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Topic: Mushy brakes / not stopping like they should

in Forum: C3 Engines, Driveline and Handling


Mushy brakes / not stopping like they should

Posted: 11/3/07 5:18pm Message 1 of 25
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
Hey guys.
 
Well, I've had brake problems with my 79 ever since I got it. I initially had the drivers front caliper locked up, so I replaced both front calipers. Was still pulling left so I replaced both front lines.
 
This unfortunatly didn't fix the problem of the brakes not working like they should. While it no longer pulls left a lot, the brakes are mushy and I couldn't get them to lock up if I wanted to. While holding the brake for a few seconds it also seems like it might be sinking to the floor, just extremely slowly. The master cyl also loses about half of the fluid in the rear reservoir every 2 weeks or so, while the front reservoir stays fine. I'm wondering if it's either the master, booster, or maybe the rear calipers or lines?
 
Any suggestions on which I should try first?
 
Great site btw, I plan on registering soon :)
 
Thanks!
-Josh
defsegx2007-11-03 17:21:09


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Mushy brakes / not stopping like they should

Posted: 11/3/07 5:38pm Message 2 of 25
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You're losing fluid somewhere. I'd pull the rear wheels and inspect the rear calipers closely for any leakage first.  Best way to bleed Corvette brakes is with a pressure bleeder. Works like magic!


Mushy brakes / not stopping like they should

Posted: 11/3/07 6:53pm Message 3 of 25
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Charleston AFB, SC - USA
Joined: 10/31/2007
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Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
[QUOTE=mkapp7879]You're losing fluid somewhere. I'd pull the rear wheels and inspect the rear calipers closely for any leakage first.  Best way to bleed Corvette brakes is with a pressure bleeder. Works like magic![/QUOTE]
 
If they are leaking, should I be able to see it when the brakes are depressed, or would it not be that obvious?



Mushy brakes / not stopping like they should

Posted: 11/3/07 9:48pm Message 4 of 25
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You don't need to press on the brake pedal to see the leaks. You might see some fluid on the insides of the tires. Look closely at the pads. Feel around with your fingers. There shouldn't be ANY brake fluid anywhere.
Check the rear of the master cylinder, too. Feel around at the bottom rear where it mounts to the booster, if you get any fluid on your fingers there's a problem.
I just went over the brakes on my 78SA. Fronts were replaced in 96 before I had it. Noticed a brake hose was bubbled at the metal sleeve so decided to pull both front calipers off and carefully JUST clean and paint them and replace both hoses. Wasn't until I had the calipers off that I noticed they had been leaking, ever so slightly. Pads were saturated. Had to rebuild both of them.
Was interesting to note that when I took a razer knife and slit the outer rubber that was bubbled up on the hose, fluid came out. I would have thought the fluid would be contained in the small diameter inside hose. Would have been interesting to have someone press on the pedal while watching the bubble to see if it expanded and contracted with the pressure.
mkapp78792007-11-03 21:59:25


Mushy brakes / not stopping like they should

Posted: 11/4/07 3:45am Message 5 of 25
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of course you should check the lines too...  specially  at those copper  uhh.. "connectors"  on the frame .  the big one on the frame left side (just go down the line from master cylinder) and  on the rear  of the frame before the wheels.
but i would think if you are leaking oil it should be visible on the floor somewhere ?

art-corvette




Mushy brakes / not stopping like they should

Posted: 11/4/07 6:10am Message 6 of 25
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Lanoka Harbor, NJ - USA
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Vette(s): 1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c
might be the master cylinder leaking into the power booster.  if you can't see any leaks on the outside thats what i would check. from your description with the pedal sinking slowly that is usually a sign of the master cylinder going bad.


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Mushy brakes / not stopping like they should

Posted: 11/4/07 12:35pm Message 7 of 25
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4

Alright well I took the rear tires off. The drivers side back caliper was covered in what looked like a thick grease, so I took off the pads and pressed the cylinders in by hand. I could see bubbles popping by the side of one of the cylinders. I guess I'm gonna go buy a new caliper and see if that does anything for the back resv losing fluid.

 
Thanks
-Josh



Mushy brakes / not stopping like they should

Posted: 11/4/07 4:53pm Message 8 of 25
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Charleston AFB, SC - USA
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Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4

Update:

So, put the new caliper on. Bled that one (decently, could probably do better), refilled master, and took it out for a drive. Got on the brakes a few times really hard and it seems to be locking them up a LITTLE better now, only now the car pulls hard left when stopping.
 
I get out when I get back and feel the rotors to see if I can tell anything, and discover two things:
 
1) hot metal burns fingertips really well
2) my passenger side aft rotor isnt even warm. all the others are toasty. SOOOO the only caliper I haven't replaced doesn't seem to be doing anything. Go figure.
 
I guess tomorrow I will replace the final caliper on the car and see how she does then, and hopefully bleed it off better. If the pedal is still mushy like it has been, next step is a new master cylinder since that's the next cheapest part.
 
Thanks for listening :P
-Josh



Mushy brakes / not stopping like they should

Posted: 11/4/07 4:57pm Message 9 of 25
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Victor, NY - USA
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Vette(s): 2004 Commemorative Edition Coupe, Auto w/HUD. 13K miles in 2015. Sold 1982 Red Coupe
I could be wrong, but I believe the rear reservoir feeds one rear and one front brake caliper, not both rear ones.
 
 



 
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Mushy brakes / not stopping like they should

Posted: 11/4/07 5:26pm Message 10 of 25
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
[QUOTE=dwright]I could be wrong, but I believe the rear reservoir feeds one rear and one front brake caliper, not both rear ones.
 
 
[/QUOTE]
 
Hrmmm... I was under the impression that they were seperated front/rear in the resv just incase one went you would still have braking on the other.



in Forum: C3 Engines, Driveline and Handling


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