Brake experts...
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
Brake experts...
Are the HD/J55 pistons same size as std? Using same seal kit?
Advise on rebuilding salvage calipers please?
How bout that $20 bias spring for the master cylinder is it worth it or pure hype?
Cheers
Check your 6
Advise on rebuilding salvage calipers please?
How bout that $20 bias spring for the master cylinder is it worth it or pure hype?
Cheers
Check your 6
Last edited by jim_hewett; Jun 4, 2008 at 11:58 AM.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
- I wouldn't unless they're just for street driving. Who knows what they've been subjected to, if they've spread, etc.
- Worth it under extreme braking (track [road course] use, I don't notice it on the street)
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
They are the same pistons. I use only used/salvaged J55's in a racing application all the time and the numerous sets I have obtained are (so far) in excellent condition. Remove the pistons by applying compressed air to the fluid inlet port; put a piece of wood against the pistons so they dont come flying out(and possibly scratch the pistons.) I have varying thicknesses of wood so I can push both pistons out only far enough so I can easily pull the pistons out by hand. You will probably find the seals to be in excellent condition, I use a toothpick to pull them out. Check the bore for corrosive pitting, if you don't see any they are good to go. As for the spreading failure mode, that only occurs on raced calipers, in fact that is the only reason I replace the calipers so frequently, it causes a circumferential pad taper. Just measure the bridge for parallelism to be sure. The bias spring is optional(I use it.) You can achieve the same result using more agressive friction compound in the rear. Also, if you decide to go with new calipers, PM me with a price, I will take them off your hands.
Last edited by Sidney004; Jun 4, 2008 at 08:23 PM.
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
They are the same pistons. I use only used/salvaged J55's in a racing application all the time and the numerous sets I have obtained are (so far) in excellent condition. Remove the pistons by applying compressed air to the fluid inlet port; put a piece of wood against the pistons so they dont come flying out(and possibly scratch the pistons.) I have varying thicknesses of wood so I can push both pistons out only far enough so I can easily pull the pistons out by hand. You will probably find the seals to be in excellent condition, I use a toothpick to pull them out. Check the bore for corrosive pitting, if you don't see any they are good to go. As for the spreading failure mode, that only occurs on raced calipers, in fact that is the only reason I replace the calipers so frequently, it causes a circumferential pad taper. Just measure the bridge for parallelism to be sure. The bias spring is optional(I use it.) You can achieve the same result using more agressive friction compound in the rear. Also, if you decide to go with new calipers, PM me with a price, I will take them off your hands.
Cheers
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
