way to fix OP's issue is to go back to a DMFW and a sprung disk. Why did you go to the single mass and unsprung disk? Are you making more than double stock torque?

Even FBO, I would only go with the 550 clutch.

[HawkeyeGeoff]

Spring disc will fix a lot of the rattles; the problem with it all is that some clutch discs and SMFW are more likely to exhibit this behavior because of their balance. Aftermarket companies do not do as good of a job at getting the balance correct as say a company like LUK therefore some will be worse than others.

My professional opinion is that you just got a worst case scenario clutch/FW combo.

If you are sensitive to the issue I'd switch back to a DMFW w/ 335is/550 clutch if you're staying stock turbos.

[V8<turbo4]

thanks I'm leaning towards putting in a sprung disk

[WaxedE82]

hey. i'm having some clutch problems as well. really just posting here to gain access. hope your problems have been fixed!