silver_evo

Long story short I just finished I just finished installing a rebuilt Tcase from shep with a WaveTrac front LSD. Prior to that I installed a segmented kevlar, sprung hub competition clutch and a fidanza light weight flywheel (with removable friction surface). I used the included TOB in the CC kit.

Now I have the decel noise. The noise is only present closed throttle, going down hill at 2400-3200 rpm in 4/5 gear. Clutch disengagement or even touching the throttle will stop the noise.

The noise has been described as rolling a coffee can full of marbles down a hill, or a coffee grinder full of rocks.

Transmission has 3x Redline MT-90 (per Shepard trans recommendation)
Rear diff / T-Case full of Mitsu diaqueen

I have googled the forums extensively and I've read anything between

1.) It's ok, all aftermarket clutch / light weight flywheel combos do this because there is less rotational dampening and any drive train noises are transferred easier.

2.) It's the ring and pinion. Doubt it, the new ring and pinion has 115 miles on it, and I have been very easy on it for break-in. The only way I see this as possible is if shep didn't get the shimming right on the bearings, which I also doubt.

3.) Input/Output bearings on Trans. Could be, possible, but I've also read about newly rebuild transmissions/tcases making the decel noise.

The noise is pretty loud and disconcerting. I have been clutching in when going down hill because it sounds like something is about to give out. At max noise level, it would interrupt a conversation in the car, and be loud enough to hear over the AC fan at 3 or 4.

Side note, with the AC compressor on, the noise is louder, which means it could be a pulley bearing. My drive belt has some slight rub marks on the inner side of it.

Anyone with the noise, please comment on how loud yours is and if you have had anything break from the harmonic vibrations. Also your installed motor mounts, clutch/flywheel and any drivetrain upgrade/repairs would be helpful.

thatguy5

iTrader: (1)

input shaft bearing, had the same problem

silver_evo

Can you describe your conditions, from what I've read, input bearings will make noise all the time (accel and decel), did you replace the bearing?

silver_evo

Like this poor guy, spent a ton on the input bearing

https://www.evolutionm.net/forums/9954789-post14.html

barneyb

I think #1 is correct. My '03 has been doing this pretty much since I drove it off the lot new. Before that I had a Rally game and it had a sound track for the Evo and the game made the noise.

cmspaz

iTrader: (1)

My VIII had that noise, thought it was the input shaft bearing too. But the input shaft bearing only spins with the clutch DISENGAGED. When it's engaged the shaft speeds are the same so there's no bearing movement.

Ended up being trans bearings, they just kept getting louder and I was planning to address them but ended up stuffing the car at the track so that never happened.

silver_evo

That doesn't make much sense, the input shaft of the transmission will spin with the clutch disk, either driven by the engine with the clutch engaged, or driven by the transmission being in gear with the clutch disengaged and the vehicle moving. The only time it will not spin is in neutral with the clutch disengaged, or if the vehicle is stopped in gear with the clutch disengaged. Any time the clutch is engaged, the input shaft will be spinning whatever RPM the engine is spinning at. When the clutch is disengaged, the input shaft will spin at what ever RPM you have selected per gear/speed. Also the input bearing will be spinning at idle with the clutch engaged in neutral.

Can you explain more what you meant by when the clutch is engaged, there is no bearing movement? The input shaft will be spinning.

I am not ruling out a transmission bearing, upon decel, the loading on the drive train is reversed, gears are riding on back faces and bearing's are loaded to the other side of the race. (Which is why mitsu should've used tapered roller bearings on the input shaft!!) It just seems that if the bearing race was damaged/pitted I would have this terrible noise all the time.

silver_evo

How loud was it? Could you hear it over the AC fan on 3 or 4? I'd rather not trust a video game's depiction of my car to my actual car.

cmspaz

iTrader: (1)

Haven't had my coffee yet... heh.

Sorry, I thought is was the TOB, then the input shaft bearing, but when the input shaft bearing didn't fix it I realized it was worse. A buddy reinforced the internal bearing hypothesis when he mentioned his wife's Mazdaspeed3 made the same noise, and Mazda ended up putting a trans in it under warranty.

silver_evo

Makes sense. I initially thought it was TOB also, but it doesn't rattle any other time than for decel @ 3k rpm > 50 mph. I think next time I am driving I will apply a tiny amount of pressure to the clutch pedal while it is rattling and see if it stops. Not enough to disengage the clutch because that will stop the noise. Which also doesn't really check with the input bearing because the input shaft is still spinning at the same speed, it is just unloaded and disconnected from the crank. Harmonic vibration yes, but I'm not ruling that bearing out completely yet.

Nimpoc

iTrader: (17)

I'm guessing it's the Competition Clutch. It seems like the splines on their disk are about half the length of the stock design (0.8"-1.4") leading to much less engagement. The fit also felt much looser. Together I'm thinking it leads to the nasty box-of-rocks rattling under decel.

Here are my observations:
https://www.evolutionm.net/forums/11100947-post483.html

silver_evo

I never measured the spline depth, or thought about it... It's been going on for about 1k miles now. I changed Trans/xfer fluid again, clean. It just keeps rattling, I kind of just ignore it, or make sure it's not getting louder or changing (which would be progressive damage to something) Again, only on decel > 45 mph in 4th/5th.

FYI, I have sprung hub, segmented disc CC kit

This is the one

silver_evo

94AWDcoupe

iTrader: (125)

whatever parts you last changed are causing the rattle. there is history of tcases getting loose in just 500 miles. wrong fluid choice can wear the ring and pinion down. but my guess in the flywheel is the problem. horrible choice if you had asked me. those flys were nothing but issues in the dsm work. also the rattle you hear wears parts out in short order. any and all splined connections, trans gears, tcase gears.. its like an impact wrench being using on the parts.

Quattlebot