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PeterW · Joined: 17 Dec 2003 Posts: 78 Location: Auburn WA

1980 931...

I had a problem with my brakes locking up a few weeks ago, so I bought new calipers. I sent the old ones in as a core, I assumed (foolish me) that the parts I ordered were going to work. Received a set of calipers that did not fit, so I returned them and ordered a different set.... which also do not fit.

(and yes, I asked if they could return my cores but I was pretty much laughed at for asking)

Here are pictures...

Notice that the caliper is fully seated to the steering knuckle, although I do not have the bolt tightened.

Here you can see the caliper frame contacting the rotor. Clearly not right. The outside of the rotor is in contact with the caliper frame, the inside is about 3mm (.140" for those of us in the US, Myanmar and Liberia) away. Tightening the bolts makes the situation worse.

Looking straight onto the caliper frame, you can see the clearance problem.

Okay - Check that the rotors are correct for the application. Measures just over 21 mm thick on the wear surface, about 285 mm in diameter with a hub thickness of about 35 mm. Seems correct. Checked part numbers of the calipers against database - Centric 141.37011 and 141.37012. Matches several suppliers as fitting the car. Second set, different supplier, exact same problem. Took a set of 944 hubs from the junk yard, they appear to match and checked that the inner bearing seal was seated correctly - again, appears correct ASSUMING that the inner bearing seal is supposed to be flush with the rim of the hub, which is what is on the 944 hubs.

Where am I screwed up?? Is the seal supposed to be pressed further into the hub? Could I have 4 bolt spindles? If so, how did this work before? Brakes were from the PO, I assumed that the donor car was a M471 option but some kind of "magic" may have been performed.
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1980 931

Nein37 · Joined: 29 Dec 2009 Posts: 513 Location: New London, CT

I had the same problem when I replaced my front calipers. One of the calipers that I received fit perfect, while the other one had the same issue as yours. I explained the problem to the distributor and after sending back the incorrect caliper, he sent me a replacement.
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1981 931 CGT replica, OEM CGT intercooler, .8 BAR WG spring, GTS Headlights, Innovative Wide band A/F, A/C delete, 16" Fuchs, Weltmeister 200lb lowering springs, Bilstein HDs front, Koni Sport rears.

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

I would try a different vendor for your parts.

Otherwise the gap for the rotor needs to be opened up to be even on both sides by a machine shop (which is where the parts company dropped the ball)

Unless someone here has a good set of calipers that need to be rebuilt, then you can return those and get some rebuild kits and go to it.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

PeterW · Joined: 17 Dec 2003 Posts: 78 Location: Auburn WA

Nein37 · Joined: 29 Dec 2009 Posts: 513 Location: New London, CT

Its probably the re-manufacturer thats f%^king things up, not the vendor... but thats the vendor's problem not yours. Unfortunately since you sent in your cores you can't explain clearly the issue. It took me a few minutes to get my vendor to understand the problem and even then he was saying it was the right part #, but I had my cores and knew it was definitely not the right part.

I'll take some pics of my old calipers tomorrow and post them up. Then you'll be able to see the difference quite clearly.
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1981 931 CGT replica, OEM CGT intercooler, .8 BAR WG spring, GTS Headlights, Innovative Wide band A/F, A/C delete, 16" Fuchs, Weltmeister 200lb lowering springs, Bilstein HDs front, Koni Sport rears.

PeterW · Joined: 17 Dec 2003 Posts: 78 Location: Auburn WA

Okay... did something else just to be sure. The calipers don't fit on a known four bolt spindle, the bolt spacing is different.
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1980 931

PeterW · Joined: 17 Dec 2003 Posts: 78 Location: Auburn WA

Problem Solved - Just want to add this so others who may run into the problem can use the search to learn from my fail.

When I replaced the bearings, they were not correct. I don't know what I had (I bought them a year ago,) but the inner bearing that I bought was slightly thicker than the correct bearing. Using a dial caliper to measure distance from the backing plate SHOULD have shown me this, but apparently I was inconsistent with the point I was measuring from (I swear, I did it!!)
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1980 931