I've replaced my rear brakes and having trouble tightening the caliper pins. I know there's an upper and lower and I've got that right, but damned if I can't get both pins to thread in. I can get one pin in fine, then the other seems really hard to tighten. So I back out the pin I got in figuring it might add a little play, but still difficult. I've taken the caliper off and threaded in both pins and they go in easy. It's something about the alignment that is cursing me. I've made sure the caliper piston is fully retracted. Any advice would be so appreciated, I don't want to bugger up the threads by forcing anything.

 

Is there something stuck in or blocking the hole the pin goes into? If it'll easily thread into the caliper half with the threads when unassembled, I'd look at the other half (the bracket really) that it needs to insert into when assembled.

 

OP, I'm assuming you've got the FSM and assembled the G (guide) & L (Lock) pins in their correct locations as shown below?


If that's the case, as ptrhahn suggested you probably have some crud in the bracket bores that is preventing the pins from sliding in & out properly. Recommend thoroughly cleaning out the bracket bores & sealing boots of all old caliper grease & debris that's in there. Lots of brake cleaner & something like Q-tip swabs will be needed to get everything out till the bores are clean & shiny. Then when the bores are all clean & dry, apply the caliper grease on the pins and try again - a little grease here goes a long way here; you want all the sliding surfaces coated, but you don't want a bunch of excess grease interfering with the in & out motion or blowing out the sealing boots.

 

Yeah, if G and L (which are interchangeable) will thread easily into (5) when disassembled, something in the assembly is impeding it, likely with (13).

 

Be careful here. These pins on the rear caliber cross thread very easily. You have to hand thread to start gently for several turns. Not saying, but you may have cross threaded the one you're having trouble with. I had to replace my rear calibers several years ago because of it.
Mike

 

Here's how I finally got the caliper pins to tighten. According to my mechanical engineering friend, the caliper and the bracket have very tight tolerances, so if the caliper is slightly misaligned, the pins won't tighten down easily. Now it's possible that I was too worried about how hard it became to tighten them down, and I was afraid of buggering up the threads, but I don't think so.
First, I made sure the caliper piston was fully retracted, thinking maybe this would give me some extra wiggle room to get the pins aligned. Then I loosened the caliper frame bolts for some more wiggle room. The manual says start with the bottom pin, I was worried about the top pin threads so I tightened it all the way and it went in easy. I then put in the bottom pin and couldn't get the threads to catch, so I slowly backed out the top pin until I could get the bottom to catch and then tightened each one a half turn or so alternating between top and bottom. They both tightened up properly. I had the same issue with the caliper on the other side of the car, so it wasn't a problem with one caliper. I hope this helps someone. I did a lot of cursing til I finally got this to work.

 

I'm glad you got it in, but shocked it was that difficult.

I change to track pads frequently, and only remove the top pin and flop the caliper back, change pads, push piston in, and it goes right back together. I've pulled the caliper away entirely to test fit new stuff, and just leave the lower pin in at all times, and just reassemble, insert and tighten the top pin. You shouldn't be needing to loosen mount bolts and such.

 

Agreed, the FSM doesn't specifically warn you NOT to do it, but really there's no good reason to ever remove the "L" (lock/lower) pin from the caliper when servicing the brakes. Unless you find that the pin is damaged (i.e., corroded, scored, bent) As for the bracket mounting bolts, the only reason to remove those is if you need the bracket off to replace a rotor or do other work that requires such disassembly. During my last brake job I pulled the rear calipers & brackets off the car so I can prep & paint them - left the L pin on & masked it for the prep & paint process and everything went back together with zero issues.