I was hoping someone with some real tech knowledge might be able to help me here, one of the problems I've had with my car was gearbox related, specifically seemed to be clutch.

Basically was having some problems where the clutch was starting to slip, so my mechanic adjusted the pedal height so it was better - and the determination was basically that it wasn't able to fully engage as it was hitting the top of the pedal (and it had 0 freeplay) - all good then. But it also always felt a bit like it wasn't fully disengaging either because gears would crunch and that sortof thing sometimes when changing a bit - even from stationary.. but it was fine to sit in neutral in first, etc.

Now I've just recently replaced my clutch, which has made things generally a LOT better.. much smoother in gears and stuff but it still feels a bit funny sometimes and seems related to the synchros.. and I'm wondering if it's still the case where my clutch isn't quite disengaging fully - or if my synchros are problematic and I need to look at getting the gearbox serviced/rebuilt internally or if something else is up. (Also FYI, transmission oil has been changed, currently running Penrite 75W-80 GL4)

I had a real extreme case today, I was driving home in the stupid perth storm whether.. busy so off/on the clutch a fair bit, and also was driving through quite a lot of puddles / really deep water like.. up into the engine bay sort-of stuff and my clutch point slowly sunk to the floor where my friction point was basically a billimeter off pulling the clutch up.. actually got to the point where I couldn't really change gears because I think it wasn't quite disengaging properly so I drove quite a bit of the end of the way to my mates place in second gear and my foot planted on the clutch the entire long wait at traffic lights.

Now with the friction point moving up in this case (something I haven't experienced before) - I don't really understand mechanically why that would have happened and the only thing I can possibly theorize that to be might be its not been bled correctly and has air in it, which I will get back too.. (because I'm going to do that to double check)

But I'm also quite curious by the fact that, with the clutch pedal fully to the ground - sometimes its a bit hard to get into 1st, sometimes not.. but interestingly if I blip the throttle slightly (especially when slowly rolling rather than stopped).. it helps it fall into gear.. and I'm quite confused because I would think that if the clutch pedal is fully disengaged.. I didn't think any power should transfer to the gearbox or synchros and that blipping the throttle shouldn't do anything.. leading me back to my wandering if the clutch isn't fully disengaging.


I'm sorry if I'm a n00b and this is obvious but I'm trying to understand it.. in all honesty I am probably going to go see someone about it (esp. since if something is broken I might be able to make a claim on my used car warranty to get it sorted) - but if someone that really knows about the situation, or who has experienced similar stuff could comment / help me understand i would really appreciate it.


Over-all I'm trying to determine if the symptoms I'm seeing (hard to get into gear sometimes, even when stationary, sometimes it feels a bit funny/bitey on the way out of first into second as well).. is going to be the clutch not fully disengaged which also explains the throttle blip/easier shift thing even when stationary.. and if so, if that is more likely air in the clutch as I suspect it is... or if I'm totally wrong and anyone has some better ideas. :)


Sorry for the wall of text, any input appreciated...

Thanks,
Trent

If you are losing pressure in the system you may have either a leaking master or slave cyl. That would be my first port of call

As for a little rev when changing gears assisting, this will be similar to rev matching when down shifting and is also letting the box settle for a minute between changes, you will most likely find if you just pause for a split second will have the same effect

Get your cylinders checked first and then you can go from there, no good looking at the box if you have a slave or master cyl issue

If you are losing pressure in the system you may have either a leaking master or slave cyl. That would be my first port of call

As for a little rev when changing gears assisting, this will be similar to rev matching when down shifting and is also letting the box settle for a minute between changes, you will most likely find if you just pause for a split second will have the same effect

Get your cylinders checked first and then you can go from there, no good looking at the box if you have a slave or master cyl issue

Would a leak also have caused the pressure to have come back after sitting for a bit? And it's usually fine?

Using the clutch a lot and finding the take up point sinking lower and lower is a clear indication of an internally leaking master cylinder, pull it apart and check the rubbers for wear on the lips. Should be able to get a repair kit from a brake shop or Mitsu. A leaking slave cylinder shows up as dropping fluid level in the clutch master cylinder reservoir. Also check that the pressure relief port in the master cylinder is not blocked, as this allows fluid to flow back into the system when the clutch is up, this won't happen if the port is blocked or there is no freeplay at the top of the clutch pedal travel.
For a quick but expensive fix, get both cylinders replaced, system bled and pedal height adjusted. Then if you have further problems, it will be the clutch itself.

Using the clutch a lot and finding the take up point sinking lower and lower is a clear indication of an internally leaking master cylinder, pull it apart and check the rubbers for wear on the lips. Should be able to get a repair kit from a brake shop or Mitsu. A leaking slave cylinder shows up as dropping fluid level in the clutch master cylinder reservoir. Also check that the pressure relief port in the master cylinder is not blocked, as this allows fluid to flow back into the system when the clutch is up, this won't happen if the port is blocked or there is no freeplay at the top of the clutch pedal travel.
For a quick but expensive fix, get both cylinders replaced, system bled and pedal height adjusted. Then if you have further problems, it will be the clutch itself.

Hrm thanks for that.. to clarify - the internally leaking part - this would also mean that it would sortof fix itself afterwards? As it equalises back out? (Because that's what happened.. sat for a bit and it's OK... and it has never happened before but this was probably the peakiest traffic i've ever driven in)

It goes back to normal, yes. The fluid refils the pressure chamber through the pressure release port. BUT the seals can go worse at anytime and you will have no clutch! Any time now, maybe the next time you depress the pedal . . . .

It goes back to normal, yes. The fluid refils the pressure chamber through the pressure release port. BUT the seals can go worse at anytime and you will have no clutch! Any time now, maybe the next time you depress the pedal . . . .

OK thanks heaps.. I'll look at this.

Easy test - start the car, put it into first, and keep the clutch down, handbrake off. If the master cylinder has an internal leak, the car will try to move forward as the fluid leaks past the seal and the clutch engages. If this happens turn the engine off so you don't drive into anything. lol Might take a minute or two, but try it anyway. If its ok, try this test randomly when you use the car, as it may be an intermittent problem.

By all means look into it - a kit and a bottle of brake fluid now are much cheaper than a towtruck later!