Im looking to update my brakes on my 87 Carrera. Will be going to x-drilled rotors, and new pads, but am also considering calipers, the 4-piston Boxster calipers. I'm told that there is no rear upgrade available for the Carrera, and I am worried about shifting too much braking to the fronts. However, I've also been told that the stock rear calipers work out just fine with the Boxster frnt upgrade. Any experience out there on the subjethis set-up?

I'm also looking for recommendations for a street/Auto-x/DE pad. For auto-x, I dont want something that takes too long to warm up. Comments welcome....

 

The Boxster front calipers with your standard 87 rear wide M calipers have a hydraulic bias ratio of ~1.83 this is a little more front bias than the normal ~1.6 for non ABS cars. Be sure to remove the p/v which is on the rear circuit.

The problem with this setup is that the rotors are the same size as you currently have . You really don't gain any ability to handle the thermal loads. The limited thermal capacity of the earlier brakes is their main shortcoming.

 

Herb, I have Alcon Brakes and rotors on my '87 and they work really well. I run Pagid pads in them for DE events. They will fit under 16" wheels and are very well built. The only problem is that you have to make a custom hard line since the Alcon's use AN-3 fittings on the calipers instead of metric.

James

 

Bill- thx for the bias number with the Boxster calipers. Regarding the pressure regulator, does it actually regulate under all conditions, or does it only come into play during hard braking? Is the bias the value before of after removing the pressure regulator? Last question (for now) is there an off-the-shelf replacement adaptor that fits in-line to take the place of the regulator? Thx

James - are you running Alcons on the fronts only, or both front and rear? Do the Pagids take a lap or so to come up to temp or are they solid cold? Thx

 

The p/v becomes effective at 33 bar line pressure, this is a fairly low line pressure and the reduction factor is .46, this means that the line pressure is almost cut in half relative to the front line pressure from that point up.

Again to improve the thermal properties of the brakes you really ought to go to 304x32(or better) front and 309x28 rear rotors with appropriate calipers.

 

Hi Herb:

I'd simply chime in and echo Bill's Boxster Brake assesment & solution.

Although it's not the cheapest, one of the very best solutions IMHO, is the Turbo brake one as it fits inside all Fuchs wheels and provides excellent thermal reserves,.......

There's no such things as a really good, effective cheap brake upgrade,......its mutally exclusive, I'm afraid.

 

What aspect of your existing brakes are you unhappy with? In other words, what do you want to correct with an update?

The answer to that question will guide the best solution.

 

Herb,

You've probably already done the research on "cross drilled" rotors and understand the differences between "cast in" holes and drilled holes, and the effect on rotor life.

If you're going to use the Boxster calipers on the track, you may want to do more research. There is some practical experience and opinions by those in the know that says the Boxster calipers can overpower the Carrera-sized rotors. That can mean rapidly boiling brake fluid and cracked rotors. There's at least one vendor who stopped selling them awhile ago, because of this type of experience with it's track customers. For the street, if you need to upgrade, it probably works fine.

You probably already know also that upgrading the brakes won't stop you any quicker. In general, a brake upgrade gives you greater heat sink capabilities, so you can go longer between needing to bleed your brakes, and may extend the larger brake pad life.

I upgraded my 911SC brakes to Turbo brakes. There's an article on tech.rennlist.com that discusses that upgrade. There are also some pictures in the last part of the 911SC FAQ, also on the tech.rennlist.com site.

 

Herb:
You could also upgrade to 993 TT brakes. I ended up doing this to my 84 911 two years ago. The plus side is, the parts are cheaper than the 930 brakes (at least that is what I found at the time). The negative is that you will have to also get some 17 inch wheels. I started club racing after doing the upgrade and first set of rotors have have lasted 5 races, plus a lot of drivers ed. Like Bill said the real advantage is greater heat dissipation. I am able to use a medium aggressive pad (which extends rotor life). Racing pads will take more heat, but are harder on the rotors. I also put in a 930 master cylinder. I know a few guys who use the Alcon brakes and are happy with them.

Remember, if you change the brakes, and plan on club racing, this will bump you up to E class.

 

As Bruce Anderson discussed in the last issue of excellence , we make the complete front and rear Boxster kit for 911. This gives you the option of a well balanced (no proportion valve or larger master needed) kit that does not require larger wheels, different offsets, etc. Despite the "thermal load " discussion, they actually work extremely well under track or street conditions. In a perfect world with larger budgets, the other upgrades suggested here would outperform this kit, but make no mistake, this set up works much better than the stock Carrera brakes and costs considerably less than the other options.

 

There's probably a very good reason why this WON'T work, but is it possible to use adapters on the Boxster calipers that would accomodate larger rotors and still fit under 16" wheels?
Greg

 

I suppose there is a slightly larger rotor out there that would work with the boxster calipers and another set of adaptors. But by the time all the prototyping, research on rotors, etc were done, it would have been less expensive and timely to buy 17" wheels and big reds/ 993TT rotors.

 

I'm not really that knowledgable about brakes, but what about getting some turbo front calipers, and just moving your existing front calipers to the rear? I know that this is the methodology a lot of american tuners use. I'm not sure if it would work here, but I noticed one or two comments about uprated new front brakes overpowering the rears.

Hope this helps, let us know what you eventually do and how it turns out!

 

Utilizing a front Boxster or front 930 brake conversion will not work properly. With either one, the driver locks up the front brakes prematurely. Installing a proportioning valve helps somewhat, but take time to set up and negates most of the gains on the larger front brakes.

 

All- thanks for the responses thus far...good to see this is a worthwhile topic. I'll try to answer some of the questions on my rationale for the brake change first. My front rotors are shot, one is warped, they both have wear. The calipers are in fair shape but the dust seals have to be replaced for sure, and while I havent popped the pistons, I'm guessing they may be ready for replacement. I rebuilt my 951 calipers a couple years ago, and the replacement parts werent trivial, when you get into adding new pistons. The steel calipers on the Carrera also weight a ton (10lbs each I guess). Hence, fresh, new, lighter calipers are sounding pretty interesting to me. I've seen the Boxster calipers for sale at Cresent for $235 each. No adaptors of course. There are other kits out there, as the folks above discussed (TRE, EBS, etc.) My rationale for using the Boxster setup is cost driven in part (none of us, OK MOST of us, arent made of cash) but also performance driven in part. My driving is mostly street, with several auto-x events per summer. For the street and auto-x, I figure the larger pad area of the Boxster brake will be an improvement. While the rotors are the same size, my expectation is that cross-drilling will help in heat dissipation (perhaps this is a wash with the reduced mass from the drilling.) In any case, street and auto-x driving doesnt put me at the thermal limit anyway...there just isnt the continuous, high-speed brake use. I plan to hit the Glen in June and there it will be a different story. However, I thinking a good set of Hawk pads, and front brake ducts should help the situation considerably. The ducting (while useless for auto-x)should be useful on the track where the average speed is a lot higher. So thats that. The turbo brake conversions sound like the way to go to get the max braking performance, but I cant justify the cost (>$3K)...at least not now. My car only has the stock 217 HPs...before I go the $3K route on stopping, I'd rather improve the handling via T-bar/shock updates (and look to get a few more HPs). Hence, if the Boxster calipers up front add a benefit, and I'm guessing they might, I'm interested (with new rotors, pads, etc). Doing front and rear in the Boxster setup is also attractive, but cost is a consideration. EBS has the front kit for $680...calipers and adaptors only.... add the pads, rotors, and lines, your good to go at $950. Not too bad. I think what I'm looking for (and likely some others) is a F/R kit for double that (<= $2K) but it doesnt exist...yet. Anyhow, thanks for the input thus far. Let me know where my logic is wrong, while I ponder how to burn my spring Carrera cash allotment.