Hi All, I tried a search with no luck. Mostly because I'm not sure what to look for.
The rear brakes on SIL's Blazer are worn on the outsides of the rotors. Both sides and not much wear on the inboard pads. My brake experience is that is not normal.

So, I push/pull on the axle with the caliper off and I can move the axle shaft out until it contacts the caliper bracket. Is this normal? How far, if any, should I be able to move the axle shafts in/out with the brake hardware off the vehicle?

I'll remove the caliper bracket tonight to see how far I can actually go. I'll also check slide pins to ensure they are not hung up. But, I did do a new hardware kit when I did brakes 2-3 years ago. And did lube with pin grease. I'll do brake hoses this time too. The front brakes still look good. And, I did front and back at the same time last time in there.

FWIW, the vehicle comes to me because "the brakes are making a noise". RR side is so bad that the brake pad on the outer side is COMPLETELY GONE. It was riding caliper on rotor. Last time the same side had the rotor snapped from the hub portion. "the noise stopped. Do you think it's ok to drive it?" was the last brake job...

 

Wearing through the outer pad can be a sign of sticking caliper sliders. The caliper brackets are typically at fault for this which is why it isn't worth the headache over the ~$12/side replacement cost.


Given the C-clip style axle design, some play is normal. I would call 1/8" on the excessive side and it does sound like you are describing something in the realm of 1/8" or more. Axle end play should be less than 0.030" (~1/32") with 0.060" (~1/16") being at the high end to where you would want to start looking at replacing components to bring it back into spec. Specifications call for measurements of 0.008"-0.025" which sometimes are not even attainable on brand new, straight from GM axles...

High end play is caused by wear on the differential carrier, differential carrier pin, axle shaft, differential side gears, and/or the c-clip. You are going to have to open up the differential to inspect those components for wear to figure out what needs to be replaced.

 

Thanks for the reply. I'll try to measure end play and add caliper brackets to my parts list.
Would acceleration/decel put any out ward pressure on the axle shaft? I've only opened a few for fluid changes.

 

Turning would push/pull on the axles depending on the direction of the turn and which wheel you are talking about.

 

I put my high quality Harbor Fright dial indicator on the axle last night. Driver side is .030 and passenger side is .045. I guess I was concerned with any movement at all as I was trying to find why the brakes were so bad.
Slide pins moved easily. My hope is that all new hardware and brake hoses resolves the issue.

Thanks for your input!

 

Those numbers look fine to me. 0.045" is a good bit over the specification, but not anything that I would be too concerned about. If it did bother you or you continue to have problems with your brakes on that side, then you could try to find a slightly thicker c-clip to take out some of the slack.

The caliper brackets can cause caliper bind even when it feels like the pins slide smoothly. This often is a result from a worn pin and/or bore that allows the caliper to **** slightly and bind under braking; sooner or later sticking and burning through the outside pad. It just isn't worth the reoccurring problem to not spend the $12 on replacement brackets.


Spray the brackets down with brake clean and give them a shot of paint before you put them on to keep them looking nice!

 

Have checked the gears in the rear end,they can be excessively worn and cause the play or movement you are talking about.

 

Gear wear will show up mostly in excessive driveshaft movment..
Not in axle in-out play, the axles are splined on the ends and
go through the spider gear then the C-clip in installed along with
The center pin and bolt....on my Zr-2 axle I have what i will call pinion
Wear but no excessive axle in-out play...although I can rotate the
tire and see some play...

 

Thanks for the replies. I'm working through the process slowly as I only have an hour or two in the evenings. I found an axle seal bad when all brake parts were removed. There was a small puddle under the drivers side. So, I pulled the diff cover and found the lube to be gray/tan in color. There was water beads on the inside of the diff cover. Would the axle seal allow moisture in? Would a short daily commute of 5 miles allow the diff to warm enough to draw moisture out of the frigid winter air?
I had changed the pinion seal about three years ago and did a new diff cover and lube. The diff cover gasket was not leaking.

 

Thats a good question on the axle seal....
I would guess if lube is able to come out... then
I could then say that moisture could be allowed in..
And im saying that only by how temp and pressure work..