Brake Bleeding on 1969 FJ40

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lespaulflame

lespaulflame

Joined
Apr 14, 2026
Threads
1
Messages
6
Location
Phoenix, AZ
Hello everyone. I just picked up a 1969 FJ40 and love it.

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I am new to this and have read other posts, but I am still having issues with my brakes. Everything stock 4 drums all around.

I was getting the old fluid out of the master cylinder and brake lines, and bled all the brakes, starting with the wheel furthest from the MC. When my son was helping me, I knew the MC had run out of fluid, so I had someone check the reservoir and bled out the system again and again. I did bleed the brakes again 4 times. I am not seeing any air bubbles in the fluid, and it is going through a lot of fluid. I have tried the traditional method and even bought an air bleeder kit, but neither worked.

The brakes build up pressure in about 2-3 pumps, and they hold. Once I let off the brakes and reapply the pedal, it falls to the floor. I also checked the drums to see if they were adjusted. They seem fine and rotate about 2 turns when spun on jacks. What am I missing?
 
You should adjust the shoes out enough to lock the drum at each wheel. Now bleed the cylinders - never let the master go dry - fill for each wheel. If you want to use the one man brake bleeder (I have a mighty-vac) then you need to remove the bleed nipple and coat the treads with Aviation Permatex and put it back in. They don't cut the proper threads any more and it will suck air unless the threads are sealed. 2 person technique will work with out the sealant. Make sure the boy doesn't allow the pedal to rise while the nipple is open or it will suck air into the system. After you get hard pedal, back the adjusters off so the drum can rotate. You might consider bench bleeding the master first. You can do it on the rig with some short hoses and some push in type fittings.
 
charliemeyer007 said:
You should adjust the shoes out enough to lock the drum at each wheel. Now bleed the cylinders - never let the master go dry - fill for each wheel. If you want to use the one man brake bleeder (I have a mighty-vac) then you need to remove the bleed nipple and coat the treads with Aviation Permatex and put it back in. They don't cut the proper threads any more and it will suck air unless the threads are sealed. 2 person technique will work with out the sealant. Make sure the boy doesn't allow the pedal to rise while the nipple is open or it will suck air into the system. After you get hard pedal, back the adjusters off so the drum can rotate. You might consider bench bleeding the master first. You can do it on the rig with some short hoses and some push in type fittings.
Click to expand...
Thank you for your prompt response. I will try that with the drums. I was trying to bleed the master. I was able to get the single (9mm) line fully loose. It just won't come out, even when the nut is spinning. I am worried I will damage the lines or threads. Am I missing something??
 
The flare on the end of the brake line has been crushed by overtightening at some time, move the running nut back along the line and then wiggle the brake line as you pull it, walk it down the threads. If it looks ok sand the outside diameter back so its a neat fit - if its rusty or the flare has splits get a new one. I would hone and rekit the master first, if its original and single circuit then its pretty straightforward, OR get it stainless sleeved. Brakes are good.
Charlies bleed info looks on the money
 
Tighten the fitting back up - you can bleed the brakes without bench bleeding the master - it will just take a little longer.
 
So I was able to get an adapter to bench bleed the MC. I was able to cap it off, and I get a very firm pedal with no drop. So I believe the MC is good to go. Now I am running into other issues with the drum cylinders. I removed the drums and then contracted all the adjusters. I then have issues adjusting them out. With the drums off, I can't get them to move freely. I am I missing something?? I thought both adjusters needed to be moved consistently. Thanks for any suggestions.
 
The screw threads on the adjusters are likely rusty. Take the shoes off. Remove the rubber cup. Grab the adjuster and try to wiggle it back and forth. Screw it all the way out, wire brush the threads, then apply a little grease and screw it back in after blowing out the hole. Put the rubber cup on and then the shoes. City Racer sells the short spoon that will fit in the confined space.
 
Okay, I have been working on this for many hours. I got all the wheel cylinder adjusters working correctly and even replaced the front drum shoes. I have adjusted them very tightly so the wheels barely move. Then bled the brakes 3 times so absolutely no air is present in the system. I still get the pedal to the floor on the first push, and it firms up between the 2nd and 3rd pumps of the brakes. I then let the pedal go, and the process repeats. I am just at a loss. No leaks or anything. Everything is in good condition.
 
You still have air in the system. Drum Brake bleeding problems are a constant issue and there are a ton of threads on the subject. A lot of folks have success by keeping the tires on, adjusting the cylinders to the max, so the pistons can't move and the tires dont spin, then bleed. Once bled adjust per the fsm. You can isolate the issue whether it's the frt or rear brakes by carefully clamping the frt or rear rubber hose with vise grips. Be careful not to crush the hose. You just want to stop the flow.
 
Follow this recommendation…

From @Pin_Head "To adjust, tighten until the wheel locks and back off 3 clicks. "

I would even go two clicks just to see if that does help

Aftermarket cylinders are harder to bleed… toyota 4 wheel drum you’ll be adjusting again in three months if you drive a lot … went to 4 wheel disc … so much better :)

But get them good now and decide later
 
I agree witn pb, clamp the soft line for the rear and see if you get hard pedal, then clamp front, see if you get hard pedal, you should with both soft lines clamped. FWIW, adjust drums with wheels bolted on, adjust them out until the drum drags a bit more than youd think. Make sure to adjust the wheel cyl equally. My drums had to be adjusted tight, ran around block a few times to heat em up/seat the shoes, then back off 1 click. My 1970 dual circuit master with booster & 4 wheel drum was a 2 pump like yours. I have always gravity bled all 4 same time, keep an eye that MC doesnt go dry.
 
Maybe the new MC is weak- just because its new doesn't mean its good. Clamping old rubber lines is asking for replacement next IMHO. The issues with new wheel cylinders is they tapped the bleed screw threads wrong. When you loosen the screw to bleed the air from the system - it is very loose and allow air in so you can't use the one man break bleeder (mighty vac) unless you use something like Permatex on the threads to seal them. Second is they cut the brake shoe slot in the adjuster straight across instead of at an angle (ramp) to help keep the shoe centered.
 
I did put a clamp on the rear rubber line, and I get a hard pedal. I spent all afternoon bleeding the rear brakes, but I still can't get a firm pedal. I did add Permatex to the threads. When I do let off the pedal, and there are a few bubbles returning to the master, but that is normal, correct...? The MC is actually not new and original. Do the rear cylinders need to be rebuilt? Can they get air into the system? Thanks for everyone's help. I really do appreciate it.
 
Bubbles are bad and shouldn't be there. Usually if the seals leak by allowing air in they will let fluid out. You could try kits for the rear cylinders - hone them before putting in the kits. Same for master cylinder.
 
Try bleeding both circuits at once, 2 man job, pump pressure up at pedal then while holding that slacken a front and rear bleeder, start with the pair furthest from master, tighten once pedal is on the floor and repeat. You'll shift a lot of fluid, keep close eye on reservoir. Alternate slackening the first nipple from front to back as you go.
My bad - if you're dealing with single circuit brakes this won't help. Can you confirm whether you have dual circuit or single?
 
Another thought go for a short rough ride to help shake the bubbles loose before you bleed again.
 
It is a single circuit system. I will try these suggestions. I did order some kits to rebuild the MC and the wheel cylinders, and I need to get some more brake fluid. I have gone through about 3 gallons with all the bleeding activities :) I will update as soon as I receive and work on eliminating and troubleshooting more.
 
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