Standard clutch setup height

[SweetBadger 93]

Hi all, I've been having issues with inconsistent clutch travel and pedal effort after fitting a single plate AP racing clutch.

 

I've replaced the clutch cable, messed with the pedal leverage but can't solve the issue.

 

I think the issue is that the single plate clutch takes more pedal effort and the setup height is lower, so the clutch fork is close to the end of its travel therefore not pushing on the centre of the release bearing. I have a replacement release bearing with shims that I can add to change the thickness of the bearing carrier in order to compensate for the lower clutch setup height.

 

What I don't know is what the standard clutch setup height is for reference.

 

Does anybody have a standard XU engine with a push type clutch out of the car with flywheel and clutch attached that could measure the std height? 

 

The measurement I'm after is the edge of the engine block to the clutch levers where the release bearing pushes (sorry pull type clutch shown, but hopefully shows the measurement):

 

 

Thanks.

 

edit: a measurement of the thickness of the standard release bearing would also be useful (e.g. from the back of the bearing carrier to the bearing face)

Edited May 16 by SweetBadger

[welshpug 1,644]

Release Bearing is 20.5mm height, there is also an 18.5mm variant, the ma gearbox used both types at some point.

 

Inconsistencies sounds like a cable issue, as everything else is fixed

[SweetBadger 93]

Hi thanks for the release bearing info, I put it down to the cable at first, but have changed it twice (one standard replacement with the earlier metal pin through the clutch pedal), and then an uprated heavy duty BE3 cable from spoox with a much thicker steel inner and metal part (instead of plastic) that goes over the hook on the clutch pedal.

 

Same symptoms with all cables - especially after heavy use on track. It's not a massive difference in travel but given the short stroke of the AP clutch (max 5.5mm), it's enough to make it difficult to get into 1st / reverse due to the clutch dragging.

 

 

 

 

[Spesh 28 1 Cars]

PXL_20240519_111609783 

 

I make it 60mm, thats on a J4RS with a BX Luk Clutch and stock flywheel. engine is a bit buried and awkward to get to so allow a bit of tolerance in that measurement

 

I've had issues with what I think is clutch drag on a TTRS flywheel with helix organic setup too.  Not sure if I've solved it as i've yet to drive the car following over winter work.

 

 

 

Edited May 19 by Spesh

[SweetBadger 93]

On 5/19/2024 at 12:22 PM, Spesh said:

PXL_20240519_111609783 

 

I make it 60mm, thats on a J4RS with a BX Luk Clutch and stock flywheel. engine is a bit buried and awkward to get to so allow a bit of tolerance in that measurement

 

I've had issues with what I think is clutch drag on a TTRS flywheel with helix organic setup too.  Not sure if I've solved it as i've yet to drive the car following over winter work.

 

 

 

Brill, thank you. The issue in your thread seems slightly different to mine but will report back if the properly spaced release bearing solves my issue.

 

I’ve pulled the box off this eve, and before doing that I made up a quick bracket so I could mark where the clutch arm was moving from / to:

 

 

With the box off I have measured that the bearing was moving about 6mm (so slightly over stroking), however it’s a smaller diameter bearing than the AP one (50mm vs 54mm), so probably about right.

 

The release bearing was not feeling great and was showing signs or wear so time for a replacement anyway! 

 

You can see that it was right at the end of the possible travel, so not ideal. To get the bearing sitting where it does on the std clutch will require most of the available shims to space it. The bearing is from pug1off and they recommend 4mm of free play behind the bearing.

 

Current bearing, clutch engaged:

 

 

Current bearing, clutch pedal depressed:

 

[Spesh 28 1 Cars]

Assume its not a fork/bush colour issue?  as in arms with a J stamped on them should be yellow bushes?

[SweetBadger 93]

No I have the correct bushes for the arm.

 

just had a measure up and I’ll need to use all of the shims. This will effectively add 10mm to the height of the release bearing

[SweetBadger 93]

Bearing shims sorted, and box is back in the car.

 

Took all of the shims (additional 10mm spacing), leaving 9mm of free play. Clutch forks are in a better position contacting the bearing carrier and the clutch arm is much closer to the std position.

 

I marked out the clutch arm travel needed for 5.5mm of bearing movement- measured at 15mm. Will mod the pedal cable pull point to reduce cable travel (and thus reduce pedal effort), and then if needed add a stop to limit cable travel to 15mm.

 

Hopefully will have a consistent clutch feel now. 

 

 

Had a moment of concern when it was all back together, and I felt something move when pushing on the clutch arm. Turns out it was the crankshaft end float. It seemed a little too much to me so I measured it, and it’s just over the max spec for 16v XU10 engines (within the range for 8v) at 0.29mm.

 

Engine was recently rebuilt, so I’m checking with the builder, but hopefully nothing to worry about given the engine is running really well.

[SweetBadger 93]

 

Put the clutch cable in today and set it up using a modified BE1 pedal - has a 2nd hole drilled closer to the pivot point for the pin that holds the clutch cable on. 

 

Initial signs are very promising - clutch pedal is much lighter (close to standard), it requires less travel, and feels nice and smooth all the way through the pedal travel.