Strange brake problem
Thread Starter
Racer
Joined: Dec 2005
Posts: 325
Likes: 0
From: Partlow VA
Strange brake problem
I am having a problem figuring out what is wrong with the brakes on my 78. Here’s what happening; when applying the brakes slow and steady no problem breaking is great. When I hit the brakes as in a hurry to stop, the front end pulls hard and dips to the left for a slip second then straightens out and finishes stopping just fine. The car has had a complete body off restoration, all new front end components, bench bled new master cylinder, all new brake lines, new combination valve, DOT 5 brake fluid, and re-built calipers from Van Steel. I have bled the brakes and the pedal does not pump up as if there is any air in the system and the pads are organic. Any ideas?? 
Thanks
Thanks
Race Director
Joined: Jul 2004
Posts: 12,686
Likes: 329
From: Scottsdale Arizona
How is the wheel alignement?
Could also be a flow restriction in the line to the right side of the front. I'd make sure that the line hasn't been crimped, especially under the frame in the front. This was a favorite spot for Bubba to jack up the car.
Could also be a flow restriction in the line to the right side of the front. I'd make sure that the line hasn't been crimped, especially under the frame in the front. This was a favorite spot for Bubba to jack up the car.
Advanced
Joined: May 2006
Posts: 69
Likes: 1
From: West Linn Oregon
Also, while you're down there check to be sure you didn't get anything on the rotor or pads...like oil or grease maybe. (It's will likely be on the right side, but you may want to check both sides just to be sure. Road grime can cause brakes to react funny sometimes, so the culprit could be on either side.)
If you do find something, use a good brake cleaner like CRC Brakleen on both the rotors and the pads, and wipe it off with a lint free cloth. Cleaning the pads will require pulling the caliper.
If you do find something, use a good brake cleaner like CRC Brakleen on both the rotors and the pads, and wipe it off with a lint free cloth. Cleaning the pads will require pulling the caliper.
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
If that's DOT 5 silicone fluid, you need to purge it completely from your system and start over with any quality non-silicone fluid. Silicone fluid is compressible and only good, supposedly, for long term storage. May or may not solve your problem, but this is an issue you should address if your Vette is a driver.
Drifting
Joined: May 2005
Posts: 1,601
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From: BETHEL PARK PENNSYLVANIA
If that's DOT 5 silicone fluid, you need to purge it completely from your system and start over with any quality non-silicone fluid. Silicone fluid is compressible and only good, supposedly, for long term storage. May or may not solve your problem, but this is an issue you should address if your Vette is a driver.
vc
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Le Mans Master
Joined: Oct 2000
Posts: 7,831
Likes: 5
From: Austin TX
Silicone will work fine - it just needs to be bled completely.
I've used nothing but silicone for 15 years.
Something is restricting braking for a moment on one side.
I agree with the previous comments of possible kinked hose or sticky caliper.
I've used nothing but silicone for 15 years.
Something is restricting braking for a moment on one side.
I agree with the previous comments of possible kinked hose or sticky caliper.
Team Owner
Joined: Jan 2003
Posts: 21,234
Likes: 19
From: Freestate Corvette Club! Elkridge, MD
St. Jude Donor '17
I know this seems too simple, but lets eliminate the easy ones. Try pumping the brakes up several times at the pedal with your foot then right way hitting it hard and see if it still pulls. If it does it is not air in the lines. Thenb we need to pull the tires and check each front caliper for corrohsion around the brake pistons. Although this is less likey as they usually stick and stay stuck - it is possible.
My best guess is the air.
Another thought have a look underneath and make sure the suspenmsion components are tight (grab a hold and give them a tug see if they have a lot of movement).
If it is air in the system, let me know, I have a decent vaccum pump set up to bleed brakes with and do not live fr from you
My best guess is the air.
Another thought have a look underneath and make sure the suspenmsion components are tight (grab a hold and give them a tug see if they have a lot of movement).
If it is air in the system, let me know, I have a decent vaccum pump set up to bleed brakes with and do not live fr from you
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Sorry if this proves to be a sidebar from the real problem at hand, but silicone brake fluid is compressible and there have been complaints that it is difficult to completely bleed 100% of the air from it. I can't vouch for the latter issue, because the first one has always been enough to dissuade me from ever using it. Also, it doesn't mix with other fluids. If you're among those who believe in it, it's your right...
Advanced
Joined: May 2006
Posts: 69
Likes: 1
From: West Linn Oregon
Team Owner
Joined: Oct 2004
Posts: 23,831
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From: Springfield MO
St. Jude Donor '07
Le Mans Master
Joined: Apr 2007
Posts: 7,353
Likes: 72
From: Graceland in a Not Correctly Restored Stingray
Batman, "doohickey" is an appropriate technical term with me. 
BTW, if anyone finds they have those lousy dual pin calipers, I'll take them off your hands, no questions.
BTW, if anyone finds they have those lousy dual pin calipers, I'll take them off your hands, no questions.
Thread Starter
Racer
Joined: Dec 2005
Posts: 325
Likes: 0
From: Partlow VA
Thanks Guys, I've checked front end components and the calipers are all new, as are all of the brake lines and pads. I never really was comfortable with the DOT 5 silicon brake fluid, it was harder to bleed than other types and getting all of the air out of the system took much longer as the fluid seems to have a higher viscosity then the DOT 3 fluid. I will re-check for air again, but am really considering purging the brake system and going with a DOT 3 brake fluid. I’m thinking I’ll open the bleeder screws, let them all drain at the calipers, refill with DOT 3, gravity bleed them one at a time until only DOT 3 fluid comes out, then pressure bleed to make sure all the air is out.
Thanks again
Thanks again