Jeff Curtis

Recently, I've trashed my right front caliper, and considering that it would cost about $100 to rebuild it, and a good used set costs around $200...I've decided to pickup a good used set -or- due to the fact that a good friend of mine is ready to "hand over" a pair of 928 S4 calipers...that has got me thinking.

As I'm aware a few of you guys have made the upgrade, and seem fairly knowledgable in regards to it, maybe you can help me out with what I need to do.

So far, I know I have to reverse the crossover tubes, but will I need different rotors and a pair of adapters?? I haven't eyeballed the calipers as of yet, as I haven't been over to my friends yet to look over the many options he has to offer...including a set of Big Reds.

My issue is that if it's going to take a different set, even custom rotors and adapter brackets, why NOT just go with the Big Reds, he has a pair of those as well, but those will cost me.

So, basically, to put the S4 calipers on, would I need a set of adapter brackets? Also, to utilize the whole rotor/pad surface, would I need a different set or even custom rotors?

I know Cupcar and someone else was "hashing this out" a few months ago on here, I may search for the thread.

Thanks for any advice, I don't need any speculation at this point...just good hard facts.

***Okay, reading through some old posts:

Are the 928 S4 calipers the same as Big Reds except for the fact that they're BLACK? Again, I haven't seen the calipers in person as of yet...so they would require the same adapters and rotors as well? Can I use my factory rotors until I have the $$$$$$ to upgrade to the proper ones??

Adrian

Dear Jeff,
The 928S4 brakes are not the same as "Big Reds". There are some web sites around which deal with "Big Reds" upgrades. Maybe you want to check these out to find the specs of the brakes. <a href="http://www.techart.de" target="_blank">www.techart.de</a> springs to mind. I did have some links to a company in the USA but I seem to have mislaid them.
Ciao,
Adrian
911C4

SteveW@stig

You should really have a look at upgrading the rears as well. Due to the unusual weight distribution of the 911 (tail heavy) the rear brakes do quite a lot of work as well. This is especially important if you have an old C2 with the 2 piston rear brakes

Adrian

Also Jeff, what a lot of people do not admit to when doing these upgrades is the brake bias problems they have and the ABS problems they have. I know you have four piston rears because you told us you changed them. I have to agree with Steve though that a full package, front and rear may end up causing less problems overall.
If you go for the fronts only, I highly recommend you install one of those adjustable brake proportioning valves rather than a fixed one. If you go fixed, you will need a 964 Turbo one. They sort of work better but most people who have been kind enough to share their problems with me via email end up with adjustables. You have to take care that you do not outbrake the rest of your systems. Also remember that you have vacuum boosted brakes and not high pressure brakes. I think the 928S4 brakes are high pressure brakes ala 964 C4 and Turbos (yes Turbolooks and the RS as well). I am not sure if the reduced pressure you have would give you much better braking anyway. Or the improvements you might need for the track. Wheel fitment over the new calipers may also be an issue.
Ciao,
Adrian
911C4

speedster 94

hallo
The S4 and GTS Brakes are not highpressured ,they use the normal Vacuum Brake booster.
Harald

Bill Gregory

Jeff,

VCI at <a href="http://www.vehiclecraft.com/Brakes/vciweb7.htm" target="_blank">http://www.vehiclecraft.com/Brakes/vciweb7.htm</a> discusses some upgrade options, looks mostly like Big Reds, though. They certainly have done that upgrade before, you might consult them. Very knowledgable about Porsche brake upgrades - they helped me when I put Turbo brakes on the SC.

willC2

I have big reds on the front of mine, (although I had mine repainted yellow ), along with 964T2 (93-94) rears. The master cylinder wasnt upgraded, as I was told this wasnt necessary.

heres the component parts from my bill (in no particular order):

95135204191 964C2 RS rear discs (299mm) x2
96535293904 964C4 rear pads x2
96461236501 964 rear sensor pad x2
zscrew Caliper Plate Bolt x16
N0331671 screw disc
99906704209 Bolt Caliper 996 x4
96535104500 964T2 (93-94)Brake Disc (322mm) x2
99361236800 993C4S front brake pad sensor x2
99335194900 993RS front brake pad x2
CB001 993to964 Caliper Bracket x2

let me know if you need any more details, for what its worth I'll be at the garage this weekend


will

Jeff Curtis

First of all, thank you so much for the advice/responses.

I feel the need to mention, that I am only concerned with the issues I'm having with the front brakes...as I'm about to takeoff on a looOOOoooooOOong adventure to the Midwest to tryout some different tracks. My rear braking setup is "in the bag", no troubles, plenty of "UMPH" back there - just a bias valve changeout away.

I've had a few people privately email me to say, "go with the Big Reds!" I know, I know, please understand, the Big Reds will cost me about $600 for the pair, new, from the same source, the S4 calipers are pretty much for a "song", I'll spare you the details, plus they come with a set of fresh Pagid Orange pads.

So, considering the expense I've gone through for this damned car in the last month or so with extended studs/spacers, powdercoated wheels and bigger Hoosiers, my "disposable income" tree has wilted. - I just didn't plan on my bonehead error over this past weekend!!

Okay, here comes the deciding question: Will the 322mm front rotors from a 965 (964 Turbo) work for my conversion, whether I'm using Big Reds -or- the S4 Calipers?? Will the backspacing on the rotor be correct for my application?? I've had people suggest the use of this rotor, and I can get them for around $125 each...so if they'll work, I'm game.

Otherwise, if this turns into a big hassle, with needing custom hats and rotors, to the tune of @ $500, not to mention the $200 adapters - I CANNOT afford this conversion at the moment! <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

I have found out that I will need the adapters whether I use Big Reds or the S4 calipers, so I've accepted that expense...just have to figure out what the "right" rotor will cost me!

If the 965 rotors will work, WHY do people have the custom hat/rotor combo on their 964s that I see at the track?? Do they last longer or is it just the lightweight aluminum hats that attract them??

I just have to figure out the rotor issue, then make a decision, heck, my friend even has a set of good 'ol 964 front calipers, that he's willing to let me borrow until I figure out this conversion. I may just eliminate all the hassle and borrow those until I return from my trip...I just hope I don't TRASH those for him! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Adrian

Dear Jeff,
I do not have all the data handy of what works with what etc. However I will issue you a warning. Take extreme care. Beware "The no problems". I do recall a number of rennlisters who ended up having to sell their "mod kits" because they do not fit. I am pretty sure that the 322mm turbo rotor will not fit your C2. I highly recommend that you approach one of the reputable companies who deal with these issues and ask their advice. I am also sure the info you want is in the archives. There was a post some time ago about all of this and it was listed what did bolt straight on, what didn´t, what you had to do etc from oneof these companies.
The end result is though, big brakes cost big money.
Ciao,
Adrian
911C4

Jeff Curtis

Actually, I JUST received a response from one of those "reputable companies", VERY reputable I might add - they say the 965 front rotor will work, but is NOT the best answer...for longevity reasons alone.

Seems that the custom billet aluminum hats and custom sized rotors are the ticket, due to weight savings and longevity. They are likely not to require replacement half as much as using factory 965 rotors...okay, I can accept that.

For now, my friend who has the S4 calipers also has a slightly used set of 965 rotors (what a resource!), both from a street driven car, I can burn them up (the rotors) at a handfull of track events...and hopefully by then, I will have the $600+ for the custom hats/rotors.

Again, as far as the rear brakes are concerned, I have done the math, R&D, you name it, I already have a solution...trust me, I'm not exactly going with the "the no problems" idiology...I'm a fairly competent DIY'r and wouldn't compromise safety for savings.

The S4 calipers will provide 45% more pad contact and the end result with 322mm thick rotors is almost a 20% increase in stopping power, not to mention a tremendous increase in "heatsink area"...not bad. SURE, Big Reds would be better, but if you don't have a set to "loan" to me, then the S4 route I go!

So, you figure I'll have about $400 invested by the end of the week, if all goes well...as usual, I'll take a bunch of pics...and probably have to sell them to interested onlookers to bail myself out! <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

Maybe I should write a book to pay for my "964 adventures"?? <img src="confused.gif" border="0">

Adrian

Dear Jeff,
Writing a book will not pay for your modifications unfortunately. By the way I never questioned your abilities. If one is asking questions then one assumes the asker is not sure of what they are doing or what they need. I only have one concern in the end and that is, nobody wastes their hard earned money. Cannot help everyone of course. If I have learned one thing since I have been a Porsche owner, "it is very easy to waste money and damage your Porsche" which costs even more money. I also recommend especially with a 1990 C2 that you check the TSBs on the wheel suspension and possibly consider installing at some same the 964 Turbo wheel suspension components. They are stronger. Yes these parts do fit. One point of interest which was passed onto myself a couple of weeks ago by somebody who knows about brakes systems and 964s. Beware the rear brakes. If the calipers are too large you may run into problems with your handbrake,
Ciao,
Adrian
911C4

speedster 94

Adrian
You are right in using the 965 Turbo Wheelcarrier
instead of the Adapter BS ,that is why Porsche is
using this on the RS and also on the CUP RS .
I too think that saving Money on the Brakes can not only damage your car but also kill yourself.
Harald

Jeff Curtis

Adrian, I don't think you were questioning my abilities at all...it's just that some are volunteering advice and voicing concern in regards to my rear brakes - and I have that taken care of, I am concerned about what I should do about the front brakes.

I know all about the factory setup, but as of a few days ago, I didn't possess the knowledge of the specifics when upgrading the front calipers/rotors and the several options available to me.

This was supposed to be a "fact finding" mission...not a source for speculation, guesses and opinions - sorry if that sounds a bit harsh, but I felt the need to "go there".

After three days of endlessly searching the web...I'm inclined to say that I now know what it takes to mount S4 calipers -or- Big Reds...and have learned a little about upgrading the rears in the process - that will come later, what I have now is sufficient.

Harold, the adapters for Big Red conversions have been used for a long time, and it's pretty much a synonymous part in regards to upgrading front brakes on any Porsche, unless of course, I were to install a 965 wheel carrier/strut assembly...which I think is ridiculous, considering the other options available. So I don't think the use of the quality adapters that are available out there will be the death of anyone.

I don't want to turn this into a debate on whether I'm doing a "proper" or safe upgrade, safety is never compromised when I perform upgrades to my car, it goes hand in hand with what decisions I make...and I think bigger/better brakes in my case is the safe route.

The facts are in, you can take a 965 front rotor and a Big Red caliper -or- a 968 M030 rotor and an S4 caliper, a pair of CNC machined aluminum adapters, which by the way are far stronger than the original ears on a 964 caliper, and have a brake upgrade from hell that is both sufficient for frequent track use and VERY safe. There are several big name companies that advocate the use of such upgrades, not to mention some big names in some of the well known racing/performance venues - so I tend to think "It's OKAY".

As of this evening, I returned home from my friend's house with a pair of Big Reds and 965 cross-drilled rotors...all I need is a set of good track pads and the adapters...and I'm going to convert my 964 to Big Red brakes!!

Adrian

Dear Jeff,
Good luck with the conversion and did you write that book overnight to pay for the "Big Reds",
Ciao,
Adrian
911C4

PS: Please also remember when driving to and from the track. It is not how quick that you stop that is important, it is how quick the person behind you stops. You might only need 35 metres but if he needs 45 metres you is in big trouble.

Manny Alban

C'mon Jeff, be a real man and learn to brake with the stock C2 calipers and rotors Nothing like having your brakes go away midway through a race to teach you how to manage your braking techniques.