Pressure testing new brake lines
Thread Starter
Burning Brakes
Joined: Oct 2010
Posts: 1,160
Likes: 23
From: Prescott AZ
Pressure testing new brake lines
Hi guys,
I just finished running all new stainless steel brake lines for my SR111 tube chassis project. I would love to be able to pressure test them some how before putting the body on. Seem like it would be much easier to correct any problems with the body off. That being said, the brake lines are not connected to a master cylinder. In fact the ends that will go to the master cylinder are not flared yet since I don't know the exact setting until I set the body on. Is there any way to pressure test them with air? or any other ideas? I don't mind flaring the ends to allow for testing. I can always cut them off when time comes to connect to master.
How much pressure should I test with?
Any ideas would be appreciated.
Thanks,
Rob
I just finished running all new stainless steel brake lines for my SR111 tube chassis project. I would love to be able to pressure test them some how before putting the body on. Seem like it would be much easier to correct any problems with the body off. That being said, the brake lines are not connected to a master cylinder. In fact the ends that will go to the master cylinder are not flared yet since I don't know the exact setting until I set the body on. Is there any way to pressure test them with air? or any other ideas? I don't mind flaring the ends to allow for testing. I can always cut them off when time comes to connect to master.
How much pressure should I test with?
Any ideas would be appreciated.
Thanks,
Rob
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Most brake systems run up to 1800psi max.
About the only way to test that is with hydraulics and theoretically is is tested at much more than that.
On the realistic side, brake fittings are always in accessible areas and I doubt that the ss tubing has pinholes that leak, so beyond a 100psi air pressure, not much you can do.
Personally, I wouldn't worry about the tubing itself at all.
About the only way to test that is with hydraulics and theoretically is is tested at much more than that.
On the realistic side, brake fittings are always in accessible areas and I doubt that the ss tubing has pinholes that leak, so beyond a 100psi air pressure, not much you can do.
Personally, I wouldn't worry about the tubing itself at all.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Plug off the ends, plumb up a pressure gauge in the line, and shoot 20 psi of compressor air into it. To test for leaks, it would be best to put a shut-off valve in that 'system'. Pressurize the line, then apply shut-off valve; watch gauge for any leakage. Air is approximately 7 times as sensitive as oil [for detecting leaks]; so that test would be similar to testing with brake fluid at 140 psi.
Thread Starter
Burning Brakes
Joined: Oct 2010
Posts: 1,160
Likes: 23
From: Prescott AZ
Most brake systems run up to 1800psi max.
About the only way to test that is with hydraulics and theoretically is is tested at much more than that.
On the realistic side, brake fittings are always in accessible areas and I doubt that the ss tubing has pinholes that leak, so beyond a 100psi air pressure, not much you can do.
Personally, I wouldn't worry about the tubing itself at all.
About the only way to test that is with hydraulics and theoretically is is tested at much more than that.
On the realistic side, brake fittings are always in accessible areas and I doubt that the ss tubing has pinholes that leak, so beyond a 100psi air pressure, not much you can do.
Personally, I wouldn't worry about the tubing itself at all.
Thread Starter
Burning Brakes
Joined: Oct 2010
Posts: 1,160
Likes: 23
From: Prescott AZ
Plug off the ends, plumb up a pressure gauge in the line, and shoot 20 psi of compressor air into it. To test for leaks, it would be best to put a shut-off valve in that 'system'. Pressurize the line, then apply shut-off valve; watch gauge for any leakage. Air is approximately 7 times as sensitive as oil [for detecting leaks]; so that test would be similar to testing with brake fluid at 140 psi.
Pro
Joined: Aug 2000
Posts: 503
Likes: 17
From: Jacksonville FL
I bought a brass tee block at the NAPA store along with a air compressor guage that screws into NPT thread. I had a -3 AN fitting to screw into one hole in the fitting and found a tire valve to put into the other with some thread sealant since it wasn't NPT but the correct thread dia and count.
That gives me a block with an air guage and a schrader valve that I can plumb into the brake line at the master cyl. connection. Shoot it with 50 psi being careful not to let brake fluid get into the guage. Look and listen for leaks at the fittings.
I cannot see how 50psi of air would hurt the calipers since they are designed to handle 1800 psi of hyd. fluid.
For standard 45 degree fittings on stock cars, use one from the belcamp collection at NAPA.
Now that I found the leaks at the flair fittings, I just need to figure out why I cannot seem to make stainless lines work this time! Maybe my flairing tool is old and scarred. I plan on borrowing a better one from a friend's race shop next week.
Locke
That gives me a block with an air guage and a schrader valve that I can plumb into the brake line at the master cyl. connection. Shoot it with 50 psi being careful not to let brake fluid get into the guage. Look and listen for leaks at the fittings.
I cannot see how 50psi of air would hurt the calipers since they are designed to handle 1800 psi of hyd. fluid.
For standard 45 degree fittings on stock cars, use one from the belcamp collection at NAPA.
Now that I found the leaks at the flair fittings, I just need to figure out why I cannot seem to make stainless lines work this time! Maybe my flairing tool is old and scarred. I plan on borrowing a better one from a friend's race shop next week.
Locke
Last edited by Locke; Nov 20, 2012 at 12:49 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
You want to test the lines...but the calipers are already attached?
In that case, my suggestion is to just hook it all together, bleed the brakes and then see if you have any brake fluid leaks.
In that case, my suggestion is to just hook it all together, bleed the brakes and then see if you have any brake fluid leaks.
Thread Starter
Burning Brakes
Joined: Oct 2010
Posts: 1,160
Likes: 23
From: Prescott AZ
Thanks for all the suggestions. I appreciate it.
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Thread Starter
Burning Brakes
Joined: Oct 2010
Posts: 1,160
Likes: 23
From: Prescott AZ
I know where the lines connect, and I do have an AIM, but since this is a custom job with a tube chassis the AIM is not going to help determine exact lengths of my brake lines especially since I have a C3 body, C4 suspension with 14" Wilwood 6 piston front and 13" Wilwood 4 piston rear brakes and using hydro boost brake booster.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Since you don't have the high pressure equipment to test properly, probably the next best method is to use vacuum.
It should still work adequately with the Wilwoods and their square cut seals.
A simple vacuum hand pump will work well and the gauge will tell of leaks.
It should still work adequately with the Wilwoods and their square cut seals.
A simple vacuum hand pump will work well and the gauge will tell of leaks.
Thread Starter
Burning Brakes
Joined: Oct 2010
Posts: 1,160
Likes: 23
From: Prescott AZ
Vacuum sounds like and interesting idea. I would definitely be able to see if it has a leak by the gauge but how would I determine where the leak would be? With pressure I could spray with soap solution and see the bubbles.