930 Brakes on a MY '87 Carrera??

[Yetis]

Hello,
I've spend the last hours to get some information about this brake upgrade but there are still some questions. Here is my situation: Porsche 911 MY 87 converted to a '73 RS Replica and I want to use the 930 brakes front and rear.

- I have to use the 2-piece front (floating) rotor even with the older fender style? Are the very expensive? Where a good source to buy?
- I have to use the mc from the 930 right?
- What kind of rims and tyres can I cun? 7" and 8" in summer and 6" and 7" in winter - all Fuchs and 16". Will this work? Any spacers needed?
- Can I even run 9" and 245 tyre on the rear with the brake an a stock fender car?
- What about the cheaper way - just use the 930 brakes on the front. Does it make sense, what have to be changed (Mc, pv)?
- I understand that I have to modify the rear calipers but this has to be done so that I can not use the calipers back on a Turbo? As I see on VCI-website the old mounting holes are "destroyed". Can this be avoided?
- What about using a 930 rear arm or modify the Carrera one? Does that work too? How does it look like?
- Do I have to cut off the backing plate mounts of the trailing arms or what to do?
- What about removing the proportioning valve - I do not really understand this matter. What has to be done and for which reason.

Last but not least what is a good complete 930 brake system worth - without the specific front rotors? What would you suggest? Sorry for all the questions but I hope to get some answers and pictures.

Thanks a lot and have a good time
Alex

[Bill Verburg]

I have to use the 2-piece front (floating) rotor even with the older fender style? Are the very expensive? Where a good source to buy?

2 piece , yes. They don't have to be floating, They can be solidly bolted up.

I have to use the mc from the 930 right?

right

What kind of rims and tyres can I cun? 7" and 8"

Tha would be the minimum, 8 and 9 are better for many reasons. 15 or 16 your choice.

Can I even run 9" and 245 tyre on the rear with the brake an a stock fender car?

that would be best, as long as by stock fender you mean stock SC/Carrrera flare

I understand that I have to modify the rear calipers but this has to be done so that I can not use the calipers back on a Turbo? As I see on VCI-website the old mounting holes are "destroyed". Can this be avoided?

Only if you replace the trailing arms w/ 930 versions.

Do I have to cut off the backing plate mounts of the trailing arms

yes

What about removing the proportioning valve - I do not really understand this matter. What has to be done and for which reason.

ye and no, this depends on many factors. The basic 930 bias is good w/o a p/v but in some situations more front can be desireable. That's what a p/v does, move bias to the front.

Last but not least what is a good complete 930 brake system worth

A complete mountable setup will run north of $3k

[Yetis]

Hi Bill thanks for the quick answer.
- So I can't use 6x16" in front or will that work with spacers? I have to try 9" if it fits the standard rear fender. Does the 930 brake on the rear affect the tyre clearance in comparison to the standard Carrera brake?
- I guess using the 930 trailing arms is much more difficult/expensive than than modifiying the rear calipers. Or what is the reason for this?
- Can I also remove the complete backing plates - any negative effects?
- About the p/v - I can let the system how it is (just change to 930 MC)and then decide whether I better remove it or not? If I do not remove it I got more brake preasure in the rear, if I remove it I got more brake preasure at front - is that right?

Thanks a lot,
Alex

[Bill Verburg]

So I can't use 6x16" in front or will that work with spacers?

Never seen it, don't believe it will fit w/o pushing the wheel out too far. But it's a bad idea anyhow. 930 brakes are capable of generating a lot more torque than stockers you need to comensurately improve road grip.

I have to try 9" if it fits the standard rear fender

9" w/245/45 is a perfect fit for SC/Carrera flares

I guess using the 930 trailing arms is much more difficult/expensive than than modifiying the rear calipers

true

Can I also remove the complete backing plates - any negative effects?

yes, not really

About the p/v - I can let the system how it is (just change to 930 MC)and then decide whether I better remove it or not?

yes, you will most likely want to remove it but it does depend on extraneous factors

If I do not remove it I got more brake preasure in the rear, if I remove it I got more brake preasure at front - is that right?

No, you have it backward

[don911]

I have 930's on my 87. Bills estimate on cost is right on. I tried to get away with $2K but in the end it was closer to $3K. That was piecing it all together myself.

For wheels, I can tell you that 7x16 and 7x15 911 fuchs fit up front with spacers. I used a 5mm spacer and filed down the calipers. I didn't like this set up because it pushes the tires too close to the fender and I was cutting tires.

My current set up on wheels:
Street - Front: 7x16 951 fuchs Rear: 7x16 911 fuchs with 5mm spacer

Track: Front: 8x16 951 fuchs, Rear: 9x16 911/930 fuchs

[89911]

6" fuchs will not fit 930 front brakes without a spacer, at least on my car.

[Yetis]

Thanks to all.
About the 6" in front - I would use them as rim/tyre combination for the winter (yes I want to drive in snow ). If this do not work or looks pretty silly I would switch to the 7" in front even in winter. What is a good source for the front rotors - is floting or non floating the better choice?

What about the less costy version - to run 930 only on the front. Does it work - what have to be changed. I feel a bit sorry about the expensive calipers to modify them . They are getting rare. Wronfg concerns? The trailing arms from the 930 is not a real and reasonable option - is it?

@ Noah I've heard about the Lindsey wheel - do you have more information or pictures of it. Unfortunately we do have the German TÜV here - it would be hard to get them regitered in the paper of the car .
@ Don I hope I do not get the problems of cutting tires with the RS front fenders. I will see - the car is just in building process. What is your tyre size f/r?

Now I got it concerning the p/v. The factory eqiped 930 cars did not run it but the Carrera does - is that right?

Thanks a lot from Germany,
Alex

[don911]

What are RS front fenders?

My tire sizesL:
Street - 205/55/16; 225/50/16

Track - 225/50/16; 245/45/16

[Yetis]

Hi,
with RS front fenders - well since I'm building up a 73 RS replica out of my '87 Carrera. I have changed the front fenders, hoods etc. That was what I mean .

No problem with the 9" and 245/45/16 on the rear? Enough tyre clearance even in front with the stock fenders?

Thanks Alex

[don911]

oh, fenders for a long hood. gotcha.

9s on the rear are no problem. finding them, now that's a problem. You can still buy new 9" fuchs but they are getting really expensive.

[Jack Olsen]

The front rotors are available from Porsche. I don't know if anyone else sells the OEM ones. Floating/non-floating is not a big part of the decision, since you need to use the same rotors either way, and then use custom-made hats for them to bolt to. VCI and others can make the hats.

I wouldn't worry about the scarcity of Turbo rotors. They're the inexpensive part of this upgrade. Besides, in addition to changing the rear mounting holes, you'll also want to machine off the cooling fins on both the front and rear calipers so you can use thinner spacers with Fuchs wheels.

[Yetis]

Hello,

@jack: if I use the old style >'79 front rotors from Porsche 930 - is there a need for the custom hats from VCI and others? I'm a bit confused. I thought the old rotor style is enough if I buy them from Porsche?

What about the solution only for the front?
About the p/v - if I run the car mostly on street, some hard driving and a few times on a racetrack - what would you suggest (remove it or not)? I guess, there are also 2 different version of the p/v.

@ Don: Do you have stock fenders in front and can run 8" with 225 tires?

Thanks Alex

[}{arlequin]

i have used 930 brakes with 6x15" wheels before. i had to use a 2-3mm spacer everywhere, even with the cooling fins machined from the calipers.

if you use the early 930 master cylinder and 930 brakes, i would not use the proportioning valve. it works great without it.

[NY65912]

I'm in the midst of doing a similar install. My '80 Sc is being fitted with 930 brakes all around.

I sourced the calipers myself. Doug over at VCI did the machining on the rear calipers and provided me with custom hats and 12" rotors for the front. The rear rotors are stock 930.

My total for the project is $2800.00

[Yetis]

Ok,
but what iIdo not really know is whether I can use the oem rotors from Porsche in front or do I need the custom hats and rotors from i.e. VCI?

[don911]

I believe you can use the OEM hats that came on 78-79 930's. I think VCI's are copies of the original I believe. I can tell you that you can use VCI hats with OEM floating rotors so that OEM hats should be no different.
I don't know if you can still buy OEM hats though.

I used OEM floating rotors with the VCI hats and T-locks. Whatever rotor you use, you will need the VCI hat or the OEM hat.

[}{arlequin]

don't forget that Steve Weiner from rennsport systems also has rotors/hats for this application.

[Bill Verburg]

Whatever rotor you use, you will need the VCI hat or the OEM hat

Not quite right. You wull need a hat and rotor that match. The VCI floating hat is a match for the oem rotor and t-lock floating setup, they also sell a floating aftermarket rotor that uses that same hat/bolt set. They also make a non floating hat which is set up for either Colaman or Wilwood(I forget which) 930 size rotors.

You can also get a similar sized setup from Rennsport Systems and probably 3 or 4 other shops.

Most are not interchangeable w/ the others so you need to decide whose rotors you want to use first.

mychoice for track use would be the oem floaters, they are more expensive but are worth it.

For street non floating is more appropriate because of the noise of the floaters.

what iIdo not really know is whether I can use the oem rotors from Porsche in front or do I need the custom hats and rotors

See above, you need 2x hats and 2x matchiing rotors from whomever you decide to purchase.

choices are

• factory '78-79, floating
• aftermarket Willwood, floating or non
• aftermarket Colaman , floating or non
• cutdown factory 993tt, non floating

In the back you use '78 -89 1 piece 930 rotors and modified 930 calipers

For wheels and tires

• 7 & 8 x15 w/ 205/50 & 225/50 x15 tires
• 7 & 9 x15 w/ 205/50 & 225/50 x15 tires *
• 7 & 9 x16 w/ 205/55 & 245/45 x16 tires
• 8 & 9 x16 w/ 225/55 & 245/45 x16 tires

* there are no really appropriate larger size 15s

[Yetis]

Thanks @ all
now it is getting brighter in the dark . I will try to get a matching pair of rotors and hats here in Germany. Either OEM or an aftermarket product. If I fail I will contact rennsport or VCI. Thanks for the tyre/rim info. By using the 930 Kit, does the wheels come "more out"? Can I use 8" at front - it seems pretty big.

What about the 930 brake solution only for the front?

About the p/v - if I run the car mostly on street, some hard driving and a few times on a racetrack - what would you suggest (remove it or not)? I guess, there are also 2 different version of the p/v - right? To make it clear for me about the p/v - I take a picture.



Is it right that the p/v is # 6. Sorry about my english

Thanks so much.
Alex

[Bill Verburg]

Motiv would be the big supplier over there, though as here the parts are available form various tuning houses.

What about the 930 brake solution only for the front?

It would be an unbalanced and dangerous setup, TUV would have a cow

most people are very happy w/ no p/v

W/ the right o/s 235 and 245 tires can be used on the front.

the 7" +23.3ET fits well, the +23.3ET 8" would like a little more o/s but also works ok. Note a spacer subtracts from o/s