Brake problem

1959 - 1978, M151, M151A1, M151A2, Technical questions and discussions, regarding anything related to the M151.
ldj1002
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Brake problem

Post by ldj1002 » Sun May 29, 2022 3:40 pm

I worked on brakes for over 65 years, no expert but do understand how they work. First I'm sure this is a coincident but I have some used tires mounted on my wheels and first time I used brakes they pulled to left. I drove a little and when parked the brake drum was hot. My first thought is brake hose going bad inside not letting fluid return. I then took wheel and brake drum off and see if shoes are fully retracted and they are. So I think I'll just back off on adjustment. Went for test drive and still pull left and brake drum getting hot. What is going on? I'm thinking MAYBE it is the brake hose not releasing and by the time I get the brake drum off to see the shoes have already retracted, possible? I think I may drive it around a couple blocks or so and only use park brake and see if brake drum gets hot. That should tell me if hose is bad. Is there a brake hose I can buy local?


ldj1002
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Re: Brake problem

Post by ldj1002 » Sun May 29, 2022 4:20 pm

I went and drive about a mile using park brake, drum stayed cool. Then drove same rout using brake and drum is hot, other 3 normal. So must be brake hose>

Rickf
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Re: Brake problem

Post by Rickf » Mon May 30, 2022 3:38 am

Is it pulling in the direction of the hot drum? And is the brake on the other side working at all? Whenever I buy a new to me old vehicle the first thing I do is replace ALL rubber brake lines, no questions asked. I don,t care about age or apparent condition, they get replaced. This is a single stage brake system so if a line fails you have no brakes. And the parking brake is just that, a PARKING brake. It is not designed to stop a vehicle moving at speed. It will lock the wheels but it will do it by locking the driveshaft so that in turn means you locked the input of an open differential so the wheel with the most traction stops and the other one starts spinning in reverse which starts the original one that stopped now spinning forward and you are upside down by now. No, do NOT play with brakes. I also replace ALL wheel cylinders and shoes. This stuff is all available through the regular surplus dealers usually cheaper than parts houses if those parts are available, which most are not. I have never seen the lines available. Unfortunately the M151 is a vehicle that did not have a lot of cross over to civilian parts. I have an updated cross reference to will be put up on the g838 Wiki as the Wiki is brought back up to speed but it is a slow process. I have a lot on my plate right now. But I will tell you there is not as much out there as most would like to see.

But as far as brakes the best route to go is replace everything with new when you get the vehicle and then you know for sure what you have on the most critical system on the vehicle. And when you replace all of the lines and cylinders that is the perfect time to decide in which brake fluid you are going to use, DOT 5 or DOT 3. I personally go with DOT 3. Availability anywhere, price, moisture doesn't not lay at the lowest spot in the wheel cylinders and when you do flush it all the moisture comes out with the old fluid whereas with the DOT 5 it still lays in the bottom of the wheel cylinders.

Just a bunch of stuff to think about.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

svramselaar
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Re: Brake problem

Post by svramselaar » Tue May 31, 2022 2:08 am

hi

drive the mutt a few miles if the drum is getting hot open the bleeder a bit and see if there is a bit pressure
if so the brakehose is clocked inside

george
1976 ? M 151 A2 AMG MUTT lost in acsedent
1978 M 416 A1 ( parkhurst ) trailer
1970 m151 A2 FORD BUDD tub
1957 Volvo sugga radio truck
M 274 mule HOME MADE MULE

lpcoating
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Re: Brake problem

Post by lpcoating » Tue May 31, 2022 7:24 am

Here you go:

https://www.armyjeepparts.com/p-2730-m1 ... 59147.aspx

I'm sure the other dealers have them as well.

Guy

ldj1002
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Re: Brake problem

Post by ldj1002 » Sun Jun 05, 2022 4:06 pm

I put new brake hose on. Still have the problem.

lpcoating
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Re: Brake problem

Post by lpcoating » Mon Jun 06, 2022 7:13 am

Did you replace the wheel cylinder? You can get them at Napa. Brakes and hardware are clean and in good working order? Did you adjust them per the TM?

Guy

Rickf
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Re: Brake problem

Post by Rickf » Mon Jun 06, 2022 9:13 am

You really need to tear the system down to be sure nobody mixed DOT 5 and DOT 3 fluids in the system. I found that in mine and I had an interesting goo in the wheel cylinders. The fluids are not compatible. That is why I suggest replacing all of the brake components. Once and done, you will not have to worry about it again. And you can decide at that time which fluid you want to use, just be sure to empty out the master cylinder and pump fresh whatever new fluid you are using through the lines before hooking up to the wheel cylinders. This way you know you have all good and compatible fluid all the way through.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

ldj1002
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Posts: 235
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Re: Brake problem

Post by ldj1002 » Sat Jun 11, 2022 1:59 pm

UPDATE: I have decided nothing is wrong with left front brake except it's not working like it should. I have a new wheel cylinder and brake hose. I have removed the 2 short steel lines and they are clear. From the "T" up front I assembled it all back and flushed with alcohol and blew out with compressed air. I have also loosened brake adjustment up a lot, about 30 clicks from dragging. Now it pulls left only a little probably not enough to notice if I wasn't looking for pull or didn't dinamite brakes. However after a short drive that left brake is hot. Tomorrow I am gona Thake brake springs off and swap right and left and see if problem changes sides.

Rickf
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Re: Brake problem

Post by Rickf » Sat Jun 11, 2022 5:03 pm

If you backed it off 30 clicks then you should have almost no brake pedal, it should be right on the floor. Are you sure the wheel cylinder is fully retracting? Same question for the adjuster? Brakes are not something to play with, This is why I always say to replace everything on a new to you vehicle and be done with it. It is your safety and that of everyone else on the road with you. If you replace all the parts with new then the problem will be solved and you will be good for the life of the vehicle.
I have harped this over and over now so I will say no more on the subject. Your vehicle, your choice.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

ldj1002
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Re: Brake problem

Post by ldj1002 » Sat Jun 11, 2022 6:44 pm

I have good peddle so tomorrow when I have drum off I'll check adjuster. I know it works at least some because I can tighten to where I can't turn wheel. However when I loosen is it just enough to turn the wheel or are the retracting all the way, I will check. I appreciate your thoughts but I want to know what problem is with left front. I have 2 new hoses, 2 a year old, new master cylinder. I new wheel cylinder, all shoe linings good and all steel lines been flushed, and 3 brakes work prefect.

ldj1002
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Re: Brake problem

Post by ldj1002 » Sun Jun 12, 2022 8:09 am

I switched brake springs, no change. I know Rick won't like this but in a few days I'm gone change front wheel cylinders from left to right. Maybe that new wheel cylinder has a flaw. I think problem is from the front T to the wheel and the new wheel cylinder is maybe just not letting the cups go together as they should for what ever reason, bore a little small, spring too strong??

Rickf
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Re: Brake problem

Post by Rickf » Sun Jun 12, 2022 8:34 am

It is not about what I like or don't like. It is your vehicle. I was not aware that you had replaced the wheel cylinder. Is it a NOS cylinder or a civilian replacement? Are the cylinders the same size side to side? This will have nothing to do with the heat issue but it would have a lot to do with the pull issue and there was a big problem with people putting A1 rear cylinders on one side of an A2 front and it caused a lot of accidents. So you should have 1" on the front and 3/4" on the rear. If the metal line had moisture inside of it it could have rust blocking it preventing fluid return. Do you have residual pressure in the wheel cylinder? This is checked by opening the bleeder after sitting and if you get a spurt you had residual pressure. Hence a line issue. I have seen this heat issue caused by rust forming between the brake shoe and the backing plate the shoe is mounted on. also contaminated shoes where they swell when hot.
You have to keep in mind that I am a professional mechanic, master certified for 45 years, so even though I fully understand wanting to save money and go with what looks like good parts sometimes you just need to bite the bullet and replace safety critical parts. Swapping side to side is a fully acceptable practice to find the problem, but no matter whether it follows or not you should still replace the parts. If you have followed my threads for any length of time you will see I am 100% in favor of full diagnosis before replacement on MOST things. Brakes are a different story, it the problem is not readily evident like a broken spring or bad line then I suggest replacement of the parts. On any old vehicle that has been setting for many years I will ALWAYS tell people to replace ALL rubber parts and all brake parts. Rubber parts meaning belt, hoses and brake lines.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone

ldj1002
G-Command Sergeant Major
G-Command Sergeant Major
Posts: 235
Joined: Fri Nov 14, 2008 5:38 am
Location: Central Texas

Re: Brake problem

Post by ldj1002 » Sun Jun 12, 2022 9:16 am

Wheel cylinder bought a Rapco, if it is bad not his fault. I open bleed valve and fluid comes out, no under pressure. !" cylinder on both sides. Shoes and backing plate clean. I'll update when I swap wheel cylinder.

ldj1002
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Re: Brake problem

Post by ldj1002 » Mon Jun 13, 2022 12:17 pm

OK, Made progress. I swapped sides with wheel cylinders and left still gets hot so It isn't the wheel cylinder problem. I decided to swap brake drums from one side to the other and now the right side got hot, so It must be the brake drum. I don't see anything wrong, no sign of it rubbing on the backing plate or the shoes. If it is out of round why would that cause it to get hot? What to do now?


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