1971 ls5 coupe power brakes
11-15-2017, 10:42 AM
#2
is this a new issue or it has always been this way?
are you sitting too close to the steering wheel?
has anything been done to the brake system as far as modifications including the car originally didnt have power brakes and someone added them?
are you sitting too close to the steering wheel?
has anything been done to the brake system as far as modifications including the car originally didnt have power brakes and someone added them?
11-15-2017, 08:29 PM
#3
Pro
Thread Starter
Found out the ls5 I bought had power brakes added to it. They used the rod that goes with kit between power booster and master cylinder. Since then the brakes has always been touchy. Could that rod be the issue?
11-15-2017, 08:33 PM
#4
Le Mans Master
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Must be nice. Don't complain. Some of us have to drag our feet.
11-15-2017, 08:56 PM
#5
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Thread Starter
11-17-2017, 09:09 AM
#6
Brakes
Google reaction disc. Sometimes when replaceine master cyl someone pulls rod from booster and it falls inside the booster.it is a rubber disc about a 1/4 thick. If it is gone you can shine a light in booster and see a shiny spot after you pull the rod out.if gone find another one ,stick on rod with a dab of grease put it together, making sure rod is adjusted properly
11-17-2017, 09:14 AM
#7
Le Mans Master
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Just remembered. The master cyl piston "depth" are different between manual & power. Thats why it is so important to order the correct MC.
Last edited by HeadsU.P.; 11-17-2017 at 09:20 AM.
11-17-2017, 10:36 AM
#8
Pro
Thread Starter
1971 power brakes
Google reaction disc. Sometimes when replaceine master cyl someone pulls rod from booster and it falls inside the booster.it is a rubber disc about a 1/4 thick. If it is gone you can shine a light in booster and see a shiny spot after you pull the rod out.if gone find another one ,stick on rod with a dab of grease put it together, making sure rod is adjusted properly
11-17-2017, 10:41 AM
#9
did you remove the steel brake lines?
11-17-2017, 11:06 AM
#11
Melting Slicks
Check to make sure the master cylinder is correct for power brakes. 1-1/8" bore for power and 1" for manual; if the PO who added the power assist neglected to install the proper master, it will make the brakes overly touchy. Ask me how I know.
11-17-2017, 12:08 PM
#12
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Thread Starter
Brakes
I read somewhere someone did this and shimmed when backing off to make brakes not so touchy
11-17-2017, 01:15 PM
#13
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If you remove the brake lines from the master, then you are in up to your elbows with bleeding the entire system. But thats another thread on here. If you just want to inspect the MC and the rod, leave the lines attached. If you are trying to figure out if the MC is manual or power you will need a picture to compare the piston ends. That picture was on this forum back in Sept. Side by side shot of both types of MC.
11-17-2017, 01:21 PM
#14
Melting Slicks
The issue in the case of manual vs. power master is cylinder bore size, not travel. Shimming won't change the effect of bore size, it will just change pedal travel before the brakes engage.
11-17-2017, 02:07 PM
#15
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If you remove the brake lines from the master, then you are in up to your elbows with bleeding the entire system. But thats another thread on here. If you just want to inspect the MC and the rod, leave the lines attached. If you are trying to figure out if the MC is manual or power you will need a picture to compare the piston ends. That picture was on this forum back in Sept. Side by side shot of both types of MC.
11-17-2017, 03:01 PM
#16
how is going to move more with the lines attached?
11-17-2017, 04:59 PM
#17
Le Mans Master
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Be careful. Don't want to kink a brakeline. You should be able to move the MC enough to see the back of unit and inspect the piston style. One is flush with the casting. One is inset. Any more than that and the lines will have to come off. Its your call.
Last edited by HeadsU.P.; 11-17-2017 at 05:02 PM.
11-17-2017, 05:09 PM
#18
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Thread Starter
loosen Master Cylinder up to shim 3/8 inch pedal has little travel before catching.
Can that rod be machined down,shorter.to give me the same or can a new adjstable rod be found?
11-17-2017, 05:37 PM
#19
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The previous owner got back to me, he said the the MC, rod and Brake booster were a kit bought from Corvette Central. The rod has no adjustment and the brake pedal is on correct hole.
loosen Master Cylinder up to shim 3/8 inch pedal has little travel before catching.
Can that rod be machined down,shorter.to give me the same or can a new adjstable rod be found?
loosen Master Cylinder up to shim 3/8 inch pedal has little travel before catching.
Can that rod be machined down,shorter.to give me the same or can a new adjstable rod be found?
Supposedly the rod has to have a air gap between the tip and the MC piston. Don't remember how much, maybe 0.100". I recall someone stating to put some clay / Silly-Putty on the rod tip. Snug down the two MC nuts, apply brake, remove MC, inspect thickness of clay (or lack off). Without a gap, it is possible to have your brake pads dragging ALL the time. Not good. But too much of a rod gap allows the pads to be retracted. Not good either.
And as far as a adjustable booster rod? I believe that is accomplished at the clevis under the dash. But I think some yrs are non-adj.
Last edited by HeadsU.P.; 11-17-2017 at 05:39 PM.
11-17-2017, 07:15 PM
#20
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Thread Starter
B
Ok, you have some history info. But still unknown is, if its the correct setup. Some MC only fit 3-4 yrs. then changed again. The power brake MC is different than manual. Its easy for a novice to order & install the wrong unit. This goes back to post #11.
Supposedly the rod has to have a air gap between the tip and the MC piston. Don't remember how much, maybe 0.100". I recall someone stating to put some clay / Silly-Putty on the rod tip. Snug down the two MC nuts, apply brake, remove MC, inspect thickness of clay (or lack off). Without a gap, it is possible to have your brake pads dragging ALL the time. Not good. But too much of a rod gap allows the pads to be retracted. Not good either.
And as far as a adjustable booster rod? I believe that is accomplished at the clevis under the dash. But I think some yrs are non-adj.
Supposedly the rod has to have a air gap between the tip and the MC piston. Don't remember how much, maybe 0.100". I recall someone stating to put some clay / Silly-Putty on the rod tip. Snug down the two MC nuts, apply brake, remove MC, inspect thickness of clay (or lack off). Without a gap, it is possible to have your brake pads dragging ALL the time. Not good. But too much of a rod gap allows the pads to be retracted. Not good either.
And as far as a adjustable booster rod? I believe that is accomplished at the clevis under the dash. But I think some yrs are non-adj.