I read somewhere (Modfied Magazine) that using a slightly heavier oil in the tranny can quiet a noisy lightweight flywheel (cement mixer sound). This was in an article in which they installed a JWT flywheel. They recommended Redline Heavy Shockproof as seen here:

http://www.redlineoil.com/products_g...6&categoryID=6

Does anyone have experience with this? I am asking because I just installed an ACT Prolight and its very noisy. I didn't have any 75w90 like Nissan recommends, but I did have some Reline MTL (which is 75W80 - thinner than the stock spec, although redline says that it can thicken to 85w when the temperature rises, which might explain why the cement mixer noise seems quieter when the car is warmed up). I used the MTL and I am thinking that it might be too light. Here is the MTL that I used:

http://www.redlineoil.com/products_g...p?categoryID=7

If nothing else, I think MT90 would have been better than MTL.

 

That sound has nothing to do with the trans. I can't imagine changing fluid would do anything.

 

actually the sound has everything to do with the transmission - that is where the noises come from. The OEM flywheel just dampens it out by virtue of its dual mass design

http://www.high-impact.net/transmiss...svsSolidFW.htm

 

If oil quiets a flywheel-clutch let me know how? My limited mechanical knowledge says that there better not be oil in either of the components. Correct me if I an wrong.

 

I might of misread it but are you hoping there is no oil in your trans?!?!?!

 

you're missing the point

the noises are there already - no matter what flywheel you use, stock to aftermarket. The factory dual mass unit dampens these noises, the aftermarket single mass units have no way to dampen them...and as such, the noises are heard (the chatter that people desribe). Using a heavier weight could help to dampen these noises, just as using heavier weight oil in any other component can dampen such sounds (valvetrain noise, ring and pinion whining, etc etc). However, using heavier oil can have it's own effect on components. I wouldn't personally recommend it, as the transmission was constructed with tolerances designed around certain oil viscosities, but it's up to people to do their own research and decide for themselves

 

It makes sense that the single mass flywheel causes more noise to be generated in the transmission, not the flywheel itself. I don't see how a clutch/ flywheel could really rattle when they are rotating together and not touching anything else. But if the vibrations thransmit through the transmission input shaft to the gears themselves, I could see the gears rattling together.

Thanks Z1 - I understand your concerns about tolerances, etc. I'm not sure if it helps, but Redline does clain that this "shock proof" stuff has some really weird properties where it acts like a 75w90 oil except under cetrain circumstances. From Redline's site:

"The viscosity characteristics allow the lubricant to resist throwoff and provide a film thickness similar to a 75W250 grade, while providing the same low fluid friction as an SAE 75W90"

I guesss you would be concerned about this stuff acting like the 75w250 grade in bearings and such? Might make shifting harder too.

If nothing else, I wonder if at least switching to the proper 75w90 (vs. the 75w80 I've got in there now) would help.

 

Sounds like a good way to screw up the tranny to me... I personally would suck it up and deal with the chatter.

 

<--- owned.

 

I use a 50/50 mix of MT-90 and MTL to reach the desired viscosity. If you live in a hot/warm climate (I'm in South FL, the coldest it gets is 70 ish), I don't see how a pure MT-90 tranny fill would cause issues.

 

I would NOT use the Redline Heavy Shockproof gear oil in our trans. It is not recommended for use with brass synchronizers. I use the shockproof in my rear diff and MT-90 in the trans and just deal with the drivetrain noise. It's part of the car's personality.