77 930 with 993 brakes - somethings wrong

[red390gt]

The previous owner of my 77 930 installed 993 brake. As you can see by the picture of the rear brakes, the wear marks show the pads are not sitting on the rotor correctly, not covering is 100% like they should, seem to be only covering the rotor area about 60%. Is this a common problem? What's wrong, did he install the wrong rotors or a wrong bracket?

[jimtweet]

we need some pics from the backside...

i dont want to scare you, but that does not look safe...id be really curious to see how that caliper is bolted on.

[red390gt]

[red390gt]

It seems to be bolted on solid, both side look exactly the same.

[IMR-Merlin]

Yeah, something does not look right to me either. I make a lot of dual caliper brackets for bikes and have seen people do this on them. The caliper mount is not even close. Could this be the for the front?

I would be wary of an installation where someone not only rattle can painter the calipers, but the brake lines, nipples and even the rubber dust covers.

Is it a safety issue? You might have some brake bias issues though. You will also have some f'ed up pad/rotor wear though.

[Flieger]

That rotor is 3 sizes too small for that caliper.

[full quack]

Well now, did '77's have front mounted calipers? I was not aware of that, seems like the later 917 style brakes changed even more than I was aware of.

I'm a machinist by trade, and those home made brackets are a disaster. I mean stacked up washers to get the caliper centered on the rotor, give me a break.

Plus 1 on the "overall" paint job, nice......

The caliper is not mounted the same on the top as it is on the bottom, you can clearly see that the caliper is crooked.

This would not be on my car...no way Jose'.

Mark

[Facey]

'Homemade' brackets that due to mounting clearances do not have the pad sitting entirely on the rotor -> leaving the inside inch unused.

A larger rotor would make more use of those callipers, and with the typical floating hats you'd not have an un-scrubbed internal area. What pads are you using? What are they wearing like?

No expert here, but I do not think that this is dangerous (assuming everything is torqued appropriately). But I do wonder why a 77 930 would have 993 sourced brakes instead of the (stock?) 917 brakes??

FWIW the inside diameter is much less surface area and does a smaller portion of the breaking.

[Les Paul]

The 76 and 77's didn't have the 917 brakes. That came the next year.

[Facey]

my mistake.

[onboost]

Originally Posted by red390gt

The previous owner of my 77 930 installed 993 brake. As you can see by the picture of the rear brakes, the wear marks show the pads are not sitting on the rotor correctly, not covering is 100% like they should, seem to be only covering the rotor area about 60%. Is this a common problem? What's wrong, did he install the wrong rotors or a wrong bracket?

Improper brackets as pictured don't work well on the rear trailing arms of the early 911/930. Depending on which caliper being used, calipers need to have the holes filled, the mounting ears machined and then redrilled to fit properly, or there is another style bracket that has the proper contour to allow the caliper to sit at the proper height on the rotor.
VCI in NJ can take care of that for you.. 800-845-5948

Originally Posted by Les Paul

The 76 and 77's didn't have the 917 brakes. That came the next year.

Exactly, 76 & 77 had the same brakes and any other 911S of the era. that being said, one of the the simplest & most cost effective updates for these cars is the TRE Boxster Brake upgrade kit... lotta brake for the money and easily reverseable for the "collector" minded.

[Rodsrsr]

I'm going with the brackets as well. I have the TRE Boxster conversion on mine (love it.) and my front left rotor was showing a similar wear pattern only not as much. It turns out that the adapters look like they can be mounted either way and physically will, but are meant to be installed in a specific direction. Turns out I had one upside down and after correcting it the pad now sits correctly. Agreed too on those washers....that looks downright scary.

[TimT]

Those adapters are effed up.... look how far from the c/l of the rotor they hold the caliper.. The three washer offset spacers are bad also..

Finally that wheel spacer does not look to be hubcentric...

I noticed lots of scary things on this car from two pictures...

can't tell if the wrong rotor is used...but from the pics I would go over the whole car with a fine tooth comb

[timc]

Hard to tell, But I don't think you have gained any braking surface here, if by some chance you have I am sure it is minimal. I get that off asap. That is just a pure hack job. Scared to ask what the fronts look like....

[red390gt]

The previous owner didnt do a good job on these brakes, that's for sure. I'll start researching where to purchase the correct brackets and rotors, chime in if you know which brackets and rotors I need, I see someone mentioned VCI so i will talk to them.

Also, once all the saftey stuff is addressed and resolved I will re-paint & detail everything to get it looking better, just Blasting everything with yellow paint just isn't cutting it for me..PO's don't always worry about the next owner.

[red390gt]

I see in one of the above posts about VCI. I went to their webpage and they look like the same brackets that I have. Maybe the PO just installed them upside down and backwards like mentioned. I'm going to pull it all part this weeknd and see if that is the issue.

THe TRE site was helpful too, thanks for that info: http://www.tremotorsports.com/gallery.cfm?Node=10321

Here's the kit on VCI's website:

[911-32]

Originally Posted by TimT

Those adapters are effed up.... look how far from the c/l of the rotor they hold the caliper.. The three washer offset spacers are bad also..

Finally that wheel spacer does not look to be hubcentric...

I noticed lots of scary things on this car from two pictures...

can't tell if the wrong rotor is used...but from the pics I would go over the whole car with a fine tooth comb

I like your posts Tim - informative and knowledgable , but how can you tell from those pictures. The camera is not over the rotor centreline, so its not apparent to me that the caliper isn't in fact centred over the rotor. Surely that is what the washers are for, no? Agree the washers are bad. Also, look at the swept area of the inside rotor face. The whole of it is clean - unlike the outside. Why is that? It may be something other than the radial location of the caliper.

Don't get me wrng, I am not holding this up as an example of a good brake upgrade, but I think it needs more investigation before its thrown in the bin just in case the adapter is not the adapter is not the only problem.

[Helmsy]

Are rear caliper adapters different to the fronts? If so, the PO has tried to dummy up front adapters to be used on the rears. Either way they are the wrong adapters.

You will need proper rear adapters for the calipers you have and will almost certainly need to machine or replace the rotors.