Very odd rear brake problem

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Re: Very odd rear brake problem

Post by artificer » Mon Jul 04, 2016 11:50 am

What happened?
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Bob Bell
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Re: Very odd rear brake problem

Post by Bob Bell » Mon Jul 04, 2016 1:09 pm

Nothing yet! A long story, but basically I have been too busy to devote the two or three hours i need to attend to the problem. Hoping to get to it next week. But thanks for asking - I'll publish a full report! Promise!

Bob
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1946 CJ2A 36116
Have owned dozens of flat fenders over the years including 1945 CJ2A 10011 which I sold in 2002.
First 4WD was an Austin Champ in 1965, and then a GPW UK license number HRO 443, sold in 1974.

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Re: Very odd rear brake problem

Post by MaxSheridan » Fri Sep 23, 2016 3:51 pm

What does the inside of the drum look like? If it's highly polished, you may be getting a "flash rust" which would cause grabbing/lock-up upon initial use, but would go away as soon as the rust is rubbed away(like after a few applications of the brakes). Cutting the drums should take care of it.(and it will improve your overall brake performance too!)

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Re: Very odd rear brake problem

Post by Bob Bell » Fri Sep 23, 2016 4:08 pm

Oh the embarrassment! I still haven't taken the time to pull the drums off. The problem is just the same, and still goes away after the brakes have been applied two or three times. I've been very busy with my main passion - music - but do hope to get to this next week. I think that the passenger side is the problem, that that side is the 'lazy' side, as it is the driver side that grabs. I don't believe it is rust as I am in California and we are in a drought. No rain for months .....

I will still order a couple of wheel cylinders, as I have another jeep to completely rebuild, so having some extra wheel cylinders on hand will be good. If I find it is the wheel cylinder, and that it needs replacing, much better to have the spare on hand while everything is apart.

I really appreciate everyone's input ... hopefully I'll have some news by the end of next week.

Bob
Bob Bell

1946 CJ2A 36116
Have owned dozens of flat fenders over the years including 1945 CJ2A 10011 which I sold in 2002.
First 4WD was an Austin Champ in 1965, and then a GPW UK license number HRO 443, sold in 1974.

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Re: Very odd rear brake problem

Post by artificer » Fri Sep 23, 2016 9:26 pm

Someone brought up hard spots in the brake drum but that usually is evidenced by pulsating BUT brakes of any type need to be perfectly balanced, on the same axle for safety & perfect brakes.

In other words replace one wheel cylinder replace both or preferably all 4 with the same brand.

Similarly all linings on that axle need to be of the same material & the MOST obvious, that may have been missed in this thread [I don't recollect] is that both side's long shoes go to the front of the vehicle & short shoes to the rear.
This vehicle doesn't have 2 short one side & 2 long on the other, or each sides a different combination, by any chance? That will match the symptoms.

Also mixing & matching drums [different sources, material composition & manufacture's for all that originality f marks & such] is a very bad idea.
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

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Re: Very odd rear brake problem

Post by Bob Bell » Sat Sep 24, 2016 9:03 am

Appreciate the tips from Artificer. Here is the scoop. When this brake job was first done, I bought all new shoes and wheel cylinders from Ron. I don't know how many brake jobs I have done over the years, but it is certainly in the dozens. As it is a job that I find boring, dirty and very unentertaining, (and plus the fact that at the time I was without a hub puller - essential for the semi-floating rear drums), I took all my new parts to the brake shop around the corner, and asked them to do it.

They charged me $300 which had they done a good job, I would have been quite happy to pay. They did a lousy job ... I had to stand on the pedal to even get the jeep to slow down. I tore down everything they did and found they had put all the shoes on backwards, had put one front cylinder on the rear and vice versa. I told the shop owner all these problems, and he gave me my $300 back. So I ended up doing the job myself anyway. Everything worked perfectly for about a year and a half, until this 'stickiness' developed.

So all this is to let Artificer know that the shoes ARE in the correct positions, the cylinders do all match etc etc. And all the drums have been machined.

Bob
Bob Bell

1946 CJ2A 36116
Have owned dozens of flat fenders over the years including 1945 CJ2A 10011 which I sold in 2002.
First 4WD was an Austin Champ in 1965, and then a GPW UK license number HRO 443, sold in 1974.

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Re: Very odd rear brake problem

Post by artificer » Sat Sep 24, 2016 9:07 am

All correct go back to what Joel indicated initially, sticky wheel cylinders....
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TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.

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Re: Very odd rear brake problem

Post by Joe Gopan » Sat Sep 24, 2016 9:48 am

And if the wheel Cylinders are not gummed up, have Artificer post the major adjustment method that is done without use of feeler gauges.
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Re: Very odd rear brake problem

Post by Chuck W. » Sat Sep 24, 2016 9:50 am

sticky wheel cylinders....
That's what I found on my CJ3B, new wheel cylinders and brake shoes installed a few years back, less than probably 200 miles on it since. Both front wheel cylinders were stuck! I'm going to pull all 4 wheel cylinders and the master cylinder and rebuild them. Thinking about going with DOT 5 fluid to get away from the hygroscopic issue, since it appears to be rust in the cylinders. Thoughts?

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Re: Very odd rear brake problem

Post by Bob Bell » Sat Sep 24, 2016 10:31 am

I do have a comment on the 'New' type of brake fluid - forget what it is called, but the one that came out twenty years ago. Its selling point was that it did not attract water. I used it on a rebuild that had ALL brand new lines, hoses, cylinders etc. And a very odd thing started to happen. About every hundred miles or so my brakes would seize up. The pedal would get harder until I could hardly depress it. The solution was to loosen one of the bleeder nipples and relieve the pressure. Then it would be fine ... for another one hundred miles or so. So what was causing it?

This was on a CJ2A, and I had left out the asbestos guard between the master cylinder and the exhaust system. Turns out that the new brake fluid heated up and expanded by its proximity to the exhaust. By the time I had figured it out, I had already 'contaminated' my nice new system with regular fluid. Back then it wasn't always easy finding the new stuff, and obviously I could not keep relieving pressure without replacing the fluid that drained out. At some point I had to refill with what I could get, and not what I really wanted. At that point, I stopped worrying about using the new stuff, never fitted the heat guard, and never had the problem again.
So the moral is: if you do use the anti water stuff, make sure you have the heat guard in place.

Bob
Bob Bell

1946 CJ2A 36116
Have owned dozens of flat fenders over the years including 1945 CJ2A 10011 which I sold in 2002.
First 4WD was an Austin Champ in 1965, and then a GPW UK license number HRO 443, sold in 1974.

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Re: Very odd rear brake problem

Post by Bob Bell » Sat Sep 24, 2016 10:33 am

DOT 5 ... of course that is what it is called. It is right there in Chuck's previous post.

Bob
Bob Bell

1946 CJ2A 36116
Have owned dozens of flat fenders over the years including 1945 CJ2A 10011 which I sold in 2002.
First 4WD was an Austin Champ in 1965, and then a GPW UK license number HRO 443, sold in 1974.

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Re: Very odd rear brake problem

Post by Gordon_M » Sat Sep 24, 2016 11:37 am

If all the brake components and surfaces look fine - do a thorough check of the hub bearings before you do anything else.
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Re: Very odd rear brake problem

Post by Joe Gopan » Sat Sep 24, 2016 12:14 pm

Best to do a periodic brake fluid flush, no matter if it is DOT 3, Conventional of DOT 5, Silicone.
The Silicone installation is not foolproof as condensation forms on the Cast Iron cylinders and end forms a brown sludge that seeks a low spot to pool. I flush my DOT 5 equipped MV's every three to four years.
Not installing the master cylinder heat shield can affect the DOT 5 in the master cylinder.
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Re: Very odd rear brake problem

Post by Chuck W. » Sat Sep 24, 2016 3:02 pm

What is your flushing procedure? Do you use a power bleeder and just suck a bunch of new fluid through the system or just open the bleed screws and pump away?

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Re: Very odd rear brake problem

Post by artificer » Sat Sep 24, 2016 6:31 pm

Do not get distracted & in the process lead others up the garden path
Bob wrote:....a very odd thing started to happen. About every hundred miles or so my brakes would seize up. The pedal would get harder until I could hardly depress it. Your pedal free travel was not correct or less likely the washer/spacer between the circlip & master cylinder piston was too thick. The solution was to loosen one of the bleeder nipples and relieve the pressure. That will temporarily relieve the symptom caused by the adjustment problem.. So what was causing it? You & everyone else reading this should know now, if they didn't before.

This was on a CJ2A, and I had left out the asbestos guard between the master cylinder and the exhaust system. Turns out that the new brake fluid heated up and expanded by its proximity to the exhaust. This is not true, but a totally incorrect co-relation of things/assumption. By the time I had figured it out, I had already 'contaminated' my nice new system with regular fluid. That is the most basic NO, NO. Brake fluids should not be mixed & in particular DOT 5 is totally incompatible with all other brake fluids. Back then it wasn't always easy finding the new stuff, and obviously I could not keep relieving pressure without replacing the fluid that drained out. At some point I had to refill with what I could get, and not what I really wanted. At that point, I stopped worrying about using the new stuff, never fitted the heat guard, and never had the problem again. This problem was never related to the heat guard or DOT5. It was related to a simple essential adjustment & operator error.
So the moral is: if you do use the anti water stuff, make sure you have the heat guard in place. This statement is related to an assumption above & it is definitely not correct.
Here are a couple of links that cover most raised in this thread about adjustment & brake fluid types. It also gives reasons why pumping the pedal bleeding can cost considerably more than it saves in time.

http://www.jeepdraw.com/images/BRAKES-101.pdf
http://jeepdraw.com/images/HOW%20to%20B ... LEEDER.pdf
John GIBBINS Member Institute of Automotive Mechanical Engineers [Ret], ASE Master Medium/Heavy Truck & Auto Technician USA -2002 Licensed Motor Mech NSW MVIC 49593 Current 2015
TO DIAGNOSE, TROUBLESHOOT OR FAULT FIND ANY AUTO SYSTEM....
Understand how system parts interact with one another. GOOD parts can then be established & the NOT GOOD problem/s part/s isolated for repair or replacement.


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