Ahmet

I've worked as a mechanic on and off for about 4 years now. The hardest brake job I've ever performed was in the rear of my 180k mile (turned today) turbo. The pads were very hard to drive in. Well, I was hoping to replace the fronts today, but the new pads just would not go in on the new rotors. I, even after deciding to get a new set of calipers, and pads couldn't even drive the pads in to drive the car this week at all, eventually hurting them pretty bad. My calipers seem quite noticably warped, is this common? I'm assuming the pads should be a piece of cake to change on this thing. It was a piece of cake on my NA as with almost all other cars I've worked on.

Please comment.
Ahmet

luckett

[quote]Originally posted by over1g:
<strong> the new pads just would not go in on the new rotors. I, even after deciding to get a new set of calipers, and pads couldn't even drive the pads in to drive the car this week at all, eventually hurting them pretty bad. </strong><hr></blockquote>

Huh?

What are you trying to say here?

Danno

They should drop right in without any force needed. Since you've got 4-piston calipers, you really only want to do one side of the caliper at a time. If you remove both sets of pads and then try to squeeze the pistons back into the caliper, it will push the opposing set out. If you push the pistons out far enough, they fall out of the bore and won't go back in. Then you'll have to disassemble your calipers to get them back in. Don't ever use more force than you apply by hand.

Ahmet

Chris, the pads will sit in the caliper at an angle, otherwise they do NOT fit the caliper with a rotor present. The old pads came out with extreme force. It looks like the caliper is deformed, I'm guessing through extreme heat at some point. Pads/rotors were glazed pretty badly as well.

Danno, I've done brakes on many 4-6 piston caliper cars before. I don't have a piston issue, the pads will not fit in the caliper, even with the caliper off the car. Old set won't fit in either, and they were stuck in the caliper really good... I started the job because my rear tires locked up whenever I hit the brakes, and I heard a kind of a crackling noise from the left front caliper (the only front one I've tried!). I didn't really think it could've been a deformed caliper (I was guessing just some cheap old pads coming apart, or pads with no caliper grease, or something else along those lines), I haven't seen anything like this before. After replacing proportioning valve, lines, master cylinder and flushing fluid I decided to install the set of race pads/rotors I had already purchased (Hawk blue, nothing fancy) thinking this would be the end of suspension/brake mods for now. I can clearly see that my calipers are NOT straight, this sucks...
Ahmet

luckett

I've had pads that were a tight fit before, but it sounds like you have something more extreme going on here.

I'm still not sure what you're trying to describe.

[quote]Chris, the pads will sit in the caliper at an angle,<hr></blockquote>

We're working in 3D here, where an angle can have any orientation and magnitude. Can you clarify what this angle is relative to and it's approximate measurement?

[quote] otherwise they do NOT fit the caliper with a rotor present. <hr></blockquote>

Why? What's blocking the pad, the rotor? The piston? The caliper?

If they fit without the rotor present, I think we have found the one variable that is preventing the pads from going in. Is there a ridge on the outer edge of the rotor that the pad might be resting on?


[quote]It looks like the caliper is deformed,....I can clearly see that my calipers are NOT straight, this sucks...<hr></blockquote>

Have you measured it with a straight edge or are you just eyeballing it? Curved objects sometimes create an optical illusion when trying to determine their dimension by sight.

[quote] I'm guessing through extreme heat at some point. <hr></blockquote>

What have you been doing to create such extreme (higher than normal brake temp) heat? Maybe a sticking piston?


[quote]Pads/rotors were glazed pretty badly as well. <hr></blockquote>

Glazed pads are not rare

Regardless of the clearance problem, it sounds like you need to do a caliper rebuild.

BRB_85.5_NA

If the rotors were warped so severely, you would have noticed while driving it before--you of course would have a lot of front end shudder when you hit the brakes. If that were the case, the fix would be turning the rotors, not replacing the calipers. I found when I did my N/A brakes the first time that you do have to do a bit of fudging to get the piston to retract, so eventhough my breaks are different I would say that fudging is what you need a la Danno's advice. The only time I've warped rotors is in trucks with a heavy load. I can't imagine warping the rotors on such a light car unless there was heavy track use. How many 944 owners out there have warped their rotors?

B

IceShark

You can warp the rotors on these cars in street driving easy enough. Especially the way Ahmet drives.

Usually the root cause is unevenly torqued lug nuts or some hard braking and shutting down the car and the pads are in contact with that hot rotor in one spot causing uneven cool down.

luckett

Yeah, but were talking warped CALIPERS here.

IceShark

BRB was commenting on warped rotors on a light weight car. I don't know what Ahmet did to warp the calipers, if he has indeed done it.

Danno

photos...

I can't imagine warping a caliper; it would probably break before bending too much. My guess this 'angle' he's talking about is a lateral angle like camber on the tire (across the car). Which leads me to believe that the ears on the spindle where the calipers bolt on is bent.

photos....

Bob S. 1984 Silver

Danno..

I agree...

I have, over many years NEVER seen a warped caliper. (I've seen ones with stress cracks, though) There is another problem here which i would have to see to understand. Most of the time this is stuck pistons. The clearances, by dexign, are tight for installation on just about any caliper.

Bob S.

Ahmet

Chris, the rotors that are on the car right now have 0 miles on them. The pads will not go in the calipers at a position that is parallell to the rotor, that is all I meant by they'll go in at an angle. So I can put them in at an angle (still with too much force IMO) if the caliper's off the car. I've only had this car for a few thousand miles and the front brakes haven't really worked since purchase. Infact all the brakes were pretty poor, I've rebuilt the rear calipers and put new pads/rotors in. I was hoping I could get away with just pads/rotors in the front but I think I'm going to get another set of calipers for the front, rebuilding these alone won't do me much good. I'm not quite sure what the problem is, or how the previous owner caused it.

BRB944, I had really badly warped rear rotors but fronts are pretty straight. The rotors that came out of either end look really cheap specially compared to what I'm replacing them with.

IceShark, I'll admit to a couple of instances of riding the brakes to see how much boost I can produce in a given gear but not for a long time. I haven't really driven this car hard yet (just accelerating when I have plenty of room) because every time I got on the brakes it would lock the rear up...

I can take measurements with these calipers if you guys want cause I think I'm going to clean them up to be used as decoration at my new place (along with that axle I broke, and various other things).
Ahmet

Ahmet

[quote]Originally posted by GeorgeK at another message board:
Hi Ahmet,
Sounds familiar. Inside the opening for the pads are "skid" plates of SS steel that are screwed to the caliper with allen screws. They are there to ensure that the pads move freely in the caliper.
what sometimes happen is that the alloy of the calipers corrodes and that creates some oxide form UNDER these plates, moving them away from their original position, thereby making the room for the pads insufficient.
The cure is to take apart the calipers (in 2 halves), unscrew the plates, clean and reassemble. I have done this once, and the screws holding the plates were so stuck...
Maybe you're better off with better calipers anyways, considering the mileage if the car was neglected before you bought it.
GeorgeK <hr></blockquote>

I think I agree with this and I'm planning to get different calipers.

Danno

photos...



One thing you can do is swap the calipers from one side (front &lt;--&gt; rear) to see if the problem goes with caliper or stays on that corner. If the problem goes with the caliper, it's in the caliper. If the problems stays, then it's something else.

"The pads will not go in the calipers at a position that is parallell to the rotor, that is all I meant by they'll go in at an angle. So I can put them in at an angle (still with too much force IMO) if the caliper's off the car."

Ah I see, so the angle is longitudinal. Like with the leading or trailing edge of the pads touching the rotor first?

Ahmet

Danno, yes.

I've had the caliper off of the car and on a bench, pads do not fit. This is clearly a caliper issue.

I'll try to get you pictures, but it looks like I'll be busy at least for a few hours, and I have a night class tonight.
Ahmet