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Hot Brake Drum

6K views 22 replies 5 participants last post by  country_hick 
#1 · (Edited)
I started noticing after a short drive, the driver's side rear brake drum is very hot.

Last week I put a new E brake cable in on that side, and everything looked okay, reinstalled everything, and adjusted the brakes. The wheel spins free, and the brakes are not over-adjusted.

In the back of my mind I wondered if it was possible to get the axle nut too tight and press against the outer axle bearing, and cause it to heat up.

After double checking the brakes, I was positive they weren't dragging, so I figured I would back the axle nut off a little bit. After consulting with a friend, he said the axle nut shouldn't be the problem, and after he inspected the bearings, he said they were borderline, and needed replaced.

I forgot to mention, when I pulled the brake drum, there was shiny metal shavings inside, as well as in the gear oil that leaked out.

I replaced the bearings today, and installed a new seal, and I'm thinking my mistake is not replacing the races, although they seemed to be in excellent condition. So I greased up the bearings, installed them, and went for a ride... Within 10 minutes the brake drum was too hot to touch. :doh:

The brakes are not dragging, the bearings or good, (races maybe??) and the axle doesn't appear to be bent.

:confused013:
 
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#2 ·
You have to ask what can cause drag on the drum.

You have

the emergency brake cable

the hydraulic wheel cylinder

the brake linings

the bearings.

That is all I can think of. That means one of those things is sticking. I would replace the wheel cylinder and maybe even upgrade to the heavier duty 37337 wheel cylinders and see if that solves your problem.

If your emergency brake is not sticking and the bearings are ok (always replace the races at the same time) the only thing left is the wheel cylinder or brake lining adjustment.
 
#4 ·
I always changed springs with at least every other brake job. I did not think of those. Yes, they can get weak or beak.
 
#5 ·
I forgot to include some information in my original post. See above in red.

Earlier I decided to adjust the brakes way in, to be sure they weren't dragging.
Last week I adjusted both sides, and both sides had equal amount of "free spin" while the truck was jacked up, yet only one side is getting hot.

So I took it for a drive, I went nearly 10 miles, and the drum was just barely warmer than the other side, where before it was too hot to touch.
In that 10 miles, I tried to not use the breaks, and I only tapped them a few times, under 10 MPH.

So after doing that, maybe it is an issue with the breaks, but it still doesn't make sense to me. That brake doesn't appear to be working harder than the other side, it's not locking up, and it was adjusted the same as the other one?
 
#6 ·
Since you are talking about rear brakes lets look at the hydraulic fluid supply system.

You have a single brake line coming to the rear axle. It then goes into a rubber line then it gets split into 2 metal lines. It then goes into the wheel cylinders and the journey is finished.

We can safely rule out the single metal and rubber line. Those would either flow well or restrict all fluid not just the fluid going to to one side.

You could look at the junction block. Perhaps there is a piece of rust of crud blocking flow to one side. If not checks out look at the metal line from there to the wheel cylinder. One side could be crimped internally from being tightened to much cutting its internal size down tremendously. It may also be crimped outside.

If you can rule out the junction block and lines the only thing left is a tight brake lining or a sticking wheel cylinder.

In my old (now gone) s-10 I forgot to adjust the rear brakes up while doing a brake job. For a year I had amost no rear brakes. I never felt them to be missing. The truck did brake better one they were adjusted where they should be. Perhaps this idea might explain why you do not feel any difference?
 
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#7 ·
Thanks for the help.

I will see what I can find out.

I took a trip to town to pick up a spring kit, and the brake drum was just barely warm when I got home, and that's with the brakes adjusted in. (the E brake barely grabs, that's how far they're adjusted in)

So I'm gonna try the new springs, and go from there.

This is kinda frustrating.
 
#8 · (Edited)
So I finally did something I should've done when I first noticed the over heating.

I jacked up the rear of the truck, and and let the clutch out in 2nd gear. Push the clutch in, without touching the brakes, the hub in question stops within a couple seconds, and the other (good) hub keeps spinning for a few more seconds.

That's not normal for an open diff is it? :confused013:

If not, then either my springs are shot, and the brake is still dragging, even though it's adjusted all the way in, or my axle is bent, or the bearing in the banjo housing is shot? :confused013:


EDIT:

Okay, there's not a bearing in the banjo housing?
(page 5)
http://www2.dana.com/pdf/AXIP-0076.pdf
 
#9 ·
FML.

Okay, I looked for myself, and there is a bearing in there? (banjo housing) Frikin' diagram didn't show one? :banghead:

So I didn't install new springs, because the old ones still retract. The brake shoes aren't even touching the drum... The drum comes off without even touching the pads.

So why the hell did retracting the brakes cause it to run cooler? Now the brakes aren't even touching and the drum still gets warmer than the other side.

I did notice the drum looks a little off from when it was last turned, so I did a little measuring, and one side (the edge of where the pads make contact) is .05 thicker than the opposite side of the drum.
And as far as I can tell the axle isn't bent.

Damn if I know what's going on...

Tomorrow I'm going to have the drum and axle looked at by a local parts store, and tell them about my troubles.
 
#12 · (Edited)
The axle bearings could be worn or sloppy. Take the drum off and look at them. You should have a full floating axle where the axle comes out. If the bearing is loose the axle would rise up into the air from pressure of the body weight. That would create a slight angle of the solid shaft in relation to the brake drum.

There was one person who had a bent axle that caused some problems. I mean the solid metal round piece with 8 bolts holding it in place that goes from the ring and pinion assembly to the outside hub and brake drum. Perhaps you want to remove yours and check it with a straight edge.

This is the only other thing I can think of besides a bent axle housing. I am not sure how you check an axle housing for straightness.
 
#13 ·
Thanks for responding, I really appreciate it.

The axle bearings are brand new, and the races seem to be in good shape. I coat them with grease every time I pull them and reinstall them.

I have to pull the axle to get the drum off, so yes, I've had it out 4 times, and I can't see that it is bent. I need to use a straight edge on it, but I have rolled it on a flat surface, and I can't see a bend anywhere.

Just by eyeballing, the axle housing isn't bent, and there's enough room in there, I don't think a slight bend would affect anything?


I got the drum turned earlier, and I put it on and took it for a drive, with the brakes still adjusted in.

I went about 13 miles, and when I got back home, the brake drum was almost the same temperature as the other side, maybe slightly warmer. Then I felt of the actual axle hub, and it was hot as a firecracker.

I immediately tore it apart to try to locate the source of the heat.

All the parts throughout the center of the brake drum were hot - bearings, races, etc, and the axle seemed to be the hottest, from the axle hub, and for about 10 inches up the axle shaft it was hot, and then it cooled back off about half way up the axle.

The back side of the axle hub was discolored from heat:





While all those parts were hot, the brake pads, and inner drum were cool. The outside of the drum was a little bit warm, but I guess that was because of the heat from the hub.


Another thing I noticed was the first two times I pulled the axle, some fluid ran out, and made a puddle about 8-10 inches across... The last two times I've pulled the axle, no fluid comes out, but there is a little bit in the housing:





And yes, the differential is full of fluid - I've checked a couple times, and even added some. It's up the the plug.

Considering the brakes were cool while the axle hub was almost too hot to touch, I think I've ruled them out.

Either fluid is not getting to the axle and bearings, or something is bent, and I'm not seeing it.
 
#19 ·
Hey Will,

The wheel bearings in the rear hubs are lubricated with differential gear oil, when you pull the axle and hub assembly-brake drum off you will always get fluid running out and when you sit the hub assembly down on the ground, gear oil will run out of it. When you reassemble the hub (inner bearing & seal) and put it back on the spindle, put some gear oil in the hub before sliding it on the spindle. After you have everything back together, take it for a test drive, then check the differential fluid level, it has to travel through the axle tubes to get to the bearings. I don't know what oil you are using, but I run 90w gear oil in mine with additive because is a Limited slip differential. (I know you have a open rear)

I really think you can rule out a bent axle or axle housing or spindle. Unless you have to use a line-up bar to align the axle flange with the bolt holes in the hub to start the bolts, nothing is bent.

Also your axle didn't get that hot to discolor the flange, They should be that way from the factory, they turn that color because of the heat treating process to harden the axle.
 
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#18 ·
So I swapped axles, and I didn't tighten the axle nut really tight like I did before.

The passenger side hub was normal, so I can rule out that axle, but the driver's side was warm, but not as bad as the last time I drove it. I think I need to replace the races, even though they look good, because I didn't torque down on the axle nut, so it wasn't pressing hard on the bearing, and it didn't heat up as bad.

I also rounded off the head on one of the bolts that holds the axle in place. :doh: Trying to work in the dark! :buttkick:
 
#21 ·
Those bearings are not supposed to be torqued down hard. They should just be tight enough not super tight. Could you be overtorquing the one side?
 
#22 ·
120 ft lbs is what it's supposed to be torqued to, according to the spec sheet for the Spicer 70.

Well, I got it fixed. I replaced the races, like I should've done in the first place, but since I didn't get a race with the inner bearing when I bought it, I figured I could skip them, since they looked okay. Not.

Anyhow, I'm in business.

Thanks to all that replied, I really appreciate it. :thumbsup:
 
#23 ·
I may be thinking of a different bearing. I know in my 1975 dana 60 it has 2 bearings that do not need heavy torque that hold the axle shaft in.

I am glad it was something as stupid and simple as races. I truly do not understand WHY they selling bearings without the required races. They should ALWAYS come as a pair.
 
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