Caliper pins hitting face of rotor!
05-09-2012, 07:06 PM
#1
Burning Brakes
Thread Starter
Caliper pins hitting face of rotor!
I took off my Z06 calipers for re-powder coating, when putting back on the right front when I tighten lug nuts and caliper bolts to spec the wheel will not turn, padlet pins are tight to the outside of the rotor. No paint on the mating surfaces. Using DBA 4000 rotors, stock bearings. Any ideas what may have caused this? Bearing seems tight, no play, the setup was working fine. I added a thin stainless steel washer between the caliper and its mount to move the caliper outward a few 1000ths and solved the problem, but I still wonder why this was needed. Thanks JWB
05-10-2012, 12:37 AM
#4
Team Owner
If everything was the same parts being mated and put back on then something happened during the powder coating process.
Let us know what the powder coater says .......
DH
Let us know what the powder coater says .......
DH
05-12-2012, 05:27 PM
#7
Burning Brakes
Thread Starter
Had some family issues to deal with for the past week, haven't had time
to recontact the guy that did the powder coating, initially, I thought the same, got a different set of calipers but I did contact him and he assured me I got my original calipers back. One of the plugs that have the threads in them that the caliper bolt goes into had come loose on the offending caliper, they are just spot welded or pressed in. He thought maybe that was the problem, I don't see how that would make a difference, as the tighter you make the bolts, the worse the problem would be, tightened to torque spec. I need to call him back and see if he did any sanding or grinding on those two mating surfaces. Thanks for all the suggestions to date!!!
to recontact the guy that did the powder coating, initially, I thought the same, got a different set of calipers but I did contact him and he assured me I got my original calipers back. One of the plugs that have the threads in them that the caliper bolt goes into had come loose on the offending caliper, they are just spot welded or pressed in. He thought maybe that was the problem, I don't see how that would make a difference, as the tighter you make the bolts, the worse the problem would be, tightened to torque spec. I need to call him back and see if he did any sanding or grinding on those two mating surfaces. Thanks for all the suggestions to date!!!
05-12-2012, 09:20 PM
#8
Drifting
Had some family issues to deal with for the past week, haven't had time
to recontact the guy that did the powder coating, initially, I thought the same, got a different set of calipers but I did contact him and he assured me I got my original calipers back. One of the plugs that have the threads in them that the caliper bolt goes into had come loose on the offending caliper, they are just spot welded or pressed in. He thought maybe that was the problem, I don't see how that would make a difference, as the tighter you make the bolts, the worse the problem would be, tightened to torque spec. I need to call him back and see if he did any sanding or grinding on those two mating surfaces. Thanks for all the suggestions to date!!!
to recontact the guy that did the powder coating, initially, I thought the same, got a different set of calipers but I did contact him and he assured me I got my original calipers back. One of the plugs that have the threads in them that the caliper bolt goes into had come loose on the offending caliper, they are just spot welded or pressed in. He thought maybe that was the problem, I don't see how that would make a difference, as the tighter you make the bolts, the worse the problem would be, tightened to torque spec. I need to call him back and see if he did any sanding or grinding on those two mating surfaces. Thanks for all the suggestions to date!!!
05-12-2012, 09:54 PM
#9
Burning Brakes
Thread Starter
I'll try that, the left caliper is ok, I'll measure the thickness of the mounting flange thickness to see if they are differ, should have thought
of that from the getgo, duh.
of that from the getgo, duh.
05-12-2012, 10:10 PM
#10
Drifting
05-14-2012, 08:40 PM
#11
Burning Brakes
Thread Starter
Well I took everything apart and took lots of measurements. Distance from caliper mount on spindle to face of rotor, same on both sides. Rotor thickness same both sides, distance between pins same both sides. Thickness of mounting ears on caliper, right side was .025 thinner
than left side. I've already lost 0.0125 due to thickness of the LG cooler plate, but those pins run pretty close the face of the rotor stock, they are about 1.35 to 1.40 apart when tight in the caliper and the rotor is about 1.25 to 1.26 wide, leaving .10 to .15 div by 2 leaving
.05 to.075 clearance on each side, if stocks are exactly centered. If not exactly centered, 0.025 could lock you up. Bottom line, calipers don't look like the ears were ground upon, so I must have not gotten my own caliper back and the 0.025 thousanths difference was enough to lock the rotor with the outside pins. Shimming the caliper outboard 0.040 centers the caliper on the rotor and my world goes around. Anyone think shimming the caliper thus is a bad thing???
than left side. I've already lost 0.0125 due to thickness of the LG cooler plate, but those pins run pretty close the face of the rotor stock, they are about 1.35 to 1.40 apart when tight in the caliper and the rotor is about 1.25 to 1.26 wide, leaving .10 to .15 div by 2 leaving
.05 to.075 clearance on each side, if stocks are exactly centered. If not exactly centered, 0.025 could lock you up. Bottom line, calipers don't look like the ears were ground upon, so I must have not gotten my own caliper back and the 0.025 thousanths difference was enough to lock the rotor with the outside pins. Shimming the caliper outboard 0.040 centers the caliper on the rotor and my world goes around. Anyone think shimming the caliper thus is a bad thing???
05-15-2012, 03:06 PM
#12
Burning Brakes
Well I took everything apart and took lots of measurements. Distance from caliper mount on spindle to face of rotor, same on both sides. Rotor thickness same both sides, distance between pins same both sides. Thickness of mounting ears on caliper, right side was .025 thinner
than left side. I've already lost 0.0125 due to thickness of the LG cooler plate, but those pins run pretty close the face of the rotor stock, they are about 1.35 to 1.40 apart when tight in the caliper and the rotor is about 1.25 to 1.26 wide, leaving .10 to .15 div by 2 leaving
.05 to.075 clearance on each side, if stocks are exactly centered. If not exactly centered, 0.025 could lock you up. Bottom line, calipers don't look like the ears were ground upon, so I must have not gotten my own caliper back and the 0.025 thousanths difference was enough to lock the rotor with the outside pins. Shimming the caliper outboard 0.040 centers the caliper on the rotor and my world goes around. Anyone think shimming the caliper thus is a bad thing???
than left side. I've already lost 0.0125 due to thickness of the LG cooler plate, but those pins run pretty close the face of the rotor stock, they are about 1.35 to 1.40 apart when tight in the caliper and the rotor is about 1.25 to 1.26 wide, leaving .10 to .15 div by 2 leaving
.05 to.075 clearance on each side, if stocks are exactly centered. If not exactly centered, 0.025 could lock you up. Bottom line, calipers don't look like the ears were ground upon, so I must have not gotten my own caliper back and the 0.025 thousanths difference was enough to lock the rotor with the outside pins. Shimming the caliper outboard 0.040 centers the caliper on the rotor and my world goes around. Anyone think shimming the caliper thus is a bad thing???
I then install some brake ducts which spaced my spindle hubs out further which brought the problem back. I now just add a shim to space the caliper.
05-15-2012, 05:36 PM
#13
Burning Brakes
Thread Starter
In talking with The Powder Coater we came to the conclusion that
that is part of the problem, the aluminum caliper ears are a little soft, with repeated torquing and removing, they get crushed some, if you look closely at the caliper ear, you can see where the shape of the spindle ear is embossed into the aluminum of the caliper, ie pressed in.
Seems to happen with guys that track their cars and take calipers off and on frequently. He was still 99.9% sure I got my own calipers back, and he does NO grinding, so the above seems a logical expanation
that is part of the problem, the aluminum caliper ears are a little soft, with repeated torquing and removing, they get crushed some, if you look closely at the caliper ear, you can see where the shape of the spindle ear is embossed into the aluminum of the caliper, ie pressed in.
Seems to happen with guys that track their cars and take calipers off and on frequently. He was still 99.9% sure I got my own calipers back, and he does NO grinding, so the above seems a logical expanation
Last edited by jwbert; 05-15-2012 at 05:41 PM.