Manual Brakes 1970
Thread Starter
Heel & Toe
Joined: Oct 2011
Posts: 18
Likes: 0
From: Nelson Bay New South Wales
Manual Brakes 1970
I bought my Vette from Denver in Jan 2012, arrived in OZ pristine, drove excellent. I did notice the brake padal had way too much free play although the car stopped in a straight line. Now, the car pulls to the right and the brake pedal is almost on the firewall. I am mechanically minded and can carry out most non major routines on the car though I'm no expert when it comes to brakes. Is bleeding the system (which I'm happy to do) the answer or am I looking at calliper work or master cylinder etc. Just need to know where to start and what to look for.
Thanks guys.
Thanks guys.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Inspecting the system is first- Look for leaks, worn pads, or anything loose. If the pads are good, then maybe flush and bleed the system. It's possible the master cylinder is going away, but I'm not one to start throwing parts at something without a cause. Maybe even have someone stand hard on the brakes while you look at the flex hoses- one could be expanding under pressure.
Kind of goes with "Let's do the cheap stuff first"
Kind of goes with "Let's do the cheap stuff first"
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Look at both sides of the rotors on each wheel. What you want to see is a smooth, shiny surface. If you see rough grooving, the associated disc pad is worn out and it is now digging into the rotor surface. Also, look for any signs of discoloration which might indicate a fluid leak.
Most leakages will be on the inside of the wheel and you will see brake fluid splatter/dripping on the sidewalls of the wheel. But, it could also be found on the caliper, itself, or from a defective seal on a caliper piston.
Usually a "pull" condition during braking is due to a rotor that is 'grabbing' (due to pad wearout or fluid getting on the rotor) or 'slipping' (mechanical caliper/piston problem or fluid blockage in line/hose). A good visual inspection can often identify what may be happening with your braking system.
Most leakages will be on the inside of the wheel and you will see brake fluid splatter/dripping on the sidewalls of the wheel. But, it could also be found on the caliper, itself, or from a defective seal on a caliper piston.
Usually a "pull" condition during braking is due to a rotor that is 'grabbing' (due to pad wearout or fluid getting on the rotor) or 'slipping' (mechanical caliper/piston problem or fluid blockage in line/hose). A good visual inspection can often identify what may be happening with your braking system.
Instructor
Joined: Aug 2009
Posts: 147
Likes: 2
From: Bargo NSW
Hi Roger,
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
Racer
Joined: Oct 2010
Posts: 373
Likes: 2
Hi Roger,
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
Peace
Frank
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Instructor
Joined: May 2011
Posts: 163
Likes: 0
From: Clayton NC
Hi Roger,
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
I went with the stainless steel lines and converted to O-ringed pistons when redoing my 1970's manual brakes. My pedal feel is awesome and there is only maybe 1-2 inches of travel before the pads grab. If you go with the O-ring pistons check and make sure your calipers have the stainless steel sleeves.
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
check for air ( bleed, then figure out how air got in)
leaky calipers with wet pads or rotors ( rebuild with o-ring kits)
also check for ballooning rubber lines ( replace them both) .
wheel bearings adjusted correctly on front?
suspension bushings/ball joints totally shot? ( alot less likely but possible)
all of the above can cause pressure differential or a different coefficient of friction at each caliper and cause your car to veer left or right upon braking.
leaky calipers with wet pads or rotors ( rebuild with o-ring kits)
also check for ballooning rubber lines ( replace them both) .
wheel bearings adjusted correctly on front?
suspension bushings/ball joints totally shot? ( alot less likely but possible)
all of the above can cause pressure differential or a different coefficient of friction at each caliper and cause your car to veer left or right upon braking.
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
Hi Roger,
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
I had a problem similar with my car and found that it was the lip seals in the calipers. They would draw air into the system, I would bleed the brakes and have a great pedal the head out for a drive and by the time I would get back the pedal had just about gone to the floor. Replace the lip seal with "O" ring type calipers and have not had a problem since.
Also a good idea to replace the rubber lines while your at it.
The origional style caliper seals had very little tolerance for rotor runout, like 0.002" max. The Oring type caliper seals will tolerate a bit more runout without problems..
Thread Starter
Heel & Toe
Joined: Oct 2011
Posts: 18
Likes: 0
From: Nelson Bay New South Wales
Manual Brakes 1970
Update on the brake issue.
Firstly, most of the issues raised by you guys were correct and contributed to solving the problem. Many thanks. I removed the front left calliper and completely dismantled it and found it contained water!!! (probably drawn in from the worn seals) and likewise for the remaining calipers. I also did the same for the master cylinder. I noticed the master cylinder had corrosion on the walls and the seals were shot. Immediately ordered a new MC and a complete seal kit for the calipers. After overhaul and reassembly I noticed I could not bleed the rear brakes! (front were fine) I blew air (about 10 psi) up the lines to make sure the lines weren't blocked and they were fine. So I ordered a new proportioning valve and installed it, bled the brakes and now the ol girl stops like new. Next time it's stainless steel sleeves and pistons as well. Hope this helps anyone with C3 brake issues. Thanks AR.
Firstly, most of the issues raised by you guys were correct and contributed to solving the problem. Many thanks. I removed the front left calliper and completely dismantled it and found it contained water!!! (probably drawn in from the worn seals) and likewise for the remaining calipers. I also did the same for the master cylinder. I noticed the master cylinder had corrosion on the walls and the seals were shot. Immediately ordered a new MC and a complete seal kit for the calipers. After overhaul and reassembly I noticed I could not bleed the rear brakes! (front were fine) I blew air (about 10 psi) up the lines to make sure the lines weren't blocked and they were fine. So I ordered a new proportioning valve and installed it, bled the brakes and now the ol girl stops like new. Next time it's stainless steel sleeves and pistons as well. Hope this helps anyone with C3 brake issues. Thanks AR.