Do I need these parts in my master cylinder?

[Larry T.]

When I disassembled my non-power M/C the parts that came out are the ones you see at the bottom of the picture. When I got my kit to reseal it had the extra parts you see at the top. The new piston, spring and seal are in the middle. I know from my CSM that the "extra" parts are the valve and valve seat.

Why would someone not put them in when it was last rebuilt? Should I put them in? My brakes worked fine before, will they work better with the valve? From my search of the archives I am not the first person to see this.

Thanks.

[Bob J.]

Re: Do I need these parts in my master cylinder?

When I disassembled my non-power M/C the parts that came out are the ones you see at the bottom of the picture. When I got my kit to reseal it had the extra parts you see at the top. The new piston, spring and seal are in the middle. I know from my CSM that the "extra" parts are the valve and valve seat.

Why would someone not put them in when it was last rebuilt? Should I put them in? My brakes worked fine before, will they work better with the valve? From my search of the archives I am not the first person to see this.

Thanks.

Check that the old check valve and seat aren't still stuck in the bottom of your MC bore.
Yes, you need to install them. Bob

[Larry T.]

Re: Do I need these parts in my master cylinder?

Check that the old check valve and seat aren't still stuck in the bottom of your MC bore.
Yes, you need to install them. Bob

They are definitely not in there.

[Harry S.]

Re: Do I need these parts in my master cylinder?

Larry, I suggest you use them.

I have the same parts in my 63.

[Bob J.]

Re: Do I need these parts in my master cylinder?

They are definitely not in there.

I'm sure they're required in drum brakes.
After thinking on this, maybe not in disc.
I can take a 65 disc brake MC apart tomorrow if nobody knows for sure. Bob

[Joe L.]

Re: Do I need these parts in my master cylinder?

When I disassembled my non-power M/C the parts that came out are the ones you see at the bottom of the picture. When I got my kit to reseal it had the extra parts you see at the top. The new piston, spring and seal are in the middle. I know from my CSM that the "extra" parts are the valve and valve seat.

Why would someone not put them in when it was last rebuilt? Should I put them in? My brakes worked fine before, will they work better with the valve? From my search of the archives I am not the first person to see this.

Thanks.

Larry------


I don't think this check valve is used with disc brake applications. The kit you got might service both disc and drum brake applications.

[Stephen L.]

Re: Do I need these parts in my master cylinder?

The check valves are not used in DISC brake applications. If you leave the check valve installed here is what happens. A slight pressure is retained in the system causing the pads to "drag" and heat up the caliper housings. This, in turn, causes some expansion of the fluid which will increase the pressure on the pads. End result is the car will slow to a halt with the brakes locked. Wait about 45 minutes for cool down and everything is fine and the brakes are no longer locked. This happened to me about 25 yrs ago and it took alot of head scratching to finally figure it out. I even went so far as to surface grind my brand new pads thinking they were too thick to allow clearance in the calipers. I didn't realize at the time that there were check valves in the orifices of the M/C.

On cars with disc front drum rear then the check valve is used on the drum portion of the system.

[Larry T.]

Re: Do I need these parts in my master cylinder?

Thank you. I appreciates all of the responses and explanation.