Brake Problems - 76FJ40 Need Expert Advice. (2 Viewers)

[45Dougal]

I replaced my air bleeder hose with clear hose and re-bled the brakes. I’m getting solid fluid from the left rear but when I get to the right rear there’s a lot of air. I’m thinking I got some bad wheel cylinders from rockauto.

There's not much in a wheel cylinder that can be bad tbf. Unless the seals aren't fitted or the cylinder is cracked.
Sounds like you need to just pump it through a bit more.

 

[pb4ugo]

FJ40 brakes are kicking my ass!!

Yesterday I replaced my front drum cylinders on my ‘71 FJ40. I used FC cylinders. Photo included. I can’t get pedal pressure on my brakes! It’s kicking my ass. I adjusted the drums to the point where the wheels wouldn’t turn and then backed off 3 clicks. I put Teflon tape on all 8 bleeder...

forum.ih8mud.com

 

[anothernz45]

Try a 2 man bleed - get someone to pump pressure up on pedal and hold it while you slacken the bleed screw with your clear hose attached and running into a container with a bit of fluid in it, do screw up as the pedal hits the floor. Repeat until no bubbles show in hose, vacuum bleeders are useful but as charliemeyer pointed out they suck air around the bleed nipple making it hard to work out what is going on.
45Dougal mentions the dash brake light senders - unplug them at the mc and run a test light from your battery and try each sender as your helper pumps up brake pressure, that will isolate which circuit builds pressure - light should go out as pressure builds.

 

[anothernz45]

And if that doesn't work bleed both front and rear circuits at the same time - gravity bleed first, crack the nipple in each circuit furthest from the mc and let run into a jar, then pressure bleed as above but run around doing both circuits at once. That way you avoid a firm pedal in 1 circuit restricting a full pump in the other.

 

[chubot]

FJ40 brakes are kicking my ass!!

Yesterday I replaced my front drum cylinders on my ‘71 FJ40. I used FC cylinders. Photo included. I can’t get pedal pressure on my brakes! It’s kicking my ass. I adjusted the drums to the point where the wheels wouldn’t turn and then backed off 3 clicks. I put Teflon tape on all 8 bleeder...

forum.ih8mud.com

Man I feel your pain. I just replaced the rr cylinders with the same CCOT I have on the LR. I’m getting solid fluid at both rear wheels and the right front caliper. But when I get to the left front caliper I’m getting a lot of air.

 

[charliemeyer007]

I don't think the bleeder's are threaded properly anymore. I had to use a thick layer of Aviation Permatex B on all the Bleeder threads to get them to stop leaking air when using my Mighty Vac. They seal fine when closed but open to bleed they leak. 2 person pressure technique likely is fine with out the goop.

 

[numby]

Air will slip in when the bleed screws are loosend. If you're getting a constant stream of small bubbles that's what is happening. It even happens with new cylinders and new bleed screws so I just ignore it. Air is not sneaking back up the lines.

If you're getting long burps of air or bubbles here and there then that's a concern and you'll need to do the two man technique. You can do it by yourself if you:

a) Tighten the bleed screw.

b) Jam a stick/flashlight/braunschweiger between the brake pedal and the front of your seat to depress the brake pedal and pressurize the line.

c) Quickly open and close the bleed screw to force out any entrained air.

d) Top up reservoir. Remove sausage.

e) Repeat starting with "b)".

 

[chubot]

I just found a YouTube video where the guy was bleeding his brakes with the truck running. He found that air was entering in through the wheel cylinder piston. He replaced the wheel cylinder and solved his problem. I’ve replaced my wheel cylinder's and still no pedal. I haven’t had time this week to mess with it, maybe I’ll try the car running technique over the holiday weekend.

 

[numby]

If there isn't any fluid leaking out of the wheel cylinders or fittings and you've got no pedal resistance then it's either excessive air in the lines (air doesn't compress well in a brake system) or fluid is bypassing the seals inside the master cylinder. If there's unexplained fluid loss then loosen the MC from the booster to make sure you're not squeezing fluid into the booster. If there's no leak out the back of the MC then you need to re-bleed the lines on both circuits or rebuild/exchange the MC.

 

[pb4ugo]

To isolate if the problem is in the frt or the rear, you can use a pair of vise grips on the rear soft line. If the pedal gets better then you still have air in the rear. Carefully adjust the vise grips. You want to block the flow and not crush the line. If no change then test the frt.

You you could be sucking air at a connection or a bleeder.

I haven't run drums brakes in decades, but have followed many threads about having problems bleeding stk drum brakes. A lot of folks have had success by putting the tires on and adjusting the brakes to the max, so the pistons can't move and the tires won't spin. Then bleed the brakes, once bled re-adjust per the fsm. .