[C1] rear brake lock up
06-12-2019, 06:59 AM
#22
Team Owner
The C1 "X" frames are built like a tank - it is not warped unless somebody rolled the car over 1/2 dozen times...
Last edited by Frankie the Fink; 06-12-2019 at 07:02 AM.
06-12-2019, 07:04 AM
#23
Drifting
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Look if ONE (not BOTH) brake hoses gets defective, they are separate to each wheel and only one wheel remains pressurized and locked up. Changing both rear hoses and bleeding the brakes is a 45 minute job and then you'll know at least those components are good. Don't over-analyze it.
The C1 "X" frames are built like a tank - it is not warped unless somebody rolled the car over 1/2 dozen times...
The C1 "X" frames are built like a tank - it is not warped unless somebody rolled the car over 1/2 dozen times...
06-12-2019, 08:01 AM
#24
Hi ,and thank you.
There is only one rubber hose at the rear of a c1 Corvette (if it is stilll looking original),that connects to a T brake block .
From this T,there are two steel lines to the drums.
A short one,on the right side,and a long one ,on the left side.
So....
1)How come that the pressure seems to be higher on the right side,pushing faster and stronger the pistons on the right wheel cylinder,or not as fast and strong a on the left? (hydraulics related?)
2)Whenever i raise the car to check things,and go for a test drive,things seem to be ok for a few hundred yards,and then RRW -lock up occurs...(suspension,weight transfer related?)
There is only one rubber hose at the rear of a c1 Corvette (if it is stilll looking original),that connects to a T brake block .
From this T,there are two steel lines to the drums.
A short one,on the right side,and a long one ,on the left side.
So....
1)How come that the pressure seems to be higher on the right side,pushing faster and stronger the pistons on the right wheel cylinder,or not as fast and strong a on the left? (hydraulics related?)
2)Whenever i raise the car to check things,and go for a test drive,things seem to be ok for a few hundred yards,and then RRW -lock up occurs...(suspension,weight transfer related?)
Last edited by the skunk; 06-12-2019 at 08:06 AM.
06-12-2019, 08:16 AM
#27
Drifting
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Look if ONE (not BOTH) brake hoses gets defective, they are separate to each wheel and only one wheel remains pressurized and locked up. Changing both rear hoses and bleeding the brakes is a 45 minute job and then you'll know at least those components are good. Don't over-analyze it.
The C1 "X" frames are built like a tank - it is not warped unless somebody rolled the car over 1/2 dozen times...
The C1 "X" frames are built like a tank - it is not warped unless somebody rolled the car over 1/2 dozen times...
06-12-2019, 08:16 AM
#28
Team Owner
Other than hoses brakes will lock up from grease on the shoes/drum, bad adjustment, cracked drum, bad wheel cylinder, glazed shoes or the slide points on the backing plate are dry or have a groove worn in them OR (and I see this sometimes) they are assembled incorrectly...
Last edited by Frankie the Fink; 06-12-2019 at 08:18 AM.
06-12-2019, 09:34 AM
#30
5th Gear
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How are the backing plate wear pads? I have seen brakes hang up because of grooves wore in the pad area. I believe there a 6 wear pads on the backing plate, 3 for each of the shoes, primary and secondary.
06-12-2019, 01:00 PM
#31
Primary shoe facing the front.
I filled the edges of the shoes
No cracks,no grooves on the backplates.
Everything lubed where it should be.
New drums,new cylinders,new hardware kit.
I filled the edges of the shoes
No cracks,no grooves on the backplates.
Everything lubed where it should be.
New drums,new cylinders,new hardware kit.
06-12-2019, 01:20 PM
#34
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Sounds like the only thing left would be the brake lines from the junction block to each rear wheel cylinder
06-12-2019, 01:23 PM
#35
Le Mans Master
Thinking about this Skunk, the rears keep locking up, right side unless blocked off then left side locks.
Maybe you have a couple fluid restrictions. Sounds like the right side rear gets more fluid than the left side rear.
They both feed off the same line that dead ends into the T, pressure should be identical out of the T to each rear wheel.
If it is not equal the only thing left is a restriction in the line. I would look at the Left Side rear brake line and inspect the T itself to make sure it is open equally both directions.
Since the Right side brakes so strongly, any restriction is on the left side.
Is it possible the left and right rear brakes have different size pistons in the brake cylinders or different size feed holes or a blockage from the brake line into the cylinders?
Something is causing more brake fluid on the right side you need to find that and it does sound like you are giving it a heroic effort.
If the brake hose feeding the rear brakes is bad, a common hose failure symtem is to allow brake fluid under pressure to pass into the brake line but when you let off your pedal the hose collapses and blocks the brake fluid return leaving your brake locked for a period after you let off.
With a hard stab of the brake pedal your front brakes should lock up, regardless of what the rear brakes are doing the front should lock up on a very hard brake application.
If this is not happening you have one more issue to address, why isn't enough brake pressure reaching the front brakes? I saw you installed a proportioning vavle which allows you to adjust a good brake system.
It really sounds like your brakes have more than one issue you are trying to identify and fix.
Since you now have a new brake master cylinder the entire master cylinder should be clean and new so you could use full range of motion to bleed your brakes. It is the Old Master Cylinders that can be damaged if pushed full range of motion.
Brake fluid absorbs moisture over time and that will cause rust in a Master Cylinder, brake lines and each wheel cylinder leading to all these issues you are facing.
You are close, you will identify the issue or issues soon.
Maybe you have a couple fluid restrictions. Sounds like the right side rear gets more fluid than the left side rear.
They both feed off the same line that dead ends into the T, pressure should be identical out of the T to each rear wheel.
If it is not equal the only thing left is a restriction in the line. I would look at the Left Side rear brake line and inspect the T itself to make sure it is open equally both directions.
Since the Right side brakes so strongly, any restriction is on the left side.
Is it possible the left and right rear brakes have different size pistons in the brake cylinders or different size feed holes or a blockage from the brake line into the cylinders?
Something is causing more brake fluid on the right side you need to find that and it does sound like you are giving it a heroic effort.
If the brake hose feeding the rear brakes is bad, a common hose failure symtem is to allow brake fluid under pressure to pass into the brake line but when you let off your pedal the hose collapses and blocks the brake fluid return leaving your brake locked for a period after you let off.
With a hard stab of the brake pedal your front brakes should lock up, regardless of what the rear brakes are doing the front should lock up on a very hard brake application.
If this is not happening you have one more issue to address, why isn't enough brake pressure reaching the front brakes? I saw you installed a proportioning vavle which allows you to adjust a good brake system.
It really sounds like your brakes have more than one issue you are trying to identify and fix.
Since you now have a new brake master cylinder the entire master cylinder should be clean and new so you could use full range of motion to bleed your brakes. It is the Old Master Cylinders that can be damaged if pushed full range of motion.
Brake fluid absorbs moisture over time and that will cause rust in a Master Cylinder, brake lines and each wheel cylinder leading to all these issues you are facing.
You are close, you will identify the issue or issues soon.
Last edited by Westlotorn; 06-12-2019 at 06:31 PM. Reason: corrected
06-12-2019, 02:23 PM
#36
Race Director
Are both rear wheel cylinders the same internal (piston) diameter? A larger dia piston in one vs the other will dramatically increase pressure on the shoes on that side.
Doug
Doug
Last edited by AZDoug; 06-12-2019 at 02:23 PM.
06-12-2019, 04:16 PM
#38
Drifting
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[QUOTE=Westlotorn;1599570119]Thinking about this Skunk, the rears keep locking up, right side unless blocked off then left side locks.
One more note on this: The lines need to be equal in length from the T to the rear wheels. A longer line on the left or right side will cause delay in pressure reaching the wheel.
Lines from the factory are unequal length. Left side much longer than right, like on mine, and it stops fine.
One more note on this: The lines need to be equal in length from the T to the rear wheels. A longer line on the left or right side will cause delay in pressure reaching the wheel.
Lines from the factory are unequal length. Left side much longer than right, like on mine, and it stops fine.