Another weak brake question

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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Rebel Walker
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Re: Another weak brake question

Post by Rebel Walker » Fri Apr 21, 2023 12:31 pm

From the pictures it is evident the adjustment is not correct especially shown in the last picture. That shoe is definitely not concentric.
Plus it looks as though those linings are a really hard material.
Were the drums perfectly clean of all wax/grease when fitted?
The older foot brake linings were never woven material, only the external handbrake lining on WW2 jeeps.

Did you measure the OD of the brake shoes v/s the ID of the skimmed drum?

Rough up these linings plus also thoroughly clean & rough up the drums, with a cross hatch pattern.

It was understood the drums were internally mounted like WW2, but the pictures show otherwise.

Mike's run in procedure, after correctly adjusting would be recommended & chamfer of the square lining corners with a file or angle grinder now the drums are off.


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Re: Another weak brake question

Post by RobertEarl » Fri Apr 21, 2023 2:11 pm

I can not get them adjusted as the drum is not concentric. When I adjust the shoe out to touch the drum, it only touches for about a 30 degree turn of the drum. If I adjust the shoe out with the other side of the drum turned 180 degrees, it is to much and I cannot rotate the drum all of the way around. I have ordered a new set of drums from Keiser Willys. I hope they will be better

Reb

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Re: Another weak brake question

Post by Wolfman » Sat Apr 22, 2023 6:38 am

2 A.M. moment.
You have CJ-3 drums on a 45 GPW ??
How does this work at all ??
GPW and early CJ-2 had 9 inch brakes. Then later the CJ-2 brakes were replaced with 11 inch. Don't know what CJ-3 have but would not think jeep went back to 9 inch.
What diameter is the I.D. of your drums ??
Even if you got around this, the GPW drums were on the inside of the wheel hubs. The lug bolts hold the drums to the inside of the hubs.
To turn these drums and get them concentric with the hub, the drums have to be turned on the hub.
And you all missed another one. :D
I said the toe and heel of the shoes were adjusted to .008".
The toe of the shoe is adjusted to .008". The heel is adjusted to .005".
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

Adam
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Re: Another weak brake question

Post by Adam » Sat Apr 22, 2023 7:07 am

11" brakes, not on the front anyway,, 9 inch up into the mid 50's at least. parts list does not show 11 inch, on fronts

just put a m100 trailer brake drum and hub, the one with 3 screws, again, on a mb axle,, fits just fine, and that is from the 50's.

This jeep has a bunch of issues with the drums, wonder if they were cut right,

Adam

Bruce W
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Re: Another weak brake question

Post by Bruce W » Sat Apr 22, 2023 8:23 am

CJ2’s, CJ2-A’s, CJ3A’s all used 9- inch inboard drums, same drums as MB/GPW. CJ2’s and VECJ2-A used the same hubs on all 4 corners as the MB/GPW. Later CJ2-A’s and all CJ3A’s used a different rear hub but still the same drum. The CJ3B’s and CJ5’s got outboard drums and better backing plates and shoes but still used the same hubs. The outboard drums will work with the older backing plates and shoes. No CJ’s got 11-inch brakes before 1972. The OP evidently has CJ3B/CJ5 drums, which should work fine.
BW
G Trp 2nd Sqdrn 3d Armored Cavalry Ft. Lewis 1970-71. 43GPW(Sarge?) 47CJ2A(Teddy) 47CJ2A(Rusty) 47CJ2A(Zak) 48CJ2A(Lefty) 48CJ2A(Uncle Linden) 53CJ3B(Bulldog) 88XJ(Pluto) NE CO

Wolfman
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Re: Another weak brake question

Post by Wolfman » Sun Apr 23, 2023 6:53 am

I was off as to when the brakes went from 9 to 11 inch. Good catch, Bruce.
First major change came after the war when the rear CJ-2a axle ass. was changed and the rear hubs went from the earlier hubs mounted on spindles on the end of the axle housing and axles shafts with flanges on the outer end of the axle shaft, to axle housings with the outer bearings in the ends of the axle housing and shafts with tapered ends and the hubs were mounted on the taper.
As for the brakes. Using Ron's parts look up on this site. There is a difference in the part numbers for the brake kits.
MB, GPW and early CJ-2a use one kit number and Later CJ-2a, CJ-3a use a different kit number. ??
All the brake shoe part numbers up to CJ-3a are the same. Big hole on the heel end for the anchor bolt.
CJ-3B shoe has a different number and the metal shoe is a different design. No big hole on the heel end being the most obvious change.
Apparently, Ron does not sell drums.
Now I am thinking online.
If you put a drum that is made to be mounted on the inside of a hub and held firmly in place by the lug bolts, slide that drum over the lug bolts on the outside of the drum. What centers the drum on the hub ???
Maybe where Robert is now ???
Guess where I am headed is, if you have a GPW, assemble it like a GPW. :D
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

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Re: Another weak brake question

Post by Bruce W » Sun Apr 23, 2023 8:27 am

Mike said: “MB, GPW and early CJ-2a use one kit number and Later CJ-2a, CJ-3a use a different kit number. ??”

Does that kit include a master cylinder? Late, late CJ2-A’s, and all CJ3A/B and CJ5 use a different master cylinder. We’re talking very late CJ2-A, much later than the rear hub change.

I would think that if the OP was trying to use inboard-style drums mounted outboard, it would be obvious that it was not going to work. The drums probably wouldn’t cover the shoes.
BW
G Trp 2nd Sqdrn 3d Armored Cavalry Ft. Lewis 1970-71. 43GPW(Sarge?) 47CJ2A(Teddy) 47CJ2A(Rusty) 47CJ2A(Zak) 48CJ2A(Lefty) 48CJ2A(Uncle Linden) 53CJ3B(Bulldog) 88XJ(Pluto) NE CO

Wolfman
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Re: Another weak brake question

Post by Wolfman » Mon Apr 24, 2023 6:12 am

I was using the different kits Ron offered as an example, Bruce.
I was wondering what the difference was myself.
The difference in the master cylinder you brought up is probably the answer.
I think the master cylinders are basically the same. The difference is the way they mount to the frame.
And I don't see how you can slide a drum on the outside of a GPW hub and have it fit properly either.
This will move the drum position out on the shoe and the drum has to fit tightly over something to be held perfectly on center. Just sliding the drum on the lug bolts won't do it.
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

Adam
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Re: Another weak brake question

Post by Adam » Mon Apr 24, 2023 6:38 am

The mb and cj drums are different depth, one is made to fit behind the hub, as on the mb,,, these are locked solid by the lug bolts, the other deeper ones, have 3 holes in them to fit on the later hub with 3 tapped holes, they also center on the hub, the 3 screws just hold it on there.

I asked for a picture of the drum mounted on the vehicle to see if it covered the brake shoes,

i would also like to see a brake shoe just sitting inside the drum on the ground,

you need the 3 screws to hold the drum on while adusting the brakes, or put a lug nut or 2 on it.

You cannot use the same drum that was removed from the mb hub and put it on the outside.

So what is the owner really using?

Adam

I see hubs for sale from india, not drilled. you will need to drill them or hold the drum on there with lug bolts, need to mark so if it is cut it goes back on in the same spot on the hub.

You can easialy bend the original hub when pressing out the studs if you do not support it correctly, or drill it to muchto get the stud out.

Adam

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Re: Another weak brake question

Post by Wolfman » Mon Apr 24, 2023 7:00 am

Interesting intel I was not aware of.
We think the owner has a CJ-3 drum slid over the lugs on the outside of a GPW hub ??
Be interesting to see how this plays out.
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

RobertEarl
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Re: Another weak brake question

Post by RobertEarl » Mon Apr 24, 2023 2:51 pm

Here are some pictures of the drum.

Reb
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IMG_0555.JPG

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Rebel Walker
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Re: Another weak brake question

Post by Rebel Walker » Mon Apr 24, 2023 9:35 pm

Wolfman wrote:
Mon Apr 24, 2023 7:00 am
Interesting intel I was not aware of.
We think the owner has a CJ-3 drum slid over the lugs on the outside of a GPW hub ??
Be interesting to see how this plays out.
At one time that was Ron sold as replacements.
They fit & work fine.
Note to mounting to the hub bells out where originals bell inward so either drum accurately aligns/positions with the lining.

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Re: Another weak brake question

Post by Wolfman » Tue Apr 25, 2023 5:46 am

In the top two pictures in your last post, Robert, you have the drum on the outside of the flange.
If you hold the drum tight against the flange, do you have any side movement of the drum on the hub if you try to slide the drum from side to side on the hub ??
There cannot be. Not even a little tiny bit.
With the drums on and the shoes adjusted, the clearance between the drum & shoe should be only .005" to .008".
That is the thickness of a sheet of writing paper.
If the side movement of the drum on the hub is more than that, the drum is going to wobble from side to side as it turns and you will experience what you say is happening. The drum will have a tight spot as it is turned when clamped tight and not perfectly centered.
Also, you are resurfacing the drums off the hub and then installing them.
No guarantee when the drums are installed the center of rotation of the drum and hub are on the same center. Again the drum will have a side to side wobble and have a tight spot.
Early jeep brake shoes are anchored in a fixed position at the bottom. No forgiveness for the drum being slightly off center so the drum must be turned on center with the hub.
Self-adjusting shoes like most newer vehicles have are free floating and self centering. If the drum is "slightly" off center with this type of shoe brake, the shoe assembly will center up.
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 50 yrs)
EAA ( 49 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB

RobertEarl
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Re: Another weak brake question

Post by RobertEarl » Sat Jun 03, 2023 11:17 am

Ok guys lets do a complete reset and start over.

Replaced the master cylinder
All shoes are adjusted out so there is a lite drag when you spin the wheels by hand.
I took the master cylinder cap off of the old one and tapped it to fit the hose on my Motiv pressure bleeder.
I pumped 3 quarts of brake fluid through the system.
I have a little more than 1/2 inch of free play on the pedal.

The pedal is soft and if I press hard I can push it to the floor.

Is there still air in the system after 3 quarts of fluid? I never saw any bubbles?
Could it possible be the wheel cylinders?

When bleeding, the flow is kinda slow. I had my son press the brake pedal down and I got a good squirt at the wheel cylinder.

The system is too simple to be this hard to get it to work.

Reb

Bruce W
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Re: Another weak brake question

Post by Bruce W » Sat Jun 03, 2023 11:56 am

What is the condition of your brake hoses? A hose that stretches or bulges under pressure will cause a "spongy" pedal. What are your steel lines like? Do they have loops and roller-coaster looking humps in them, to use up extra tubing? High points in the steel lines can hold air and be very difficult to evacuate. Air that tends to want to stay in the wheel cylinders can sometimes be persuaded to come out by tapping on the backing plate with a hammer while bleeding.

"The system is too simple to be this hard to get it to work."
You're right. BW
G Trp 2nd Sqdrn 3d Armored Cavalry Ft. Lewis 1970-71. 43GPW(Sarge?) 47CJ2A(Teddy) 47CJ2A(Rusty) 47CJ2A(Zak) 48CJ2A(Lefty) 48CJ2A(Uncle Linden) 53CJ3B(Bulldog) 88XJ(Pluto) NE CO


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