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Author Topic:   hard and soft brakes
ss#4
Dirt Maniac

Total posts: 110
posted May 06, 2004 09:20 AM  
I am having some consistency issues with my brakes. Basically 1 time I have brakes the next I don't, have to pump to get pressure. I have a dual MC on the floor. I don't have any leaks and I am pretty sure all the air is out. Is this anything the residual pressure valves will help? If so what pressure rating 2 or 10 psi?
thanks

NJantz
Dirt Forum Champ
Total posts: 755
posted May 06, 2004 09:38 AM  
how old are your master cylinders?

ss#4
Dirt Maniac

Total posts: 110
posted May 06, 2004 09:42 AM  
Not real sure I got them with the car last year. They don't appear to have been run.

mod70
unregistered Total posts: 110
posted May 06, 2004 10:44 AM           send a private message to ss#4   Edit/Delete Message   Reply w/QuoteBBBBBB
Sounds to me like you might have a leaking fitting somewhere in the lines, or that the MC's need a rebuild kit. Look for air bubbles if you run plastic lines, if you run steel or braided, then look for air pockets as you bleed the brakes. A common problem when you take apart brake lines is the crush rings don't go back correctly, and you get a leak. I've learned from experience that every time you take apart a fitting you should replace the crush ring. At a dime or less apiece, it's good insurrance.

outlawstock17
Dirt Forum Champ
Total posts: 1363
posted May 06, 2004 11:09 AM  
you should only need a residual pressure valve if your master cylinders are lower than your calipers. 2 lb. is for discs and 10 lb. is for drums.

ss#4
Dirt Maniac

Total posts: 110
posted May 06, 2004 11:13 AM  
yes the calipers are higher than the MC. So are the residuals always required in this condition?

Chad
Dirt Freak

Total posts: 269
posted May 06, 2004 11:35 AM  
Another thing to consider; maybe your rotors are pushing back the pads down the straights. I had this problem. Found the issue to be the caliper brackets on the rearend were mounted incorrectly. They need to be square to the rotor, or the situation you described will happen. Also, a warped/bent rotor will cause the same problem.

outlawstock17
Dirt Forum Champ
Total posts: 1363
posted May 06, 2004 09:06 PM  
if everything checks out okay on your braking system, then the residual pressure valves may be the answer. with the master cylinders mounted lower than the calipers, a small amount of fluid may drain back into the master cylinders and give your pedal a spongy feel. they aren't absolutely necessary though......you can compensate by lightly pumping the pedal on the straights before you need to brake. have you ever watched NASCAR "foot cams"? you see a lot of drivers doing just that.

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