Gear Rattle + Release Bearing Chirp

[Heylin]

Actually a non Toyota question but good technical discussion question. Looking forward to advice.

I recently did an Autoclutch upgrade on a Mitsubishi Colt Ralliart Ver R (pressure plate, kevlar disc, flywheel grind) plus obtained a new release bearing (Sachs, comes mounted to fork).

Issue \ Question : 1
After install I am now getting ALOT of gear rollover noise in neutral with chirp from the release bearing and also in gear at low speed. Almost like they are coinciding with each other. Pressing the pedal in about 1 inch eliminates most of the noise and once fully disengaged perfectly fine. Car shifts fine,clutch engagement is great, no slipping, pedal feels nice. Driving at speed in 3rd gear or above = no noise.

My gut feeling is lack of pre load on the release bearing (this is a self adjusting hydraulic system) which is resulting in the bearing skipping on the pressure plate (chirp noise) + vibration that equates to more gear rattle than stock.

Any other thoughts people ???


Issue \ Question : 2
If gear rattle is still present after trying everything I can (short of reverting to stock setup again or a new gearbox $$$$$). I am tempted to try the UUC Motorwerks cocktail (Redlin 75W140NS + D4 ATF) to see if will dampen the rattle or eliminate it. Anyone know of any reason why this would be a big no no ?? apprently BMW guys use it on their Getrag boxes after lightweight flywheel upgrades and it works a treat...no detrimental effects. Note the colt has a Getrag box, and gear rattle is common. (just not as loud as I am getting it).

[sergei]

Gear rattle is normal on solid/stiff center of the clutch.

There is no preload on release bearing. If the bearing is stiff it might chirp a bit, since it touches the pressure plate fingers slightly when it is released. The chirping should go away after a while if it is the case.

[Heylin]

Its a sprung center, oem, just new facings. The clutch system is also self adjusting hydraulic so there has to be preload.

[sergei]

Its a sprung center, oem, just new facings. The clutch system is also self adjusting hydraulic so there has to be preload.

There is no adjustable preload on the the hydraulic clutch. All preload is provided by the small spring in the slave cylinder. If your slave cylinder is rusty inside it might cause chirping issues that you are describing. The spring is very weak, you can squash it with the fingers.
Try pushing lightly on the fork with fingers and see if the noise goes away.

Have you bled the clutch?

If you use synthetic oil (lower viscosity) it will make the gear rattle louder. Every single car I had with synthetic oil had gear rattle to a degree.

When you are stationary and full force on the brake, try gently pushing into 5th gear (but not engaging it, any gear will do as long as it has syncrhos), without using the clutch, just enough to make syncros work, if the rattle goes away, then don't worry about the noise. If the rattle does not go away, you probably have bearing issue.

[Heylin]

Clutch bled, feels great, good engagment. Prior to install didnt have any issue gearbox side other than light rollover and shaft seal leak. Only has 90,000 kms on the clock.

[Heylin]

Its a sprung center, oem, just new facings. The clutch system is also self adjusting hydraulic so there has to be preload.

There is no adjustable preload on the the hydraulic clutch. All preload is provided by the small spring in the slave cylinder. If your slave cylinder is rusty inside it might cause chirping issues that you are describing. The spring is very weak, you can squash it with the fingers.
Try pushing lightly on the fork with fingers and see if the noise goes away.

Have you bled the clutch?

If you use synthetic oil (lower viscosity) it will make the gear rattle louder. Every single car I had with synthetic oil had gear rattle to a degree.

When you are stationary and full force on the brake, try gently pushing into 5th gear (but not engaging it, any gear will do as long as it has syncrhos), without using the clutch, just enough to make syncros work, if the rattle goes away, then don't worry about the noise. If the rattle does not go away, you probably have bearing issue.

Ok tried it, it pretty much goes away when doing that in 4th and 3rd.

So does that mean gear rattle?

[sergei]

Its a sprung center, oem, just new facings. The clutch system is also self adjusting hydraulic so there has to be preload.

There is no adjustable preload on the the hydraulic clutch. All preload is provided by the small spring in the slave cylinder. If your slave cylinder is rusty inside it might cause chirping issues that you are describing. The spring is very weak, you can squash it with the fingers.
Try pushing lightly on the fork with fingers and see if the noise goes away.

Have you bled the clutch?

If you use synthetic oil (lower viscosity) it will make the gear rattle louder. Every single car I had with synthetic oil had gear rattle to a degree.

When you are stationary and full force on the brake, try gently pushing into 5th gear (but not engaging it, any gear will do as long as it has syncrhos), without using the clutch, just enough to make syncros work, if the rattle goes away, then don't worry about the noise. If the rattle does not go away, you probably have bearing issue.

Ok tried it, it pretty much goes away when doing that in 4th and 3rd.

So does that mean gear rattle?

Yep. Don't worry about it .

[Heylin]

Its a sprung center, oem, just new facings. The clutch system is also self adjusting hydraulic so there has to be preload.

There is no adjustable preload on the the hydraulic clutch. All preload is provided by the small spring in the slave cylinder. If your slave cylinder is rusty inside it might cause chirping issues that you are describing. The spring is very weak, you can squash it with the fingers.
Try pushing lightly on the fork with fingers and see if the noise goes away.

Have you bled the clutch?

If you use synthetic oil (lower viscosity) it will make the gear rattle louder. Every single car I had with synthetic oil had gear rattle to a degree.

When you are stationary and full force on the brake, try gently pushing into 5th gear (but not engaging it, any gear will do as long as it has syncrhos), without using the clutch, just enough to make syncros work, if the rattle goes away, then don't worry about the noise. If the rattle does not go away, you probably have bearing issue.

Ok tried it, it pretty much goes away when doing that in 4th and 3rd.

So does that mean gear rattle?

Yep. Don't worry about it .

Hmmm thought as much.

Not much of a fan of it, but I guess that's the Trade Off.

Soo next question, is worth trying the Redline 75W140NS + D4 ATF cocktail to quieten it up a little ?

[Heylin]

Ok so i added the uuc redline cocktail, no difference . Im just gonna drive it and look at going back to oem clutch and new gearbox for good measure.

Got me stumped how a pressure plate uprate and different facing material could cause gear rattle to that extent.