Clutch pedal travel / stop

[ian_uk1975]

On fast/aggressive 2-3 gear changes, my gears sometimes grate. Box is a Tremec TKO500 and clutch is new. Clutch is hydraulic with the slave bolted to the bellhousing and a small push-rod acting on the clutch fork. The previous owner had fitted a make-shift pedal stop fashioned from a bit of wood (classy!) and I'm wondering if the clutch isn't quite disengaging fully due to the pedal having insufficient travel. Gear changes in normal driving are absolutely fine. Box has only covered around 3,000 miles, so I don't think it's anything more sinister.

How can I establish correct clutch pedal travel? The slave has an adjustable end... would it also help to adjust the push-rod so it's a hair longer?

Edited by ian_uk1975 on Friday 23 March 00:22

[Steve_D]

First question is where in the travel does the clutch bite?

If it is half way or higher then the clutch has to have cleared when fully down.
If it is just clear of the floor then you do need to look at adjusting it but bleed it first as that may be the problem.

Steve

[Sam_68]

ian_uk1975 said:

The slave has an adjustable end... would it also help to adjust the push-rod so it's a hair longer?

Possibly, but there needs to be some nominal clearance at the pushrod, otherwise you are in a situation where the clutch fork is continually pressing the thrust bearing against the clutch diaphragm... which will cause the thrust bearing to wear out in no time flat.

Also, though it shouldn't be possible with a well-designed system, if you adjust the system so that it can push the diaphaghm further in an attempt to disengage the clutch fully, you might make it push too far and push the clutch over-centre.

[ian_uk1975]

Steve_D said:

First question is where in the travel does the clutch bite?

If it is half way or higher then the clutch has to have cleared when fully down.
If it is just clear of the floor then you do need to look at adjusting it but bleed it first as that may be the problem.

Steve

Of course... obvious really, and I should've thought of that! The clutch does indeed begin to engage probably around half-way up on the pedal, so it must be fully engaged with the pedal all the way down.
I'll look at bleeding it.

Still, the question remains though... how do you set the pedal so it doesn't over-extend the clutch? I've removed the aforementioned bit of wood and I'm going to install a proper adjustable pedal stop consisting of some threaded bar stock with a nut on either side and a rubber cap on the pedal end.

[ian_uk1975]

Sam_68 said:

Possibly, but there needs to be some nominal clearance at the pushrod, otherwise you are in a situation where the clutch fork is continually pressing the thrust bearing against the clutch diaphragm... which will cause the thrust bearing to wear out in no time flat.

Also, though it shouldn't be possible with a well-designed system, if you adjust the system so that it can push the diaphaghm further in an attempt to disengage the clutch fully, you might make it push too far and push the clutch over-centre.

Definitetly don't want to wreck my nice new release bearing or clutch by doing either of those things.

How much clearance would you say is necessary between the slave push-rod and the clutch fork? I'm thinking as long as there's some clearance, it's fine? 'fag paper' enough clearance, for example?

As I just posted above, what is the correct way to make sure your pedal stops short of over-extending the clutch?