Brake pedal feel question

[Bglad]

So I just got done rebuilding all four calipers, new pads (Hawk HP+), rotors on all four corners and installed SS lines. Bled the system with RPF600 300ml rears, and 200ml fronts to ensure I had a good flush.

Now my issue is that when I push the brakes while driving the pedal is a little soft/delayed, then another quick tap on it and its good and firm. I can pump the pedal in the car with it off and it builds pressure and remains and I've checked for leaks at all places with none to be found. I was going to bleed the system again in the next couple days and see if that fixes it. Other than that the brakes work amazing.

Just seeing if anyone else has had a similar issue and what it was?

Car is a 91 318is BTW.

[matthugie]

Sounds like it needs to be bled again, or you might have a caliper that didn't seal properly and has a small leak.

[Bglad]

Thats what I was thinking too. I'm doubtful its a bad seal in the caliper, but anything is possible. I bled the system by myself during the half time show. Well see what happens.

[Todd Black 88]

Did you replace the guide bushings in the calipers, when you rebuilt them?

That was my issue

[Bglad]

Did you replace the guide bushings in the calipers, when you rebuilt them?

That was my issue

Yes I did. I used ATE rebuild kits. I'll take a look at it tonight to make sure nothing is hanging up as I lubed everything well.

[nando]

sometimes when I bleed the brakes, I tap the calipers with a ball peen hammer while I've got the bleed screw open. seems to pop some of the stuck air bubbles free. I use a pressure bleeder too, but you can still get bubbles stuck in places.

[TobyB]

+1 for the tapping. The other thing to do is to go out and stand on them hard a few times.

The rubber seals are what retract the pistons just a thou or 2 when you release
pressure, and after a re- sealing, often they over- retract. So the pressure and heat
of a number of good, hard stops usually helps with that. AND it helps with bleeding.

What I've found.

t

[jalopi]

Tis probably some air in the system, somewhere. Are you bleeding it alone? Try having someone 'stand' on the brakes (apply as much force as humanly possible) while you look for leaks if the sponginess doesn't go away from bleeding.