Warped Calipers? Please

1.2gees · 1.2gees's Garage

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

drew1 · 05-01-2002, 10:42 PM

Ahmet,

Were the old pads wearing even?

drew1

1.2gees · 1.2gees's Garage

They seemed to have been...

The old pads took a lot of force to come out, new ones straight out do NOT fit. I can't put the old set on either, those also will not fit. Under anything more than moderate braking I locked up the rear tires, which is why I wanted to do the fronts, but I guess I'm going to need some calipers! Any suggestions for cheap upgrades? I've got a brand new set of rotors for the stock brakes, so I may just stick to that.
Ahmet

Scott R · Scott R's Garage

This is very interesting to me. My pads are too loose and move in the calipers. I was told that if I had purchased the correct pads that they would be a very tight fit and would not move. Do you mind me asking the make of the pads?

Lawrence Coppari · 03:22 AM

My pads are relatively loose too. They actually make a slight clunking noise when you back up as they move in the caliper when you first apply the brakes. I use PF which do it more than Rebco pads did. The Rebco pads would not hold up for track use but were fine for street.

Which dimension is off? Pad thickness or size of metal backing plate? Pads come in differing thicknesses - PF does anyway.

When you say 'drive in', do you mean driving the car to seat them or do you mean using a mallet to drive them into the caliper? Hammers and mallets should only be used on nails and some people.

emilysgranny · 05-02-2002, 07:05 AM

When it comes to brakes all kinds of wild things can happen . There can be a lip formed on the outer edge of the rotor from wear and rust build up.You can remove the caliper ,but can't put it back.We can eliminate this by simply having the rotors cut. Dirty fluid can stop the pistons from going in unless under pressure.An often over looked rubber hose that collapses and causes the pistons inability to return when you let your foot off the brake pedal, resulting in what appears to be a frozen caliper.Stainless lines help in this problem.Clicking of course is a sign of a loose pad in the carrier. Generally the carrier clip or the pad tangs are at fault here.You did not say if you had the rotors cut but if you believe the pad size is correct ,I would try having the rotors cut to eliminate that built up ridge ,then try your pads again.

GeorgeK · 05-02-2002, 07:12 AM

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

1.2gees · 1.2gees's Garage

I think George nailed it. I am getting different calipers btw...

Scott R, the pads should be somewhat easy to put in by hand, I wouldn't be concerned with a bit of movement personally. The pads are Hawk Blues, and I've double checked the part #s to make sure they are indeed what I should use, but ofcourse when I couldn't put the old pads in either I knew something was up...

Lawrence, the pads seem too tall. By 'drive in' I mean using force to make them fit. I know this isn't what I'm supposed to do but I did that only after decidint to get calipers for this car just so I could drive it until I got calipers, but no such luck.

Emilsgranny I've got new rotors with 0 miles on them, SS lines, new master clyinder and hard lines as well.

George K, I've replaced everything in the system except for the pedal, booster, and the front calipers, I guess I'll do the calipers now, thanks for pointing this out.

Thanks again for all the responses.
Ahmet

bogomili · 05-03-2002, 03:38 PM

Ahmet

Would you be willing to get an S4 caliper upgrade? I know it's some $ with adapters and all, but I've known of racer-types selling the kit for under $600 when they upgrade to big reds. They are amazing brakes and tremendous bang-for-the-buck. They have the same pad length as big reds/blacks and are as large as you can go and still keep 16" wheels. It sounds like you might need new rotors anyway, so you will be putting a few bills into brakes anyway.

You have an '86 Turbo right? If so, just getting the '87 & up calipers are a noticable improvement over the earlys (bigger forward pistons - less fade) and you can find these a little easier.

However, I think you could prob. find a few people that think of you as fortunate that you have tight fitting pads as everybody I know curses the way theirs knocks around in their slots. . .

Hope that helps
Matt

1.2gees · 1.2gees's Garage

I actually have new cross drilled rotors for this brake set, SS lines, new master cylinder etc. I machined my pads to fit in the calipers for this time around because I have some money invested in this set of pads/rotors. However I will consider another set of calipers (always had the thought in the back of my head) from an S4 if I could make it work. If you have a plug feel free to share it with me

I installed the pads as I mentioned after shortenning them a little bit.

Thanks again for all the responses.
Ahmet

bogomili · 05-03-2002, 10:22 PM

Ok, I feel quite foolish recommending S4's for you since your hub/ brake rotor offset is just not suposed to work without some exotic adapter and rotor combo like on Tom Pultz's S2 (www.944s2.com). Kinda throws the cost effectiveness of this upgrade out the window.

That said, I think a later caliper (still just baby Brembo 951 caliper, just the one w/ 40mm forward piston) might be a good upgrade. It may sound like it wouldn't matter much seing they are only 2mm bigger than your '86 pistons (38mm x 36mm) and will run same brake pad, but my experience is it does.

My 270 hp 86 would definately experience brake fade after pushing it hard on a given mtn. road - new x drilled rotors, new ss lines, new ATE blue fluid, pressure bled, new metal masters, stock 5/18 valve).

My 400 hp 87 w/ bone stock brakes and new blue juice & older metal masters, I could not get to fade on same road, and w/ increased hp, I push it further and brake later - considerably more stable and better poised under braking.

Perhaps there are other variables in this example, but thought I'd share one persons experience. I still am going to the S4 brakes because I want it for track events, but perhaps the late calipers are for you as your next step.

Matt

1.2gees · 1.2gees's Garage

bogmili, I know the S4s won't bolt up I'm still interested as I'm planning to track this car often.

On the otherhand, I think my brakes will be fine with agressive pads (Hawk Blue racing pads), and as for the fade of your 86 vs 87 drilled rotors will fade more compared to non-drilled using the same rotor size. If your 87 does NOT have drilled rotors that would explain your situation IMO.
Ahmet