Brakes Binding

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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kenfholt
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Brakes Binding

Post by kenfholt » Tue Jul 29, 2014 6:37 pm

1952 M38A1. Brakes seem to tighten up after driven a few miles. Took it to a reputable dealer, they could find no apparent problem, adjusted brakes. Same problem, took it to a second shop. They said drums,shoes, brake cylinders, etc. were all in good condition, but out of adjustment. They adjusted. Fine for a few miles, problem returned during a 200 mile trip. Does not seem to roll freely, brakes squealing intermittently at parking lot speeds. During one stop. brake lights remained on without pedal depressed Brake pedal has an inch of free travel and is then hard. No traces of lost brake fluid and I assume (probably a mistake) they checked the master cylinder level when they did the adjustments. Likely problem?


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Re: Brakes Binding

Post by Joe Gopan » Tue Jul 29, 2014 7:17 pm

If the wheel cylinders heck out OK, then the Master Cylinder is suspect. It may be the bypass port needs to be cleaned. A kit or replacement should be considered. This is a typical Jeep Master Cylinder symptom.
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Re: Brakes Binding

Post by artificer » Tue Jul 29, 2014 9:34 pm

Suggest you can get better advice from some here than from any of your dealers, who obviously went to the same Jeep school as
Joel wrote:If the wheel cylinders heck out OK, then the Master Cylinder is suspect. It may be the bypass port needs to be cleaned. A kit or replacement should be considered. This is a typical Jeep Master Cylinder symptom.
This is a typical non mechanic approach/answer. It is a good idea to diagnose properly before you start pulling apart or replacing anything.
Ken wrote:During one stop. brake lights remained on without pedal depressed
This tells us everything we need to know to get you on the right track diagnosing your problem.
What you told us is that there is still pressure in the system when the pedal is right off.
So we are isolated to the master cylinder, in particular the piston &/or the primary cup position with brakes released or much less likely a blocked compensating port.
Firstly you need to check if:
1. the master cylinder piston is fully returning to the circlip &
2. the piston is being held from fully returning by the push rod [free travel should always be checked @ the master cylinder].
Peel back the dust cover & have a look whether both these things are OK.
The compensating [bypass] port can be checked for correct functioning by checking for the 'last little squirt' in the master cylinder reservoir after the the pedal is fully released.
If not it means:
3. the master cylinder primary cup is the wrong one or more likely swollen & not uncovering/fully uncovering the compensating [bypass] port.

1. & 2. don't need the master cylinder to be physically pulled apart.
3. needs a master cylinder replacement parts kit, if the cylinder bore is not pitted & corroded.

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Re: Brakes Binding

Post by Joe Gopan » Wed Jul 30, 2014 2:44 am

This symptom is usually the master cylinder more often than not. They gather sludge, moisture and get gummed up after long use.
The Jeep Master Cylinder life is affected by the heat from the exhaust pipe next to it.
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kenfholt
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Re: Brakes Binding

Post by kenfholt » Wed Jul 30, 2014 4:38 pm

I failed to mention that when jeep has been sitting overnight, the first application of the brakes produces a violent jerk to the left, almost as if the left front brake locked up and the right front did nothing. After applying the brake a couple more times, it smooths out and from that point on tugs very slightly to left when braking. Right front drum and linings clean, no grease. Had a new master cylinder installed today. Shop called and said when they test drove it after doing their thing that it jerked to the left when braked. Suggested installing a proportional valve. I don't know much but was pretty sure that's not the answer so I said no. Could it be as simple as a right front cylinder defective? Thanks again.

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Re: Brakes Binding

Post by artificer » Wed Jul 30, 2014 5:05 pm

Suggested installing a proportional valve.
Where do you find these people? That is not the answer....
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: Brakes Binding

Post by Joe Gopan » Wed Jul 30, 2014 6:26 pm

Check front wheel bearing adjustment and the presence of grease or brake fluid on the front linings.
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Marty, SoCal
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Re: Brakes Binding

Post by Marty, SoCal » Thu Jul 31, 2014 9:39 am

There very well could be could be a problem with the right front wheel cylinder being frozen up/stuck, or the left front wheel cylinder stuck when cold and the first application popping it loose.

Brake hoses that are coming apart internally can also cause pulling issues.
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