'78 930 Turbo Brakes, looks cool, why not? Options

[kdfoust]

So I'm browsing around on EBAY today and run across a turbo caliper from '78. Is there any big downside to using a set of them on my conversion car? Obviously, I've got to find a set first... (IMG:style_emoticons/default/biggrin.gif)

Here's a link to the auction so you can see what caliper I'm talking about.

Later,
Kevin

[Mueller]

So I'm browsing around on EBAY today and run across a turbo caliper from '78. Is there any big downside to using a set of them on my conversion car? Obviously, I've got to find a set first... (IMG:style_emoticons/default/biggrin.gif)

Here's a link to the auction so you can see what caliper I'm talking about.

Later,
Kevin

only downside is cost...I think all 4 calipers will run you about $1500 min.........but they will fit under 15" rims (IMG:style_emoticons/default/smile.gif)

[byndbad914]

the conversion gets brought up a lot - you could probably even do a search about it. I have them on my V8 car - you need 911 struts with the correct bolt spacing on the front calipers and the correct rotor and hat. The struts you just have to be sure you get the right set. The rotors and hats are available from VCI

http://vehiclecraft.com/Brakes/930_upgrade.htm

or you can use stock early stuff (either 77-78 or it's 78-79, you'd have to verify) but the stock stuff ain't cheap.

The rears require the caliper mounting be remachined. VCI does this and includes the spacers and such - then they bolt right up and use a turbo rear rotor.

I got all my floating rotors/hats/machining from VCI. I bought the calipers used and have RSR front struts fyi. Supposedly the VCI rotors wear faster than stock, but I can't verify that personally as I have limited use thus far. They work awesome though! And are about the only good upgrade caliper that still fits under 15s.

[Aaron Cox]

as mueller said... they arent cheap!

and i think boxsters fit under 15's

[Jeroen]

mounting turbo calipers isn't the problem (they bolt right up to a 3.5" strut)
the trouble is in the rotors

the 930 had spacers incorporated into the wheelhub so the rotor has a different offset than a narrow bodied 911

so if you mount the turbo rotor to a narrowbody wheelhub, it won't fit inside the caliper

and if you use 930 wheel hubs, the wheels are not gonna fit inside your fenders (unless you have flares)

so to use the turbo calipers on a narrow bodied car, you'll need custom rotors (or custom hats with floating rotors)
those are expensive and since rotors are a service item, that's not such a good idea (IMO)

also, do you really need calipers that big?
how big are your tires?
if the calipers are too big, all you gonna do is lock up your brakes

I don't know about your car, but you could be better of with SC or Carrera 3.2 calipers/rotors
the 3.2 has the same caliper (padsize) as the SC, but it's spaced a little wider to fit over thicker rotors

if those are not big enuf, you could use the 3.2 rotors with 944 turbo calipers (which only need a very small modification to mount to a 911 3.5" strut)

lots and lots and lots cheaper (both on initial purchase and later when you need to replace your rotors) and probably more than enuf braking capacity

[Aaron Cox]

whats a floating rotor?

[Jeroen]

oh... the 944 turbo calipers won't fit in 15" wheels (you need 16")
if you want to use 15" wheels, check on Boxster calipers (about the same size as the 944T calipers and also use a 3.2 rotor IIRC)
you need special mounting brackets for those
check with Rich Johnson (see the "resources" forum) for those

[Jeroen]

whats a floating rotor?

seperate rotor and hat
the rotor is bolted to the hat (you buy the hat only once)

check the VCI site, mentioned above

[dlee1967]

I love my 930 brakes. My only concern is when it is time to buy new rotors. Cha-Ching$$$ To get the most out of them you should use an agressive pad and they are not rotor friendly. DLee

[Aaron Cox]

whats a floating rotor?

seperate rotor and hat
the rotor is bolted to the hat (you buy the hat only once)

check the VCI site, mentioned above

oh got it....

slick.

[byndbad914]

whats a floating rotor?

seperate rotor and hat
the rotor is bolted to the hat (you buy the hat only once)

check the VCI site, mentioned above

yes and no... you can have non-floating with a rotor and hat (NASCAR setups for instance like Wilwood).

Floating is best described on the VCI site - but the short story is that the rotor is on "T" instead of hard bolted to the hat. The rotor can move back and forth on the T so that when you go through a corner, the rotor doesn't distort with the hat and hub. Keeps the rotor and pads parallel more or less.

They make a small rattling noise when you drive them, which is the rumor why Porsche went solid later - customers kept complaining that the car made noise while they drove it and wanted it fixed and couldn't understand why it couldn't be fixed. That is the rumor at least...

edit = a link
http://vehiclecraft.com/Brakes/rot_ques.htm

[John]

We simply bought a complete 930 front suspension and bolted it up to the front of our flared track car. We then got rid of all our front wheel spacers. 930 front ends are 2" wider than 911 front ends. 1" per side.

You will need a bigger master cylinder with 4 piston calipers. A 23mm works well.

For the street, I can't imagine NEEDING that much braking, but on the track with 2 drivers, we need all the cooling we can get.


Good luck Kevin.

I gotta go bolt my 3.2 in my car at last.....

[turboman808]

Is the rotor supposed to have some play in it. I noticed mine wiggles a bit but I figure thats how it is supposed to be.

Since when they wear out they just need the disc and not the hat I would think the price wouldn't be that bad (IMG:style_emoticons/default/confused24.gif)

[byndbad914]

Is the rotor supposed to have some play in it. I noticed mine wiggles a bit but I figure thats how it is supposed to be.

Any play you feel in a stock 914 setup is bearing play. There should be a minimal amount of play (can't describe, something you have to feel "right" at some point to know in the future). As races/bearings wear, you get more play until you sieze up and launch a wheel (IMG:style_emoticons/default/blink.gif)

Did that once on my old Mustang by over-tightening the bearing set I replaced (IMG:style_emoticons/default/headbang.gif) First time I ever did a set of bearings, and clearly didn't know what "feels right" was. Had a friend show me what "right" was the 2nd time around. Tore the rotor up pretty bad and the caliper is the only thing that kept the front tire on the car when it went...

[Jeroen]

yes and no...

err... you're right
you've got 2 piece rotors (still a seperate rotor and hat, but they're bolted together rigidly)
a floating rotor is "loosley" bolted to the hat (special mounting system, check the VCI site) that allows the rotor to expand (in diameter) when heating up
they can be noisy or have a "shudder" when cold
from what I know, that's primarily used to prevent warping

[Mueller]

Is the rotor supposed to have some play in it. I noticed mine wiggles a bit but I figure thats how it is supposed to be.

Since when they wear out they just need the disc and not the hat I would think the price wouldn't be that bad (IMG:style_emoticons/default/confused24.gif)

or your rotors can be loose with the attachment hardware about to fall out.......not a good thing.....

[turboman808]

so they are supposed to be able to float or not (IMG:style_emoticons/default/confused24.gif)

All the bolts were in and it was loose all around evenly. I better make sure with Dave (IMG:style_emoticons/default/biggrin.gif)

[jd74914]

do you have 930 brakes?

[kdfoust]

Holy mackarel! (IMG:style_emoticons/default/splat.gif)

I guess I had "forgotten" about these brake calipers and when I ran across them again today I un-forgot them.

If you can look at that VCI webpage and not want those calipers (IMG:style_emoticons/default/drooley.gif) you oughta sell your Porsche(s) (even the NARPs!) and buy a Prius.

I've actually got a set of S2 calipers sitting in the garage now waiting for that phase of the project (6 mos out). This car will have 17" as the primary wheel at that point. I don't see any reason to worry abou the 16" wheel minimum given that. I've been finding that the leading edge of high performance tires is quickly leaving everything below 17" behind anyway.

But back to brakes, simply put, I like the looks of the 930 calipers. It's not really a matter of necessity now is it? It sounds like quite a commitment in making the switch to those calipers though; much more than any other common conversion.

I'm gonna put the 930 calipers on my "watch list." If I find a used set I might just snap 'em up. I've 6 mos before I pull the trigger on this anyway. (IMG:style_emoticons/default/beer3.gif)

Later,
Kevin

[wbergtho]

Try to buy a 930 complete front suspension and bolt it right in. You'll have everything you need including the aluminum crossmember and the torsion bars...it all bolts right in.

Bill