6G Celicas Forums

Hi Lar,

maybe I didn't explain correctly...

I'm not having a gear problem, I'm quite sure, I personally rebuilt my gearbox, and I'm not getting noises on changing gears...

when I told you harsh disengagement, I was talking about clutch disengagement, that is to say when you press the clutch pedal ( engage ), change the gear, and then release the pedal ( disengage ).

When you upshift, fw is making more rpm than the clutch plates, this is why the engine turns rearward on the supports;
but when you are downshifting and releasing the clutch pedal, fw is making less rpm than the clutch plates ( and in fact you could see the engine rotate forward on the supports ).

So when I downshift the gears I have not one problem, but when after that I even release the clutch pedal, I'm getting instant disengagement ( even if I'm releasing the pedal ssssllllllooooooowwwwwllllyyyyy ), harsh clunk and strong hit on the car.

I already checked for the exhaust touching somewhere in the crossmember zone, and it isn't.
Moreover I'm getting this noise from the clutch zone.

That's why I'd like to know from you, as the only one person over me using that clutch!, how are your feelings when you downshift and then release the pedal.

PS: there is not a cable for upshifting and one for downshifting: one moves the gear leverage forward/rearward, and the other one left/right, so you use all the two lines for up and down shifting.

Thakn you, bye.

Hi Wolf_tm....

I see... I see... I think I understand what you are trying to say.

After reading... ", but when after that I even release the clutch pedal, I'm getting instant disengagement".
The first thing that pops up is your clutch pedal.

Ok... Try this, drive your car to 3rd gear@3000rpm and hold it then downshift to 2nd gear without releasing your gas pedal.
If your harsh clunk and strong hit on the car is gone then you can just adjust your clutch pedal to have a longer disengagement distant.

When you had your GD newly installed, did you have your clutch pedal adjusted for a longer disengagement distant as well??

When I had my GD newly installed, I had to adjust my clutch pedal a few times to get my comfortable disengagement distant to sync with my right foot.


Anyway, if my suggestion does not work....... . Well.. We've figure something out ok.


Cheers,
+: Lar' :+

I just checked the pedal, and I already have the leverage to be the longest possible...

I changed the oil already two times, looking for bubbles in the circuit.

I'm going to think I could have assembled it in the wrong way... every piece of the clutch is one way, you could not assemble it in the wrong way... except one... the spacer that stays between the two disks:
you could mount it with the spring upward or downward... and the manual doesn't talk about it...

No no.... but looking at the manual, the top spacer has the spring downward, so I mounted the middle spacer with the spring downward too... then I think the problem is not here...

Thank you, bye

Hi Wolf_tm...

How long have you been using your GD clutch??


Cheers,
+: Lar' :+

My engine is new, and I'm making the running-in... the clutch has around 300 kms...
did you have the same problems when it was new ?

I'm going to think it could even be an engine bushing problem...
upshifting and releasing the clutch, the engine turns backward, but downshifting and releasing, the engine moves forward:
the front engine bushing it's new, but it could be possible that I gave it not enough preload ( there is a "buttonhole" on the front bushing support, and an arrow on it tells you to push up the engine and then tighten the bushing bolt )

Bye !

Hi Wolf_tm....

I had discussed your clutch problem with my mechanic friend.
He said that there is no problem with the clutch.
You had change the clutch fluid twice and there are no bubbles(I assumed) in the system.
Therefore, your clutch master cylinder is fine so your clutch pedal would still give precise engagement and disengagement motion.
His last opinion was maybe you are still new to engage and disengage the twin plate clutch and need more time sync the rhythm and timing with your gas pedal.

Since you mentioned the engine bushing support. I remembered my clunking and a strong hit problem, but a little different from yours.
The "clunking" occured during clutch disengagement only as well, but in both upshifting and downshifting the gear.
My "strong hit" was from the rear of the car. The culprits were the gear bushing support and the rear differential bushing support. They were both cracked up and torn.
This may not be the solution to your problem, but there is no harm checking your gear and rear diff bushing supports.


To answer your question... "did you have the same problems when it was new ?"
No... I did not this problem when I newly installed my GD.
The only problem that I had was launching my car on 1st gear in a traffic jam. It took me 1 whole day to sync my left foot with my right foot. Then I got my clutch pedal adjusted to my comfortable disengagement distant, after that every gear change was fun.


Cheers.
+: Lar' :+

I hope he is right !





I even tried MANY times to release very very very... VERY slowly, 1/10 of a mm at a time, the pedal, but when the disc touches the flywheel....... KABOOOOOM ! immediately all the clutch is totally disengaged !

I read somewhere this could be due really to the front engine bushing, not correctly preloaded, that makes the engine to wind...

I will try to give it more preload then...


Thank you !

Bye

", but when the disc touches the flywheel....... KABOOOOOM ! immediately all the clutch is totally disengaged !"....

Yap... That's the main concept of a multi plate(disc) clutch, to make the disc grab the flywheel as quickly and as firmly(minimum slippage) as possible.
The quicker the disc catches the flywheel, the lesser the energy loss from the flywheel = more energy goes to the drive train.

Unlike a single plate clutch, there will always be some slippage of the disc with the flywheel.
This slippage would give some ease while the clutch is disengaging, so you won't feel that clunking or jerking motions.
However, some energy from the flywheel will be lost(due to slippage) in exchange for the comfort in clutch disengagement.

2 of my friends sold away their OS Giken twin plate clutch set after using it for only 1 week. They can't fully controlled and were tired of the heavy and fast total disengagement of the clutch.


"I will try to give it more preload then..."

Please come back and update when you have given the front bushing more preload ok??
Man... I wish I could be in Italy right now. I really want to check out what's going on with your GT-4.


Cheers,
+: Lar' :+

Hi Lar,

I re-make the front engine bushing with harder rubber,
and now the chattering almost totally disappeared !

Thank you