Very odd rear brake problem

1945 - 196*, Willys CJ series, questions, discussions, regarding anything related to the post war jeep.®
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Bob Bell
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Re: Very odd rear brake problem

Post by Bob Bell » Mon Nov 13, 2017 2:28 pm

Look again at your backing plate, they have short 1" raised pads either side of the wheel cylinders that the shoes rub against.

I know the pads that Ben Dover is talking about from other vehicles. However they are not present on either of the rear backing plates on this jeep. The only pads are the ones midway on the shoes that the two guidance 'forks' are attached to.
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Ben Dover
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Re: Very odd rear brake problem

Post by Ben Dover » Tue Nov 14, 2017 4:55 am

And I may be off an inch or two. :wink: Some of the Jeep backing plates do have those pads.
Last edited by Ben Dover on Wed Nov 15, 2017 1:31 pm, edited 1 time in total.
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Re: Very odd rear brake problem

Post by fiveftsix » Tue Nov 14, 2017 6:00 pm

I`d still check out that bearing while the hub and drum was off
Which you obviously haven`t done yet
4. The bearings are well greased.
5. I have NOT checked the backing plate for tightness, and will do so.
You can`t see that bearing and there is only one until you undo the backing plate bolts and remove the grease slinger etc
if the inner seal isn`t doing it`s job you could well be pumping grease down the axle tube
It can`t be a sticky cylinder now you implied you had changed it in a previous post
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Re: Very odd rear brake problem

Post by Ben Dover » Wed Nov 15, 2017 5:21 am

I use a 5/8" Slide Hammer that has a Deep Nut that matches the thread on the slide hammer and welded another Deep Nut that matches the thread in the axle. Three whacks and the axle is out. The rear wheel bearings on CJ's, and M-38/M-38A1 are the most ignored bearings on Jeeps. Chances are your inner seals are worn and the wheel bearing that is pressed on the axle shaft has a good chance of being corroded and pitted.
Last edited by Ben Dover on Wed Nov 15, 2017 1:38 pm, edited 1 time in total.
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Bob Bell
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Re: Very odd rear brake problem

Post by Bob Bell » Wed Nov 15, 2017 9:50 am

When I said the bearings are well greased, that is what I meant. No, I haven't pulled the axle shaft and inspected the bearing itself, BUT when I changed the seal I was able to see that it was well greased (plus I gave it a couple of squirts with the grease gun while I was at it).

So is the suggestion here that the bearing itself is causing the initial squeal?

I actually fabricated a tool for pulling the axle shaft earlier this year, as I am working on a 1951 3A, a frame up rebuild. I have completely rebuilt the trans, transfer, overdrive, front and real axles, so I am aware of the wear that can occur in these neglected areas.

And I agree that it is likely / possible that the inner seal is bad. However I keep a very close eye on the rear diff, and have not had to add oil. Also, each time I remove the brake drum, I do not see contamination.

I have driven the vehicle probably about 50 miles since the last time I took the drum off, sanded the linings etc. The squeal is still there, although it does go away pretty quickly. Initially, while the squeal is there, that wheel DOES lock up first. So sticky cylinder AGAIN???

Once brakes have been applied a couple of times, the vehicle stops well, quickly, and in a straight line. Sometimes quietly, sometimes not.
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Re: Very odd rear brake problem

Post by Ben Dover » Wed Nov 15, 2017 1:29 pm

The Semi Floating Wheel Bearings run in grease(I use GAA), and are serviced via the grease fittings on the rear axle tubes next to the backing plates.
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Re: Very odd rear brake problem

Post by fiveftsix » Wed Nov 15, 2017 5:35 pm

Bob, you seem to have checked the wheel cylinder several times as have you the shoes and back plate etc.
that doesn`t leave much else it could be that`s causing this squeal
And if you already have the hub and drum off your already 3/4 the way there anyway
So why not just pull the shaft ,wash off the bearing and inspect it thoroughly as well as spinning it by hand for roughness
I`d renew the inner seal too at the same time.
Even if the inner seal is not doing it`s job it`s quite possible the grease you`ve pumped in is preventing a great loss of Diff oil
But just enough is giving a slight lub to the bearing.
It could be squealing by the shaft rubbing either the seal or the metal slinger when weight is transferring when braking
Or the bearing itself causing it.
You may not see any contamination Bob as that would be caught by the outer grease slinger and will only be revealed once it`s off
But whatever it should be checked out only if to eliminate it from the equation !!!
Geoff Bull

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Re: Very odd rear brake problem

Post by Bob Bell » Mon Dec 11, 2017 5:32 pm

Sorry about the delay in replying - I was in the UK for a while.
Geoff, thanks for all the suggestions. You may well be right regarding a rough bearing, although I kind of doubt it. The squeal is to my mind too intermittent to be caused by that. Sometimes it won't squeal at all, and then another time it will squeal for a few brake applications, and then not squeal at all for a long time.
I had the drum off again a couple of days ago, and once again got the shoes squeaky clean. (Sorry - couldn't resist that). I had finally replaced my long busted compressor, and was therefore able to blow the shoes, backing plate and drum very thoroughly. (Hadn't been able to do that before). Result? Complete silence. For a couple of days anyway. Now it is back again, now and then.
The tool I made for removing the axle involves removing the backing plate and placing three legs of the tool against the end of the axle housing. That means having to bleed the brakes again etc after the job is done. I'll get myself a slide hammer and figure out a way to remove the axle without removing the backing plate so I don't have to go the brake bleeding route. I can't really afford to have the jeep off the road for more than a day or so. From what I recall regarding the inner oil seal, it is at the diff end of the tube, and the diff and carrier has to be removed to replace it. I just rebuilt an entire rear axle for another jeep so I am familiar with the process. There is a bushing at the backing plate end, but that is not oil proof. (One would have to tilt the jeep very dramatically for oil to actually flow past it however).
Bottom line here is I don't really want to buy a new bearing unless I need one, and I don't want to take the axle out without having a spare bearing on hand in case i DO need one.
Thanks again for the interest and suggestions. I'll keep you posted.
Best,
Bob
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Re: Very odd rear brake problem

Post by Ben Dover » Mon Dec 11, 2017 5:42 pm

It's likely still going to leak . The Semi Floating (CJ-2A in addition to the MB Style rear axle, used the Spicer 41 Semi Floating. There were no seals the differential end, there was an inner seal at the outer ends of the axle tube and the Axle shafts with their pressed on bearings had to be removed to service the seal.
Last edited by Ben Dover on Mon Dec 11, 2017 9:10 pm, edited 1 time in total.
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Re: Very odd rear brake problem

Post by artificer » Mon Dec 11, 2017 5:47 pm

Not sure what is still leaking?
Wheel bearings don't squeal when brakes are applied [in my experience] & a rough bearing can be felt/heard by driving down a deserted road & rocking steering side to side....this places abnormal load on wheel bearings & will be evident.
Are all brake linings made of the same material?
Is there a visible hard/hot spot in the offending side's brake drum?
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Re: Very odd rear brake problem

Post by Ben Dover » Mon Dec 11, 2017 5:52 pm

Semi Floating CJ Axle, correct?
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Bob Bell
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Re: Very odd rear brake problem

Post by Bob Bell » Mon Dec 11, 2017 5:53 pm

Nothing is leaking. All is clean and dry. One brake guy did suggest my drum might need machining. Another scoffed at that and said the pads on the backing plate needed lubricating. There are no pads on my backing plates ....
Anyway, it doesn't squeak all the time. Only when I pull up next to a crowded bus stop.
Yes, a semi floater.
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Re: Very odd rear brake problem

Post by Bob Bell » Mon Dec 11, 2017 5:55 pm

PS all brake linings are the same material and the same age - all were replaced at the same time. There are no visible high spots on the drum - nothing that I can feel with my hand.
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Re: Very odd rear brake problem

Post by artificer » Mon Dec 11, 2017 6:08 pm

Heat sink after hard braking & holding the brakes on can introduce a hard spot in the cast iron, not a high spot. The appearance of the metal will alter in that particular spot & give a slip & hold feature to braking, evidenced by squealing.
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
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Re: Very odd rear brake problem

Post by Chuck W. » Mon Dec 11, 2017 6:28 pm

Swap rear drums from one side to the other, and see if the sound moves with it. Very quick and easy to do.

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