Long pedal after new calipers- multiple bleeds

SKL1 · 07-07-2019, 09:27 PM

Replaced all 4 calipers (nice "new" calipers from Eric) and pads on my '72 T targa. Even after multiple bleeds with Motive and another with a friend the old fashioned way, still have a really long pedal with horrible feel. Not getting any air out but pedal won't firm up. Pedal feel was great before I started...
I've been doing this for 40+ years but what am I missing????

manbridge 74 · 07-07-2019, 09:32 PM

Take the pads out and put a thin shim on each side. Press pedal a few times. Remove shims and move pistons back just enough to put (actually force) pads back in. Bleed as usual and again a day later. Search “exercising caliper pistons” for more info..

Bill Douglas · 07-07-2019, 11:55 PM

Unlikely...

But this is what I did :blush: I put the calipers on upside down. They fitted up fine and worked OK, just a bit spongy. Being upside down the air wasn't floating upwards and out the bleeders.

Good luck with finding the solution.

Roswell · 03:45 AM

Firmly tap (HIT) the caliper several times with a wrench while you are bleeding. Helps to move the air bubbles out of the caliper.

Quicksilver · 07-08-2019, 04:14 AM

It isn't unusual for it to take a while for the seal retraction to take a while to settle down but Eric's would be the least problematic calipers available.

The question is if the problem is a caliper or farther upstream in the system.
I'd put the car up on stands and use a caliper (machinists caliper) to measure the travel of the pads on each wheel. If one is noticeable longer you have something to chase down.
If they are all the same you can look at lines and the master cylinder.

Test, test, test!

dannobee · 07-08-2019, 06:21 AM

When you removed the calipers, did you remove them one at a time, or did you replace them all at once? If all of the fluid ran out, you might have to bench bleed the master cylinder.

Jack Stands · Jack Stands's Garage

I found that taking the car out for a drive on some bumpy roads while the pedal was still less than optimum helped to shake the air bubbles up to the bleeders. One more bleeding operation (I seem to remember I used a pressure bleeder that time), and the pedal became wonderfully firm.

yelcab1 · 07-08-2019, 07:47 AM

Quote:

Originally Posted by Bill Douglas

U...I put the calipers on upside down. They fitted up fine and worked OK, just a bit spongy. Being upside down the air wasn't floating upwards and out the bleeders.

Good luck with finding the solution.

9 times out of 10, this is the problem. If your bleeder valves are pointing to the ground instead of the sky, this is your issue. Simply swap left to right and rebleed.

True story: My neighbors rebuilt his calipers on a 914-6 and went through a gallon of brake fluid without getting firm pedal. I came over to assist and noticed his bleeder valves pointed down instead of up. We swapped sides, and it firmed right up. He was not amused with himself.

Funny thing is the very next weekend, Car Talk had a puzzle that is exactly like that. I called the neighbor up and told him to call in to Car Talk to solve the puzzle.

theiceman · 07-08-2019, 07:56 AM

Quote:

Originally Posted by Quicksilver

It isn't unusual for it to take a while for the seal retraction to take a while to settle down but Eric's would be the least problematic calipers available.

The question is if the problem is a caliper or farther upstream in the system.
I'd put the car up on stands and use a caliper (machinists caliper) to measure the travel of the pads on each wheel. If one is noticeable longer you have something to chase down.
If they are all the same you can look at lines and the master cylinder.

Test, test, test!

this ...

go out and bed the brakes,,, long travel will go away quickly.

SKL1 · 07-08-2019, 09:03 AM

Just talked with Eric and it's probably the new seals retracting the pistons. He mentions this in his FAQ section of his website... Need to bed the pads and seals and get everything hot- not a problem here in Scottsdale this time of year!
Will drive the car though I hate a long pedal!!

Quicksilver · 11:00 AM

Quote:

Originally Posted by SKL1

Just talked with Eric and it's probably the new seals retracting the pistons. He mentions this in his FAQ section of his website... Need to bed the pads and seals and get everything hot- not a problem here in Scottsdale this time of year!
Will drive the car though I hate a long pedal!!

Imagine a 2000 mile road trip with a "pump it every time" pedal.

When I got home I called Eric to get good rebuilt calipers...
__________________________________________________ _____

BTW - To anyone who doesn't know: The "Eric" we are all referring to is Eric at PMB.

Jameel · 07-08-2019, 11:14 AM

Ditto on what Jeff said. It's also what Eric told me to do on mine when I asked him at Rennsport last year. Try it. It worked for me.

VFR750 · 07-08-2019, 11:19 AM

Quote:

Originally Posted by manbridge 74

Take the pads out and put a thin shim on each side. Press pedal a few times. Remove shims and move pistons back just enough to put (actually force) pads back in. Bleed as usual and again a day later. Search “exercising caliper pistons” for more info..

This is a very typical result of a rebuild. The seal retracts the piston too much.

Do this process and you will at least addressed the most common problem after a rebuild.