TR2/3/3A Brake Bleeding problem on a TR3A

[Jerry]

Group,
I am looking for ideas on brake bleeding. First push is now 1/2 pedal and full pedal on second pump. ALL parts are new. Master, brake lines, brake cylinders, brake shoes. rebuilt calipers (Type B) with new pads. I have pulled a quart through the system so far. I do not seem to get bubbles from the front disks. But , the rear drivers seems to have bubbles.

I have checked for leaks, none found. Tightened all the joints more than once. I am worried about more tightening of the wheel cylinders since they are aluminum. A friend who is actually a mechanic says to use the brakes till they warm up and then re-bleed. He does not think I have air coming in if I don't have leaks.

Any ideas for me?

Jerry
1960 TR3A

 

[martx-5]

Do you have the rear shoes properly adjusted? Turn the adjuster until the drum locks up, and back off one notch. The drum should just rotate easily then without lost motion from the brake cylinder and shoes.

 

[tinman58]

Jerry
Do you have the one way valve at the five way connector at the right front wheel? If you don't (they are hard to find) that did cause the same symptons on my TR3. I just found one on E-bay for $40 bucks installed it bled the brakes, first pump good brakes.

 

[TuffTR250]

What type brake fluid are you using? I am using silicon. I had a similar problem. All new stuff but couldn't get it to hold. At first I was seeing black bits in the fluid coming out. It must have been rubber bits from all the new rubbers in the system. After bleeding two times, I went and bought speed bleeders off eBay for both front and back and clutch slave to make bleeding by myself easier. After that I must have bled it 5 or 6 times over a month long period. (The speed bleeders were a great help for this). I was more and more careful at each bleeding to not introduce bubbles into the fluid, including trickling the fluid down a clean screw driver blade into the master cylinders. Eventually both the brake and the clutch systems started working correctly and are still holding good. I'm still not real sure why it failed at first and then eventually held. Good luck with yours!
Regards, Bob

 

[Geo Hahn]

...First push is now 1/2 pedal and full pedal on second pump...

Is that 1/2 pedal after you have been driving and then get on the brakes?

It is normal for the stock front axle stubs to flex a bit and knock the pads back a tad. First pump has to push the pad further than subsequent pumps. The restrictor valve was meant to compensate for this but can itself be a problem causing the pads to drag.

As noted, could also be the handbrake adjustment or air bubbles suspended if using DOT5.

 

[Jerry]

1. rear shoes are adjusted, one click off of No turning.
2. The one way valve is there, is there any way to install it backwards?
3. Using NAPA DOT 4.
4. 1/2 pedal after it sits for an hour. Then one pump and it is full pedal. I have not driven it more than a mile since it is not legal yet. (no headlights or turn signals installed yet)
5. The front pads seem to have to play. I was prying on them with a screw driver yesterday just to see if they did but I saw no movement. Handbrake adjustment has not been checked but the brake works. I have parked it in the driveway and set the brake without movement of the car. I will check that.

 

[Geo Hahn]

...I have pulled a quart through the system so far. I do not seem to get bubbles from the front disks. But , the rear drivers seems to have bubbles...

Just so I understand where you are... you say 'pulled' so does that mean you are vacuum bleeding? With that method you can often see bubbles that are being drawn in around the threads of the bleed screw rather than being air that is in the system.

I know of no reason why vacuum bleeding wouldn't be satisfactory (though I never use it) but if it is the method you've employed then you might try a conventional pedal bleed or a pressure bleed.

 

[Jerry]

I have tried vacuum bleeding and a clear tube bleeding. I switched to the clear tube to identify bubbles. The vacuum pulls so fast, you can't really see what is coming through the tube.
Jerry

 

[TR3driver]

2. The one way valve is there, is there any way to install it backwards?

No, but it is possible that the valve has been disabled (mine has).

Sorry I don't really have anything useful to suggest; except making sure there is some slack in the MC pushrod after you release the pedal.

After that, I think you are looking at a leak, very possibly a seal that only seals when there is hydraulic pressure behind it. They are all shaped like check valves, and once in awhile you get one that acts like a check valve.

Since you are seeing air bubbles, I don't think rear brake or handbrake adjustment can be the issue. But you can double-check by retesting with the handbrake set.

I've been lucky, I guess. Been using DOT 5 since 1985 and never had a problem with bleeding. I used to take all sorts of precautions, but now I just dump it in and go to lunch or whatever, to give the fresh fluid a chance to 'breathe'. The speed bleeders also worked slick when there was no one handy to push the pedal while I worked the bleed valve.

PS, here's what the inside of the valve looks like

 

[Jerry]

Thanks Randall. I will take that valve apart and see if all the parts are there.
Jerry

 

[TexasKnucklehead]

Jerry, Jerry here, and I have almost the same problem and am having some trouble diagnosing. I am using DOT5-Silicon, all new everything including lines -only thing not new is the front calipers. I now have over 60 miles on my car and have not had to add any fluid. Brakes are always solid and it stops straight. But, the first push on the brake pedal goes farther than it should (not 1/2 way, but more than usual). If it sits for 10 minutes, or maybe during driving after a couple 5 minutes, the first push is farther than expected. When the pedal does travel more, it seems the master piston does not return with the pedal. That is, push, release and push again quickly and it feels like only the pedal moves because the piston hasn't returned for the push rod to push it. If I push, release, wait a second or two, push again, the second push is the normal distance of push, and each subsequent push is the same, and always solid. -It is not "pumping" up.

I would think if I was getting air into the system it would get worse. I bled a few weeks ago, more than once, and could see no air coming out the clear line into a container while pumping. The book shows to have a small gap between the push rod and MC piston, and I have adjusted that to less, and to more without really changing the issue.

I know I took apart that valve, and I know I replaced the brake switch with a plug because I have installed a mechanical switch on the pedal, but I can't remember if I gutted, or re-installed the valve.

-I'm not trying to steal your thread, but I feel your pain and would like to see resolution. Any suggestions are welcome.

 

[Jerry]

Well, I checked that valve as Randall suggested, no leaks and it is tight with the copper washers. Randall also says it is not needed because it was just to keep some tension on the front calipers. I have the uprated axle stems so I am not going to worry about flexing. I bled the system again today. Slightly better, still getting a few bubbles, at random wheels today. So I will try bleed again and see if it slowly gets better. Last time I had an issue like this the air was in the master cylinder. Replaced the master and the issue went away. That seems like an expensive fix, so I will bleed a few more times. Jerry

 

[Jerry]

Group,
Update on the brake issue. Great brakes but the first push is half a pedal and second is perfect. I have bleed more than a quart of DOT 4 through the system and don't see bubbles anymore. I have tried the brakes with the E brake on, and still same thing. It seems like there is not enough volume to the system with the first pump. I have Type B calipers on the front and 10 inch drums on the back. I am beginning to think the new master cylinder is bad. Or, was there a larger size for the cars with Type B and larger rear drums? What size was the original master cylinder?

Jerry

 

[TexasKnucklehead]

Jerry, I had a very similar issue but I am using DOT5 silicon fluid. Even tho the first brake pump would travel farther, it would be solid, and the car would stop straight. I removed the residual valve, but I don't think that was the issue. Normally when I bleed the brakes, I raise all 4 wheels and proceed as usual. This last time, I only raised the front, and after removing the valve, bled the front only, let it sit over night, and bled the front again in the morning. Then, I lowered the front and raised the rear only. Bled the rear, let it sit overnight and bled the rear again. The odd thing is when I bled the rear I saw something I had never seen before. With the wheel off, I attached my one-man-bleeder clear tube to the bleed nipple. I cracked the nipple open and as fluid started to enter the clear tube, a tiny stream of air bubbles in the center of the stream appeared. They flowed into the tube for several seconds. I waited for it to stop and bled as usual. Now my brakes are solid every time and the first push is not any farther than any other push.

I think letting the car sit at an angle allowed some air to settle where it could be bled. ?

 

[Jerry]

I could try that, it only costs brake fluid and that is cheaper than a new master.

Jerry

 

[sp53]

Interesting Tex. I was following the thread with interestbecause I have had a similar problem. I figured I was experiencing what Geotalked about, but I will give your idea a try. Are you using silicon BF andwhen you say you hooked up the clear tube was that one of those vacuum bleederdeals or just a clear hose.
.

 

[CJD]

I personally think you just need to wait till the "new" brake linings bed themselves. When new, they have not conformed to the shape of the rotors and drums. Seat them per the recommendations on the new lining instructions (many hard brakes with rolling time in between to cool them between each hard brake).

If you waited 30 seconds and the pedal went halfway, I would worry. It sounds like you have to wait 30 minutes or more...that would not worry me at all, till after I got some time on the new brakes. Shoot, my TR3 brake pedal would stick for the first week!



Also, this does not sound like a valve issue, by the description.

 

[TexasKnucklehead]

Yes, Silicon Brake fluid. No, not a vacuum bleeder, just a clear hose to a small container. But the tiny air bubble stream flowed up for more than a few seconds. I am sure air entered when I removed the valve, so I have no way to know if it was old, or new air.

John, you may be spot on. While I had the back end in the air, I pulled of each drum off, and checked for leaks. Then I blew off the dust, wiped it clean, and adjusted both sides about 1 full rotation of the adjuster. Actually I went 2 flats past a full rotation, but they started to drag, so I backed it off. Driving in Houston, even if only 300 miles, is probably a good way to brake in the new linings.

 

[Jerry]

I tried you idea of jacking up the rear of the car. I only let it sit for an hour but bled the rear brakes then. The bubbles if there, were inconsistent but the pedal did improve a little. I will try it again when I get back from Triumphfest. I did put the car into the autocross and had fun. I forgot what a large turning radius the TR3 has, missed the 180 twice, but got it on the last run. It was fun!

Jerry

 

[PatGalvin]

What Jerry, no video of the tangerine machine at the autocross?