fading brakes

[Popeye31]

I have been noticing the brakes on my 29 CCpu are fading when I use them at 30mph and above pumping the brakes will slow the fade down but the other day they faded to nothing and I need to fix it. pulled the hubs and all the shoes look good and I started to adjust the brake rods to make sure all the slack is out but need to let a few of the pins soke because they are rusted on the rods so I will work on it tomorrow. but my question is what have you done to eliminate brake fade. I have the stamped drums. does any one know what the thikness of the drums suppose to be so I can see if I need to change to a fresh set of drums. any advice or comments are welcome.

[Jim Parker Toronto]

If you can measure the drums, at 11.060" they should be replaced!

[TerryH]

From what you are describing it almost certainly is fade, probably caused by too thin drums that do not dissipate the heat that builds up. You likely need a new set of drums and should go to cast iron which are much more fade resistant. Good luck!

[Tom Wesenberg]

When the brakes are cold how far down does the brake pedal go before applying the brakes?

[pat in Santa Cruz]

do the shoes show wear indicating full contact? Are all drums equally hot after braking? ( use an infra red remote thermometer). Shoes having partial contact can aggravate fade. Having only one or two drums doing the braking due to un equalized adjustment will cause it as well. But, as mentioned by other posters, the drums expand when they get hot, more so when thin. If the pedal is too low to begin with, it only gets lower as the circumference of the drum expands. Cast drums with well centered and arced shoes, adjusted so each drum brakes equally are the usual solution.

[Popeye31]

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the pedal only goes down 1/2 to an inch before the brakes grab. and the brakes are getting good contact on all wheels. the brake shoes are smooth from top to bottom except for the driver front but I readjusted that one the other day. will be checking the rod adjust ment today. but I think all the posters have confermed the need for some new drums. will let you know how it turns out.

[Patrick L.]

It can be quite a feat to properly adjust these brakes.. I think I'm one of the few that still like steel drums.. I think new steel drums are about .140-.150" thick and shouldn't be turned much more than just a clean-up cut which means they should be no thinner than about .125-.130".. Like the fellas said, thinner than that and they'll fade more than normal.. From your post though it seems like this fade problem is fairly new, so, something else could also be the problem.. Steel reinforcement rings are made for steel drums which is supposed to reduce the fade, but, they require a clean-up cut once installed so I'm not sure whether they work that well or not.. When you try to adjust the brakes, are you using an adjustment board??

[pat in Santa Cruz]

one more thing, check to see the rods are all straight. One bent one will give you a squishy pedal. An old "trick" I have seen from back in the day of no money and no brains was to crimp the back rods into a 90 degree angle back at the rear clevis. The idea was to shorten the rod more after the clevis had been run all the way up. Well it did that, but it also caused the rod to stretch back with pedal pressure, limiting the amount of brake power, and giving the effect of brakes going all the way to the floor. That combination with hot drums would cause bad fade for sure. But if everything looks hunky dory, then measure the drums. If they're thin, they need to be replaced. Good steel drums with bands work well, if you can find them. But I love cast drums....no fade whatsoever, even on very long downhill grades, like in the siskyous or crater lake area.

[Marco Tahtaras]

Originally Posted by Popeye31

the pedal only goes down 1/2 to an inch before the brakes grab. and the brakes are getting good contact on all wheels. the brake shoes are smooth from top to bottom except for the driver front but I readjusted that one the other day. will be checking the rod adjust ment today. but I think all the posters have confermed the need for some new drums. will let you know how it turns out.

First, shoes that APPEAR to have good contact by the wear pattern are more often than not misleading. What folks don't realize is undersized shoes pivot on the adjuster shaft and rock within the drum as pressure is applied. This means you can have 100% contact with less than 50% contact at any given time! The only way to know is to remove one shoe at a time (so they don't get mixed up) and check it's fit in the corresponding drum. You may even need to hold one end of the shoe snug against the drum and slide feelers in the other end to get a true picture. That is probably the SINGLE biggest cause of drums getting extremely hot during flat ground driving.

As suggested, it would also be wise to check for uneven heating of the drums. This would indicate a couple wheels doing most of the braking. This can be easily done with your bare hand CAREFULLY. After just a couple stop get out and check them by feel. Drive some more and check again. Do enough of this to reach a strong conclusion.

As far as drum thickness, I regret never measuring my NOS drums before installing them on the Roaster. It doesn't matter too much to me but I've found others choose that as their point of reference. For me, I get everything true enough that .060" over (11.060") works fine although mine are smaller. At .080" over they can get hot enough to burn paint on the perimeter so that is a no-go for me. As noted numerous times cast iron drums have great benefits but I'm mostly involved in cars that are both shown and driven and on those cars cast drums are not an option.

[Popeye31]

UPDATE I adjusted the rods and sentered the shoes. works great now no fade. but I doo have a little squeeking not much but enough for me to fix. because I don't want them to squeek. will update again when the squeek is gone.