MDL

I think it could be either of those things, but I still think there could be a problem in the booster.

old man neri

Tested the booster by holding the brakes and then turning on the engine. The pedal sank slightly as it should. I assume that means the booster works.

-matt

rusnak

Matt,

If you do multible pumps, can you get the pedal to come back up to normal level? Hold the pedal down. If it does not sink but stays at the same level, and multiple pumps brings the pedal higher, then I think you have brake pistons too far retracted in the calipers.

One of these at your local Pep Boys or Kragen will help you to fix this. Brake pad spreader. You tap on the brake pedal with the pads removed, then put the pads back in with the caliper off the rotor. Spread the pads just until you can slip the caliper over the rotor with the pads in place on the pins. Bingo, perfect adjustment of the brake pistons.

old man neri

Pedal does not sink but multiple pumps don't seem to make a difference. I felt what over-retracted pistons were like right after I rebuilt them. The pads are very close to the rotors now, from visual inspection. One can feel a slight drag as well when it is on the hoist.

Hopefully it's a big air bubble in a 5th brake line I forgot to bleed or something.

-matt

MDL

My booster problem on the Camaro was intermittent. Maybe yours is to.

It will be interesting to see what the shop finds.

rusnak

I guess I'm confused as to what the symptoms are now.

Multiple pedal pumps = no stoppy, no pedal feel? Sounds like a fluid leak or yes I agree...bad master cylinder. If there was air in the system at least you'd feel spongy brakes & slow stoppy. Bad booster? I dunno but it seems to me you'd have higher pedal effort but still have solid pedal.

RoninLB

I vote MC seal leaks.

maybe you did this while pedal bleeding after the caliper rebuild?

and I file the edge of new pads so I can slam them between slightly over extended pistons. If you look at the piston ring it looks like it wants to pull the piston away from the pad.

it seems like you have a few prob's going on?

old man neri

The Verdict is in.

Basically there was nothing major that was wrong. A few minor issues however.

1) The front rotors are slightly curved, not warped. The surface is actually concave, that is to say the out and inner edges are higher than the centre of the wear surface. When I got new pads I didn't turn the rotors so there was the slight issues of a flat pad on a curved surface. This was never an issue before the caplier rebuild because the pads were still very close to the surface. Now that they are a little farther out more water could get in there. So when I was braking in the wet the pads were actually riding on steam. Thus whenever I brake frequently it wasn't a problem but not using them for a few min cause them to get completely soaked. Normally the pads should be slightly dragging causing the water to be displaced. The wrench recommended I change front pads and rotors in the spring.

2) The pads are still ever so slightly retracted. The wrench played with them a little and lubed the pads/retaining pins where they touch the caliper with anti seize. I had never done this or heard of this before but he suggested it.

3) System was bleed. No air was found.

4) The change in pedal feel was explained like this. When I first bought the car all the calipers were slightly stuck so the pads were dragging on the rotor more than they should. Thus when I pressed the pedal there was no movement at all and the pedal was solid, it barely budged. When I replaced the pads I freed them a little and the pedal feel changed. When I rebuilt them all I really freed them and thus the pedal now had movement. The wrench, a 911 owner himself, explained that this is in fact how the pedal is suppose to feel. Another tech there also drove my car and he thought nothing was wrong.

So in the end there was nothing really wrong. Just a light issue with curved rotors and the pads ever so slightly over retracted. I was just use to driving a car with stuck calipers.

He also noticed one of the front bearings was a little loose, he took care of that. The final recommendation was that I stop being a ***** and really use the brakes. I guess I was afraid of burying the brakes because of the different pedal feel and I was tip toeing on them.


I am happy that there was actually nothing wrong and that I didn't botch the work I did.

Thank you all for the great advice and input you all provided. I really appreciated it. May you all have a wonderful new year.

-matt

Ed Hughes

Interesting, thanks for the report.

MDL

Yep, concave rotors, that was my next guess.

Interesting. Did they turn the rotors.?

old man neri

Nope. He just said to replace them in the spring.

Ed Hughes

IMO, it is a sin to turn rotors on a P-car. That is contrary to the goal so many have in upgrading brakes; increasing the heat displacement.

rusnak

+1, but 3.2 911s have a little bit more meat on the rotors than earlier cars.

Still, the rotors are so cheap I usually replace them with every other pad change, or sooner.

I'd think about changing the rotors now (you installed fresh pads?).

Also, next time you rebuild the calipers, might want to lube the bores with a dab of ATE caliper grease. Also try the brake pad expander thing that I mentioned. The calipers and pads will seat properly. It's a matter of safety.

old man neri

Pads probably have about 10K on them. The only reason he suggested waiting was that it was not really critical and because of the weather. I might do it once I get out of this salty area. I wouldn't exactly describe the rotors as 'so cheap'. The rotors for my civic are cheap.


Hopefully I will not have to rebuilt them. I did use a lube (wasn't ATE) on the bores. I didn't have the expander, what I did was just bolt the calipers back in and then manually push the pistons in the minimum needed to get the pads to fit.

old man neri

Update,

I finally got around to replace the rotors and pads (the problem sort of went away after a bit of time.) and getting parts shipped was a biatch.

The question I have is; Do I need to recheck the bearings torque/tightness/setting after a set amount of miles?