bleeding brakes
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
bleeding brakes
I have been driving my 68 convert for over a year with a pesky small air bubble hung up somewhere in the left front caliper. Repeated bleedings with vacuum bleeding and pressure bleeding did not get the small amount of air out- it was just enough to make the left front brake work at about 50% of the braking force of the opposite right brake, so the car pulled to the right. Today I pressure bled the left front again while my helper used my air chisel to vibrate the caliper while bleeding. I put a piece of hard plastic tubing over the end of the chisel so it would not damage the caliper. It made enough vibration that it dislodged the air from wherever it was hung up. I finally have the car stopping straight as an arrow and it only took a year and pulling out half of my hair.
Instructor
Joined: Aug 2017
Posts: 216
Likes: 10
From: MD
Good job.
Just saw this video today: would this work on the C3s?
https://www.youtube.com/watch?v=L0oUejw5Edc
Just saw this video today: would this work on the C3s?
https://www.youtube.com/watch?v=L0oUejw5Edc
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
if your calipers have lip seals the answer is at best..... not very well and at worst NO....if they have O ring seals it probably will work...... I could never succesfully bleed my brakes using vacuum even though on many other cars it was my go to method
those one person bleeders with check valves in them work very well and so does gravity. i use a motive pressure bleeder for the c3 brakes
those one person bleeders with check valves in them work very well and so does gravity. i use a motive pressure bleeder for the c3 brakes
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
if your calipers have lip seals the answer is at best..... not very well and at worst NO....if they have O ring seals it probably will work...... I could never succesfully bleed my brakes using vacuum even though on many other cars it was my go to method
those one person bleeders with check valves in them work very well and so does gravity. i use a motive pressure bleeder for the c3 brakes
those one person bleeders with check valves in them work very well and so does gravity. i use a motive pressure bleeder for the c3 brakes
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
I replaced the bleed screws with SpeedBleeders on all of the calipers. The calipers, installed by the PO have o-ring seals, but the left front side would not spit out some small air bubble that was probably lodged in a rough spot on the interior casting, despite bleeding by both pressure and vacuum methods several times. I could have smacked the caliper with a mallet, but the air chisel set on low pressure did the same thing and worked. I've bled hundreds of drum and disc brakes and this was the most stubborn I have found. One of my lab technicians came up with the idea. We get rid of trapped air bubbles on chromatography columns using a little battery powered vibrator and hold it against the column and tubing while flowing buffer thru the system. The air chisel was just the industrial version.
good job I will have to remember that one, any reason an impact wrench on a low setting hitting caliper mounting bolts wouldn't do the same thing?
Last edited by bobs77vet; Jul 9, 2018 at 10:13 PM.
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Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
bobs77vet said "impact wrench on a low setting hitting caliper mounting bolts "
That probably would work too. When we clear the air out of our tubing and columns in the lab, you can see the air through the clear plastic tubing and housing. The vibration appears to break the surface tension and makes the air bubbles break free and float in the liquid so they can be flushed out. I am assuming something similar happens inside the caliper and tubing with air in the brake fluid.
That probably would work too. When we clear the air out of our tubing and columns in the lab, you can see the air through the clear plastic tubing and housing. The vibration appears to break the surface tension and makes the air bubbles break free and float in the liquid so they can be flushed out. I am assuming something similar happens inside the caliper and tubing with air in the brake fluid.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
bobs77vet said "impact wrench on a low setting hitting caliper mounting bolts "
That probably would work too. When we clear the air out of our tubing and columns in the lab, you can see the air through the clear plastic tubing and housing. The vibration appears to break the surface tension and makes the air bubbles break free and float in the liquid so they can be flushed out. I am assuming something similar happens inside the caliper and tubing with air in the brake fluid.
That probably would work too. When we clear the air out of our tubing and columns in the lab, you can see the air through the clear plastic tubing and housing. The vibration appears to break the surface tension and makes the air bubbles break free and float in the liquid so they can be flushed out. I am assuming something similar happens inside the caliper and tubing with air in the brake fluid.
Last edited by bobs77vet; Jul 10, 2018 at 11:06 AM.
Thread Starter
Drifting
Joined: Jul 2015
Posts: 1,765
Likes: 254
From: Catlett VA
i may try that next time...one person pumping, and me at the other end with a wrench on bleeder valve in one hand and battery operated impact on the other hand.....you could even use an impact driver on a low setting with the square drive adapter. all you need for it is to bounce around and get carried off in the flow. I wonder if works the same with silicone fluid that sometimes you need to let sit over night so all the bubbles group together and become one
Race Director
Joined: Sep 2004
Posts: 11,874
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Melting Slicks
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From: Wichita Kansas