Brake frustration

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salt1019

10 Year 15 Year
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Jan 2, 2010
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I've got a 1966 Fj40. I rebuilt the front kuckles I decided while I was in there to re-do the brakes. I installed new wheel cylinders, shoes, drums, and brake hoses. After getting it all back together I cannot get a good pedal( worked fine before and I did not touch the rear brakes).
The brakes are very spongy I can pump them up a little but the pedal is still very low.
Here is the back story this thing has been modified by a previous owner it has power booster installed and a master cylinder from a 8/80-1/90 fj40. I decided to replace the master and bought the exact one no success. I noticed that this particular master was set-up for disc front and drum rear so I tried installing a 10lb residual valve to the front line no success. I can plug up the master and get a good pedal then connect the rear line(front still plugged) and get a good pedal. As soon as I hook up the front brake line sponge city! I have bench bled the master and all wheel cylinders using the proper sequence everytime. I would like to get this thing back on the road and im not opposed to getting a new MC just want to make sure it gonna match my wheel cylinders. Any ideas?
 
The low pedal that pumps up is because the rear drums need to be adjusted tighter. If it is still spongy after adjustment, the brakes also need bleeding. Are the front calipers mounted upside down? If so the bleeder valve is at the bottom, which makes them hard to bleed.
 
My procedure for adjusting drum brakes: jack the wheel off the ground and spin it. Tighten the brake adjuster until you hear the brake scrape on the hub. At that point either back off a hair or if it just barely scrapes then leave it.
Spongy is air in the lines. It might take a little more aggressive bleed to get the air out, how are you currently bleeding?
 
Thanks for the replies yall. Sorry, forgot to mention that I tried adjusting. I even moved adjusters all the way out until the wheels were completely locked, still spongy. I tried to different versions of bleeding one at a time always starting from the rear brake cylinder farthest away from the master. The bleeder closed pump em up then open version and the open bleeder with a tube in a jar then pump slowly version. I have drums all the way around so do not have any calipers. I thought about purchasing a pressure or vacuum bleeder but I just can't imagine that its just air I have literaly bleed the hell out of the lines.
 
I would bet there is an adjustment issue. I assume a '66 has 8 wheel cylinders like my '71 used to and a couple turns off on a couple makes a BIG difference. Been there!! Also if the two on a single wheel are not in sequence can make a big difference. Just a thought...
 
Also if the two on a single wheel are not in sequence can make a big difference. Just a thought...
Click to expand...

Likewise - my PO did this and never did figure it out. To restate - make sure the wheel cylinders are turned approximately the same number of turns - that the shoes are centered.

CAZ
 
I adjust them evenly as possible and as far out as you can and still get the drum on when replacing everything as you did. If the drums were turned there is no ridge so a big head start!! That way there is little as possible error zone which works for me. :) Also verify cylinders are in the correct position (Lefts on left and rights on right) Just a thought...
 
OK. according to sor and cool cruisers they are all the same for the 66 but I did make sure to orient them the same way as the old when I installed them. I'll double check just in case. I did try locking up the adjusters on all wheels but that did not change a thing. I'll try adjusting them as evenly as possible. Thanks again if anyone has any other ideas they are welcome. Anyone think the master cylinder is the culprit?
 
After you adjust them out tight, start it up and pump the pedal a few times as this will center the shoes in the drum and you may be able to adjust tighter then. It can be fustrating until you get it right and then you see how a little off can make a big difference. Properly adjusted with new hardware like you have will put you thru the windshield when you get it right. BUT, you will have to re-adjust regularly, thats the down side I found before I went to disks...
 
air in the wheel cylinders

I recently got help for a similar problem. You said you get a good pedal when the fronts are plugged but the rears are operating so you have air in the fronts then. Did you replace the wheel cylinders, if so where did you get them.

I was told CCOT cylinders are different from Toyota and have a tendancy to trap air in them, if you take the front drums off and put a c-clamp on all 4 cylinders at the same time so they can not open, if you have a hard pedal the adjustment is off, if you still have a soft pedal you have air in the wheel cylinders.

I thought I had air in my rears, but with all clamped off found out that my adjustments weren't even, backed all the wheel cylinders all the way in and adjusted them an even number of turns till i almost couldn't turn the drum by hand. Now I have great brakes and no drag.
 
I did get the cylinders from CCOT so thats very interesting that you had the same issue. Ill try the c-clamp trick then adjust as suggested. If it is air what was the technique for getting it out?
 
I used CCOT stuff. My bet is still on adjustments. You just dont know until you get it correct. A couple clicks on each can make a BIG difference Just a thought...Brian
 
Tried adjusting tightly but not EVENLY gonna try it out tomorrow after work. thanks homebuiltcruiser good to hear others were having similiar issue thought I was going nuts.
 
air removal

This is what I was told to do, although I never ended up having to do it. Clamping the cylinders will at least tell you if it's adjustment or air. I hope its adjustment...less hassle!

"From what I recall, I hooked up a pressure bleeder to the master so I didn't have to worry about emptying the reservior. I removed one drum to work on one set of cylinders at a time, you have to remove the top of the cylinder until you get the rubber internal seal out. While doing this you will have a bit of a mess on your hands so have a lot of rags. I switched over to silicon before having my soft pedal problem so it was not that big a deal. You must then turn the rubber seal vertical and press it down inside the cylinder full of fluid and then rotate it flat into it's final position. This will fill the void with fluid and eliminate the pocket of air that was captured in the rubber dome that was compressing giving the double pump pedal. I spoke to many people that never had a problem gravity bleeding or the normal step on the pedal and bleed method with the stock cylinders. This problem only started after purchasing the cheap ccot cylinders and ended after performing the method above. If I didn't switch to rear disc, the cost of new Toyota cylinders would have been well worth the aggrivation that this encountered."
 
My vote is first to lift rear axel off ground, adjust shoes to rubbing, start engine and pump pedal several times, re-adjust to tight! Repeat on front axel. My money is on adjustments...
 
I replaced cheap ccot wheel cylinders with sor cylinders a little better but still not firm. Wondering if anyone has any other ideas before I toss this thing in the San Antonio river.
 
I ran into this trouble a few years ago with CCOT cylinders. The only solution I found was to remove the top dustcover and piston from each wheel cylinder and let gravity push the fluid up and out, then I quickly pushed each piston back in, making sure not to trap any air. Lots of friends and "experts" said I was crazy and I shouldn't have to do that but it fixed the problem immediately and I had a hard pedal. I wasted weeks of time with other methods. Good luck.
 
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