Brake Caliper Piston not going completely In

[Matthew K]

Hello all,

I've been having a wonderful experience(not) trying to change the front brake pads on my 99' Ram 2500 (8800GVW). In the past on other vehicles I've been able to get the pistons back in with relative ease using a c-clamp. This truck is not making it that easy. I've been advised to take out the bleed valve so they fluid just goes out instead of back up the pipe, that helped me get it most of the way but not all. On one side I went ahead and took the caliper completely off to see if taking the pressure hose off would help, it did not.

Today I even went to autozone and borrowed their brake caliper tool, it nor the c-clamp are unable to move the piston the last 1/2in or so on both front calipers. I tried to put the new pads on with the pistons like this and they do not have enough room to fit. I've added a picture to show what is left that needs to be pushed in. Do I need new calipers or am I missing something?

Thanks.

 

[Cooter]

Hello all,

I've been having a wonderful experience(not) trying to change the front brake pads on my 99' Ram 2500 (8800GVW). In the past on other vehicles I've been able to get the pistons back in with relative ease using a c-clamp. This truck is not making it that easy. I've been advised to take out the bleed valve so they fluid just goes out instead of back up the pipe, that helped me get it most of the way but not all. On one side I went ahead and took the caliper completely off to see if taking the pressure hose off would help, it did not.

Today I even went to autozone and borrowed their brake caliper tool, it nor the c-clamp are unable to move the piston the last 1/2in or so on both front calipers. I tried to put the new pads on with the pistons like this and they do not have enough room to fit. I've added a picture to show what is left that needs to be pushed in. Do I need new calipers or am I missing something?

Thanks.

I would just get a new caliper. The ones on my F-150 would stick and on hot days I would sometimes get a sticky brake. After several years of messing with them I got new calipers and they haven't given me any trouble. With your trade-ins, they shouldn't be too much.
If you're determined to get them working, maybe try soaking them. Otherwise it sounds like you've done everything you can do. Be careful using compressed air to push them back out, I've made that mistake!

 

[FormerHangie]

I would just get a new caliper. The ones on my F-150 would stick and on hot days I would sometimes get a sticky brake. After several years of messing with them I got new calipers and they haven't given me any trouble. With your trade-ins, they shouldn't be too much.
If you're determined to get them working, maybe try soaking them. Otherwise it sounds like you've done everything you can do. Be careful using compressed air to push them back out, I've made that mistake!

I agree with Cooter, I'd just go get replacements, chances are either the piston has some rust on part of it, the caliper's cylinder is warped or has some corrosion, or the seal is swollen. In the days of old you'd typically get a new piston and seal, but replacement calipers are pretty inexpensive these days.

 

[Clip4]

Take a synthetic hammer and tap around the edges, and try again.

 

[SoCal RV Flyer]

I'd bet there's significant pitting/corrosion in the bores if the pistons don't easily retract. My tool of choice to push them back in is a big pair of Channel Locks. Sounds like new calipers are the way to go, but I'd do a post-mortem on the old ones just to satisfy curiosity.

I did rebuild some old Porsche 911 calipers that had mild corrosion by cleaning out the bores with fine emery cloth. Great results here, but if there's any noticeable pitting, I'd scrap 'em.

 

[Chip Sylverne]

Not going to be applicable here, but I did some rear Porsche calipers once that for the life of me I couldn't get the pistons to retract fully. Come to find out, here was a good reason why. The rear pistons had an internal threaded rod that prevented full retraction as part of the parking brake system. Turns out you had to press them so far, and twist them the rest of the way.

 

[jsstevens]

Not going to be applicable here, but I did some rear Porsche calipers once that for the life of me I couldn't get the pistons to retract fully. Come to find out, here was a good reason why. The rear pistons had an internal threaded rod that prevented full retraction as part of the parking brake system. Turns out you had to press them so far, and twist them the rest of the way.

That's common on rear disc brakes. It's for the parking brake. My daughter's Mazda 3 is the same way.

 

[Matthew K]

That's common on rear disc brakes. It's for the parking brake. My daughter's Mazda 3 is the same way.

Yea I've read about that "fortunately"(not) this truck has drum brakes on the back.

 

[Matthew K]

Update: Went ahead and just bought new calipers and rotors for the front. Going to put them on tomorrow. Downside, spent a few hundred more than intending. Upside: I have effectively brand new front brakes.