Anyone using 944 turbo calipers on early 930

[jly535]

I am looking at a pair that have been modified to fit 3.500" spacing. Has anyone done this swap, and is it much of an improvement over stock aluminum S calipers. Here is a pic, I plan on using these up front and putting aluminum S on back. Jamie

[spuggy]

I wouldn't rat-tail those holes. Your choice...

Here's how it's done properly, not cheap: http://www.vehiclecraft.com/Brakes/VCI911_2_964.htm

Your biggest issue with the early brakes is the rotors anyway - and you should run 28mm rotors with those calipers. At least on 911's, this requires a spacer to clear the A-arm, although there's a guy on the 911 forum who got away with notching it slightly IIRC - don't know if that's an issue on the Turbo Carerra.

I'd say nix on the S calipers on the rear.

Your best bang-for-the-buck bolt-on upgrade is 3.2 rotors and calipers front and rear, I think. My shop prepares many track cars - they say it's nowhere near good enough for the track, but it seems perfectly adequate for use on the street if you're sane. Depends on you and what you do with the car.

Anything has to be an improvement over the stuff you have on there. But keep it in a box if the rest of the car is original (it's got little re-sale value separately anyway).

I never drove my car with the original 'S' calipers, but the PO tracked it like that (he tracked Bimmers with chocolate brakes, and was young and brave). He says the 3.2 upgrade was/is a tremendous improvement.

I would personally go with the Brembo GTP-L kit or Instant-G's 993/996 TT setup, I think. I decided this after I bought a set of Boxster calipers, naturally...

[jly535]

Spuggy, what shop are you in? The calipers I am thinking of buying are same calipers in VCI kit, they are from an 86 turbo 944. I thought I would mill out the mounting holes a tad on each side to fit my mounts, really not much material removal. I am looking to upgrade to do occasional drivers events. If anything I would have the front calipers needed, just need to get rears then have VCI do their magic. The previous owner of my car ran several track days with Aluminum S in fronts and stock rears, not ideal, but held up. Just looking for best, cost effective upgrade. Anymore ideas? Jamie

[spuggy]

Originally Posted by jly535

Spuggy, what shop are you in? The calipers I am thinking of buying are same calipers in VCI kit, they are from an 86 turbo 944. I thought I would mill out the mounting holes a tad on each side to fit my mounts, really not much material removal. I am looking to upgrade to do occasional drivers events. If anything I would have the front calipers needed, just need to get rears then have VCI do their magic. The previous owner of my car ran several track days with Aluminum S in fronts and stock rears, not ideal, but held up. Just looking for best, cost effective upgrade. Anymore ideas? Jamie

Jamie,

Ive been thinking about and researching brake upgrades for quite some time now. And I've never even lost the pedal.

I see I wasn't clear. I don't own a shop, or work at a shop. I meant the shop I use to work on my cars since 2003. Owned and run by this guy (props to Craig 930 RS for posting the scan):



He knows a thing or two about Porsches. He's brought up the topic of brakes. Like when he PPI'd my car...

Bill Verburg over on the 911 forum is the resident brake expert. He considers the VCI upgrade "interesting", notes that it's mid-way in heat capacity between the 3.2 and the 930 brakes. When using the 951 rotor, please note. You were thinking of using the 951 28mm rotor, right?

Bill V has also said that hogging out the mounting holes on 964/951 calipers is not a good practice.

I think I'd prefer the machining and billet adapters, if you think about the forces involved when standing a 2500 pound car on it's nose from high speeds. But if you go that route, it's not cheap, and the 944T calipers don't then save you much over better (and bigger) solutions.

The VCI solution also has you modifying the pads on the rear to prevent overhang.

I haven't done the math, but you should check the bias ratio front/rear if mixing & matching random calipers...

If you've not seen it, take a look at this http://home.nycap.rr.com/wmv/generalbrmd.htm - and there's also lots of 911 brake upgrade threads already on the 911 forum.

3.2 brakes are a definate upgrade to SC/S brakes.

They're dirt cheap, parts are readily available (and also very cheap), bolt straight on, and I think they work fine on a light car. Certainly handle heat better than the smaller SC/S calipers over 20mm rotors would.

FYI, I also seem to recall that the aluminum S calipers overheat faster than the cast iron SC calipers. Ho hum.

After 3.2 brakes, it gets spendy pretty fast to do it right. Boxster calipers are light, stiff and look nice (TRE do a nice adapter kit) - but the weak link in 3.2 brakes is actually the thermal capacity of the rotors and the Boxster calipers just generate more heat. Somewhere around here you need to factor in a master cylinder upgrade as well.

930 calipers are not getting any easier to obtain, and 911 folks have been fitting them as upgrades for years, which doesn't make them any cheaper or easier to find.

The big issue with a narrow-body car is the '78-79 style hats and the scarce (or custom) rotors, because you can't use the late 930 rotors with the built-in spacer. If you can use stock late 930 front rotors (with the built-in spacer) in conjunction with your hubs/flares, that would be a lot cheaper.

But I'd suggest that stock 993 calipers are easy to find used (probably for much less than 930 calipers) and get adapters for to use over the stock 930 rotors. No machining.

Beyond a certain size, you need to start factoring wheel size/caliper clearance into the equation as well. Not to mention you're kidding yourself if you don't increase tire size.

Bang for the buck? Stock 84-89 3.2 brakes over 3.2 24mm rotors gets my vote, for >95% street use. Especially in a car that's lighter than a 3.2.

You might have all the same overheating problems at DE's that Brakezilla 3.2 owners have, but rotors, pads fluid etc. are cheap, you get to keep your stock M/C, and you don't have to change the wheels/tires. And learning not to over-rely on the brakes makes you faster anyway, (or so I'm told).

If you can use late-style (81-up) 930 rotors up front, I'd fit 993 calipers front and rear over factory 930 rotors in a heartbeat.


Good luck!

[iamchappy]

Hogging out the holes, is not good practice, but i have yet to hear of any caliper failures in doing it and many cars running on the track have done so.
My 914 has the 944t calipers on all corners, the fronts were hogged out by the PO to fit. My car
was a track car and must of managed to get through inspections that way. On rotors, the 84-89
Carrera rotors which i think are 24mm can be used as long as you keep and eye on your pads and dont allow them to get thin.
If you do choose to use them, use a nice sized washer to help spread the torque and support over
the mounting ears.

Those caliper ears look like they still have a good amount of metal around the holes.

[jly535]

That is a good write up on brake upgrades, answered alot of my questions. I think I will just plan on saving up for the 78 turbo setup with floating rotors or go for the 993/S4 setup. Thanx, Jamie

Originally Posted by spuggy

Jamie,

Ive been thinking about and researching brake upgrades for quite some time now. And I've never even lost the pedal.

I see I wasn't clear. I don't own a shop, or work at a shop. I meant the shop I use to work on my cars since 2003. Owned and run by this guy (props to Craig 930 RS for posting the scan):



He knows a thing or two about Porsches. He's brought up the topic of brakes. Like when he PPI'd my car...

Bill Verburg over on the 911 forum is the resident brake expert. He considers the VCI upgrade "interesting", notes that it's mid-way in heat capacity between the 3.2 and the 930 brakes. When using the 951 rotor, please note. You were thinking of using the 951 28mm rotor, right?

Bill V has also said that hogging out the mounting holes on 964/951 calipers is not a good practice.

I think I'd prefer the machining and billet adapters, if you think about the forces involved when standing a 2500 pound car on it's nose from high speeds. But if you go that route, it's not cheap, and the 944T calipers don't then save you much over better (and bigger) solutions.

The VCI solution also has you modifying the pads on the rear to prevent overhang.

I haven't done the math, but you should check the bias ratio front/rear if mixing & matching random calipers...

If you've not seen it, take a look at this http://home.nycap.rr.com/wmv/generalbrmd.htm - and there's also lots of 911 brake upgrade threads already on the 911 forum.

3.2 brakes are a definate upgrade to SC/S brakes.

They're dirt cheap, parts are readily available (and also very cheap), bolt straight on, and I think they work fine on a light car. Certainly handle heat better than the smaller SC/S calipers over 20mm rotors would.

FYI, I also seem to recall that the aluminum S calipers overheat faster than the cast iron SC calipers. Ho hum.

After 3.2 brakes, it gets spendy pretty fast to do it right. Boxster calipers are light, stiff and look nice (TRE do a nice adapter kit) - but the weak link in 3.2 brakes is actually the thermal capacity of the rotors and the Boxster calipers just generate more heat. Somewhere around here you need to factor in a master cylinder upgrade as well.

930 calipers are not getting any easier to obtain, and 911 folks have been fitting them as upgrades for years, which doesn't make them any cheaper or easier to find.

The big issue with a narrow-body car is the '78-79 style hats and the scarce (or custom) rotors, because you can't use the late 930 rotors with the built-in spacer. If you can use stock late 930 front rotors (with the built-in spacer) in conjunction with your hubs/flares, that would be a lot cheaper.

But I'd suggest that stock 993 calipers are easy to find used (probably for much less than 930 calipers) and get adapters for to use over the stock 930 rotors. No machining.

Beyond a certain size, you need to start factoring wheel size/caliper clearance into the equation as well. Not to mention you're kidding yourself if you don't increase tire size.

Bang for the buck? Stock 84-89 3.2 brakes over 3.2 24mm rotors gets my vote, for >95% street use. Especially in a car that's lighter than a 3.2.

You might have all the same overheating problems at DE's that Brakezilla 3.2 owners have, but rotors, pads fluid etc. are cheap, you get to keep your stock M/C, and you don't have to change the wheels/tires. And learning not to over-rely on the brakes makes you faster anyway, (or so I'm told).

If you can use late-style (81-up) 930 rotors up front, I'd fit 993 calipers front and rear over factory 930 rotors in a heartbeat.


Good luck!

[Gumba11]

I did my big brake conversion with VCI and He set me up with 13"X1 3/8" thick two piece (Non Floating) front rotors. Front, Rear calipers as well as rear 13" rotors are from 996 GT3. While this set up was as I recall near $5K with the master cylinder upgrade, it coupled with stainless braided brake hoses offers hand of god stopping power all day long.

My point being, I thought of looking for less expensive alternatives as well, but after years of trying to find just the right set up I went with the big stuff. I would hate to go to all the trouble of fitting calipers, rotors, etc... just to find out I still have brake fade issues.

Last, I dont like the idea of using a rat tail file to open up the holes on something that your life depends on EVERY single usage. I would find some kind of adaptor to make what ever you end up doing that isnt a direct fit work. Beyond just protecting your life, you could also end up threatening someone elses if something went wrong on the track or the street. I hate lawsuits.....

Just my .02............................................... Chris

[spuggy]

Originally Posted by Gumba11

I did my big brake conversion with VCI and He set me up with 13"X1 3/8" thick two piece (Non Floating) front rotors. Front, Rear calipers as well as rear 13" rotors are from 996 GT3. While this set up was as I recall near $5K with the master cylinder upgrade, it coupled with stainless braided brake hoses offers hand of god stopping power all day long.

My point being, I thought of looking for less expensive alternatives as well, but after years of trying to find just the right set up I went with the big stuff. I would hate to go to all the trouble of fitting calipers, rotors, etc... just to find out I still have brake fade issues.

Sweet.

I agree; I nearly fitted the Boxster upgrade, but then I decided I was going to do the upgrade once and do it right.

Last, I dont like the idea of using a rat tail file to open up the holes on something that your life depends on EVERY single usage. I would find some kind of adaptor to make what ever you end up doing that isnt a direct fit work. Beyond just protecting your life, you could also end up threatening someone elses if something went wrong on the track or the street. I hate lawsuits.....

Just my .02............................................... Chris

Again, +1.

The thing that makes me twitchy about brakes is that they could work fine with gentle usage for months. But all the forces and stressors are at their maximums when you're really, really, getting into the pedal.

Which is presumably because you need to either stop completely or to scrub off serious amounts of speed. That's not a good time to discover that your brake installation just isn't up to par...

[A930Rocket]

Unless you are smoking by everybody at the track, I keep the stock one. Pads are WAY cheaper. If you have to have bigger brakes, Big Reds up front and your stock front calipers moved to the rear will do it. I have Big Reds all the way around, but if I had to do it again, that's what I'd do.

What you don't want to do is over caliper the rotors by adding heat they can't handle. I tried 928S (or 928GT?)calipers up front and wasn't happy with them.