Caliper/pad opening vs. rotor thickness

[Pete99]

Doing my first front disc brake job on my '97 Ranger, and ran into a problem getting the new pads on the rotor.

I did the standard C-clamping and the pin boots seem pretty well compressed all the way down, but the new Wearever Gold pads are still too proud to fit over the rotor.

The opening with the new pads, if I had to guess, looks like 11/16". The rotor is over an inch, maybe 1-1/8". (No tape nearby at the time, but these numbers are close.)

Should I be using thinner pads? Will the caliper open further somehow? It'd be good to know before I go futzing too much more than this if these pads are never going to fit.

Thanks!

 

[adsm08]

Wearevers should fit in there just fine. It's likely that you don't have the caliper compressed the whole way. That is easier to do on a dual piston setup like the 97's have. You actually need to have 2 clamps, one for each piston, or as you push one in the other pops out a bit. Both piston faces need to be flush with the caliper's case.

Best way to do the job is one side at a time, turning the pistons in evenly with one clamp on each piston so it can't pop back out at all. Even one clamp with a the old pad in there won't do the job correctly.

 

[Tedybear]

Going to do an additional to adsm's post. I've seen quite a few people doing their own brakes make a key mistake that can create problems.

Please ensure you remove the master cylinder lid while compressing the piston back into the bore. It's possible that fluid can press the rubber seal into the cap and actually slightly pressurize it--so when you remove the c-clamp? The piston will sneak back out a whisker. (don't ask me how I found that out....felt like a right knit-wit.) Also the cap can also burst off and damage things if it's not left loose when you compress the piston.

As most shops doing maintenance will top off fluids? Brake fluid will drop as your front disc brakes wear--shops replace that fluid as they should-- But try to compress that back into a limited space? It can do some odd things.

S-

 

[Maritime Storm]

What I was taught years ago, as an apprentice, was to open the bleeder screw before compressing the caliper pistons. By doing so, you are not forcing the old fluid from calipers back through the system and at the same time you're introducing fresh fluid into the system. In a multiple piston caliper it also allows you to reset the pistons one at a time. Getting back to the OP issue, either you have too much of a rust ridge on the rotor to get the new pads over the rotor(in this case you should replace the rotors), you have the wrong pads for the application or piston/s are not completely reset. You need to determine which.

 

[Pete99]

What I was taught years ago, as an apprentice, was to open the bleeder screw before compressing the caliper pistons. By doing so, you are not forcing the old fluid from calipers back through the system and at the same time you're introducing fresh fluid into the system. In a multiple piston caliper it also allows you to reset the pistons one at a time. Getting back to the OP issue, either you have too much of a rust ridge on the rotor to get the new pads over the rotor(in this case you should replace the rotors), you have the wrong pads for the application or piston/s are not completely reset. You need to determine which.

I didn't open the bleeder screw. It's been a couple of years since I've done any brakes and I have probably forgotten a few other little details too, but I'll be sure to do so when I go back in there.

It's not rust swell in the rotors -- there's some wear but not actual structural rust. I have new ones to put in, but am also new to undoing the bearings, and will need to take a little time to approach them carefully.

Anyway, once I finally get a little time, I'll go back at it and report back.

 

[Tractor Dan]

One other bit of advice. Feel the length of the hose from the caliper to the metal brake line. Make sure there are no spots in there that feel abnormal or weird. I had a 93 Topaz and after freezing in my friends pole barn for a day we gave up since we couldn't feel our fingers and had class the next day. Needless to say i sent it to my mechanic and the problem was the stupid hose had a bad spot in it. Had i not been freezing and thinking clearly i would have realized this. Live and learn i suppose.

 

[Pete99]

Success! Stupid bleed screw. Knew it couldn't be that hard. Many thanks to all those who responded!