Clutch bite point changing as engine warms up... Normal for Exedy stage 1?

[KK-M5]

Hi everyone, new on this forum, but long time owner.

So here's a really odd one. Just before the lockdown started in March, I had a new clutch fitted to my Rev2 Turbo. I decided to go with a stage 1 Exedy, as a means of future-proofing, in case I run more boost at some point. The work was carried out by a very well-known MR2 specialist here in the North West, well, technically he's in North Wales, I'll leave it at that. Parts were supplied by the garage, except the fluid, which I asked to be flushed out for some Castrol SRF that I provided.

My issue is as follows. I set the biting point myself so that it would match the point from the old clutch, and it does (about half way up the travel of the pedal). However, as the engine warms up, the bite point moves up as well. At normal operating temperature, the clutch bites at the very top of the pedal's travel. And I mean literally AT THE TOP. If you're driving along, as soon as you barely touch the pedal, the clutch disengages. It's incredibly annoying! Once the engine has cooled down, biting point returns to normal (about half way), and then when I drive it again, as the engine gets up to temp, bite point steadily moves up to the top of the pedal again...

Spoke to the garage on the phone, they said they'd never had this happen and that they could look into it. Now the car is actually there for some other work, and they tell me that this is how uprated clutches behave, and that it's normal. They even claimed it's the same principle as having more aggressive brake pads, where the friction material grabs more with heat. And that's when alarm bells started ringing!!! I have Pagid RS29 pads on my other car and know exactly how they behave. If what they claimed was true, the effect would be the exact opposite.

There's no leaks anywhere in the system, and part of the bottle of brake fluid I supplied, I had actually used in my other car a week prior, so I am positive it has nothing to do with that.

I truly hope someone can shed some light on this. I like this new clutch, but am now seriously thinking about biting the bullet and going back to a stock clutch.

Even if you don't know what the problem could be, do you think this is normal by any chance, because it certainly doesn't make any sense to me.

Thanks

[Race Idiot]

Exedy stage 1 should pretty much feel like a standard clutch as far as I remember.

Surely the biting point should be fairly low on a new clutch anyway?

I run a twin plate clutch that has a tiny biting point but it doesn't move around

[KK-M5]

Thanks for your reply.

It's a pretty smooth and mild clutch, like the stock one. Just requires a bit more effort on the pedal due to greater clamping force I imagine.

Any more views on this would be very welcome, I would really like to get to the bottom of this.

I've done over 1000 (annoying) miles with this clutch, so it's well broken in too.

[oVerboost]

What about if you set the bite point once it's hot? Is it then too low when it's cold?

[KK-M5]

Yes, exactly that. If I set the bite point about half way when the engine's hot, then when it cools all the way down, the bite point is literally a couple millimetres off the floor.

[oVerboost]

Yes, exactly that. If I set the bite point about half way when the engine's hot, then when it cools all the way down, the bite point is literally a couple millimetres off the floor.

Can you bleed the clutch line on MR2's? It could be fluid related thats changing due to temperature.

[KK-M5]

Clutch line was bled, fresh fluid used.

[yokomomr4bx]

I fitted an Exedy stage 1 myself about 5/6 years ago and the bite point started about 1 inch off the firewall and is still in that same place now. Hasn't mattered if the engine is hot/cold/summer/winter, hasn't changed one bit. Damn good clutch, although I'm religious about not riding it or holding it down in traffic etc.

Truth be told I wasn't aware you could change the bite point on our clutches...? How did you go about initially adjusting it when you said you set it up so it was about half way through it's travel?

[fastasfkk]

i had an exedy stage 2 5 years superb clutch never moved

[KK-M5]

Thanks for all your input guys. There's definitely something wrong then.

The bite point can be adjusted on the pedal itself. If you contort yourself in a certain way and look at the top of the clutch pedal under the dash, you will find a locking nut on a rod. Undo the locking nut and twist the rod to make it longer or shorter. Longer means the bite point will move away from the floor.

If you google "mr2 turbo clutch bite point adjustment" and go to images, the first 2 of them will give you a good idea about what you are dealing with. It's really easy to do actually.

[yokomomr4bx]

Ahhh yes I know, apologies, I thought I had missed some kind of volume adjustment on the master or slave!

Is the flexible hose that runs just before the slave still in ok condition? Not perished or cracking etc? It might not be leaking but could be changing in wall rigidity as the temperature rises. I'm imagining that if this hose was particularly perished, when you push on the clutch pedal when it's hot, the hose is bulging due to being softer/weaker and the hydraulic force is expanding that hose rather than pushing on the clutch spring...and hence your bite point gets higher as the temperature rises and more pressure is 'lost' to that hose expanding.

A bit far fetched but maybe worth a 5 minute poke around.

[KK-M5]

Thanks for the suggestion, I shall investigate accordingly.

[androo007]

clutch bite point should not move. take it back to the fitted.

[mr2garageswindon]

I'd certainly be checking the slave cylinder for leaks and smooth operation.
A Blue print replacement is about £70 I think.
Just pull the rubber boot back. Its probably weeping possibly drawing in air.

[KK-M5]

Thanks everyone, they have agreed to look into it in detail. Hopefully, it'll get sorted soon.

I appreciate everyone's input.

[yokomomr4bx]

Be great to hear what the outcome is!

[KK-M5]

I'll make sure I post here when it's sorted, no worries.