hydraulic clutch residual pressure valve

[bostru]

Where can I buy a residual pressure valve for 1960 GMC Pickup with hydraulic clutch. And does anyone know what the pressure value is in P.S.I

[Funky61]

Welcome Bostru!

Is this valve on the hydraulic slave cylinder and would you mind posting a picture?
If it is, I know that some did not have that valve on there.
My 61 does not have one; it just has a bleeder screw.

[bostru]

Truck is in storage so I can't get pics but the valve is at the slave cylinder right where the line goes into the cylinder . It is about 3/4"long looks like a brass adapter. Not all trucks used these apparently but were used in brake systems on early cars and trucks where the master cylinder was located on the frame . idea was to hold slight residual pressure (approx. 10 PSI)
on the brakes . I assume this valve does the same with clutch

[James]

Truck is in storage so I can't get pics but the valve is at the slave cylinder right where the line goes into the cylinder . It is about 3/4"long looks like a brass adapter. Not all trucks used these apparently but were used in brake systems on early cars and trucks where the master cylinder was located on the frame . idea was to hold slight residual pressure (approx. 10 PSI)
on the brakes . I assume this valve does the same with clutch

The purpose of the pressure is to make sure the wheel cylinders/slave cylinder seals from collapsing and allowing fluid to leak out. This is used on all vehicles with drum brakes/hydraulic clutch. With drum brakes it is located in the master cylinder. On the clutch I am not sure if it in the clutch master cylinder (I would think it would be here) or the slave cylinder.

[bostru]

The residual pressure check valve in a brake system is to keep slight pressure applied to the brakes at all times which will reduce pedal travel and make the brakes apply quicker . (probably splitting hairs as to how much quicker) .The valve in the hydraulic clutch system works in the same way . Do you know where I can get an OE valve for the clutch on a 60 GMC with a 305 ?

Thanks for your reply

[James]

The residual pressure check valve in a brake system is to keep slight pressure applied to the brakes at all times which will reduce pedal travel and make the brakes apply quicker . (probably splitting hairs as to how much quicker) .The valve in the hydraulic clutch system works in the same way . Do you know where I can get an OE valve for the clutch on a 60 GMC with a 305 ?

Thanks for your reply

I know a lot of website is saying the same thing. However applying brake quicker was not the original issue, it is leaking wheel cylinders. Please refer to the expert at: https://www.freeasestudyguides.com/residual-check-valve.html
This is in a practice ASE test.

[bostru]

Thanks ,do you know where I can get one for my clutch and do you happen to know the value in PSI for the clutch valve

[Funky61]

I would check with this company

https://www.wilwood.com/Search/PartNoSearch?q=Residual%20pressure

I’m certain they could provide more specifics as well as the valve.

[jagarra]

These are available. https://www.speedwaymotors.com/Wilwood-260-13784-Red-10-PSI-Residual-Pressure-Valve-with-Fittings,233816.html

[bostru]

Thanks, Funky61 and Jagarra I am aware of the aftermarket valves but am looking for an Original Equipment piece for another project N.O.S. or nice used .
Thanks again

[James]

The slave cylinder comes in two sizes, 1" or 1-1/6". Which size do you need so we know what to look for?

[James]

This one is 1-1/16":
https://www.summitracing.com/parts/dhb-cs36124

[bostru]

Thanks, but as posted in the first post I am looking for the residual pressure valve not the slave cylinder .

[James]

This place has both sizes, however it is listed for a 1961 instead of a 1960. The only different I see is the 1961 listing has a CS in the part number.
https://www.rockauto.com/en/catalog/gmc,1961,1500+series,5.0l+305cid+v6,1340941,transm ission-manual,clutch+slave+cylinder,2044

[James]

Thanks, but as posted in the first post I am looking for the residual pressure valve not the slave cylinder .

This day and age you might not be able to find an OEM residual pressure valve for the slave cylinder. This is why I suggest the slave cylinder. The only possibility is NOS parts on ebay, but you might have to wait for someone to list it.

[Funky61]

Here is information from the early manuals I have and they call it a Hydraulic Fluid Damper.

[bostru]

Funky 61 ,I have located one . Thanks fo the pics, your 61 does not have one ?

[Funky61]

That's great news Bostru!

Where did you source one and is it factory and do you know what PSI it is?

No my slave cylinder does not have one.

[bostru]

Junkyard find ,don't know anything about it . Not much info on these and the service manual doesn't tell much either .

[James]

I found one NOS GMC:
https://www.oldsobsolete.com/products-page/gmc-chevy-truck-parts-for-sale/1960-1962-gmc-pickup-nos-clutch-hydraulic-fluid-damper-valve-gm-5460337/

[Funky61]

Awesome Work James!

[bostru]

Second that ,bought a junkyard piece should work fine for what I am doing but good to know I have a second choice . Can't imagine much demand for this part . Thanks for your help !!

[James]

This is what teamwork is all about. There is not one person with all of the answer, but with everyone help we get there.

[bostru]

Yes indeed!!