Installed new wheel cylinders. Lines all good. Master cylinder is good (new) and we checked it - pedal firm. Front brakes are good, but got no back brakes. Have bled system twice. Is it possible that air is trapped in the top of the wheel cylinders? Any suggestions or comments welcome. Thanks
Brakes again
- Thread starter Bertieboy
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Can you tell us what vehicle you have and production date as well as what brake system you have installed (OEM, drum, disc etc?) What does "got no back brakes" mean? You press on the pedal and the wheel turns? The wheel turns but there is some resistance? If you want good answers you have to give thorough information.
40 Drum Brakes are very touchy to get them right. The very best help I got was right here in the 40’s FAQ Section. Many many people...including me, have had their questions answered by reading and following @Poser post On 40’s brakes.
Getting these brakes working properly is most certainly doable...but often takes a whole bunch of fiddling. Check out @Poser s post and you will get on the right track w/o a lot of hunting around and WAG.
Getting these brakes working properly is most certainly doable...but often takes a whole bunch of fiddling. Check out @Poser s post and you will get on the right track w/o a lot of hunting around and WAG.
I agree that the adjustment procedure is 90% of getting the rear drums right, adjust with wheel bolted on tight, it changes the drum shape a bit.
Prior to that, given you said hard pedal but no rear brakes is odd. You may want to remove the drums, put a strap around brakes shoes and have someone press pedal, verify the WC's are working properly, the strap keeps the pistons from blowing out of the WC so make it snug. The only other time I have seen that is when the hard line running to rear was pinched, the front driveline will smack it right behind the shock tower if you have had a busted front drive line.
Prior to that, given you said hard pedal but no rear brakes is odd. You may want to remove the drums, put a strap around brakes shoes and have someone press pedal, verify the WC's are working properly, the strap keeps the pistons from blowing out of the WC so make it snug. The only other time I have seen that is when the hard line running to rear was pinched, the front driveline will smack it right behind the shock tower if you have had a busted front drive line.
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- #7
Sorry about lack of info. It is a 1970 FJ40 manufactured in August 1970 with stock drum breaks. Front brakes working OK. Back breaks we can still turn wheels, but there is some resistance. Pedal fades to nothing. Got new wheel cylinders from CCOT. No pinched lines. Everything appears fine. Would speed bleeders be a possible solution?
With drum brakes, there are 2 brake cylinders per wheel and 2 sets of adjusters in the front. Both need to be adjusted to get the brakes to contact the drum correctly. The fronts need to be adjusted before the rear
For the rears - from Chilton's:
Turn the star wheel adjusting star wheel to expand the shoes fully. While doing this, step on the brake pedal occassionally to center the the shoes.
Tighten the shoes until the wheel will not turn.
From this position back off the adjuster until the wheel turns with a slight drag.
Back off the adjuster an additional 5 notches. The wheel should turn smoothly.
Bleeding starts from the wheel farthest from the master cylinder.
Have your helper slowly depress the brake pedal. Open the bleeder screw 1/3 to 1/2 turn and allow the fluid to run through the tube. Close the bleeder screw before the pedal reaches the end of travel.
Continue until there are no bubbles in the line. Make sure you do not empty the master cylinder of brake fluid.
Note - if the brake pedal is depressed to fast, small air bubbles will form in the brake fluid.
Bleeding the rear brakes is always a pain. I always start with the wheel farthest from the master cylinder. Follow your brake lines. So, I bleed rear first, then front. However, I have front disc brakes.
Hope this helps.
For the rears - from Chilton's:
Turn the star wheel adjusting star wheel to expand the shoes fully. While doing this, step on the brake pedal occassionally to center the the shoes.
Tighten the shoes until the wheel will not turn.
From this position back off the adjuster until the wheel turns with a slight drag.
Back off the adjuster an additional 5 notches. The wheel should turn smoothly.
Bleeding starts from the wheel farthest from the master cylinder.
Have your helper slowly depress the brake pedal. Open the bleeder screw 1/3 to 1/2 turn and allow the fluid to run through the tube. Close the bleeder screw before the pedal reaches the end of travel.
Continue until there are no bubbles in the line. Make sure you do not empty the master cylinder of brake fluid.
Note - if the brake pedal is depressed to fast, small air bubbles will form in the brake fluid.
Bleeding the rear brakes is always a pain. I always start with the wheel farthest from the master cylinder. Follow your brake lines. So, I bleed rear first, then front. However, I have front disc brakes.
Hope this helps.
I replaced mine with Speed Bleeders. Worked great the first time. The second time, one of the four needed to be unscrewed more than the others.
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- #11
Would you recommend them? Where did you get them? Cost? Stainless or regular?
- Thread starter
- #13
Thank you.
Checked them out - they suggest using a thread sealer, but they don't have any (backorder). What other thread sealer will work?
I think they come preinstalled with thread sealer. Otherwise, you can use Locktite or other thread sealer.
I don't know if I'd use Loc-Tite there, maybe Teflon tape?
Looking at the Speed Bleeder site, they have threadlocker preinstalled. You don't need any additional until they've been used several times. Locktite is compatible with brake fluid, but you'd have to really clean the surfaces for it to work.