MC residual valve?

-
mod5v

mod5v

Well-Known Member
Joined
Feb 17, 2006
Messages
694
Reaction score
174
Location
fortworth
IMG_1571.JPG
Ok so I read about half the posts on here but I still haven't found a definitive answer on wether there is a residual valve in the stock 74 disc drum master cylinder. I put rear disks on so now have 4 wheel discs but after bleeding brakes I have quite a bit of drag on the rear. Just wondering if there is a valve built in to the master cylinder I am not useing a proportioning valve. It's a dirt track race car.
 
The car is a 74. The MC is how old? There is no way to to answere that question from here.
Except, to say that no 74A ever had rear disc brakes and so, all 74As would have had R-valves. Would have had.

Ok but you are past that. You have two choices; 1) go try to push a piston back into it's bore. If it pops right back in, then your M/C either has no R-valve ,or it is defective, so who cares. or 2) take off the line from the M/C and probe the port.

Now, as to the dragging rear brakes. Are you sure that you are not feeling the SureGrip or the tranny bands. If you really want to know, remove the driveshaft and measure the drag again.
 
Why not find the casting number,on the master cylinder..and back track it ,from there? A 1 Cardone's website,has a search by casting number feature. Or better yet....: Take that number to a good parts guy..., let him do the research... O Reillys,Napa ,Carquest, ...my recommendations...
 
Yes, that year and model of MC should have the residual valve in the rear port. We bought one about 1 year ago that had it. If you look into the port on the MC that feeds the rear system (which will be the front port on the MC itself), you should see a shiny, cone shaped disc with a small hole in the center. That is the residual valve (or the retainer for the spring for the residual valve). You should not see one in the MC port for the front system.

You just remove this disc and anything behind it and, voila, no more residual valve in the rear system.

Here is a thread with an illustration of a dual drum MC with the residual valves shown in each port.
using drum MC on front disc setup
 
Last edited:
nm9stheham said:
Yes, that year and model of MC should have the residual valve in the rear port. We bought one about 1 year ago that had it. If you look into the port on the MC that feeds the rear system (which will be the front port on the MC itself), you should see a shiny, cone shaped disc with a small hole in the center. That is the residual valve (or the retainer for the spring for the residual valve). You should not see one in the MC port for the front system.

You just remove this disc and anything behind it and, voila, no more residual valve in the rear system.

Here is a thread with an illustration of a dual drum MC with the residual valves shown in each port.
using drum MC on front disc setup
Click to expand...
Thankyou
 
You must log in or register to reply here.
-

Back
Top