Hydraulic clutch setup

[Erlend / bug66]

I've seen this a few times lately, and can't really understand why it's like this.

Why would 2 seemingly equal hydraulic clutch setups have different pedal feel?


I've got:

Stage 4, thick Black Magic. 5/8" master and 7/8" slave cylinder. AN3 lines, line lock and restrictor valve for clutch management.

Pedal is fairly heavy (became better after driving it some)


Other have the same-ish setup, but pedal is so much lighter.

I don't mind a longer throw on the pedal, if that gives me a softer pedal.


Smaller master or bigger slave? AN3 or AN4?

[richie]

I was thinking this would make a good tech topic and maybe even a sticky if enough info is added with CM included



Length of clutch arm on gearbox makes huge difference, I have been making longer arms for mendys & bus boxes myself. Its not always possible to fit longest arm on stock bodied car as it interferes with boot floor area



I use 1 3/4 master cylinder and cnc 7/8 slave cylinder, steel 4.75mm[ 3/16th? ] front to back, then -3 flexi from chassis/pan to slave, I hated way 1 5/8 master felt when I tried it.

Also I am sure people are using different valves for CM, and the push through flow will be different on them so add to different feel as well

Finally have you shimmed clutch cover at all? that makes difference to how it acts and feels as well

cheers Richie

[Erlend / bug66]

I tried the stock length Type 1 arm, but needed to shorten it, to get enough throw, to release the clutch.

Shortened about 1/2". 

[Berger]

A T25 has a hydraulic clutch that feels very "normal". Would be nice to know the exact spec on parts from those if anyone have?

[Erlend / bug66]

A T25 has a hydraulic clutch that feels very "normal". Would be nice to know the exact spec on parts from those if anyone have?

Sure does not have a Stage 4..

[Berger]

A T25 has a hydraulic clutch that feels very "normal". Would be nice to know the exact spec on parts from those if anyone have?

Sure does not have a Stage 4..

No, but was thinking more about travle, flow and ratio. My guess is it would handle stage 4 pretty well

[dragvw2180]

 My setup is almost exactly the same as Richie has with the exception of my lines, I use AN- 4 PTFE lines all the way through . I do have a line lock installed in between for my delay box . Mike McCarthy

[richie]

I tried the stock length Type 1 arm, but needed to shorten it, to get enough throw, to release the clutch.

Shortened about 1/2". 

That's your problem then, no wonder its heavy, I am using 100mm arms. So did you not have enough travel at slave? was it maxed out? or was there not enough travel at pedal to move slave fully? Guessing you are using the in the tunnel kit? I don't know anything about ratios on those

cheers Richie

[pWolf]

Doesn't Kalle (beetlebug) have a nice setup ?

[Erlend / bug66]

I tried the stock length Type 1 arm, but needed to shorten it, to get enough throw, to release the clutch.

Shortened about 1/2".  

That's your problem then, no wonder its heavy, I am using 100mm arms. So did you not have enough travel at slave? was it maxed out? or was there not enough travel at pedal to move slave fully? Guessing you are using the in the tunnel kit? I don't know anything about ratios on those

cheers Richie

Yes, I understand that shortening the arm will make my left foot stronger

I tried a 75mm arm, but when the master was fully depressed, if did not pull the slave and arm enough. The point of clutch release was with the pedal almost all the way back.

CNC kit with 5/8" master and 7/8" slave. Master with a straight link behind the pedal.

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[Fiatdude]

CNC kit with 5/8" master and 7/8" slave. Master with a straight link behind the pedal.

there's your problem --- Master should be in the range of twice the size of the slave to make the system behave nicely

[Erlend / bug66]

CNC kit with 5/8" master and 7/8" slave. Master with a straight link behind the pedal.

there's your problem --- Master should be in the range of twice the size of the slave to make the system behave nicely

Ok? Every thread I've read states that if the slave/arm has enough travel; the smallest MC to SC will give the lightest pedal, but needs to travel further?

[richie]

So maybe slave can move more?  and a bigger master would move more fluid for same pedal travel and move slave more[ I think]

[Erlend / bug66]

So maybe slave can move more?  and a bigger master would move more fluid for same pedal travel and move slave more[ I think]

I don't think it will have a a softer pedal then? Just move the arm more?

[richie]

So maybe slave can move more?  and a bigger master would move more fluid for same pedal travel and move slave more[ I think]

I don't think it will have a a softer pedal then? Just move the arm more?

But then you can use longer arm

[Erlend / bug66]

So maybe slave can move more?  and a bigger master would move more fluid for same pedal travel and move slave more[ I think]

I don't think it will have a a softer pedal then? Just move the arm more?

But then you can use longer arm

That's true 

[richie]

The other thing that occurred to me is, why the hell you are using a stage 4 and black magic, I expect to see 8s at least with that much clutch  

[stussyrich]

is there enough throw on that pedal. does it activate the master fully.

[Erlend / bug66]

The other thing that occurred to me is, why the hell you are using a stage 4 and black magic, I expect to see 8s at least with that much clutch  

Better to have too much clutch, and manage the clutch slip, than having too little

8s will never happen. If I break into sub 10.5s I'll be really happy And then chase a 9.99  

[Erlend / bug66]

is there enough throw on that pedal. does it activate the master fully.

Yes, the MC bottoms out before the pedal

[stussyrich]

ok cool just looked like it wouldn't, maybe just the pic.

is there enough throw on that pedal. does it activate the master fully.

Yes, the MC bottoms out before the pedal

[Erlend / bug66]

ok cool just looked like it wouldn't, maybe just the pic.

is there enough throw on that pedal. does it activate the master fully.

Yes, the MC bottoms out before the pedal

I shortened the MC pushrod, but it's bottoming nicely before the pedal hits the wall.

I'll measure how much throw the SC has and see if I can get away with a longer arm.

[stussyrich]

I noticed with mine that if the arm wasn't perfectly centered when the pedal was depressed it would catch and seem to bottom out but it wasn't doing.

ok cool just looked like it wouldn't, maybe just the pic.

is there enough throw on that pedal. does it activate the master fully.

Yes, the MC bottoms out before the pedal

I shortened the MC pushrod, but it's bottoming nicely before the pedal hits the wall.

I'll measure how much throw the SC has and see if I can get away with a longer arm.

[Erlend / bug66]

I noticed with mine that if the arm wasn't perfectly centered when the pedal was depressed it would catch and seem to bottom out but it wasn't doing.

ok cool just looked like it wouldn't, maybe just the pic.

is there enough throw on that pedal. does it activate the master fully.

Yes, the MC bottoms out before the pedal

I shortened the MC pushrod, but it's bottoming nicely before the pedal hits the wall.

I'll measure how much throw the SC has and see if I can get away with a longer arm.

There is no movement up or down. It's on the millimeter throw wise. 

[bedjo78]

How to modify clutch arm? Weld it to make it longer ?
Or is it avalaible aftermarker parts?

[Erlend / bug66]

How to modify clutch arm? Weld it to make it longer ?
Or is it avalaible aftermarker parts?

VW made 75mm and 100mm

[richie]

How to modify clutch arm? Weld it to make it longer ?
Or is it avalaible aftermarker parts?

I get the 100mm versions and cut them off at base of arm and do same to mendy arm then weld them on, will see if I got a pic of one

cheers Richie

[bedjo78]

[/quote]

I get the 100mm versions and cut them off at base of arm and do same to mendy arm then weld them on, will see if I got a pic of one

cheers Richie
[/quote]

Thanks I will make the same...

[Stripped66]

...line lock and restrictor valve for clutch management.

Assuming you have comparable leverage with your pedal setup, have you inspected/measured the size of the orifice in the line-lock? Several folks (myself included) found that the orifice in our line-locks were so restrictive that the Parker valve was the path of least resistance. The Biondo line-lock solenoid was the common denominator for at least 4 of us with this problem...FWIW.

[Erlend / bug66]

...line lock and restrictor valve for clutch management.

Assuming you have comparable leverage with your pedal setup, have you inspected/measured the size of the orifice in the line-lock? Several folks (myself included) found that the orifice in our line-locks were so restrictive that the Parker valve was the path of least resistance. The Biondo line-lock solenoid was the common denominator for at least 4 of us with this problem...FWIW.

I've heard the same issue. They can be bored out, but I need to bleed the clutch again, and I think I'll try to skip the management to see if the pedal is better without.