brake caliper problem

marc79euro645 · Post by **marc79euro645** » Sat Jun 17, 2017 6:26 pm

My 79 euro 645 has 4 pot ate calipers on the front, with a vacumn booster.I had a problem with the driver front caliper sticking and dragging , getting hot, so I replaced them with rebuilt calipers. Now I've got the same problem. Even a short drive is enough to cause the wheel to drag causing a shimmy and motor temp rises.
I came home today after short drive and jacked up front wheel, it was locked up, so i cracked open the bleeder on caliper, it's still locked up with bleeder open. I wait 1 hour for it to cool off and brakes are free, no drag at all.So I was thinking that if the problem was in master cylinder or booster, cracking open the bleeder would release the pressure and free up brakes, but no difference. I can't believe the newly rebuilt( from professional rebuilder) caliper is the problem, It was the same wheel before the new calipers. The brake hoses were replaced about 2000 when I got the car,and show no signs of collapse or kinks.
any thoughts appreciated!
marc

franky2fingaz · Post by **franky2fingaz** » Sat Jun 17, 2017 11:41 pm

The Brake fluid was flushed? I've seen new calipers seize from contamination in the fluid. Like excessive water or other oils. If you take apart the calipers check if the piston seals swelled up...

Mike W. · Post by **Mike W.** » Sun Jun 18, 2017 12:58 pm

I can well believe that rebuild calipers would be so poorly done, I definitely can. I did all 4 of mine earlier this year and it took a bunch of time. With the little that's being charged for rebuilt calipers I have to assume no TLC went into it. I would guess the seals are ok, but the caliper bores and pistons weren't cleaned well. But if you crack the bleeder and it's still seized, the caliper is the only thing it could be.

marc79euro645 · Post by **marc79euro645** » Mon Jun 19, 2017 7:28 pm

Update and correction
I was wrong about cracking the bleeder because these 4 pots have 2 cicuits and 3 bleeders, so now I have learned the lower pucks are on a different circuit and when I crack the lower bleeder it 's instantly free to move. I decided to pressure bleed again starting on passenger front I got good flow from both lower bleeders, but driverside bleeder all out , I get nothing.This is the same bleeder that released when I opened it!
So i tried back bleeding from that lower inside bleeder up to the master cylinder. It won't back bleed either , no flow.
So I start the car and apply the brake, I get out and check the disc, it's locked, I crack open the lower bleeder and it releases.
About this time the power bleeder hose blows off the cap (no clamp)and sprays brake fluid all over the car.
so now I'm pissed off and confused, an all too common experience for me.

marc79euro645 · Post by **marc79euro645** » Tue Jun 20, 2017 6:47 pm

Well it turned out to be the rubber brake hose. I've heard of this before, but kinda thought it was urban legend. The hose shows no sign of problem on the outside but even 120 psi won't pass thru. So this time I'll get s.s. braided lines. What a pita job! I remember when I first resurrected this car in 2000, brake hoses were one of the first projects, so I've spent the last 17 years trying to get this car to look good and run good at the same time,and have yet to accomplish that goal.
Now I'm starting over at the top of the list again.
I'm beginning to question the feasibility of ever getting this car 100%.

RonDwyer · Post by **RonDwyer** » Tue Jun 20, 2017 9:07 pm

Replace the rubber lines with the same thing. Just because yours wore out doesn't mean they were flawed. If someone can prove to me that there is a teflon line that passes a 180 degree kink test without shattering then I will believe they are DOT approved. Otherwise, the only thing you are getting with externally stainless braided hoses are rubber hoses with pretty covers. I know, I worked for Aeroquip back in the 80's.

Road debris hitting a hose is the reason for the DOT requirement. Off-road and racing applications are at the discretion and peril of the driver.

Get some Kroil and spray the threads and wait an hour before taking them apart. You will round off the nuts otherwise and ruin the steel lines. Use a line wrench.

Mike W. · Post by **Mike W.** » Wed Jun 21, 2017 11:25 am

marc79euro645 wrote:Well it turned out to be the rubber brake hose. I've heard of this before, but kinda thought it was urban legend. The hose shows no sign of problem on the outside but even 120 psi won't pass thru. So this time I'll get s.s. braided lines. What a pita job! I remember when I first resurrected this car in 2000, brake hoses were one of the first projects, so I've spent the last 17 years trying to get this car to look good and run good at the same time,and have yet to accomplish that goal.
Now I'm starting over at the top of the list again.
I'm beginning to question the feasibility of ever getting this car 100%.

I had brake lines on a Bav swell internally so badly I couldn't even get a drop out with full pedal pressure and from what I've read that would be over 1,000PSI. It's not just urban legend.

marc79euro645 · Post by **marc79euro645** » Wed Jun 21, 2017 7:45 pm

I do use a line wrench and still managed to mess up 1 of the steel line nuts, so I start looking at the wrench and realize there is a chamfer on the inside that misses the lower half on the nut. I ground the wrench to eliminate the chamfer and get full contact on the nut. The rest of the lines came free without rounding the nut.
I still hate brake jobs.

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brake caliper problem

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