Brake pressure valve needed for clutch?

[John]

Question for the SL-C guys:

I'm installing the 2 lb brake pressure valves to my pedal assembly and wondered if you guys use one for the clutch also?

Seems like similar fluid dynamics would apply but could not find anything in a search, the wiki or the manual.

Thanks,
John

 

[Will Campbell]

No- don't use a residual pressure valve for the clutch.

 

[Alex]

No- don't use a residual pressure valve for the clutch.

this.

 

[John]

Thanks guys. Will proceed without it.

I am curious though, why are those valves used just for the brakes?

 

[Dave Bilyk]

John, with the brakes you press the pedal to load the pads against the discs, when you release there is no pressure in the system so the pads can move apart due to disc flexure and play etc. The residual pressure valve keeps them in light contact to ensure there is no gap to take up and that there is little or no pedal travel before re-establishing contact the next time you brake.
By contrast, with the clutch you press the pedal to oppose clutch springs and remove load from the clutch facing. When you release the clutch, the springs put the load back on, so residual pressure in the system would be counterproductive.
Dave

 

[A.J. Schreder]

I also spoke to the Wilwood guys about this. The short story, it's for brake pedal feel. Without the valves, the first application will never be firm, and may even require a 2nd pump.

A.J.

 

[P Roth]

Another important piece of information, Disk brakes take 2 psi valves and Drum brakes take 10 psi valves.

 

[Randy V]

Another important piece of information, Disk brakes take 2 psi valves and Drum brakes take 10 psi valves.

I have seen troubles with the 10 PSI residual valves with drum brakes. On some cars, the brake shoes will not retract enough to allow the self-adjustment pawl to engage the star wheel. I have switched over to only using 2 PSI for brakes regardless of the type of brake.