I heard a steady thump, which was obviously related to road speed, from the front end of my '91. When I removed the wheel, I found that there was so much clearance between the caliper and its mounting bracket (the manual calls it the caliper adapter) that the outer pad was touching the hub. Every time it touched a high spot on the hub, the caliper was slammed forward and hit the bracket hard enough to make a noise I could hear in the cab.
The manual doesn't say anything about taking up play or even checking the ways ( the sliding surfaces where the caliper contacts the bracket) for wear, so I assume these parts aren't supposed to wear. The caliper retainers are badly rusted, and I'll have to replace them, but it doesn't look like that will cure the problem. They press the caliper toward the hub, and it's already too close. I haven't checked the other side yet to compare it, but I suspect it has a similar problem. Rotating it by hand, I can hear a click. It's just not bad enough yet to hear over engine and road noise.
Is there any way of taking up the slack, or do I have to repace parts? If parts replacement is the only solution, is there any way of measuring the wear on the caliper and bracket separately so I know which to replace first?

 

Mine was doing the same thing alittle back and it turned out i was missing a little clip that holds the brake pad away from the caliper mount, they are like 60 cents or so at any auto parts store.

 

It would be great if replacing a 60-cent clip would fix it. I'm not sure what clip you mean.Do you mean the caliper retainer clip, or the anti-rattle spring, or is this an after-market clip (not in the manual) designed to fix this problem? If it isn't in the manual, it would help if I had a name, a description, or best of all a part number when I try to convince the kid at the parts counter that it exists.

The retainers and anti-rattle springs are so badly rusted that I doubt if they're doing much, so I'll be replacing them anyway. I guess I should do that first and then road-test it before I replace anything more expensive.

The manual shows an o-ring under the upper retainer clip. I've never seen this ring, so either they stopped using it, or it had rotted away on any brakes I've taken apart. There doesn't appear to be a groove to locate it. Does anyone know what its function is?

When I got the caliper out, I could see that the sliding surfaces ("ways") on both the caliper and bracket were uneven (as in "not flat"). I doubt if they were made that way, so presumably that shows wear. Trouble is, I don't know how to measure the wear and if I could, I don't know how much is acceptable. BTW, I was having trouble removing the bolt that holds the lower retainer, so I took the caliper out with the retainer in place. Does the fact that I was able to do so indicate too much clearance?