I have been searching for instructions to remove the rear rotors for replacement, but I have not had any luck. Does anyone know if there are disassembly instructions for the rear brakes somewhere in the forums. Oh, and my car is an '81 308 GTSi. Thanks.
Those are held by mostly the lug bolts, and the two guide pins, but crud accumulates making them seem to be welded on. Assuming you've already removed the 2 guide pins, put some penetrating oil where the rotor meets the hub, use a soft wire brush at same to get rid of some of that crud. A tap from behind with a rubber mallet should do it.
I didn't see any pins. I see two small holes in addition to the five lug bolt holes. Am I missing the two pins? It is the same on both sides, no pins. What do the pins do? Do I need them? I got the calipers off alright, but there is a lot of rust in there. I found Birdmans description of rebuilding the calipers, and that showed how to install them and adjust the pistons, so I have that. I'll try the rubber mallet tomorow. Thanks.
RJ, with the rotors on (mounted to the hubs) you won't be able to see the two guide pins because the guide pins extend out of the hub and into the backside of the rotor. I don't believe your rear rotor has a locking bolt (usually a small socket cap bolt with a recessed head) in addition to the lugs and guide pins holding the thing on, however, do give it a brush with a wire brush and see if you see an extra hole where a locking bolt may be located. The locking bolt serves to merely hold the rotor on the hub while the wheel is removed. If there's no locking bolt, and you have the lugs removed then the rotor should indeed come off the hub. As suggested above, give it a shot or two of penetrant (WD-40 is good) and a hit with the hammer. I usually use a block of wood against the backside of the rotor and hit the wood block with a framing hammer - seems to work well. Hit it once, then rotate the rotor 180 degrees, hit it again, rotate, hit, rotate, hit.....it'll come off.
You'd see the guide pins as soon as you took the wheel off if they were there, but it sounds like they are missing. The pins (#22 of attached) hold the rotors on when the wheel/ lug bolts are off, but I suppose the calipers do too. The pins (2 / each wheel) make it much easier to put your wheels back on. Using the pins and the small end of your lug wrench makes putting the wheels on easy. Image Unavailable, Please Login
Seemed like mine were welded on too. You could beat on them all day long with a rubber mallet and I promise you they ain't going no where. Save your self some heart-burn and go to a local auto parts store w/ a rent-a-tool program and rent a rotor puller. The only thing to quickly (and safely) pop those babies off.
Thanks for all the tips. I am going to try the WD-40 and mallet tapping first. I don't have great hopes for that since I tapped around a little last night, and they really did feel like one solid piece. If that doesn't work I'll have try to find a puller, as described above. I don't want to risk damaging them, since I planed to get them surfaced.
I did not have luck with that tapping approach. What I did use was a propane torch to heat up the interface areas, and a 2 lb hammer with a 2x4 piece of wood over the back of the rotor. And then, it took a tremendous amount of pounding. They came out.
I'm a fan of WD-40, but I'd try a couple others a well. For getting into crannies like that I like PYROIL Penetrating oil, and for outside nuts/ bolts like for your CV joints I like PB Blaster.... could be my imagination. I also was beginning to wonder if mine weren't one piece, and I was about to get a puller; but I kept at it with PYROIL and got a little more aggressive with the mallet, and they came off. You may want to save yourself some grief by just getting the puller as t3thomas suggests. You will be absolutely amazed how easy they go back on and come off once you clean that crud out of there. Good Luck!
When it comes time to reassemble, clean all the rust off and apply a light coat of anti-seize to all the areas of the rotor and hub that touch each other.
Thanks for all your tips. I have tried them all, even the torch, and the rotor is still absolutely welded. I will keep applying solvents as I am busy on another project this weekend, but if it does not come loose by Sunday night I am going to have to resort to cutting it off. I have already probably hit it too hard to reuse anyway. I can't believe the way the rust has fused the rotor on. I have seen bad before, but this is something else altogether. Strangely, the other rotor came off no problem. Just this one side.
After trying every method on this thread to no avail, the rotor finally came off yesterday. I had to remove the half shaft anyway to install a new cv boot. So with the shaft off, I removed the lower and upper a arm bolts and the damper bolt and took off the whole upright, hub, rotor and all. The caliper is still on the car. I took the upright to a friend who has a 10 ton press. I kept increasing the pressure and tapping with a hammer and the rotor finally popped loose. I think I was pretty close to the full 10 ton pressure. It would never have come off while still on the car. If I had kept wasting my time hammering at it, I would have eventually damaged something. Today I have to take the rotors to a machine shop and see if I bent it when I tried to remove it while still on the car. Hopefully it is okay to surface, but if not I learned a lesson for the future. Lesson is: If the rotor wont come off with a reasonable application of penetrating oil and light mallet work, pull the whole assembly off and use a press. It is really not that difficult to do. Plus, you wont damage the rotor in the process. If you don't care about saving the rotor, it might be quicker and easier to cut it off the car with the hacksaw method, but using a press works too. BTW, I used an extra long allen fitting that I bought at harbor freight on my 3/8 ratchet, and had no problems taking the half shaft off. I could reach up from underneath and reach both sides. I used an extension on the wrench to free the bolts, then ratcheted them off. It took about 30 minutes for both sides, and they were fairly rusty to begin with. The long allen wrench fittings were on sale for $9.99 for the set. Money well spent.
This may sound a bit obvious, but make sure the parking brake is released and you have removed the cables. If the brake is released but the cables are still in place, they can put enough pressure on the rotor so it won't come off. Guess how I found that out. <grin>
I don't know how much force it took when I used a rotor puller, could have been 10 tons, but whether it was psi, psf, or bmf I don't know. The puller bolt was so tight I had to use a cheater bar on it and just when I was about to give up it came off with a bang! Scared the s**t out me!
