Carrera - Brake - M/C and lines are replaced

[nhromyak]

What a HUGE disappointment.

I have a slightly spongy pedal. I get about 1" free-play then another inch of spongy pedal. This second inch is where the brakes are decent but almost everything else I have driven feel better.

---------------BEGIN SHORT STORY --------------------
Got the car about four years ago. Great pedal.

1 year later, and my first auto-x, I have about 1/2 - 1" extra pedal travel, but the brakes are still "OK".

Only OK because compared to my 97 Mitsubishi Galant's (4 door) brakes my 911 brakes are HORRIBLE!

Another year later, I replace the pads and lines to the front and rear brakes. Bleed the brakes with Promotive Power Bleeder.
Went with ATE Blue.
Good thing too, the "Gold" was turning black.

Brakes are still just "OK".
The brake pedal goes about 1 1/2" to 2" before good braking comes on. I get the "normal" (is it normal?) 1" pedal travel before the brakes begin to drag. About another inch pedal travel until heavy braking, but this last 1" is spongy.

Bleed brakes again. No change.

No leaks - it must be the Master Cylinder - RIGHT???

------------ END SHORT STORY------------

Another year later (today) I change the Master Cylinder (ATE unit).
I use the Promotive Power Bleeder and new ATE Blue brake fluid.

Same result...

Caliper rebuild????

If I pump the brakes about 8 times, I get a hard pedal as I would expect.... But it only lasts for one stop.

Should I adjust the brake pedal travel to get LESS free-play pedal travel???

Thoughts? Questions? Suggestions?

TIA

[89911]

Did you replace it with the larger (turbo) master cylinder? I've never had the problems with my stock setup that you have had and I've done everything you have. Sound as if you may still have some air trapped in your system. You might want to have a helper to help pump the brakes while bleeding next time. I've since replaced my system with the larger MC and turbo calipers. My pedal now has about an inch of travel until full lock up.

[Rick Lee]

You may need to bleed it several times after changing out the MC. When Marcesq put new calipers on his '77, he/we bled them several times - drove it in between and bled again.

[BGCarrera32]

Take a peek at your pads. Is there a gap from the pad surface to the rotor when not steeping on the pedal? If there is have an assistant press the pedal while you watch the pads engage the rotor surface...have them lift off the pedals...and watch the pads retract! Walla! The seals have memory...you may have to pull your pads out one caliper at a time, press the pedal a few times to squeeze the pistons out a little ways, then pry them back just enough to weasel the pads in...I had to tap mine in with a rubber mallet. I just did my brakes and had the same issue (pump the pedal a few times til they firm up- annoying!) and it was because the pads were so far away from the rotor (like 1/16" per pad).

I also know this sounds *really* dumb, but make sure the bleed screws are at the top of the calipers...such that someone hadn't pulled them off once and switched them from one side of the car to the other by accident...

Hope this helps- sorry if you've already tried this...

-BG

[arcsine]

I second BG's suggestion. Get the pads on the disk and see if that helps.

[JDaniel]

After pulling, cleaning, & replacing all the hardware/seals on my calipers it took about 1000miles before the pistons managed to begin engaging at the proper point.

You can bleed all you want, it won't make a difference.

When you pump the pedal a few times, and it begins to engage at the proper height, if you keep your foot on it does it slowly sink? or remain as it should?

[juanbenae]

i think you nailed it with a caliper rebuild, best 25 bucks i have spent on my car, fun job too.

[jhugh]

Also, make sure your vacuum line is in the right place and is not leaking. After I'd rebuilt my engine, it had been so long since I'd had the car on the road that, even though braking wasn't so confidence-inspiring, I didn't think there was anything in particular wrong with my brakes... I figured they just required more effort than other cars - that's "feel" right? Well, I recently took the car to a Porsche mech to do some other stuff and he put the vacuum hose on properly. Wow, now it's a COMPLETELY different braking experience. For what it's worth, I prefer my Carrera's brakes to any car I've driven. (ABS freaks me out).

good luck,

[nhromyak]

Well this is the way it's been for about 2 or more years before the M/C change.

I will try the pad movement/reset. Then I think I will rebuild the calipers.

ANy other suggestions?

[Crachian]

I had the same sticking problem and just did the rebuild. The problem was instantly apparent upon tear down:



and like someone said earlier, it's just a matter of cleaning.

After:

[nhromyak]

I hope my pistons look as good....

I will see - maybe this weekend.

Thanks for the replies!

[RoninLB]

hey Nick... the tight piston/hammer act is a fact to prevent some pedal travel before engagement.. but you pumping the brakes a few times for a tight pedal leads me to believe air in the system.. I don't know if you have a brake proportioning valve, but they can trap air.. so if you got one maybe a bleed at the valve, WTF..

[nhromyak]

THanks for the reply Ron.

How do you bleed the porportioning valve?

I think the P/valve is at the bottom of the car near (or at) the fuel pump.....

Anyone?

[RoninLB]

Originally posted by nhromyak

How do you bleed the porportioning valve?

I think the P/valve is at the bottom of the car near (or at) the fuel pump.....

I never did one.. my simple logic says to crack the line up stream, then down stream.. there may be technique other than that/don't know.. it would make for a new subject post because that valve can be a PIA..
I read awhile ago that yours may be located in smugglers box.. and when you use the power bleeder, try to use low pressure.. Richard mentioned to bleed a few times after a ride to loosen trapped air which is reality, but I don't think that's your situation.. so anyway, you have checked for trapped air after a ride.. and if yes do you find air in the same caliper repeatively?.........................Ron

[RoninLB]

Originally posted by jhugh
[B For what it's worth, I prefer my Carrera's brakes to any car I've driven. (ABS freaks me out).

, [/B]

yep Carrera brakes would be an easy up grade for me..

and you brake booster wasn't available before.. so there is a vacuum booster around somewhere, that Carrera has and I don't..

so if the amp. was a NG, would the same disability that you had before be the same with a bad amplifer?................Ron

[dimps8]

Nick,

Has your 85 Carerra got bleed nipples on the inner halves of the rear calipers? I remember replacing my master cylinder for no reason because i missed bleeding the inner halve of the rear calipers. My front calipers had one nipple each and the rears had two each....just a thought.


Damon

[nhromyak]

Bleed nipples on the INNER halves of the rear calipers???

WHERE???

I just ordered the rebuild kits for front and rear calipers...

LMK ASAP.

TIA
Nick

[BGCarrera32]

If you have stock ATE calipers on your 85 you've got 1 bleed screw per caliper. CHECK YOUR PAD CLEARANCE...

[caliber60]

One thing understand about brake bleeding is the recommendation from this site is "bleed several times", "bleed, drive few miles and bleed again several time". How can a repair shop do that? I think it only take the shop one bleed and that it. Do do not have whole day just to bleed your brake. If they can do your brake in a short period of time, why do I need to bleed several times on each wheel? Any comment?

[RoninLB]

quote:
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Originally posted by nhromyak

How do you bleed the porportioning valve?

I think the P/valve is at the bottom of the car near (or at) the fuel pump.....


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Originally posted by RoninLB
I never did one.. my simple logic says to crack the line up stream, then down stream.. there may be technique other than that/don't know.. it would make for a new subject post because that valve can be a PIA..
Ron

Hey Nick...
If all the routine stuff/bad seal allowing air, etc is over and still FU, then I would dump the proporting valve for another one.. probably a trick one from maybe Kelsey-Hayes..............Ron