After putting in my ACT and Gruppe-s light FW the car now has a noise when I let off the gas or downshift. It is only when the tranny is driving the engine and not vice versa. It is sort of like a grinding whine, as well as some vibration. Occasionally there is some rattling, that sounds like metal.
It is more pronounced in 3rd and 4th than other gears.

Any Ideas where to start looking????

TIA
AUS

 

act clutches make that "coffee grinder" noise during decel. its normal, mine does it too

 

Aside from the diagnosis above, here is a post made by Dirk (ACT's owner) regarding the noise you are describing. From your description it sounds like torsional vibration from the disc and lightened flywheel, but what Dirk has listed are other possible causes of the noise too.

"Flywheel: It just spins at engine speed and can't make noise unless it is rubbing against something. Of course a lighter flywheel does allow more torsional vibrations to get though to the disc and untimately the transmission which is usually the noise you hear. If the flywheel was not tightened adequately, then there is also a chance to get a noise on or off throttle from the torsional vibrations of the flywheel rattling on the bolts. If that is the case, fix it quick or you will be buying a new crankshaft and flywheel!

Pressure plate: It just spins along with the flywheel. It also functions up and down. There is no noise associated with it either unless it hits something which also would be consistent. If the relase bearing came partially detached, you will get a noise and vibration when you press the clutch pedal. Shifting becomes difficult too.

Clutch Disc: It only spins when the clutch is engaged. The disc doesn't really make noise itself, but it allows the engine's torsional vibrations to transmit to the transmission. Much of these vibrations are dampened out by the springs in the disc's center, but with different spring rates, more vibrations can pass though which means more noise, especially at idle, high gear coast and decel.

My guess is that it is probably the difference in having a stronger disc, but I am only giving a keyboard diagnosis. I don't presume to know the whole situation. If it happens to be that your flywheel is not tight enough, that is a serious issue that should be dealt with immediately. We get very few complaints about noise with the EVO, especially an 03. Most come from people running our solid race discs but that is understandable and we get some complaints from people who have the EVO 9 or other later models that originally have the really weak springs in the disc center.

Keep in mind that lighter flywheels, hot cams, more boost, aftermarket pulleys, etc all cause increased torsional vibration which means more transmission noises. Obviously I am not there to hear the noise you are encountering so I don't know if it is a normal noise or not. Please feel free to contact me directly for more information.
__________________
Dirk Starksen
President/CTO
Advanced Clutch Technology Inc. '

Here is a link to the thread

https://www.evolutionm.net/forums/sh...ghlight=actman

 

I have the same noise on my car after I installed my Cosworth cams and it is more pronounced when the A/C is on, which adds validity to what was mentioned above. FWIW it worth my car has the stock clutch.

 

I had an Excedy street clutch, a front LSD and lightened flywheel from RRE installed in my '03 Evo 10 months ago by a local mechanic. Everything was quiet before the work.

The noise was there when I got the car back. It seems to be getting gradually louder, but the change is so gradual, it's hard to be sure.

The symptom happens during deacceleration on compression. The sound goes from a rattling noise at low rpm to a low-frequency, almost a bell-like sound at higher rpm, when I back off. Slowing on compression from 60-70mph in 5th, I think of it as a bell being cut by a buzz saw. There is no unusual noise on acceleration.

RRE thinks the noise is from the transfer case; backlash in the ring-pinion alignment. Based on their recommendation, I am looking at a $50, 1 lb. can of molybdenum disulfide powder (MDP, 1-5 micron) that arrived yesterday. Dosage is 1 tablespoon per quart of gear oil. I have a can of DiaQueen LSD Gear Oil (90 SAE) and am considering replacing the TC lube with with the DiaQueen spiked with the MDP.

My other thought is to have the ring and pinion backlash checked, but the mechanic who installed it is (ahem!) hard to reach.

Let's stay in touch as we work through the problems.

Steve

 

i have also heard of this problem with people with lighter flywheels

 

I have an ACT sprung 6puck HD setup and I have minimal noise on deceleration but so far from what I've read this is normal for running the clutch setup that I have.

 

Sounds like you got the old infamous decel noise. My 03 has had it since I drove off the lot.