Any ideas to help me with a"soft" brake pedal on my 930?

Notice at MAM that the brakes felt a littke soft, so last week at HPT we bled them and to me they still feel soft when I am really hammering them. The brakes on my 964 are rock solid.

Repalced the original 1982 master this weekend. Bench bled master , then did a full bleed using pressure. Still felt too soft. This AM, I re bled everything pushing a full Motive catch bottle through each bleeder. Thought I got a little air out of the right rear, but they still feel soft to me, especially at full lock..

I should be able to slam them on and lock everything up (on street tires) should I?

going to RA in two weeks, so want these suckers to work!

Any suggestions?

Thanks

Bob
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Bob -

Are they consistent or does the pedal go down after they get hot? I can't remember, but doesn't the 964 have power assist/anti-lock brakes? Does it brake straight with hands off the wheel? It's a very simple system, either a MC problem, a caliper problem, or the lines in between. I'm assuming you are still using the Performance Friction 97's so rotor deposits or pad issues aren't it.. I found the brakes more than adequate when I tracked her at Watkins and Limerock, maybe have someone that drives an older 930 do a comparison... BTW, I gave you that invoice because it was the only record of the B&B Header purchase. I bought them through Dan, the cash went to a customer of his.

 

are you saying you can not lock them up on street tires?

...I agree with Gary, the early systems are simple. no leaks any where? how old are the lines going to the calipers?

 

Brand new OEM Joe... (Edit- Bob changed them and installed SS lines, see below).

 

thanks for the response guys. yes I know the system is simple, that's why I am a little perplexed. Pedal still feels a little soft at the end of it's travel. No leaks that I can find and I bled the you know what out of them over the weekend, twice. I replaced the flexible lines with SS before the MAM event, although looking at the documentation after, I noticed that Gary had replaced the rubber ones last summer.

Brakes straight, hands off and now I can lock up the right front.

It might be just me. Good advise to try another car or someone with experience with 930's. There are a couple of cars and guys around.

I did not notice it changining or getting worse as the track sessions went on (and we had some 30 minute sessions on Sunday).

When I changed the SS lines, Karl put in a new set of EPT yellow pads. these are the same ones he uses in his car with pretty good results. I have the pads she came with so maybe I'll try and put them back in and see if there is a difference. Can't imagine pads causing wierd pedal feel.

Of course, it may just me being paranoid now that i am going alot faster!

 

Pads themselves won't cause a soft pedal Bob, I was just talking about general braking problems. Some pads leave a deposit on the rotors and in doing so reduce their efficiency. I know the PF97's, from experience, do not and are my personal favorites (though I am trying out Pagid RS14's (Black) in the rear of my car at the moment)...

 

Go out to your car now (cold) and step on the pedal as hard as you can and report back.

 

I see Castrol SRF coming into the conversation....

 

BTW, pads can cause weird pedal feel. PFC 97's get a lot of initial bite. When you switch to other pads with less initial bite, you feel like you're not slowing down the same way so you push more on the pedal. It can feel like the pedal is traveling even further than normal.

 

when i step on the pedal cold with the engine idling it seems hard enough. When driving and stomping on it, it seems as if it travels farther and is not as solid at full application.

 

What do you mean you can lock up the right front?

 

Before I replaced the master and did the major bleeding no matter how hard i pushed on the pedal i could not get any of the wheels to lock up ( 40 MPH panic stop). After the new master and much bleeding now I can get the right front to lock up but that's it.

I di not bleed the clutch system even though it is supplied from the same resovoir. I clamped off the clutch supply tube abd then topped it off with a turkey baster before reconnectiong to the resovior. Clutch action is fine. Surely the clutch system has nothing to do with the brakes?

BTW, I have a G50 in the car (1982 930) so don't think I am crazy talking about the clutch hydraulic system.

One other thought is that I left some air in the MC during the install. I bench bled it thoroughly and then used the little plastic cups to plug the holes while I installed it. Lost a little fluid while hooking up the two lines but I would think that would have been cleaned up during the thorough bleeding after the install.

B

 

Are you seeing uneven pad wear?

 

no...but i will check the new pads this week, but it may be two early to tell.

 

no uneven wear prior though?