brake pedal travel issue

[lindbergh]

My brake pedal goes down about 2 inches before I get any braking at all and max braking (no lockup but hard braking) occurs at about the same time my pedal hits the floor. I have replaced the master cylinder twice and rebuilt all 4 calipers. The system has been bled 4 times with no indication of air after the first bleed and the master have been properly bled. I don't think there is air in the system unless conventional bleeding does not work on this car. I feel confident there is no air in the system and believe the master cylinder is good. Any ideas of what else it could be?

Thanks.

[DMCMW Dave]

My brake pedal goes down about 2 inches before I get any braking at all and max braking (no lockup but hard braking) occurs at about the same time my pedal hits the floor. I have replaced the master cylinder twice and rebuilt all 4 calipers. The system has been bled 4 times with no indication of air after the first bleed and the master have been properly bled. I don't think there is air in the system unless conventional bleeding does not work on this car. I feel confident there is no air in the system and believe the master cylinder is good. Any ideas of what else it could be?

Thanks.

Have you seen any issues bleeding it (such as low flow)? Have the hoses been replaced? Bleeding can be slightly tricky in the front as the feed hose and the bleeder are on the same side of the caliper, i.e. it's hard to get air out of the outer piston chamber sometimes.

[PJ Grady Inc.]

This is normal to experience a lower pedal after rebuilding calipers as they use a square seal in an offset bore. As they gradually adopt a "set" your pedal will get firmer as the pistons get closer to the pads. I remember everyone complaining about low pedals in 1981 when the cars were brand new. The complaints went away within a year as everyone's calipers settled in. Back then disc brakes were the exception rather than the rule and were rather crude by todays standards. If your flex hoses are new or at least not restricting flow and the system is properly bled then this is your culprit and it will eventually solve itself.

Additionally some replacement brake master cylinders (such as the Saab intended unit) will make for a lower pedal unless you adjust the booster pin. I'm quite sure I've explained this here before so try looking it up in the recent archives before I go on doing it again. One very big caveat is that if you overadjust the pin as the brakes settle in they could start to drag and toast your rotors and pads and could cause a sudden loss of stopping power.
Rob

[EdR5150]

Yes, adjust the booster pin, or rod, or whatever it's called. There isn't any procedure for this in any manual. I documented the same issue in my blog with pictures:
http://www.16908.info/?p=1605

[David T]

Yes, adjust the booster pin, or rod, or whatever it's called. There isn't any procedure for this in any manual. I documented the same issue in my blog with pictures:
http://www.16908.info/?p=1605

Yes, you may have to adjust the rod but do it in small increments, a small adjustment can have a large effect and as Rob says, if you make it too long the calipers won't release and you will toast the brakes. You do not have to disconnect the brake lies to the master cylinder. remove the 2 nuts and just move it away from the booster. Use 2 wrenches, one to hold back so you don't turn the rod, only the end to make it *slightly* longer. Be SURE you get FULL release on the brakes.

[EdR5150]

...however about two inches of travel in the pedal is exactly where you want braking to start. If you're going all the way to the floor, there could still be air somewhere. Does the pedal feel spongy? Did you accidentally swap a right and left caliper?

[PJ Grady Inc.]

Only a total moron would cross calipers and the day I see that will signal to me it's time to start looking at retirement communities!

Rob



...however about two inches of travel in the pedal is exactly where you want braking to start. If you're going all the way to the floor, there could still be air somewhere. Does the pedal feel spongy? Did you accidentally swap a right and left caliper?:bootyshake:

[Lou and "Boo"]

I rebuilt my calipers when I first bought my car and got it running. I did not change the master cylinder. I have the low pedal issue and they are not spongy at all just low and I've driven many miles and it hasn't improved at all.

[David T]

I rebuilt my calipers when I first bought my car and got it running. I did not change the master cylinder. I have the low pedal issue and they are not spongy at all just low and I've driven many miles and it hasn't improved at all.

Although YOU may not have changed the Master Cylinder, it may have been changed BEFORE you bought the car. I small adjustment of the pushrod may be all you need.

[lindbergh]

...however about two inches of travel in the pedal is exactly where you want braking to start. If you're going all the way to the floor, there could still be air somewhere. Does the pedal feel spongy? Did you accidentally swap a right and left caliper?

No chance of swapping, it was done one at a time. The brake does not feel spongy just have to put it on the floor to get decent braking. I will try a small adjustment of the rod. Thanks for the tips and for the booster pin procedure.

[PJ Grady Inc.]

Ed is right about the first two inches of travel before engaging being both normal and necessary. These brakes do not have the high solid feel of newer disc bake systems. That's where you can get into trouble if you try for the pedal height of a modern car brakes. If it's lower than 2" the pin/rod adjustment is your answer. Typically with a new Saab style master, which we used to run without problems, you will have to adjust 2 to 3 turns to get it right. It is tricky in that the first 2 turns often make little difference and the last part of the adjustment is very sensitive when it gets close to being correct. You'll need patience if you adjust in 1/2 turn increments as it could typically take anywhere from one to six adjustments to get it right. Unfortunately there is no substitute for experience. BE VERY CAREFUL NOT TO OVERADJUST.
Better a little loose than a little tight as the calipers could still need to settle in. Both mtr cyl. & caliper servicing often require adjusting the pin especially when both are done at once as they usually are. Remember to check for dragging again as things start to settle in with some mileage on them.
Rob


No chance of swapping, it was done one at a time. The brake does not feel spongy just have to put it on the floor to get decent braking. I will try a small adjustment of the rod. Thanks for the tips and for the booster pin procedure.