Brake pedal issue-----Solved!

-
BobW

BobW

Curmudgeon At Large
Joined
Jun 26, 2020
Messages
545
Reaction score
547
Location
Central, FL 34705
My Valiant is a '64 with a '66 front clip, 66 /6motor with 4spd OD. It has the K-H 4 pot discs with a manual dual reservior MC, both res are the same size. Rear axle has all new braking parts, less than 500 miles. Fluid was changed when the rear parts were installed.
Brakes were working fine, good pedal, easy to lock up all 4 wheels.
Just changed upper & lower control arm bushings. and reassembled everything.
I hung the calipers from a wire in the wheel well rather than undoing the hoses.
Now the brake pedal traveled about 3-4 inches with poor braking, but will pump up and exhibit good braking, firm pedal lock up.
I've always experienced this as the rear brakes needing adjustment.
My normal method is to tighten the adjustor until I can't turn the wheel, then back it off 4 clicks.
Adjusting the rears required ~ 8 clicks to tighten the wheel, then I backed the off 4 clicks. Both sides were equal.
I bled/flushed the brakes just because the car was jacked up and I was in there. No air bubbles, pedal was not soft.
Pedal is better, travels about 2-3 inches but still need a pump to lock up the wheels.
It's not a soft mushy feel, and it's firm when everything locks up.
It holds at that point, doesn't travel further like the MC is by passing.
Any ideas?
 
Does your distribution block have a switch in it? It may be switched to one side. You don't have the correct M/C on it. Disc brakes more fluid to activate hence the M/C has a larger reservoir for the discs.
 
No switch on the brass distribution block.
The brakes/MC worked fine previous to the control arm work.
 
Not finding any real clue as to the cause of the problem, and all parts being of questionable age and condition, I decided to replace it all!
Everything on the rear axle was changed when I bought the car as it had a leaking axle seal. All new rear brake parts were installed.
New Dorman MC, new distribution/proportioning valve from Dr Diff, new hoses, caliper rebuild seals and wheel bearings while it was all apart. The rotors were in good shape.
Got it all back together, fluid flushed and bled.
I have brakes, put you in the dash brakes!
I installed MOOG offset bushings in the UCA's and got the alignment done to the second line specs in the SKOSH chart.
That, and the upgrade to 892/893 torsion bars has made this /6 Valiant more comfortable and fun to drive!
 
Set the emergency brake on hard, pump up the foot brake, then release, - try and see if you still have excessive pedal.
If the pedal is higher, you need to re-adjust your rear brakes .
 
inertia said:
Set the emergency brake on hard, pump up the foot brake, then release, - try and see if you still have excessive pedal.
If the pedal is higher, you need to re-adjust your rear brakes .
Click to expand...
First thing I did.
Since I had to take the system apart to change any of the suspected parts I just replaced all the wear items. Flush & bleed once.
~$200 to potentially save a life and give me peace of mind!
 
Since the only thing you really disturbed, was the front calipers, I'm thinking execssive caliper piston movement was the cause of your problem.
 
Charrlie_S said:
Since the only thing you really disturbed, was the front calipers, I'm thinking execssive caliper piston movement was the cause of your problem.
Click to expand...
Brake pads are relatively new there was just enough piston release to release the pads from the discs. These are the 4 piston K-H brakes, no major piston retraction into the caliper body.
I think the hoses may have been damaged from being bent when I hung the calipers, and moved around while removing and replacing the UCA's. They were older, may have started coming apart internally. I didn't have a second person to inspect them under pressure to see if they were expanding.
At any rate I now have fully functioning brakes for what I consider a reasonable price.
 
Long shot here but once apon a time with myself, same scenario, the rubber brake line cracked.
 
If you ever run into this problem again, use a clamp on each brake hose and see if pedal improves. That will isolate the problem.
 
You must log in or register to reply here.
-

Back
Top