Brakes don't Bite Options

[bkrantz]

As part of my rebuild I completely replaced the brake system:
calipers and rear pressure valve rebuilt by PMB
new ATE 19mm master cylinder
new hard and flex lines
new disks and Porterfield R4-S pads

I went through many (many!) episodes of bleeding, with different methods. The pedal feels very firm from the first push, and does not pump up. Rear clearance is set at .004". I went through the PMB bedding process, and have driven around a bit.

But the braking force seems weak. When I get on the brake pedal, I do not feel any "bite". Another 914 friend drove the car and also agrees.

Any suggestions?

[PatMc]

I would try a conventional bleeding method…one person on the pedal, one person at the calipers. If this is a late car, make sure you’re bleeding at the top bleeders. With the higher pressure doing it this way, you create substantially higher fluid velocity which will carry more air with it.

Another trick you might try…pull the front pads out and replace with something about 1/2 the thickness, then pump the pedal up to run the pistons out a bit…then push them back in. Sometimes pushing fluid towards the master, rather than towards the calipers can find and expel more air. Of course, put the pads back in after this.

Lower HP/slow cars can be a bitch to bed in when using a high temp pad because by the time you get it back up to speed after the first brake application, they’ve had some time to cool off. In some cases like this, more of a “normal” street pad will work better since it’s designed to work properly at lower temps and doesn’t require the rather rigorous bed-in that a higher temp range pad typically needs. A lower temp pad that IS bedded in will many times out perform a higher temp, higher friction level pad that is NOT bedded in.