Brake or axle issue?

Ratrod312 · Mar 2, 2023

1992 C1500 4.3 rclb

So for a while now ive had a "pulsating" in the brake pedal while braking a slow speeds; also the truck would shake (sometimes pretty violently) when quickly braking at higher speeds. I summed this up to warped rotors/drums. Today i replaced the front rotors, pads, and rear drums. Now the problem is about 10x worse, to where it's really not even driveable. The issue is definitely coming from the rear, and i can almost watch the driver side rear wheel wobble, and now a loud noise is also heard once during each rotation.

Could there possibly be something loose in the rear brake hardware causing this? Or do i have a bent axle that is just showing it's face more now because of the new parts? Any help is appreciated!

termite · Mar 2, 2023

Ratrod312 said:
1992 C1500 4.3 rclb

So for a while now ive had a "pulsating" in the brake pedal while braking a slow speeds; also the truck would shake (sometimes pretty violently) when quickly braking at higher speeds. I summed this up to warped rotors/drums. Today i replaced the front rotors, pads, and rear drums. Now the problem is about 10x worse, to where it's really not even driveable. The issue is definitely coming from the rear, and i can almost watch the driver side rear wheel wobble, and now a loud noise is also heard once during each rotation.

Could there possibly be something loose in the rear brake hardware causing this? Or do i have a bent axle that is just showing it's face more now because of the new parts? Any help is appreciated!

Double check the brake assembly for correct placement of all components. Service manual is on a sticky thread here somewhere if you need a reference for assembly. Others may chime in with more experience and expertise.

Ratrod312 · Mar 2, 2023

termite said:
Double check the brake assembly for correct placement of all components. Service manual is on a sticky thread here somewhere if you need a reference for assembly. Others may chime in with more experience and expertise.

Could something being off in there cause this?

Rock Hard Concrete · Mar 2, 2023

I had the rear brakes completely redone on my truck last summer and the brand new drums were so out of round that the truck almost shook off of the road. The shop had to order new drums and install, the drums they put on originally were so out of round they couldn't even be machined round. Unfortunately most new parts for these trucks are chinese garbage. You probably installed bad drums and need replaced again.

thinger2 · Mar 2, 2023

Almost certainly a rear brake problem.
I noticed you only mention replacing the rear drums and not the shoes or the hardware
Did you put new drums on the old brake sets?
If that is the case, new drums with the added thickness and a non-glazed surface can make "Grabby Brakes" much worse.
But they dont solve the initial problem.
They just give more surface area and a closer contact because of the added thickness for that brake problem to act upon.
In other words, that new drum amplifies the problem you already had
The first thing to do is get a good year specific brake diagram for your truck.
The usual knowledge is to only take one side apart at a time so you can use the other side as a reference if you get lost while putting it back together.
Dont do that. That whole internet theory assumes that some random stranger 20 years ago put it together correctly.
You can only use that as a reference if YOU put it together correctly.
The shoes are two different sizes, a leading shoe and a trailing shoe.
They are not only commonly installed backwards but Ive seen a couple of occasions where one side had both short shoes and the other had both long shoes.
The hardware and the way it is installed is also pretty important.
Dont assume that it is correct.
The brake adjusters too.
Look at the backing plate.
It is really common for the steel frame of the brake shoe to dig deep grooves into the pads on the backing plate that the shoe rides on when it moves.
Those deep groves make the shoe hang and twist and may keep the edges of the shoe in contact with the drum becuase the shoe is stuck.
Really common.
You can weld and grind those flat without pulling the axle if you are carefull about the heat.
But, If you actually see the wheel wobbling you have a much more serious problem.
Bent rim, bad tire, Bad wheel bearing, Or an axle that is ready to slide out when you go around a corner.
You can check for out of round and endplay and bearing slop on the axle flange when you take it apart.
I suspect you need to do a complete rear brake job and check the bearing play while you are at it.
Pay attention to the brake adjusters.
They are often in backwards.
Dont assume that your new drums are actually round either.
They are about 25 percent garbage right out of the box.
Is your brake fliud clean and clear or is it cloudy and dirty?
Dirty fliud is an air leak or a fluid leak that is pulling water and dirt back into the system.
These trucks are old enough that component failure is just the indication of system failure.
Every new brake part you install will be money thrown away if you dont repair the actual problem.
In other words, bight the bullet and fix the entire system and drive it for another 20 years.
Then, move on to the next system and fix it and drive it for 20 more years.
Thats just how you have to do it.
Look at it this way, unless you are vegetarian,
If someone gave you a thousand pounds of steak and the only thing you had to do in order to get that steak was wake up in the morning and butcher it and cook it on the grill.
We us car guys would do that just to make people around us happy and for the Yep! of it all.
Just to be left with some moment of quiet in the garage.
Thats just the old fart car guy world.
Whats really starting to happen is that younger women are starting to get much more into racing and building.
It aint the 50s anymore, Women are not gonna hang out in a ******* poodle skirt and feed you sandwiches.
My nieces get to do the crazy **** that I got to do.
Now we have a real world connection.
They are both just as ******* nutty as I am.
We are getting it all squared and trying to figure it out but I might for ***** sake and despite my better judgement maybe race a boat next year.
****.

Ratrod312 · Mar 2, 2023

thinger2 said:
Almost certainly a rear brake problem.
I noticed you only mention replacing the rear drums and not the shoes or the hardware
Did you put new drums on the old brake sets?
If that is the case, new drums with the added thickness and a non-glazed surface can make "Grabby Brakes" much worse.
But they dont solve the initial problem.
They just give more surface area and a closer contact because of the added thickness for that brake problem to act upon.
In other words, that new drum amplifies the problem you already had
The first thing to do is get a good year specific brake diagram for your truck.
The usual knowledge is to only take one side apart at a time so you can use the other side as a reference if you get lost while putting it back together.
Dont do that. That whole internet theory assumes that some random stranger 20 years ago put it together correctly.
You can only use that as a reference if YOU put it together correctly.
The shoes are two different sizes, a leading shoe and a trailing shoe.
They are not only commonly installed backwards but Ive seen a couple of occasions where one side had both short shoes and the other had both long shoes.
The hardware and the way it is installed is also pretty important.
Dont assume that it is correct.
The brake adjusters too.
Look at the backing plate.
It is really common for the steel frame of the brake shoe to dig deep grooves into the pads on the backing plate that the shoe rides on when it moves.
Those deep groves make the shoe hang and twist and may keep the edges of the shoe in contact with the drum becuase the shoe is stuck.
Really common.
You can weld and grind those flat without pulling the axle if you are carefull about the heat.
But, If you actually see the wheel wobbling you have a much more serious problem.
Bent rim, bad tire, Bad wheel bearing, Or an axle that is ready to slide out when you go around a corner.
You can check for out of round and endplay and bearing slop on the axle flange when you take it apart.
I suspect you need to do a complete rear brake job and check the bearing play while you are at it.
Pay attention to the brake adjusters.
They are often in backwards.
Dont assume that your new drums are actually round either.
They are about 25 percent garbage right out of the box.
Is your brake fliud clean and clear or is it cloudy and dirty?
Dirty fliud is an air leak or a fluid leak that is pulling water and dirt back into the system.
These trucks are old enough that component failure is just the indication of system failure.
Every new brake part you install will be money thrown away if you dont repair the actual problem.
In other words, bight the bullet and fix the entire system and drive it for another 20 years.
Then, move on to the next system and fix it and drive it for 20 more years.
Thats just how you have to do it.
Look at it this way, unless you are vegetarian,
If someone gave you a thousand pounds of steak and the only thing you had to do in order to get that steak was wake up in the morning and butcher it and cook it on the grill.
We us car guys would do that just to make people around us happy and for the Yep! of it all.
Just to be left with some moment of quiet in the garage.
Thats just the old fart car guy world.
Whats really starting to happen is that younger women are starting to get much more into racing and building.
It aint the 50s anymore, Women are not gonna hang out in a ******* poodle skirt and feed you sandwiches.
My nieces get to do the crazy **** that I got to do.
Now we have a real world connection.
They are both just as ******* nutty as I am.
We are getting it all squared and trying to figure it out but I might for ***** sake and despite my better judgement maybe race a boat next year.
****.

I did only put new drums on the rear because the shoes looked good with a lot of meat left on them. The brake fluid is dirty, and the truck is my endless project as far as slowly replacing everything....however just yesterday i drove this truck 300 miles. I'm unsure how replacing drums caused it to drive so poorly now (i only drove it down the street and back twice)

Ratrod312 · Mar 3, 2023

So today I put the old drum back on, just too see if it made any difference, and it did. The noise is gone, and the truck seems to roll easier, however i can still feel pulsations in the brake pedal, and I can visibly watch the wheel wobble as i am driving. I even tried a different wheel back there to rule out a bent wheel, and got the same result. Does this pretty much guarantee a bent axle now?

TreeGeared · Mar 3, 2023

If you are seeing the wheel wobble check the wheel bearings as mentioned by thinger2. Remove the drum and see how much side to side and up and down movement you can get out of the axle. Should be next to none.

Could be different ID of the old drum vs new drum is taking up the play and creating the difference.

Schurkey · Mar 4, 2023

You swapped drums and the vibration got better, but didn't go away completely.

Tells me the new drums are worse than the old drums. The new drums need to be returned to where you got them.

If the wheel wobbles, and it's not a bent wheel...it pretty much has to be a bent axle flange or--maybe--a wiped bearing/bearing surface on the axle. The bearing rollers ride directly on the machined surface of the axle shaft--if the bearing is bad, it'll show up as defects in the machined surface of the axle shaft. Anything from pitting, to scoring, to gouges, to an eighth-inch canyon carved into the steel.

Some axle shafts are enormously worse than this, and this had a small but perpetual leak at the seal.

You must be registered for see images attach

Seems most likely to be a bent axle shaft in your case. A dial-indicator on the flange would tell that tale. If it's bad enough, a tape-measure would confirm. So check for bent parts first.

IF (big IF) you don't see the flange wobbling, verify the bearing.

If the axle shaft is bent, you're gonna drop the differential cover, pop the C-clip, and slide the shaft out. When you do that, you'll see the bearing area of the shaft. If it's in poor condition, you'll replace the bearing and seal when you replace the axle shaft.

thinger2 · Mar 5, 2023

Ratrod312 said:
So today I put the old drum back on, just too see if it made any difference, and it did. The noise is gone, and the truck seems to roll easier, however i can still feel pulsations in the brake pedal, and I can visibly watch the wheel wobble as i am driving. I even tried a different wheel back there to rule out a bent wheel, and got the same result. Does this pretty much guarantee a bent axle now?

Maybe. But you certainly need to eliminate it as a possibility before you go forward.
A magnetic base dial indicator, even a harbor freight cheap one will help.
Jack up the rear. Pull the drum,
Check for bearing play.
Up, down, side to side, in and out.
You shouldnt be able to feel any
Wire brush the rust and crud off of the axle flange and mark any dents or burrs on it with a sharpie.
That way you can see if your dial is measuring out of round or out of flat because of damage to the axle flange.
I have seen people beat the snot out of the axle with a sledge hammer trying to do brakes or crack an old drum open.
Make sure the face of the flange and the "standoff center" is clean and flat and that the inside of the rim and the center hole in it are clean and flat and round.
Especially if you have alloy rims.
It is really common for the center of all of your alloy rims to be gacked because over the years they have been swapped onto the same bad axle flange and whacked with an impact.
Anybody who ever took a set of Centerlines to the local hillbilly shop probably had some kid knock them on at 180 foot pounds without the wheel seated and centered when they did it.
Dont assume that another old rim is any better.
Are you seeing the rim wobble or are you seeing the tire wobble?
While Im at it, make sure you have the correct lug nuts and that the lug holes arent chewed up and out of round.
And make sure your lugs can actually hold torque and they arent weak and stretched from the high impact kids
Everybody needs a torque wrench.
I look at it this way, if I under torque a head bolt, I might blow a head gasket.
If I over torque a head bolt I might break the bolt.
If I under torque a wheel lug, The rim might come off in traffic.
If I over torque a wheel lug, the rim might come off in traffic.
Start from the inside and work your way out while checking off problems as you go.
Wheel bearings and end play, Axle flange and studs. Rim and fittment.
The things that are not directly brake related, but the brakes are dependant on that being correct
If all that passes the only thing left is the brakes.

Brake or axle issue?

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