964 Brake Question

[Matt_West]

I have a 1980 911 SC. It is time to replace the master cylinder. Last year I overhauled the stock setup putting new rotors, pads and lines in the car.

The calipers probably should have been rebuilt at that time but were not. I just mounted a new to me set 16 inch set of welded Fuchs on the car. I was advised that these wheels are conventional offset and were not designed with the extra 1/8th inch caliper clearance.

Eventually I would like to replace the calipers and rotors with a more substantial set. I have an option for a good deal on 964 calipers. I notice the rotors are slightly smaller than 930 Turbo rotors but significantly larger than my SC rotors.

I don't know how the calipers vary diminsionly from the 930 calipers but note that the 930 calipers will fit inside of a 15 inch wheel...

So the questions are:
1. What wheels will 964 calipers fit inside of?
2. Which master cylinder should I buy? (23mm or 19mm)
3. What are the pros and cons between the 930 and 964 calipers?

[Todd Simpson]

Matt-

I don't know how much research you've done yet, so forgive me if you already know some of this.

The 964 calipers will not bolt up to your car, nor will the rotors. They can be modified in several different ways, none of which are cheap or easy. Here's a thread where I reviewed some of the details of the VCI 964 conversion on my '71T, which has the same suspension you have.

VCI 964 brake upgrade

So the questions are:
1. What wheels will 964 calipers fit inside of?

I bolted up a 17x8 Lindsey fuch to the front of my car. That wheel uses a 16x6 center so that wheel should fit as well. 16x7's also fit well, no spacers needed.

2. Which master cylinder should I buy? (23mm or 19mm)

23mm once you've gone to 4 piston calipers.

3. What are the pros and cons between the 930 and 964 calipers?

The 930's are better in my book because you can easily use the 930 28mm rear rotor while the 964 wants a 24mm rotor. You can squeeze a 28mm rotor in the rear with some additional machining and sanding down of the pads. 964 fronts are also not as wide.

Here's another page to give you more detail. Bill Verburg is the resident brake expert here and a search on his name will get you dozens of pages of brake upgrades. In addition to Bill, several others here have documented their 964, 993 and 930 upgrades in detail.

http://home.nycap.rr.com/wmv/generalbrmd.htm

[Jcon]

A lot of folks here believe the 993 calipers are a better option. I'm in the middle of this upgrade right now on my 81 SC. That being said VCI has a kit to get 964 calipers onto your SC

Here's the link http://www.vehiclecraft.com/Brakes/VCI911_2_964.htm




I don't think you can get these under 16 inch wheels.

You should look up Bill Verburgs home page. He has a whole section on brake upgrades along with pros and cons and whats needed.

Good Luck

Jeff

[Jcon]

Heres the link



http://home.nycap.rr.com/wmv/generalbrmd.htm

[Matt_West]

Thanks I appreciate the thoughtful responses and links. I know from having used the search button that questions around brake upgrades get beaten to death... and I also know that I don't want to get Bill riled by suggesting that I might use the 4 mm thicker Carrera and just oval out the holes on the 964 caliper...

Still I hear the 930 calipers while easy to change out brake pads are prone to squealing. Plus I have called around and have not located a used set at a reasonable price. Thus the interest in options.

The key here is going to be a phased upgrade. Thus, Can I run a 23 mm master cylinder on SC hardware? I would guess yes, but that the pedal might firm up quicker and require more pressure to effect the same stop as the 19mm cylinder.

Thanks again!

[Bill Verburg]

I also know that I don't want to get Bill riled by suggesting that I might use the 4 mm thicker Carrera and just oval out the holes on the 964 caliper

If you don't care about improving performance and only want to change the appearance of your brakes and want to use Carrera rotors then get Boxster calipers, they shafre the ease of mounting of the 993 calipers but are happy w/ 24mm rotors

Still I hear the 930 calipers while easy to change out brake pads are prone to squealing

calipers have little to do w/ squealing, pads do

you obviously have a lot ot learn, trial and error will get expensive, good luck

[Matt_West]

Thanks for contributing Bill. I will continue to study your web pages and previous posts. Hopefully I will be able to find my way without too much needless expenditure.

My comment on the sqealing was related to a tech article I think by Thom Sharpes and also feedback from a shop owner friend (although in truth it may also have been due to the floating rotors.)

Anyway I can't seem to find the thread where people were warning the the swap to the 23 mm master cylinder with otherwise stock SC hardware might not necessarily be an upgrade. It was in this thread that there was some talk of what the effects would be.

This matters to me because I have a failed MC that I would like to replace. I would like the replacement to allow for future upgrades.

[trak ratt]

I did the 951 front calipers, Carrera rears and Carrera rotors on my SC last year. I used the Turbo master cylinder and CM#97 pads all around. Oddly enough the #97s for the 951s are cheaper than the Carrera’s. They fit nicely under my 7” and 9” by 16” Fuchs and look like they would under 15s too. Even taking my time to maximize the pad fitment egging out the front calipers only took about 2 hours. I needed a new master anyway so I upgraded rather than rebuild. If you check with some of the local shops and older track guys you will probably find that this was a common swap 15 years or so ago. I got all my the pieces for next to nothing but you can likely source all four of the Carrera calipers for what a rebuild kit cost for the 951s.
The strictly Carrera rotors and calipers on the SC is a nice upgrade but would require a bias valve.

[Bill Verburg]

This matters to me because I have a failed MC that I would like to replace. I would like the replacement to allow for future upgrades.

The 23 can be used w/ your stock calipers, the down side is increased effort for a given stop.

although in truth it may also have been due to the floating rotors

floating rotors do make noise, I wouldn't describe it as a sqeal

The strictly Carrera rotors and calipers on the SC is a nice upgrade but would require a bias valve

that is true, but if you only do the fronts where the issue is, then you don't need the p/v

[Matt_West]

Just wanted to post an update. I have installed a 23mm master cylinder with the intent of some sort of caliper swap in the future. As many had indicated the pedal is much firmer and higher than stock. The brakes function fine, but are harder to modulate near the limit. I attribute this to the combination of a greater pedal effort over a shorter travel.

Imagine pushing really hard and trying to find the perfect place to hold accross a very small amount of pedal travel, versus an appropriate amount of resistance across an appropriate range. The first is the effect of what I have done, the second is what excellent engineers do when designing a proper SYSTEM.

[martin_gibson]

Matt,

Have just installed the 993 front calipers (Probraking) and 965 rear calipers (VCI) to my SC using 7"x16" 951 fuchs on the front and 8"x16" 911 Fuchs on the rear and a 23mm MC.

The brakes are incredibly powerful and very well balanced and I would highly recommend this configuration.

Martin Gibson
911SC 3.6

[JeremyD]

Originally posted by martin_gibson
Matt,

Have just installed the 993 front calipers (Probraking) and 965 rear calipers (VCI) to my SC using 7"x16" 951 fuchs on the front and 8"x16" 911 Fuchs on the rear and a 23mm MC.

The brakes are incredibly powerful and very well balanced and I would highly recommend this configuration.

Martin Gibson
911SC 3.6

I'll second this - they work great on the track - probably 3x adequate on the street.

You can also use the 964 calipers on the 911 - probably the largest shortcoming is the rear where you can get some nasty effects if the pistons are pushed out too far - and the pad does not quite fit properly. and VCI wants big money for the maching.