New wheel cylinder Question

W

warren va

Senior Member
Just put my two new rear wheel cylinders from Macs on my 40ford . Both of
the cylinders were leaking at the hard line fittings. Seems like I read a posting on the barn that the Chinese pipe threads were different from ours.
Could this be the reason for the leaks? Any suggestions or ideas to remedy my problem.
I forgot to mention I also have changed over to silicone dot 5 fluid.

Thanks

Warren
 
The seal should be at the flare and not the threads unless they are so bad as to not align and tighten on the flare properly. The issue would more likely be the flare on the tubing or the flare seat on the wheel cylinders. Are these new brake lines? If they are the old lines it is not uncommon for them to not reseal once the flare has been tightened once or twice.
 
DOT 5 has smaller molecules than DOT 3/4 and will leak when the others will not..try tightening them really well, if this does not cure it, remove the line and look for cracks around the flare-which will happen when old lines are getting brittle on the ends due to work hardening. If you try to re-flare use a little brake fluid as a lubicant on the flare-this sure helps
 
Thanks everyone for your help.
The leak is at the threads on the flared fitting on the rear cylinders. I re tightened them as advised and was worried I might strip the threads but so far they are not leaking now. Left some paper towels under both rear wheels . Will know if that did the the trick when I check them in the morning .
I bled the system again before leaving the garage and I still don't have hardly any pedal yet, but thank goodness it was not leaking again...

Warren
 
Almost every imported wheel cylinder I installed using DOT 5 leaked around the rubber cup as soon as installed, still on the lift. Took them apart sanded the bore with 600 and still leaked. Ordered new rubber cups from Wagner, installed and no more problem. If you look at the foreign cup they are straight up on the outside of the walls or contact surface. The Wagner's are a softer material and flare out at the top of the side wall. G.M.
 
are the brakes adjusted properly? how much pedal travel? DOT 5 is a little difficult to bleed-it will entrap air and requires some finess to get a good pedal but well worth it in the end, my 40 wagon has had DOT 5 for over 20 years and 16,000 plus miles with no problems, no rust no wear
 
When using DOT 5 NEVER shake the container! When pumping the pedal to bleed the brakes, pump slowly to avoid making air bubbles in the system. I have used DOT 5 for 30 years and never had a problem with leaks or rust. Don't be afraid to lean on the fittings to get them tight. When using any type of brake fluid, adjust the brakes first in order to get the proper pedal feel. Always use double flairs and fittings and be sure they are square with the tubing. Double flairs can be difficult for beginners.
 
I just got finished installing new wheel cylinders and brake lines with the factory flared ends. I had tightened them what I thought was an adequate amount as I had in the past, and they all leaked! I had to tighten them way more than I expected to get them to stop leaking. So much so that I was afraid I would strip the threads.
I have concluded that these new (Chinese?) products angles don't match, and rely on us wrenching on them to reshape the flare angles to match.
In the begining I had even thought of machining some tiny copper washers to go in there between the flares to conform to the unmatched flare angles.
 
When I install new lines I tighten and loosen the flairs 2 or 3 times to seat them.
This seems to work pretty well and not leak.

John
 
Another question? With all the talk of the Chinese made crap is it just better to hone and rebuild my original wheel cylinders vs replacing with Chinese? Maybe just buy what is said to be good repo ones from Chris over at Shoebox central?
Did I just answer my own ?
Randy
 
Rand, if your wheel cylinders show no signs of pitting, then hone and rebuild. You can also send them to White Post and have bronze or ss sleeves installed-last set I did that to was over $200 for the pair. Use a little brake fluid as a lubricant on the flare fittings and that also seems to help seat them. I had purchased a set of wheel cylinders for my 41 truck and 3 came from Israel, one from Italy and they were in US boxes.
 
Rand said:
Another question? With all the talk of the Chinese made crap is it just better to hone and rebuild my original wheel cylinders vs replacing with Chinese? Maybe just buy what is said to be good repo ones from Chris over at Shoebox central?
Did I just answer my own ?
Randy
Click to expand...

Yep...I think you did.

Bob
 
You must log in or register to reply here.
Back
Top