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TR2/3/3A TR3A Disc Braked not releasing
- Thread starter RonR
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BRSLimited
Jedi Trainee
Offline
Without having it right in front of me I could only guess it's either the seals in the calipers are too tight, the hoses are bad, or a problem in the master cylinder.
trrdster2000
Luke Skywalker
Offline
Take the pads out and get the pistons running freely. Use a couple of paint sticks on each side to keep the piston from coming out. One of the pistons has a bit of off set and needs some help.
Wayne
Wayne
vivdownunder
Jedi Warrior
Offline
If it's not tight new pistons/seals, check for the restrictor valve playing up. It's on a 5 way connector on the frame near the exhaust downpipe.
The restrictor's inside bits tend to rust, but it can be dismantled and wire brushed clean.
Viv.
The restrictor's inside bits tend to rust, but it can be dismantled and wire brushed clean.
Viv.
Got_All_4
Luke Skywalker
Offline
Can you blow air both directions through the flexible hoses? The reason I bring this up is a few years ago my TR3A had a problem with a caliper locking up and staying locked. The flexible rubber hose had a chunk of rubber that came loose and was acting like a flapper. Only letting fluid go one direction and not back to the reservoir.
Just happened again in May to my work car. 220k on it so I thought I'd replace the calipers and that would take care of it. Wrong. Still did it so I replace the hose ($12) and that cured it.
Just happened again in May to my work car. 220k on it so I thought I'd replace the calipers and that would take care of it. Wrong. Still did it so I replace the hose ($12) and that cured it.
Here is the update.
I removed the restrictor valve and cleaned it out with air pressure. The front disc brakes still lock up. They release when I loosen the bleed screw. The flexible hoses are new from the Roadster Factiory but maybe I should blow them out with air too. With the caliber off the car, I can move the pistons with my fingers.
I did blow out all the metal brake lines prior to reassembly when I rebuit the hydraulic system.
When the front brakes lock up, the master cylinder piston does not return to it's full"forward" position. Eventually, after some length of time, the brakes release and the master cyclinder returns to normal. However, when driving the car, the brake fluid gets hot and I lose brakes all together
The rear brakes do not lock up.
I am thinking there must be some dirt or crud in the metal brake lines feeding the front brakes, unless someeone else has a suggestion.
Thanks
Ron
I removed the restrictor valve and cleaned it out with air pressure. The front disc brakes still lock up. They release when I loosen the bleed screw. The flexible hoses are new from the Roadster Factiory but maybe I should blow them out with air too. With the caliber off the car, I can move the pistons with my fingers.
I did blow out all the metal brake lines prior to reassembly when I rebuit the hydraulic system.
When the front brakes lock up, the master cylinder piston does not return to it's full"forward" position. Eventually, after some length of time, the brakes release and the master cyclinder returns to normal. However, when driving the car, the brake fluid gets hot and I lose brakes all together
The rear brakes do not lock up.
I am thinking there must be some dirt or crud in the metal brake lines feeding the front brakes, unless someeone else has a suggestion.
Thanks
Ron
hondo402000
Darth Vader
Offline
do you have a brake booster on the car? if so there is a small round headed screw and bolt that you adjust the booster to contact the master cylinder, one turn too far and the brakes wont release pressure, I found out the hard way
Hondo
Hondo
TimK1955tr2
Senior Member
Offline
Long shot....
Are the rotors within thickness spec? If too thin, maybe the pistons are extending too far and getting "stuck" out...
Are the rotors within thickness spec? If too thin, maybe the pistons are extending too far and getting "stuck" out...
Folks,
No brake booster.
Rotors are within tolerances.
Since the master cylinder piston is not returning to the full "forward" position, I think the problem is within the master cylinder. Although, it would seem that the back brakes would lock up too. Regardlwss, I will take the master cylinder apart today and see what I find.
Thanks for all the suggestions.
ron
No brake booster.
Rotors are within tolerances.
Since the master cylinder piston is not returning to the full "forward" position, I think the problem is within the master cylinder. Although, it would seem that the back brakes would lock up too. Regardlwss, I will take the master cylinder apart today and see what I find.
Thanks for all the suggestions.
ron
TR3driver
Great Pumpkin - R.I.P
Offline
How tightly do they "lock up"? Will the car not move at all, or can you just not turn them by hand?
What happens if you loosen the outlet fitting at the MC?
Getting two bad hoses at the same time seems like an awful coincidence to me, especially since this isn't a common failure for new hoses. But if cracking the fitting at the MC doesn't release the brakes, then it's not a MC problem.
My next step would be to loosen a fitting between the RPV and the front brake hoses. If that releases them, the problem is most likely the RPV itself, doing what it is supposed to do (especially if you just can't turn the wheels by hand). The cure is to leave out the guts of the RPV.
What happens if you loosen the outlet fitting at the MC?
Getting two bad hoses at the same time seems like an awful coincidence to me, especially since this isn't a common failure for new hoses. But if cracking the fitting at the MC doesn't release the brakes, then it's not a MC problem.
My next step would be to loosen a fitting between the RPV and the front brake hoses. If that releases them, the problem is most likely the RPV itself, doing what it is supposed to do (especially if you just can't turn the wheels by hand). The cure is to leave out the guts of the RPV.