The Stovebolt Site Forums The Shop Area Driveline Brake issues

I have changed all the brakes, new linings , new drums , 2 new wheels cyls , 2 recon wheels cyls , recon master cyl.

Bled the fliud till it's clear .

Pedal seems fine when the truck is stationary , and under gentle braking , there is gentle retarding of speed.

BUT ! if I brake harder , the rate of deceleration is not much changed. The pedal will go down another inch and the rate of slowing down seems less.

It's kinda scary to drive , and I NEED to fix it in the next 2 days as I'm off on a 1000k trip.

I;m guessing it's a master cyl issue , but need your thoughts please. What might I have done wrong , I followed the shop manual proceedure. (original M/C for the truck.)

Are these Huck brakes?
If so, you'll need to check & readjust all 4 sets of shoes.
I had to readjust mine 2 times after bleeding my rebuilt Huck brakes.
Also if the recon Master Cyl is a replacement and not the one that was removed, check/adjust the free play of the actuator rod.

Good luck
Dave

I vote for brake adjustment to ensure shoes have full contact on drum.

thanks guys , these are bendix. I have the shoes dragging and initial brake effectivity is high up on the pedal. then extra force on the pedal produced little more braking force , even though the pedal goes down another inch.

Yes I adjusted the freeplay on the rod. There is good clearance there.

My concern is , is it the master cyl not performing , or do the linings require a bed in period.

Either way , I have not had this problem before.

Jack it up & prop the pedal down to make sure you are getting braking on all the wheels. Although it should show up on the bleeding process it may have a pinched brake tube or swollen brake hose. It doesn't sound like a problem with the master cyl. The linings do require a wear in to get full contact with the drum. Some of the linings we get know are really crudy. They have taken out the asbestos & who knows what they are using.
This is a tough one.

I'm betting the master cyl has an issue. Does it keep going down if you just keep pressure on it while stationary?

Dennis

Dennis , the m/c holds steady with both feet on the pedal.

Did you bench bleed the MC before install? If not, that's probably it.

Is there any spongy feeling when you depress the pedal? If so, repeat the bleeding procedure. When I adjust brakes, I turn the adjuster wheel until the wheels are very snug. The book says to tighten until some resistance is felt. I don't know what 'some' resistance is exactly, but I do know what really snug feels like. After that, I back them off until they aren't quite free spinning. I want some contact to promote some friction to aid in machine matching the shoes to fit the drums. Pay attention to the drum temperature on your first trip to make sure you don't have too much friction. If they are too hot to touch, back them off a couple of clicks. You say you have new shoes and new drums. Chances are, being after-market, they aren't a perfect fit to each other. This will prevent the entire shoe to contact the drum. Some time on the road and a number of readjustments may be necessary to get things stopping properly.
Carl

Deve , I was pretty sure that would be the problem , but I did the bench bleed , and after this issue , I cracked the line on the M/C outlet and pumped plenty of fluid out there as well.

In desperation , I have disassembled the front brakes again , I see , after road tests , that the linings are just touching at the tips , for about 2", on one wheel and on the other , there are several random contact points . It looks like a poor match , I'm going to the brake shop who arced the shoes to see what they have to say.

52Carl. Your proceedure is what I do , this time it just doesn't work.

Have them match the shoes to the drums. Also, make sure you have a fine cut on your drums.

Guys , thanks for all your helpful suggestions .

I'm a dork ......... I'm a dork ............... I'm a dork!

Every thing I did was ok but for one WEE thing .......

I put the leading and trailing shoes back to front . That is , I had the long lining at the front instead of at the back of each wheel.

Instant fix !!

What a waste of 2 days stuffing around . I am so [censored] off with my self.

On the plus side , I now know I have all new brakes for my 10 day trip away and they work well. The truck is going to be much happier now , when it's carrying the camper

Dusty, I believe I would have kept that one to myself. In fact I HAVE kept that same goof up to myself. Well, until just now anyway.
Carl

I am always happy when someone finds something easy. You will never make that mistake again. Its great for everyone! Have a great trip!

Tell us is it short shoe to the front or the rear? Inquiring minds want to know?

On a Bendix or Duo-Servo type brake system, the short shoe goes to the front, long shoe to the back.

Good deal. Glad you ciphered it out. I guess I'll come clean too, yepper, BTDT

Well now, there is one good thing we can now say about the old Huck brakes, you can't mixup front & back shoes

Dave

Can you see the contact patch on the shoe - btw, you didn't mix up the front shoes and swap the sizes did you? - you might be getting contact at the leading and lagging edges of the shoe. Find somebody that can do a radius cut on them and have that done. What happens is the leading and lagging edges become like a spring and when more pressure it applied they don't dig in deeper as much as flex a little without letting more of the lining touch the drum.