alternative rotors for 79 930 turbo

[fredmeister]

Anyone have experience with replacing the front rotors on a 78-79 930 turbo? they have "floating rotors" which are bolted to a hat that in turn gets bolted to the hubs. Apparently the hubs were changed for later models 1980 and later to allow a cheaper one piece rotor. Can a different rotor be made or machined to fit such as a 993 or some other model that would save some $$. Any leads on this and a shop or dealer that does this work would be great.

[PhatA55]

Subscribed because inquiring minds want to know.

[WydRyd]

Don't know about just the rotors, but here are some nice upgrade options for the front:

993 TT caliper with 993 TT rotor.
996 TT caliper with 350 x 34 mm rotor.
Cayenne turbo caliper with 350 x 34 mm rotor.
Corvette Z-06 caliper with 355 x 32 mm rotor.

Then you can move the front callipers/rotors to the rear

[dewolf]

What's the difference between the front and rear calipers. Mine uses the same brake pad front and back, are they all like that? Is it the piston size that's different?

[PhatA55]

Originally posted by dewolf
What's the difference between the front and rear calipers. Mine uses the same brake pad front and back, are they all like that? Is it the piston size that's different?

It's not the calipers that are the issue, it's the rotors. Look at the cost difference for the 1978-80 turbo as opposed to later turbos. The front rotors will cost you over $800, that's JUST the rotors. The 1978-80 turbos get hosed on price more than any other model it seems. I wonder if they could be "upgraded" to 1981-89 brakes.
http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_BRKpad_pg4.htm#item11

[David]

EDIT: forget what I just erased here and go to the thread

a good thread on the subject The ultimate brake upgrade page.

[Jim2]

I'm currently running Coleman rotors spec'd and purchased through VCI. They saved some $$ over stock replacement Brembo/Zimmerman's, and they bolt-on.

I was a little concerned about some bad press in some old posts but once I tried the rotors they performed just fine. I've got a little over one season on them, mostly track use.

Jim

[turbodog]

This is a subject that has interested me since I also own a car with these "orphan" rotors. In regard to upgrading these brakes, I think you are missing the point. These are great brakes, torn from the 917 race car. I love that. Like the fredmiester I to am left a little breathless at the cost of these rotors. I have found replacement rotors at VCI but don't have any idea how good are: http://www.vehiclecraft.com/Brakes/vciweb4.htm
I too would love a good option.

[PhatA55]

I'm happy with the stock 930 brakes. I'm curious about the difference between 1977-80 brakes and 1981-89 brakes. Is one superior to the other? If not, what would it take to convert to the later style? Is it simply swapping the hub? I didn't see anything in the above threads that compared old style to new as far as OEM.

[fredmeister]

as far as I know there is no difference in stopping ability between them as the calipers are the same and the rotors are the same dimensionally.
If you look at the floating rotor design, from a pure racing/standpoint they are better because of the fact that they float and are independent of the hub deflections and thermal stresses from a fixed rotor. But are they worth the expense is a better question.
The change should invovle a later style hub which would allow using the later rotors, but what is the break even point to do this as a hub is not cheap either.
There has to be a way of using a 993 or other model rotor and machine it to fit the floating "hat"......at least I hope so, but noone has chimed in yet to let us know if this is true.

[David]

Originally posted by Jim2
I'm currently running Coleman rotors spec'd and purchased through VCI. They saved some $$ over stock replacement Brembo/Zimmerman's, and they bolt-on.

I was a little concerned about some bad press in some old posts but once I tried the rotors they performed just fine. I've got a little over one season on them, mostly track use.

Jim

That's good info, thanks.

At this point I'm thinking of doing the big red fronts and move the 930 front calipers to the rear, but it's good to know there's a reasonable alternative.

[PhatA55]

Originally posted by fredmeister
The change should invovle a later style hub which would allow using the later rotors, but what is the break even point to do this as a hub is not cheap either.

The upgrade cost would only be the first time, though. After that you're just paying for rotors at less than half the cost.

[palle7688]

fredmeister, you are right. Change to newer type hub and rotor will do it.
Be sure to sell your hats to someboby with narrowbody car that wants 930 brakes. PM me if interested in selling, cheap offcause:-)
Someboby metioned calipers diffs, piston size is the diff.

[fredmeister]

Anyone out there no of machined rotors that could be made to fit these floating hats?
Would really like to do that than change over to the later style hubs and rotors. Floating hats and rotors would be nicer, as they do have "better" characterstics technically.
Someone must have found a better way to skin the cat out there.

[BoxxerSix]

Originally posted by fredmeister
Anyone out there no of machined rotors that could be made to fit these floating hats?
Would really like to do that than change over to the later style hubs and rotors. Floating hats and rotors would be nicer, as they do have "better" characterstics technically.
Someone must have found a better way to skin the cat out there.

What's the bolt circle patterns of the 930 rotor? Example, a common bolts pattern for some floating rotors is 8 on 7, that is 8 bolt hole pattern on center to a 7" circle. I don't know that off hand right now, but if I can get that info I can search through the brake companies that I distribute for and see what pops up...

i want to say it's a 12 on 8 but i don't know for sure

[fredmeister]

I can try to find out, but I am not sure how because I would have to measure it and the rotors are currently on my car. I will see if it is called out in the spec manual.
Anyone else have a rotor off the car that could check this more easily than me?
thanks Adam, for the help in advance.
Fred