brake caliper not installing

[flomulgator]

As part of my "manual hubs" project I replaced all the seals, and since I got that far I replaced the U-joints and the wheel bearings and races. I'm finally putting it all back together. Right caliper went on fine, but the left one won't. I've tried screwing the spindle nut down tighter temporarily to pull the disc in, but it still won't go in enough to sit right to let the long bolts holding the caliper aim right. Hammer isn't fixing anything, so more force is not the answer. Could it be the bolts that hold the spindle on?? I have fairly new brake pads, I'm almost tempted to just shave the outer pad or something to gain the clearance. Caliper went on fine when changing the pads months ago. Kinda at a loss here.

FWIW, the trouble disc now seems more inboard that the working disc/brake combo.

[DmaxMaverick]

First, make sure the pad isn't on backwards. I've done this myself, and they somehow just "look" better when they're backwards (I guess). Then, use a large C clamp or caliper compressor to retract the piston. Make sure the MC isn't full, or you'll come up short on fluid when they're pumped up ('cause the fluid will be everywhere but in the MC).

[flomulgator]

backwards in which sense? seems to me the inner and outer can only go on one way, but maybe that perception is the problem.

Piston fully retracted. Its a fight between the backing plate and the outer pad...thus me cranking on the spindle nut to pull the disc inboard. Kinda want to grind the pad because it goes on fine without the pads.

[DmaxMaverick]

I don't think you can install them backwards. Just saying you need to look at the whole picture and make sure everything is correct.

If it worked before you removed it, something got changed. Is it possible the disc is backwards? It should work, so if you reduce the pad, you are compensating for a part not installed correctly. Bad things may happen.

[flomulgator]

disc rotor never came off hub and I kept my left and right straight. Since I'm not hearing any obvious solutions I'm going to take the hub and spindle back off and look at those six bolts holding on the backing plate....If the mating surface is off and it had a degree of tilt that could be it. Maybe the bearing races arent fully seated? I shudder to think of that. I feel I have the same clearance on the between the rotor and the backing plate on the working and non-working sides though, but I'll break out the calipers and check.

Just kinda rambling here really....when I figure out what the problem is I'll report back. I'm glad I did this job once, but I don't really want to ever get into bearings and spindle nuts again.

[DmaxMaverick]

Which axle model do you have?

Unfortunately, SFA wheel bearings are a regular maintenance item. They should be done AT LEAST with every brake job, or at least once more in between for heavy use. It's a trade-off for the IFS.

It could be an unseated race. They should be installed on a press with the correct driver. I use square-cut PVC and soft mallet. Once they start square, it doesn't take much force to seat them. If you used a punch, it may be cocked and bound short.

Did you use a gasket on the spindle flange? If so, did you remove the old one? How did they compare in thickness? How do the exposed threads on the spindle end compare now, to before? Did you take pics before (hindsight)?

[flomulgator]

Those are some good ideas I will look into.

The axle is a 8.5" 10 bolt off a ~'86 K250 w/ 8 lug.

I borrowed a tool from the local Autozone that is an aluminum disk and rod that matches the race...it can still get a little crooked but not like a brass punch could do, and I tried to check as best I could that it was seated properly. It did take some noticeable force though. Maybe the hub showing it's age?

I'll compare the gaskets and all that, unfortunately no pics. Since I'm taking it back off, the one item that I had and didn't replace because it was a nightmare was the needle bearing inside the spindle that rolls on the axle when in 4WD....everything I tried failed and looking on the internet only gave horror stories. Got any ideas on driving that thing out?

[DmaxMaverick]

Yeah, the 1/4 shaft float bearing. Slide hammer with the "heal" hook. Pops right out, but renders it useless (can't reinstall it).

The race metal is harder than the hub. When they wear out, the race gets sloppy in the hub, or spins, due to the hub enlarging. If it's tight, the hub is probably OK. When properly seated, there will be no space between the race and seat. I put a dab of grease on the seat in a few places. When it bottoms, out comes the grease. Wipe the grease, and there should be no more than a hairline of it left. A positive visual indicator.

I don't like the disc/driver installer. As you've found, it doesn't guarantee a square install. I don't recall the sizes, but PVC pipe can be matched to all the sizes I've done.

[flomulgator]

Yeah I don't own a slide hammer, but maybe I should get one. With the hook, do you use a pushing or pulling motion? The forces would seem to be much better with a pushing but a pulling may hook better?

I got new bearings and had planned to replace. Do you consider these 1/4 shaft needle bearings a regular maintenance item too? Thanks for all the advice, I didn't know 1/2 this stuff and I really like the PVC pipe idea.

[DmaxMaverick]

The inner works of the axle are overhaul items, not maintenance. Only the hub bearings/seal are periodic maintenance.

I suggest the "heal" hook because it goes both ways. A couple light taps in both directions to loosen it. The bearings can be a real bugger, like they're glued in (I haven't ruled out that notion). I've done a lot of these, but it's been many years since the last one.

If you don't have a slide hammer (set), get one. Not too spendy at Harbor Freight. You'll be surprised when you realize how handy they are. I use them whenever I can, in place of a punch/hammer, and often screw type pullers. Very precise placement, and you can vary the force infinitely. A good set will have 3 or 4 sizes, with a generous selection of bits. The only drawback is they're large and heavy, which serves their purpose, but inconvenient to transport. I carry a lot of tools in my truck all the time, but the "hammers" stay home.

[flomulgator]

So the primary culprit was the spring wire that provides additional sealing strength the the inner hub seal; it was unseated and caught up and half torn out. After clearing that out I was able to get the caliper on, but it's still very tight and still way too much parasitic drag. I haven't had the chance to drive it yet or use the brakes.

The caliper looks like there is way too much space between the shims and the plate....but I believe the screwing happens in the shims? I think that caliper is shot; I've been having other issues with that brake locking (could also be a brake balance/MC issue) and the caliper boot is torn. Anyways, at this point the "bad" rotor is well inboard of the "good" rotor and still binding. I checked all the races and they are all flush. Additionally I made sure the spindle was seated gutentight. Also, I borrowed a slide hammer from the local store and got the needle bearing out of the spindle using a adjustable 2 armed attachment. Even properly set up it took a LOT of force! At least I got something extra done right.

I've been in a hurry to get a working truck so I left the hub seal as is for now...how critical is that spring wire to seal longevity?

[DmaxMaverick]

If it's that tight, something is still not right. It needs to be correct. If it's binding without any pedal pressure, something is still not right. I don't think I'd trust it, especially if you've had issues with that caliper before.

The missing spring on the seal won't affect longevity, but it may not seal. Steer clear of water/puddles.