Drum brake help (1 Viewer)

[fatfoot]

I just went completely through the brakes (4 wheel drum) on my 74 fj40. Replaced everything, including the master cylinder. Bench bled the master, and all of the wheel cylinders, adjusted the shoes and I still have to double pump and stand on the pedal. I understand that a reasonable amount of pressure will have to applied. But it seems a little hard to me. I am going to go through and bleed the lines again just to make sure that there wasn't any more air trapped back towards th blocks that I did not get worked out before. Anyone have any other suggestions? Did I miss something? Or are my expectations too high?

 

[laguna80]

You're expectations definitely aren't too high. Drum brakes can stop a 40 just fine with only one pump. I have heard that some aftermarket wheel cylinders can get air stuck inside that is really stubborn to bleed out.

 

[Gundy]

Adjust till wheel can't be turned by hand for each cylinder. Back off a click or
two. Drive it. You may have to do this procedure again.
Adjusted till scrubbing will not get it done. Trust me on this...or do a search.
Bet you get like two dozen threads with this explanation.
Consider this your rookie mulligan.

 

[John McVicker]

Once you are satisfied they are properly bled, do exactly as Gundy describes & you will be good.

This is one of the few times you don't want to follow the FSM which calls for backing off 5 clicks I believe. One or two max will work.

Hopefuly you turned the drums also.

John

 

[lostmarbles]

Hi Fatfoot.

I strongly recommend you read this thread:

https://forum.ih8mud.com/40-55-series-tech/213410-master-cylinder-residual-valve.html

 

[fatfoot]

Thanks for the help guys. Everything is new and the drums were turned. I will try adjusting the shoes out. Right now, I have them set to where there is friction, but can still be easily rotated. Two pumps and the pedal is hard, so I doubt there is air in the line. I will give adjusting another shot and go from there.

 

[FJROSS]

Fatfoot, I recently ended up replacing my rear wheel cylinders on my 77FJ40. I also replaced my booster master and soft brake lines. After many days of presure bleeding, vacuum bleeding, and adjusting, I ended up with a pedal that would pump up. Eventually, I isolated the fronts from the rears by capping the llines and found out that the rear was my problem. Mud Member MarK A. suggested bleeding the wheel cyclinder. This was done by leaving the brake drum on the oppsite side of the vehicle and applying a c clamp on the wheel cylinder next to the unit that your trying to bleed. this needs to be done so that when you dont push the piston out of the cylinder adjacent to the one your working on. I removed the top retainer and cap, then carefully pulled out the seal. I then submerged the seal sideways and then rotated flat while submerged in the fluid. As you reinstall the cap you can relieve the pressure with the bleeder screw to get the cap back on. Make sure to keep the master reservior full while doing this. After bleeding all 4 rear cylinders, I blead and adjusted a final time and got a hard pedal. I don't know if this is a problem with just CCOT's cylinders, but seals are designed different from the O.E.M. Even though I'm going to do a total restoration eventually, I wish I would have spent the money in the O.E.M.cylinders. Many people I've spoken to never had a problem removing the air, yet others that I. heard from never resolved there double pump problem.

Dave