Clutch pedal position problem (1 Viewer)

[wolfbak]

I have a new build with a new OEM clutch master and secondary cylinders, stainless hard line, and braided flex line. There are no leaks.

I've bled the system a few times following everything I know, plus the Haynes manual, until there there are absolutely no bubbles - just clean fluid. The problem is that the first press of the pedal goes down further than normal before activating the clutch than the subsequent presses, which are normal travel. if I wait 10 seconds, the pedal again goes down further than normal. In other words, it takes 2 pumps to get the right travel.

It makes it impossible to properly adjust the plunger at the pedal or at the clutch fork.

Is there air trapped somewhere that I'm missing that doesn't make it to the secondary cylinder?

Thanks

 

[igotta40]

Bleed the master cylinder yet?

 

[Skreddy]

How is the pushrod free play and the pedal adjustment? Should be able to set both of those and see if it’s better.

Are the master and slave both for the same year?

 

[wolfbak]

How is the pushrod free play and the pedal adjustment? Should be able to set both of those and see if it’s better.

Are the master and slave both for the same year?

I played with pushrod play and pedal adjustment, but if I set it for initial press, it’s way too tight for subsequent presses. Both master and slave were bought as a set for my ‘76.

 

[wolfbak]

Bleed the master cylinder yet?

No. Bleeding the master by itself before the whole system? Is that a thing?

I’ve heard of bench bleeding a brake master but not a clutch. Is there an outlet on the master?

 

[igotta40]

I take a piece of scrap brake line and loop it back to the reservoir and just pump it a few times until there’s no bubbles, then attach the clutch fluid pipe.

 

[wolfbak]

I take a piece of scrap brake line and loop it back to the reservoir and just pump it a few times until there’s no bubbles, then attach the clutch fluid pipe.

Thanks. I’ll give it a try.

 

[fjc-man]

Just an idea, is there a return spring on the slave cylinder?

 

[wolfbak]

Just an idea, is there a return spring on the slave cylinder?View attachment 3439140

Good thought, but I have a return spring. I’m really thinking it’s air in the master.

 

[pb4ugo]

1st check pedal height. Then pedal freeplay adjustment insures a full stroke of the master. Have someone slightly depress the pedal while someone else watches the slave as it starts to move. Its not when you feel pressure/resistance. My slave is on the drivers side, so I able to use my hand on the pedal and watch the slave at the same time. After that adjustment, Then adjust the slave rod. The return spring is needed to bottom slave piston in the cyldr.

 

[wolfbak]

View attachment 3439801

1st check pedal height. Then pedal freeplay adjustment insures a full stroke of the master. Have someone slightly depress the pedal while someone else watches the slave as it starts to move. Its not when you feel pressure/resistance. My slave is on the drivers side, so I able to use my hand on the pedal and watch the slave at the same time. After that adjustment, Then adjust the slave rod. The return spring is needed to bottom slave piston in the cyldr.

I went through that process. My pedal height was perfect at 8.5 inches. I then adjusted the free play and slave rod to specs. The problem is that when I do that. it's perfect for the first press of the pedal, but then the second press gets pressure much sooner than the first and the adjustments are way too tight. If I do the adjustments after the second press of the pedal, then the first press(es) (after waiting for 10-15 seconds) take the pedal almost to the floor before engaging the clutch.

There must be air trapped somewhere that isn't making it to the slave when bleeding the system that requires me to do a double pump. I'm gonna try bleeding the master by itself as igotta40 suggested and see what happens. It's weird because I've never had to bench bleed a clutch master before and most of the posts I've read say it isn't necessary on a 40. We'll see...

 

[pb4ugo]

Make sure the fittings tight, you could be sucking air in. Did you use the copper washers during assembly?

 

[wolfbak]

Make sure the fittings tight, you could be sucking air in. Did you use the copper washers during assembly?

Good thought! I used copper washers but will check tightness. Definitely no fluid leaks.

 

[gmr76]

Did you buy or make the hard line. I have all new parts and am planning on swapping out soon but that is the one thing I need to source.

 

[wolfbak]

Did you buy or make the hard line. I have all new parts and am planning on swapping out soon but that is the one thing I need to source.

I bought stainless brake and clutch lines from Cruiser Solutions. I believe the clutch line is $35.

 

[45Dougal]

Sounds like the fluid isn't returning fast enough back through the hole in the master because either the master is not fully returned, or maybe its blocked??
Had similar on my motorcycle front brake, cleared it out with a pin.

 

[peesalot]

What year ? stock trans & motor ? where did you get the new oem MC & slave ? any pics of these ? was any clutch work done ?
FWIW, the whole double pump thing is not right as a clutch should return so you would just be releasing the clutch again , it should not pump like you can with brakes.

 

[peesalot]

Set it all up tight with the first push like you had it with correct pedal , even if it pushes to floor does it release clutch ? when foot off clutch take inspection cover off and see how far fork is from throw out ? If these are right then you either have air or the MC is not moving enough fluid for the slave, in any event you have to verify all the above before going after either of those issues. I have always gravity bled the 40 with success.

 

[wolfbak]

What year ? stock trans & motor ? where did you get the new oem MC & slave ? any pics of these ? was any clutch work done ?
FWIW, the whole double pump thing is not right as a clutch should return so you would just be releasing the clutch again , it should not pump like you can with brakes.

‘76, all stock. They match exactly the Aisin master and slave I replaced. No clutch work done.

 

[Adarcy]

I had a very similar problem. Ended up being the bushings at the top of the clutch pedal. $4 replacements and problem solved.