Cleaning caliper pistons

I've had that problem on what I'll call "keyed" (as opposed to slide-bolted) calipers. Yours are probably a little heavier than mine were on Ford E-Series. I found that if I could get my knee against the side of the caliper opposite the hub and bear against it, it'd stay close enough to work on. You need to get it into actual position before you reach for the key or it won't start into place.
If you can squeeze the caliper toward the centerline of the axle, it'll want to support itself once you get it into its slides.
Perhaps you could rig a bungee cord around caliper and hub.

John&Joey wrote:

ScottnSherrie wrote:
The hardest part is holding up the heavy caliper and getting the key and spring started to install them. I think I'll try to figure out a way to hold the caliper up with one of the scissor jacks I use to stabilize the motor home.

Not sure what you got going on there, but sometimes you can wire up the caliper so as to take the weight off of the hose.

I'm replacing all the hoses and pulling calipers to rebuild. Original problem was overheating brakes possibly due to the 25 year old hoses failing.

ScottnSherrie wrote:
The hardest part is holding up the heavy caliper and getting the key and spring started to install them. I think I'll try to figure out a way to hold the caliper up with one of the scissor jacks I use to stabilize the motor home.

Not sure what you got going on there, but sometimes you can wire up the caliper so as to take the weight off of the hose.

Thanks for all the input. Ditto that the cylinder bore never contacts the piston. The seal is the only part that contacts the piston. Also, I've decided to replace all the pads.

At least now I know how to get the calipers off for regular maintenance. I've done car brakes several times and the Dayton truck brakes don't mount the same. No slide bolts. The bottom slide groove has a key and spring that has to pounded out for removal and then pounded back in to install.

The hardest part is holding up the heavy caliper and getting the key and spring started to install them. I think I'll try to figure out a way to hold the caliper up with one of the scissor jacks I use to stabilize the motor home.

Just a few things to think about before recommending a rebuild:

The OP stated in a prior post that he cooked the brakes. This means the brake pads will start to flake off at the edges. Some would say the pads are no good now, others would say not to worry and they would keep on truckin'

The O ring has two surfaces, the groove and the wall it rides on. If the wall it rides on is scratched or compromised in any way (i.e has a set micro lip) the O ring will be short lived and will become a leaker. Also as the O ring is being driven into the cylinder it can twist on itself creating a weak spot. When a brake becomes a leaker it can not build up hydraulic pressure to stop, so in effect it also takes out the opposite brake on that line leaving the driver with only two working brakes on a heavy rig.

Given the vintage of the coach and the amount of use it is getting then I think rebuilding does makes a certain amount of sense. Why put on new calipers only to watch them once again rust and hang up from lack of use. Just keep a very good eye on things for awhile until you know for sure the rebuild was successful and the brakes are, and will, remain functional. MH isn't a car where you can pull/push the emergency brake if you have too and expect to stop.

I've rebuilt calipers and I recommend it.

The Piston in a Caliper does pretty much what the BORE does in a Wheel Cylinder. In a Caliper, the only surfaces that really matter are the O-Ring Groove and the Retaining Groove for the Dust Seal. Naturally you want any gunk and loose rust out of the caliper's "cavity" but if the O-Ring fits well (given the Piston is OK) it should work without leaking. And if the Dust Seal is retained properly, it should stay clean.

What you are doing should be just fine, but.....

By rights you should really be honing outthe brake cylinder. This will get rid of any issues (pitting) that may have caused the piston to stick in the first place. Of course using the tool can also cause problems (leaking) if you've never done it before.

I often wonder how many that recommend rebuilding calipers have ever really done it in real life, and not just read about it on the forum and regurgitating the idea.

Again, what you are doing should be just fine, but there really is more to it then just slipping on new seals and away you go. Most the time you will be OK, just keep an eye on things in the beginning and the brake fluid level. If nothing else you won't have much money invested into the job and can always buy rebuilds if you have too.

ScottnSherrie wrote:

darbyjudy wrote:
When I worked as a mechanic I uses brake cleaner along with fine steel wool to clean the caliper pistons and the caliper bore.

I'll give that a shot. Thanks.

I wouldnt, the chances of leaving pieces of the steel wool in there is too high, and it rusts very fast. Instead use an aggressive scotch brite pad. It accomplish the same thing and it wont rust.

darbyjudy wrote:
When I worked as a mechanic I uses brake cleaner along with fine steel wool to clean the caliper pistons and the caliper bore.

I'll give that a shot. Thanks.

When I worked as a mechanic I uses brake cleaner along with fine steel wool to clean the caliper pistons and the caliper bore.