I'm an idiot re: troubleshooting brakes. UPDATE!

[Allan Songer]

I am a decent enough shadetree mechanic with nice tools and what I thought was a pretty good set of troubleshooting skills, but I am totally at my wits end with a braking problem in my wife's '55 E7 pickup.

We restored the truck for the second time about 18 months ago and it preformed flawlessly until 2-3 weeks ago. The left front brake began dragging and making quite a racket. I took the drum off, inspected everything and found NOTHING obviously wrong, so I bolted it all back together and readjusted everything and drove the truck about a mile and all seemed well. My wife drove the truck the following day and after about 2-3 miles the problem came back.

So, I decided that the brake hose must be the problem and I replaced it. Again, I readjusted everything and put it back together and even installed a new wheel cylinder because I had a fresh one on the shelf. Next day same story--after 2-3 miles of driving the problem came back--this time is was WORSE than ever! I then added even MORE free play in the pedal (started with about 3/4" and now was up to 2"). No dice, same problem. For the heck of it I popped in a new wheel bearing too. Still the same story.

So, after getting some advice on the Monday Chat Night, I decided that it HAD to be in the master, even though the problem was PRIMAIRLY only on the left front, the right front was also dragging a wee bit as well. I have a frame rail mounted Corvette dual master with a tiny 7" booster, so off came the master for a brand new one. Now that the master, brake hose, wheel cylinder, shoes, springs were all new, I figurued all was well. And it WAS--FOR ABOUT FIVE MILES AGAIN.

I really wish we had never put in the dual master, but my wife INSISTED on it when we redid her truck. And the system worked FLAWLESSLY for about 7,500 miles.

My wife is about to shoot me. I am totally at a loss. Can anyone here give me some advice?

[Carl Purdy]

My wife's 65 Ford done that and it was the backing plate was not tight enough. I tightened them and the problem went away. You might check.


7G-Q1 49 2R12 10G-F5 56B-D4 56B-F2
As soon as you find a product you like they will stop making it.

[Allan Songer]

quote:Originally posted by ST2DE5

My wife's 65 Ford done that and it was the backing plate was not tight enough. I tightened them and the problem went away. You might check.

If that's the problem I will shoot myself! But I will check. Can't imagine why it would loosen up suddenly and it wasn't obvsiously loose ALL OF THE TIMES I HAD THE DARN THING APART over the past 3 weeks!

[sbca96]

The simple fix is dont drive it further then 2 miles.

I agree check the backing plate, you dont have any leakage issues that
could be saturating the shoes, you would have found a bad inner grease
seal when you did the bearing(s). Couldnt be loose lug nuts since you
have obviously had the wheel on and off, you ruled out the Master. Is
the setup running an adjustable proportioning or auxillary residual
pressure valve? If the whole system is on one circuit, did you do a
check on EVERY rubber hose? You could have one in the rear that has
a weak area thats allow to balloon, then deflate "adding" extra fluid to
the system. Have you noticed the master "losing" fluid with no leak?

Tom

'63 Avanti, zinc plated drilled & slotted 03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, soon: TKO 5-spd, Ported heads w/SST full flow valves, 'R3' 276 cam, Edelbrock AFB Carb, GM HEI distributor, 8.8mm plug wires

[Mike Van Veghten]

quote:The simple fix is dont drive it further then 2 miles.

More correct sentence -
The simple fix is, don't drive it farther thAn 2 miles.

Sorry...couldn't help myself.
Been a while, how's things goin Tom?

Mike

[Mike Van Veghten]

Another situation to check -

Remove the shoes from the backing plates, carefully check the "rub pads" on the backing plate for "steps" rubbed into them.

As the shoes move back and forth, they grind into those pads and eventually wear steps or grooves into them. Your shoes may getting stuck if you have this problem.

Just take a file to the pads to smooth things out nicely. If they end up too deep....a bit of weld to build the pad back up, thEn regrind/file the pads smooth.

Good luck.

Mike

[Allan Songer]

quote:Originally posted by Mike Van Veghten

Another situation to check -

Remove the shoes from the backing plates, carefully check the "rub pads" on the backing plate for "steps" rubbed into them.

As the shoes move back and forth, they grind into those pads and eventually wear steps or grooves into them. Your shoes may getting stuck if you have this problem.

Just take a file to the pads to smooth things out nicely. If they end up too deep....a bit of weld to build the pad back up, thEn regrind/file the pads smooth.

Good luck.

Mike

Never even thought about backing plates being an issue--probably because in 35 years of messing with cars I have never run into this!

This would explain why the problem is pimarily on the front left--perhaps the front right is NOT a problem at all, or only in the very early stages of a problem!

THANK YOU!

One more time apart come Saturday morning!

EVENTUALLY I'll get this fixed!

[BRUCESTUDE]

Also check the return spring, they lose tension over time. A little brake lube on the backing plate "nubs" previously mentioned helps too.

[mapman]

Also check for a kinked or crushed brake metal brake line. It can inhibit the return flow of fluid and cause the shoe to drag.
Rob

[sbca96]

quote:Originally posted by Mike Van Veghten
Sorry...couldn't help myself.

[Allan Songer]

quote:Originally posted by Mike Van Veghten

Another situation to check -

Remove the shoes from the backing plates, carefully check the "rub pads" on the backing plate for "steps" rubbed into them.

As the shoes move back and forth, they grind into those pads and eventually wear steps or grooves into them. Your shoes may getting stuck if you have this problem.

Just take a file to the pads to smooth things out nicely. If they end up too deep....a bit of weld to build the pad back up, thEn regrind/file the pads smooth.

Good luck.

Mike

BINGO! A VERY pronouced groove in the upper front pad, smaller ones all the way around the other pads. Sanded smooth, a bit of grease and one 40-50 mile trip later in the morning with NO problems at all.
Keeping my fingers crossed . . .

[Neal in NM]

I have seen that before on a friends Ranchero. The grooves were so bad that he had them welded up and I machined them down. Neal

Mike
[/quote]

BINGO! A VERY pronouced groove in the upper front pad, smaller ones all the way around the other pads. Sanded smooth, a bit of grease and one 50 miles trip later in the morning with NO problems at all.


[/quote]

[Allan Songer]

Well, a 70 mile trip yesterday brought the problem back again. Didn't have time to do anything but pop the drum off and take a look. I can't see ANYTHING wrong here. I am flummoxed. I mean, we have new shoes, new springs, new wheel cylinder, new master, new wheel bearings, etc. etc. etc. Brakes started dragging and SCREAMING about 2-3 miles from home and by the time we pulled into the driveway the drum and wheel were literally smoking again. Again it was the left front ONLY--the right this time didn't even drag a bit--though it was never the problem the left front was.

[gordr]

My GT Hawk did this when I first got it; turned out to be an out-of round drum that caused the self-adjusters to over-adjust.

IIRC, '55 pickups did not have self-adjusters, but I think those from cars can be retro-fitted to them.

Another thing to check: next time the left front locks up, crack open the bleeder screw, and see if you get a jet of fluid, followed by the brake releasing.

Gord Richmond, within Weasel range of the Alberta Badlands

[Dick Steinkamp]

I'd sure suspect something holding pressure in the system.

Get the brake to drag (drive it a little). Jack up that corner and try to spin the wheel. It should not move or move with a lot of force if it is dragging. Open the bleeder on that wheel. If the wheel now spins freely, then something is holding pressure in the system.

Main culprits would be a bad flex hose or MC push rod not adjusted correctly.



If the wheel doesn't release, it's something mechanical in that brake. Brake return springs, sticking wheel cylinder, etc.

Dick Steinkamp
Bellingham, WA

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