At Wits End- Bleeding Brakes
10-21-2022, 04:16 PM
#1
At Wits End- Bleeding Brakes
1982 Corvette with low miles ~50k brake parts all original.
Brakes started getting soft when driving one afternoon, by the time I got home they were nearly gone. Not sure what happened- no leaks anywhere etc. Replaced master cylinder with a generic GM clone but made of aluminum and replaced all hoses with earls DOT stainless hoses and could not brakes to bleed.
Replace master cylinder with Wilwood 1.125" bore 1.1" stroke unit, still could not get any pedal when bleeding brakes with two people, read many forums and decided to replace all calipers due to age etc.
Replaced calipers with Wilwood aluminum models, still can't get brakes bleed, no air seems to be coming out of the top bleeders any longer but pedal still has no resistance.
I'm almost $2000 into brake parts, replaced with high quality stuff and still cant get any pedal.
I have a Motive Power Bleeder but I don't have an adapter that fits the Wilwood master and Motive does not have any in stock. I might fab one up out of aluminum. However, I think there must be something more basic going on since there is no more air coming out of the calipers but I still cant get any pedal at all. I have not replaced the brake switch/proportioning valve but it is bone dry- no leaks there or anywhere else.
Begging for any suggestions-
Brakes started getting soft when driving one afternoon, by the time I got home they were nearly gone. Not sure what happened- no leaks anywhere etc. Replaced master cylinder with a generic GM clone but made of aluminum and replaced all hoses with earls DOT stainless hoses and could not brakes to bleed.
Replace master cylinder with Wilwood 1.125" bore 1.1" stroke unit, still could not get any pedal when bleeding brakes with two people, read many forums and decided to replace all calipers due to age etc.
Replaced calipers with Wilwood aluminum models, still can't get brakes bleed, no air seems to be coming out of the top bleeders any longer but pedal still has no resistance.
I'm almost $2000 into brake parts, replaced with high quality stuff and still cant get any pedal.
I have a Motive Power Bleeder but I don't have an adapter that fits the Wilwood master and Motive does not have any in stock. I might fab one up out of aluminum. However, I think there must be something more basic going on since there is no more air coming out of the calipers but I still cant get any pedal at all. I have not replaced the brake switch/proportioning valve but it is bone dry- no leaks there or anywhere else.
Begging for any suggestions-
10-21-2022, 04:29 PM
#2
Le Mans Master
What about the booster?
10-21-2022, 04:38 PM
#5
10-21-2022, 05:17 PM
#6
Prior to buying my Motive pressure bleeder I made a pressure bleeder. Took a piece of 1/4" flat stock steel just a bit wider and longer the openings in the master. Glued on a piece of old tire inner tube to seal it to the top of the master. C-clamped it down. I drilled a tapped two holes, one for front and back. Then connected them to a "T" and then to a air line. Ran about 20-30 psi. Worked well. I did have to check the fill level in the master as I bled the brakes.
10-21-2022, 05:38 PM
#8
Prior to buying my Motive pressure bleeder I made a pressure bleeder. Took a piece of 1/4" flat stock steel just a bit wider and longer the openings in the master. Glued on a piece of old tire inner tube to seal it to the top of the master. C-clamped it down. I drilled a tapped two holes, one for front and back. Then connected them to a "T" and then to a air line. Ran about 20-30 psi. Worked well. I did have to check the fill level in the master as I bled the brakes.
10-21-2022, 05:48 PM
#9
Le Mans Master
Member Since: Aug 2017
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You guys and your Wilwoods. WHY?
Generic & clone are two words that do not work well in the C3 brake system vocabulary.
If the original design GM Delcos made it 40+ yrs, why wouldn't rebuilt Delcos go another 40? And for a fraction of the costs.
For one thing, the distance between the booster rod and the MC piston is critical at 0.060. It's so important that you can not use just any Vette MC and expect it work properly. GM changed the design of the back of the MC over the years.. They also changed the design of the booster rod and changed the design of the brake pedal assembly.
Because you went aftermarket, Lord knows what that gap is now.
As far as a MC lid fabrication, click on my profile, then photo albums, brake bleeding for some ideas.
Just my opinion, but, its hard to beat the Vettes 4 piston design once you figure out what to do, what not to do and how to bleed the system correctly.
You really should consider going back to Delcos.
Good Luck.
Generic & clone are two words that do not work well in the C3 brake system vocabulary.
If the original design GM Delcos made it 40+ yrs, why wouldn't rebuilt Delcos go another 40? And for a fraction of the costs.
For one thing, the distance between the booster rod and the MC piston is critical at 0.060. It's so important that you can not use just any Vette MC and expect it work properly. GM changed the design of the back of the MC over the years.. They also changed the design of the booster rod and changed the design of the brake pedal assembly.
Because you went aftermarket, Lord knows what that gap is now.
As far as a MC lid fabrication, click on my profile, then photo albums, brake bleeding for some ideas.
Just my opinion, but, its hard to beat the Vettes 4 piston design once you figure out what to do, what not to do and how to bleed the system correctly.
You really should consider going back to Delcos.
Good Luck.
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10-21-2022, 06:16 PM
#10
You guys and your Wilwoods. WHY?
Generic & clone are two words that do not work well in the C3 brake system vocabulary.
If the original design GM Delcos made it 40+ yrs, why wouldn't rebuilt Delcos go another 40? And for a fraction of the costs.
For one thing, the distance between the booster rod and the MC piston is critical at 0.060. It's so important that you can not use just any Vette MC and expect it work properly. GM changed the design of the back of the MC over the years.. They also changed the design of the booster rod and changed the design of the brake pedal assembly.
Because you went aftermarket, Lord knows what that gap is now.
As far as a MC lid fabrication, click on my profile, then photo albums, brake bleeding for some ideas.
Just my opinion, but, its hard to beat the Vettes 4 piston design once you figure out what to do, what not to do and how to bleed the system correctly.
You really should consider going back to Delcos.
Good Luck.
Generic & clone are two words that do not work well in the C3 brake system vocabulary.
If the original design GM Delcos made it 40+ yrs, why wouldn't rebuilt Delcos go another 40? And for a fraction of the costs.
For one thing, the distance between the booster rod and the MC piston is critical at 0.060. It's so important that you can not use just any Vette MC and expect it work properly. GM changed the design of the back of the MC over the years.. They also changed the design of the booster rod and changed the design of the brake pedal assembly.
Because you went aftermarket, Lord knows what that gap is now.
As far as a MC lid fabrication, click on my profile, then photo albums, brake bleeding for some ideas.
Just my opinion, but, its hard to beat the Vettes 4 piston design once you figure out what to do, what not to do and how to bleed the system correctly.
You really should consider going back to Delcos.
Good Luck.
What is the purpose of the gap between the booster rod and the piston? Is it to keep the piston from bottoming out which I believe can damage the piston seals on an OEM style master? The instructions for the Wilwood cylinder says the piston MUST bottom out before the pedal stops so maybe that is not a concern with the Wilwood?
10-21-2022, 06:22 PM
#11
Le Mans Master
Wilwoods will not bleed out 100% of the air when bolted on. They have a pocket of air trapped at the top that needs to come out but will not if bolted on the car. Crappy design! Angle is wrong.
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10-21-2022, 06:27 PM
#12
Le Mans Master
Member Since: Aug 2006
Location: mount holly NC
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C3 of Year Finalist (appearance mods) 2019
You might want to test the Master Cylinder to be sure it works.
You will need 2 plugs one size 9/16/18 and one size 1/2 /20
The plugs might be in your bleeder kit.
Remove the front hard line and plug the M/C, the pedal should be rock hard.
Remove that plug and reinstall the hard line and remove and plug the rear M/C port.
If the pedal is not rock hard again then the M/C is bad.
You will need 2 plugs one size 9/16/18 and one size 1/2 /20
The plugs might be in your bleeder kit.
Remove the front hard line and plug the M/C, the pedal should be rock hard.
Remove that plug and reinstall the hard line and remove and plug the rear M/C port.
If the pedal is not rock hard again then the M/C is bad.
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ElmrPhD (10-23-2022)
10-21-2022, 06:27 PM
#13
Melting Slicks
I had issues when I replaced everything during restoration.
After trying pumping, presure bleeding etc. I finally got all the
air out by gravity bleeding all 4 calipers.
My 2 cents....
After trying pumping, presure bleeding etc. I finally got all the
air out by gravity bleeding all 4 calipers.
My 2 cents....
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kansas123 (10-21-2022)
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HeadsU.P. (10-21-2022)
10-21-2022, 07:06 PM
#16
Hmm, the back of the master where it bolts to the Booster is lower than the front due the way the car is positioned on jackstands at the moment. Would reversing that so the car is level or having the rear up higher help the issue?
10-21-2022, 07:07 PM
#17
Le Mans Master
Member Since: Aug 2017
Location: Cool Northern Michigan
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What is the purpose of the booster rod gap?
If the gap is too wide, there will be a delay before the MC even starts thinking about applying the brakes.
As you know, with C3s the brake pedal travel is very short on distance. Unlike cars of the 40s / 50s where the brake pedal traveled a foot, the C3 is mere inches with full engagement really close to the carpet.
Too little of gap does not allow the caliper pistons to retract. There is virtually no place for the Dot3 to go. With no gap, the calipers will actually drag constantly.
No so much that you would hear the rotor but enough to create unnecessary and abnormal wear & tear.
If the gap is too wide, there will be a delay before the MC even starts thinking about applying the brakes.
As you know, with C3s the brake pedal travel is very short on distance. Unlike cars of the 40s / 50s where the brake pedal traveled a foot, the C3 is mere inches with full engagement really close to the carpet.
Too little of gap does not allow the caliper pistons to retract. There is virtually no place for the Dot3 to go. With no gap, the calipers will actually drag constantly.
No so much that you would hear the rotor but enough to create unnecessary and abnormal wear & tear.
10-21-2022, 07:08 PM
#18
I have not measured so I don't know for sure but the Wilwood instructions only say that it is required for the piston to bottom out BEFORE the pedal hits the floor which I believe it is but I'll double check.
10-21-2022, 07:11 PM
#19
What is the purpose of the booster rod gap?
If the gap is too wide, there will be a delay before the MC even starts thinking about applying the brakes.
As you know, with C3s the brake pedal travel is very short on distance. Unlike cars of the 40s / 50s where the brake pedal traveled a foot, the C3 is mere inches with full engagement really close to the carpet.
Too little of gap does not allow the caliper pistons to retract. There is virtually no place for the Dot3 to go. With no gap, the calipers will actually drag constantly.
No so much that you would hear the rotor but enough to create unnecessary and abnormal wear & tear.
If the gap is too wide, there will be a delay before the MC even starts thinking about applying the brakes.
As you know, with C3s the brake pedal travel is very short on distance. Unlike cars of the 40s / 50s where the brake pedal traveled a foot, the C3 is mere inches with full engagement really close to the carpet.
Too little of gap does not allow the caliper pistons to retract. There is virtually no place for the Dot3 to go. With no gap, the calipers will actually drag constantly.
No so much that you would hear the rotor but enough to create unnecessary and abnormal wear & tear.
The following users liked this post:
HeadsU.P. (10-22-2022)
10-21-2022, 07:13 PM
#20
You might want to test the Master Cylinder to be sure it works.
You will need 2 plugs one size 9/16/18 and one size 1/2 /20
The plugs might be in your bleeder kit.
Remove the front hard line and plug the M/C, the pedal should be rock hard.
Remove that plug and reinstall the hard line and remove and plug the rear M/C port.
If the pedal is not rock hard again then the M/C is bad.
You will need 2 plugs one size 9/16/18 and one size 1/2 /20
The plugs might be in your bleeder kit.
Remove the front hard line and plug the M/C, the pedal should be rock hard.
Remove that plug and reinstall the hard line and remove and plug the rear M/C port.
If the pedal is not rock hard again then the M/C is bad.