Rear piston - can't get it reset for new pads

[drano38]

Putting new Centric rotors and Carbotech XP-8 pads on the rear of the Boss tonite, but can't get the piston turned back in far enough.
I'm using a kit like this to turn it:
http://www.amazon.com/Precision-Brake-Caliper-Wind-Back/dp/B00GAC768Q/ref=sr_1_4?s=automotive&ie=UTF8&qid=1432091485&sr=1-4&keywords=disc+brake+piston+tool
New rotor and pads measures 2.07". Max I can get the piston pushed back in is ~ 1.9"
I've tried rocking the piston back and forth, but not gaining anything.
I installed SS brake lines tonite also, so the caliper is empty of fluid--that shouldn't matter should it? I opened the bleeder too, and no luck.
It seems the piston just doesn't want to go in any further, and I'm putting pretty good pressure on the tool trying to turn it.
Just need to put more pressure on the tool? Or is there some trick I'm not aware of?
Thanks in advance for the help.

 

[VoodooBoss]

How far is the piston sticking out? It should be all the way flush. Not sure if not having fluid it there would make a difference but I doubt it.

 

[Flyboygsxr]

Remember you have to line up the dimples on the pad with the cut outs on the piston. You might think it's not going in far enough but in reality you aren't lining it up. Hope that makes sense

Adam

 

[Grant 302]

Did you line-up the slot in the piston to be 'vertical' relative to the caliper? So the pins in the pad sit in the slot.

Can't think of anything else if you got the pistons to be flush with the interior caliper face.

Did you also lube the sliding pins? Might help to take the caliper and bracket apart.

Good luck!

 

[F.D. Sako]

What I've noticed is that after every couple of turns of the piston, you have to re-tighten the tool to ensure it pushes the piston in. If you don't re-tighten the tool, then the piston will eventually lock in place. You may have to rotate it counter clockwise to get it free and then tighten the tool and start rotating clockwise again... Hope that made sense

 

[drano38]

The piston is not flush yet, so I need to figure out why.
Not a pins issue, because I can't even get the caliper started onto the pads, but I will make sure those are lined up once I get to that point.

I'll also try re-setting the tool to make sure the piston doesn't lock up.

Both driver and passenger pistons turn Right correct? I'm currently working on driver side.

 

[TMSBOSS]

Only idea I have is to ensure the piston is turning and has turned enough for the distance pushed in.

I finished my rear brakes about 12 hours ago. I ran into the pin not aligning myself. Had to rotate.

Suggest really cranking down on the piston, rotation and see if the caliper will then collapse the last bit you need. I believe the E-Brake is the only item which will hold the piston out if it's moving freely.

Good luck.

 

[302 Hi Pro]

Ensure the parking brake is released. The brake fluid in the caliper will release to the brake line, so crack the brake fluid reservoir cap.

The piston should compress. If you still have problems, check the other side to see if that caliper piston will compress.

Good luck,
Dave

 

[drano38]

I tried all the ideas, and neither piston will move in enough to get over then new pads/rotor.
Gap from piston to outer caliper is still 1.9", and that's all it will move.
Reinstalled old pads, bled brakes to get fluid back in the caliper (replace rear brake lines last nite). Then pumped brakes to get pistons back out so I could start over--same result.

Anyone have a NEW set of rear pads laying around that they can measure how thick they are? These Carbotech XP-8 pads are 1.328" when measuring them stacked face to face. Add .75" rotor, and the pad/rotor combination is 2.07". Here's a pad photo:


Here's a couple of the piston. Does this look fully seated?
Anyone have any ideas? I've done rear pads a few times, and don't remember any problems.
This is really getting frustrating.

 

[steveespo]

Try putting the old pads in and cycle the parking brake 3 or 4 times and then pump the pedal up until firm. Then remove and try and wind the piston in again. That piston is close to a half inch out from where it can be turned in. if you can't free it up go get a rebuilt from auto parts store. Not worth fighting it for $45.
Good luck
Steve

 

[wwilde001]

Try putting the old pads in and cycle the parking brake 3 or 4 times and then pump the pedal up until firm. Then remove and try and wind the piston in again. That piston is close to a half inch out from where it can be turned in. if you can't free it up go get a rebuilt from auto parts store. Not worth fighting it for $45.
Good luck
Steve

+1 From the pictures you still have quite a bit to go until the piston is flush. As others have suggested, might want to back off counter clockwise and then continue clockwise. Only other thing: As my dad would say, put some *ss behind it!
Good Luck!

 

[VoodooBoss]

Here's a couple of the piston. Does this look fully seated?

It's not in and should be flush with the caliper when full in. Are you able to turn it in at all? That's very strange. Looks like Steve has a good idea so give it a try.

 

[drano38]

Here's a thought--can the banjo bolt be sticking in there too far and getting in the way of the piston?
I noticed when I put the Goodridge rear lines on, the Goodridge banjo is a lot thinner. Stock banjo is .454". Goodridge banjo is .325". So .129" thinner (making the bolt go into the caliper that much further).
Is this an issue or not?
Thurs I'll give Steve's input a try, if no-go, then a new set of calipers--will have to paint them black to be Boss calipers!
Here's a pic of the caliper to show possible banjo bolt to piston interference.

 

[VoodooBoss]

I think that's potentially a problem.

 

[F.D. Sako]

Did you have the same problem on the other side as well?
Asking to see if you used the goodridge banjo bolts on both sides.

 

[drano38]

Same problem on both sides.
My Goodridge lines did NOT come with new bolts.
I bought them from a BMO member, (never installed), and the 2 plastic bags were stapled shut.
So did anybody shorten their banjo bolts when they installed new lines?
I'm late to the the game of finally taking my stockers off (heck, Gary already replaced his first set of SS lines!).
Thurs I'll do Steve's inputs--if no luck, then I'll back the banjo bolt out and try again. If still a problem, its time to buy new calipers--unless I learn I need Goodridge banjo bolts.

 

[VoodooBoss]

Pull the bolt then measure the bolt then the distance from the opening to the piston to determine if the bolt is too long.

 

[steveespo]

Good catch with the bolt. Pull one and wind it in. If that works you know its bolt length. If not then try my first idea. Pretty sure the Ford hose block is thicker than the Goodridge end. Can't remember if I changed Banjo bolts when I did mine, think I did.
Steve

 

[wwilde001]

Ah, yes that is a very good catch. My money is on the Banjo Bolt, especially the way it comes in from the side of the cylinder.

 

[drano38]

I bet its the factory bolt on the smaller Goodridge hose ends.
I talked to a retailer today, who pulled one out of a box, and it has bolts. Mine didn't.
I'll test it tonite by backing the bolt out.
If it allows the piston to reset, I may order Vorshlag lines--I like their square hose end fitting that prevents them from rotating.
And they'll use my factory bolts.