Porsche Boxter Brakes ?

[OhChit]

I have a complete Set of Porsche Boxster Brakes that I would love to install onto my Suby powered 1987 Westy.. Only problem is how do I do it? Also my wheels are the 5x112 Mecedes so I want to keep them. I guess I'm looking at some sort of bracket for the Calibers, and Rotors with 5x112 lug paterns. But how do I get this to work?
Any help would be appricated.
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Fast Cars, and Slow Women Makes me DrooL.

[Dingchowping]

Hi OhChit,

Do you have standard Boxster or Boxster S calipers? I'm in the process of installing Porsche "Big Red" brakes from a 993 Twin Turbo on my van using an adaptation of the BIRA System 1. The bracket is drawn up and the plans are at the machine shop, so its just a matter of time for him to make up the first set. Once I get the brakes installed on the van and insure proper fitment and performance I was going to offer a limited run of these brackets to anyone interested in an attempt to cover some of the initial machining costs.

Off the top of my head I know my bracket will work with the S caliper and I'm pretty sure it'll fit the standard boxster caliper, but not 100%. You'll need to use the brake rotors for a 2000-2002 Audi A8L/S8, and you'll need to turn the stock Vanagon brake rotors down to use as hubs. I also machined down a couple hub centering rings...one to better locate the rotor to the hub, and the other to adapt from the hub to a wheel with a 66.7mm center bore, but these aren't necessary. Still not sure what I'm going to use for brake lines. Haven't gotten that far yet. This system will fit behind most (but not all) 16" wheels.

I ran the numbers in the initial planning stages and discovered that installation of these brakes will cause a large brake bias deficit (surprise surprise) if the stock rear drums are kept, so rear brake upgrades are necessary to keep the van stable under hard braking and fully take advantage of the new brakes' performance. My solution (at least on paper) is the rear rotor from an Audi S5 with a caliper off the rear of an Audi V8 or a 200 with vented rear rotors. This isn't a perfect solution...ideally the rotor needs to be a bit larger, but then I'll run into clearance issues with the 16" wheels I'm running. Any bias issues that may surface can be compensated for with an adjustable bias valve.

Let me know if any of this sounds interesting and I'll keep you posted on the progress.

TTFN,
Adam

[BlackDogVan]

Hey Dingchowping, what size / source rotors are you planning for the fronts?

[porker buzz]

dingchowping are these for early or late vanagon front spindles

[Dingchowping]

As mentioned in my first post the rotors are off the front of a 2000-2002 Audi A8L/S8. Its just shy of 13" diameter and will fit behind most 16" wheels when used with the Porsche 993 brake calipers (not 100% sure about the 996 monoblocks, but they're virtually identical dimensionally so they should clear).

I'm putting these brakes on a '90 Multivan, but assuming the wheel offset is the same between early and later models the different rotor offset shouldn't matter, since you'll be cutting off the rotor. The only thing I'm not sure about is the mounting location for the caliper bracket. I'd have to look at an early Vanagon to see how it differs from mine. You may need to swap to later Vanagon uprights for my bracket to work.

TTFN,
Adam

[pete000]

Tristar Eric has done it. You need to make adapters and hubs to accommodate the rotors. I have been kicking this around forever. just too much effort for me right now. I have a set of 996 front brakes collecting dust on my work bench.
_________________
1990 Vanagon
--------------------
Koni Shocks
Witech Springs
Addco Sway Bars Front-Rear
OEM Porsche Wheels
Recaro Power-Heated seats
JL Audio, Kenwood, Soundstream, MB Quart, Audiocontrol

[Dingchowping]

[BlackDogVan]

[dbo550]

If i recall correctly at the shop that I used to work at we had better luck with the brakes from the 968. Mostly on jettas and golfs though.
_________________
1985 Westy
2001 Audi Allroad
1999 Volvo v70 xc
1995 Volvo T5-R, Yellow
1998 Jetta GLX

[Dingchowping]

[Tristar Eric]

I made 2 versions,

Version 1 is similar to what you're trying. 930 front rotors mounted to cut down Vanagon rotors, with Boxster S calipers.

Version 2, uses a custom machined hub that slips right onto the Vanagon spindle using Vanagon bearings. The hub has a custom machined hat that accepts a 993 TT rotor. 328mm dia Then I use the famous 993 TT calipers aka "big reds". They mount to the upright using my custom machined caliper adapter.

Version 2 is the ultimate in braking for the Vanagon.

My rears are from an 88 930... using Boxster S calipers as well.

Post some pics!
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Vanagon/Transporter flares here: www.terrawagen.com
[email protected]

[Dingchowping]

Hi Eric,

Just curious, how's the pedal travel/feel? That's a LOT of pistons you're displacing! I spent a lot of time calculating master cylinder piston displacement vs. stock in an attempt to avoid excessive pedal travel. You're the only one I know running a similar setup...I'd like to know what to expect.

Also, how did you deal with the parking brake? Separate caliper? Or just don't use it? I'm using the V8 rear caliper because I want to keep the parking brake function.

TTFN,
Adam

[Tristar Eric]

Pedal is super firm with the stock master cylinder. I also use a Wilwood adjustable brake bias valve. I found the rears to be locking first with the stock bias valve.

I made an internal hub e-brake like the 911's.

_________________
Vanagon/Transporter flares here: www.terrawagen.com
[email protected]

[Dingchowping]

[quote="Tristar Eric"]Pedal is super firm with the stock master cylinder. I also use a Wilwood adjustable brake bias valve. I found the rears to be locking first with the stock bias valve. [quote]

I bet! My calculations show that the stock brake torque bias is about 1.57:1. My guess based on the slightly smaller pistons used on the Boxster calipers vs. Big Reds is your static brake torque bias is somewhere around 1.2 without the bias valve. My system will err in the other direction, increasing bias 1.7:1. I'd like to get that number a bit closer to stock, but that requires bigger rotors (I'm already planning to run the biggest rotors that will fit behind 16" wheels with the V8 calipers), or bigger calipers, which isn't an attractive option for other reasons (cost, added piston displacement, rotor availability/compatibility, etc...).

[quote=]I made an internal hub e-brake like the 911's.[quote]

That is VERY cool Eric! Nice job. That would open a world of possibilities for more ideal caliper choices, assuming you can find a compatible rotor with internal drum. That would allow the Brembo 2 piston caliper used by Subaru for the STI and by Stoptech (the ST20). Thanks for the pics, Eric.

TTFN,
Adam

[a914622]

[quote="Dingchowping"][quote="Tristar Eric"]Pedal is super firm with the stock master cylinder. I also use a Wilwood adjustable brake bias valve. I found the rears to be locking first with the stock bias valve. [quote]

I bet! My calculations show that the stock brake torque bias is about 1.57:1. My guess based on the slightly smaller pistons used on the Boxster calipers vs. Big Reds is your static brake torque bias is somewhere around 1.2 without the bias valve. My system will err in the other direction, increasing bias 1.7:1. I'd like to get that number a bit closer to stock, but that requires bigger rotors (I'm already planning to run the biggest rotors that will fit behind 16" wheels with the V8 calipers), or bigger calipers, which isn't an attractive option for other reasons (cost, added piston displacement, rotor availability/compatibility, etc...).

[quote=]I made an internal hub e-brake like the 911's.

[Dingchowping]

Hi Jeff,

Are you talking about using the Toyota brakes for the front or rear? Do you have the specs handy? Rotor diameter, offset, bolt pattern, center bore, and caliper piston diameter/count? Is the caliper a floating style? I assume it is, in which case its a moot point.

TTFN,
Adam

[a914622]

Toyota 4 pot fronts from a 96 solid like the brembos/ 996 porsche . rotors are 12.4 dia. and 1.26 thick. I think the pistons are staggered size. 20mm front 19 mm back but im not sure of that. The rotors are almost the same as the Syncro offset and one of the 2 bolts on the caliper is almost the same as the vanagon. Rears are floating audis.

I was just think if you had a program that spit out the bias, it would be interesting to see what im running..

thanks jeff
_________________
87 gl powerd buy 2.5subaru
75 914 getting 2.2t subaru scratch that SVX subaru

[Dingchowping]

[pete000]

Here is an old picture I had of Erics Boxster set up.

Hey Eric I just noticed the bleeders are pointing down, whats up with that...

And is that a prototype H & R Cup spring on there? Interesting bend. I didn't notice that before either.

_________________
1990 Vanagon
--------------------
Koni Shocks
Witech Springs
Addco Sway Bars Front-Rear
OEM Porsche Wheels
Recaro Power-Heated seats
JL Audio, Kenwood, Soundstream, MB Quart, Audiocontrol

[onwardtothestars]

I'm not Eric but there's two bleeders, one up one down, so the caliper can be used universally on the left of right side of the van/car
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Beetle, Ghia, Vanagon Syncro, and more