Any Clutch / Gearbox experts on here? Strange problem...
Discussion
I got a new uprated clutch (ATC) about a year ago from my tuner and have realised there's a problem somewhere, but not sure what it could be caused by. Car is a Mazda MX-5 Mk3.
Most importantly: This issue ONLY occurs when the engine (bay) is warmed up. It never occurs in the first few minutes of driving.
Here's the symptoms:
- Holding the brake (or whit handbrake engaged) when pressing the clutch pedal fully, attempting to select first gear, it will not go into gear. If I try to force it, the engine revs will drop and the gear lever will start to wobble in my hand. The car wants to move forward.
- If I keep the clutch pressed, but release pressure on the gearstick after attempting to put the car into gear, then put pressure on the stick again, it will go into gear.
- Alternatively, if I keep the pressure on the gearstick and blip the throttle, it will go into gear.
- If I don't hold the brake and try to put it into first with the clutch pressed fully, the car will roll forward.
- If the car is already rolling, then it'll go into first without the trick of releasing pressure on the gearstick then applying pressure again.
Other point that may be of note is the biting point is very low to the floor.
I must stress again that all these symptoms ONLY occur with a warm engine bay.
Can I get any opinions from any experts on here as to what could be causing this issue, and/or potential fixes?
Most importantly: This issue ONLY occurs when the engine (bay) is warmed up. It never occurs in the first few minutes of driving.
Here's the symptoms:
- Holding the brake (or whit handbrake engaged) when pressing the clutch pedal fully, attempting to select first gear, it will not go into gear. If I try to force it, the engine revs will drop and the gear lever will start to wobble in my hand. The car wants to move forward.
- If I keep the clutch pressed, but release pressure on the gearstick after attempting to put the car into gear, then put pressure on the stick again, it will go into gear.
- Alternatively, if I keep the pressure on the gearstick and blip the throttle, it will go into gear.
- If I don't hold the brake and try to put it into first with the clutch pressed fully, the car will roll forward.
- If the car is already rolling, then it'll go into first without the trick of releasing pressure on the gearstick then applying pressure again.
Other point that may be of note is the biting point is very low to the floor.
I must stress again that all these symptoms ONLY occur with a warm engine bay.
Can I get any opinions from any experts on here as to what could be causing this issue, and/or potential fixes?
Edited by tolksee on Thursday 13th September 13:33
TooMany2cvs said:
Clutch isn't releasing properly.
^^^ That.tolksee said:
I got a new uprated clutch (ATC) about a year ago
Perhaps the geometry of the pressure plate has changed such that the release mechanism doesn't have enough travel for the new clutch.If you keep driving with this problem it's reasonably likely that you will wear out the gearbox synchro hubs which will make gear selection difficult even after you fix the clutch. Go further so that you damage the balk rings and the damage could be more expensive.
Edited by GreenV8S on Thursday 13th September 14:29
Steve_D said:
Don't just bleed it change the fluid.
This.DOT brake fluid is hygroscopic - it absorbs moisture from the air. It then rusts out master and slave from the inside, if it's not changed regularly - ideally every couple of years. Few people bother with brakes. Even fewer bother with clutch.
TooMany2cvs said:
Steve_D said:
Don't just bleed it change the fluid.
This.DOT brake fluid is hygroscopic - it absorbs moisture from the air. It then rusts out master and slave from the inside, if it's not changed regularly - ideally every couple of years. Few people bother with brakes. Even fewer bother with clutch.
sure some may do but trust me in percentage terms its small and worse still some charge for it and dont do it 
like mentioned purge the old stuff out completely 
it never makes things worse only improves action Sardonicus said:
it never makes things worse
I did have a clutch master die once while bleeding the new fluid through - as it moved down a different part of the bore, it just ripped the seals apart. When I took the old one apart, it was more a question of how it had still been working. Looked like something out of the Titanic...You can try putting the car in 1st gear,keep the clutch pedal pressed and start the engine,then release the clutch slowly to find the biting point,this should give some idea of how much pedal travel there is to help diagnose if the clutch is not disengaging properly due to already mentioned fluid/cylinder issues.
Another possible cause of your symptoms could be that the friction plate splines are a tight fit on the g/box input shaft and it was forced on during installation,there may be just enough clearance when everything is cold and the clutch is operated that it works correctly but as it warms and there is slight expansion the friction plate may still be spun by the flywheel as it doesn't totally break contact with it.not such an issue when on the move but awkward for pulling away from a standstill.
ETA oops,I see the op mentions a low biting point already.
Another possible cause of your symptoms could be that the friction plate splines are a tight fit on the g/box input shaft and it was forced on during installation,there may be just enough clearance when everything is cold and the clutch is operated that it works correctly but as it warms and there is slight expansion the friction plate may still be spun by the flywheel as it doesn't totally break contact with it.not such an issue when on the move but awkward for pulling away from a standstill.
ETA oops,I see the op mentions a low biting point already.
Edited by garagewidow on Sunday 16th September 11:24
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