Brake upgrade - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Brucelee · 02-28-2005, 02:28 PM

For 3 large, I would drive more slowly!

andicati · 02-28-2005, 05:57 PM

Brucelee hit the nail on the head. 3k is a steep price to pay to avoid the headaches. There is nothing sweeter than simple bolt on kit but the way I look at it , if I can get the job done, even with headaches, AND I save some coin in the process, the feeling will be even sweeter. When I eventually get started, I will post some blow by blow pics.

By the way, the equivalent bolt on kit using the Twin Turbo brakes retails at 4.5k!

Brucelee · 02-28-2005, 06:06 PM

If it were me, here is the way I would handle a brake job. I have a very good, very reasonable mechanic who charges me about $60 per hour to work on stuff he can handle.

With a brake job, he can handle that fine.

I then go and find the parts, which I get at dealer cost. I bring them to him and I am usually out the door at 50% or less than Porsche dealer cost.

Obviously, I cannot do that on many Porsche repairs but when I can, I do.

I hope that helps somewhat.

Good luck''

JFP in PA · 02-28-2005, 07:29 PM

I've tried the twin turbo brakes, and while the mass due to the size difference will help disapate heat, I am yet to find anyone that has overwhelmed the S brakes...... In reality, brakes can become too large, and then you need to add more tire to compensate. "Seek balance, cricket".

And, unless I'm mistaken, the TT brakes will require a new master cylinder and brake bias system as well....................

andicati · 03-07-2005, 02:07 PM

Our learned friend JFP is mostly correct. Comparing the various brake systems we see the following:
Boxster Front 298 x 24mm
Rear 292 x 20mm
Boxster S Front 318 x 28mm
Rear 299 x 24mm
996 Twin Turbo Front 330 x 34mm
Rear 330 x 28mm

The increase in brake area shows:
Boxster => Boxster S: Front +20%; Rear +7%
Boxster => Twin Turbo: Front +33%; Rear +41%
Boxster S => Twin Turbo: Front +11%; Rear +30%

These calculations are based on rotor machined area, not the actual swept area which will vary slightly, but it gives you an idea of why the Boxster can massively benefit from an upgrade to S brakes as most of the braking bias is towards the front. The Twin Turbo brakes are only +10% larger than the S at the front which will most likely be hard to notice under normal driving conditions.

BUT! I don't have an S, just the standard Boxster. I do however, have Twin Turbo brakes. The marriage of the two seems be a good thing for slowing me down, especially after I have fitted a supercharger. As JFP suggests, larger rubber should follow the larger brakes. Luckily, I have the larger rubber already, wearing 225/45 and 265/40 17" Potenzas.

After spending a couple of hours on the car with a micrometer today, I have learnt that the rear calipers and rotors will be a simple bolt on with an 8mm spacer installed between the rotor and the wheel hub (as opposed to wheel spacers that are between the rotor and the wheel). I will see if I can utilize either the H&R or Eibach spacers, but they are both 7mm and will likely require the OD to be shaved a bit. Otherwise I will make my own.

The front system is going to be a bit more tricky. The caliper mounting bolts are 130.6mm apart on the Boxster compared to 142.3mm on the Twin Turbo. Also, the calipers will need to be raised 19mm above the wheel carrier to accomodate the large diameter rotor. This will then likely necessitate a 5mm wheel spacer to make sure my 3 piece speedlines clear the calipers fully, although I am praying that they will clear as is. I have a bracket design in mind, and will get this worked out on CAD to see if it will fit - anything to avoid $1400 + $1000 labor to install new wheel carriers!

I have been taking pics as I go along, so I will post these sometime soon so that other fools who follow won't be quite so foolish as me.

andicati · 03-28-2005, 07:29 PM

Progress to date: New Twin Turbo Claipers are installed but I miscalculated the rear caliper vertical positioning (i.e. distance from the center of the hub). The rear calipers require a 5mm spacer to put the pads in the perfect position for the rotor.

The other (strange) problem encountered is the park brake. The Twin Turbo brake change resulted in my park brake being completely out of adjustment. I haven't worked out if this is a "normal" function of messing with the brakes, or if there is some dimensional difference that I didn't notice.

Mods so far:
Front
- repositioned mounting holes on wheel carrier to account for wider spacing.
- 2mm spacer between rotor and hub to center discs in caliper and clear the dust cover
- 2mm spacer between wheel and hub to widen track and partially accomodate the rear widening

Rear
- 8mm spacer between rotor and hub
- 5mm spacer to raise caliper on wheel carrier mounts

Total cost so far: $1,640, including brakes, tools, and custom machined spacers. Compare with kit price of $4,495 plus labor quoted at $1,000.

The brakes look fantastic. Question is whether they will perform as hoped once I have finished this project. I have been taking photos and will work out how to post them.

Adam · 03-28-2005, 08:07 PM

Sorry to hijack your thread...but this is about brakes so I figured why not? Are the OEM brakes on the S made by brembo or Zimmerman? I see Zimmerman everywhere for replacement rotors. And, what is a reasonable price for OEM replacement rotors?

steven · 03-17-2006, 08:51 AM

have a look here at this forum http://www.germanlook.com/Forums/forumdisplay.php?f=10

Its a forum for VW beatles who tend to upgrade to porsche brakes quite often. My friend is in the process of upgrading the brakes on his beatle with 996 (i think) brakes and the cost is becoming ridiculous. There should be some useful info on problems you may encounter on the forum.