Boxster Calipers, got them installed today! Options

[SirAndy]

Question for you peeps...
did you orient the rear calipers so the larger piston was the leading piston? (i.e. LR becomes RR, and RR becomes LR, and you have to flip the bleeders to the top, and the x-over to the bottom).

Or did you just bolt them on, and let the smaller piston lead?

(I see a mix of the above on this thread)

Just bolted them on and ignored the pistons. Mounted so the bleeders are on top.

I doubt it will make any noticeable difference ...
(IMG:style_emoticons/default/popcorn[1].gif)

[Aaron Cox]

Question for you peeps...
did you orient the rear calipers so the larger piston was the leading piston? (i.e. LR becomes RR, and RR becomes LR, and you have to flip the bleeders to the top, and the x-over to the bottom).

Or did you just bolt them on, and let the smaller piston lead?

(I see a mix of the above on this thread)

I doubt it will make any noticeable difference ...
(IMG:style_emoticons/default/popcorn[1].gif)

I would tend to believe that also.. but the fronts use the larger piston as the leading piston (or so i thought?)
did a little digging on the reason for stepped/differential caliper bores. Sounds like bolt them on and go!

Differential bore calipers -- As the surface of the rotor heats up, the clamping force of the pistons has to be increased to avoid brake fade. If the caliper has multiple pistons (or multiple pairs of pistons), the brake rotor surface is initially heated by the pistons pushing against the brake pad at the leading edge of the caliper, making the rotor surface hotter when it rotates back to the pistons closer to the trailing edge of the caliper. Therefore it helps if the pistons closer to the rear edge of the caliper are larger. Differential-bore calipers use smaller pistons up front, larger pistons toward the back

[SirAndy]

Differential bore calipers -- As the surface of the rotor heats up, the clamping force of the pistons has to be increased to avoid brake fade. If the caliper has multiple pistons (or multiple pairs of pistons), the brake rotor surface is initially heated by the pistons pushing against the brake pad at the leading edge of the caliper, making the rotor surface hotter when it rotates back to the pistons closer to the trailing edge of the caliper. Therefore it helps if the pistons closer to the rear edge of the caliper are larger. Differential-bore calipers use smaller pistons up front, larger pistons toward the back

In that case it seems the way i mounted mine is correct? (IMG:style_emoticons/default/confused24.gif)

On the rear, the smaller piston is on top. I have to check on the fronts. (IMG:style_emoticons/default/idea.gif)

(IMG:http://www.914world.com/bbs2/uploads/post-179-1330327130_thumb.jpg)

[Aaron Cox]

Differential bore calipers -- As the surface of the rotor heats up, the clamping force of the pistons has to be increased to avoid brake fade. If the caliper has multiple pistons (or multiple pairs of pistons), the brake rotor surface is initially heated by the pistons pushing against the brake pad at the leading edge of the caliper, making the rotor surface hotter when it rotates back to the pistons closer to the trailing edge of the caliper. Therefore it helps if the pistons closer to the rear edge of the caliper are larger. Differential-bore calipers use smaller pistons up front, larger pistons toward the back

In that case it seems the way i mounted mine is correct? (IMG:style_emoticons/default/confused24.gif)

On the rear, the smaller piston is on top. I have to check on the fronts. (IMG:style_emoticons/default/idea.gif)

Yep..sounds like you were right. bolt on and go!

[okieflyr]

i have boxster S calipers too. (IMG:style_emoticons/default/poke.gif)

i would love to do this to my 914 too, the boxster is 50% heavier than the teener and stops on a dime- this is going to be great on the track with your teener! (IMG:style_emoticons/default/beerchug.gif)

i dont have a track car, so would be overkill i think for my 2.0, but maybe the
BMW upgrade might be worth it? what do you advise- i am on a 4 lug ...

For your stock-ish car there is more benefit to getting your factory equipment brakes
rebuilt to tip top shape. Less weight, designed balance, and can be less cost.
I used the 911 parking brake setup from Tangerine Racing and it is effective.
All these "upgrades" add more mass, and depending on the use, may not make your competition times any faster. ymmv.

[SirAndy]

All these "upgrades" add more mass, and depending on the use, may not make your competition times any faster. ymmv.

The Boxster calipers are *light*. They are most certainly much lighter than the (smaller) Carrera calipers they replaced.

They might even be lighter than the stock 914/4 calipers.
(IMG:style_emoticons/default/popcorn[1].gif)

[Aaron Cox]

pretty sure they're lighter than the front M-calipers i replaced them with...

The rear is a toss up. Heavier rotor (vented), and 911 ebrake hardware to make up for the lack of integrate p-brake.

[jim_hoyland]

Just after reading the Boxster caliper update thread, I came across a pair of adapters to mount the Boxster front calipers on the stock 914 spindle ( 3" )

Wondering if anyone else has made this conversion. I'm probably not gonna do it at this point and will be listing in the classifieds shortly

[Aaron Cox]

Just after reading the Boxster caliper update thread, I came across a pair of adapters to mount the Boxster front calipers on the stock 914 spindle ( 3" )

Wondering if anyone else has made this conversion. I'm probably not gonna do it at this point and will be listing in the classifieds shortly

I've never seen 3" M struts to Boxster adapters. They all are 3.5" A/S caliper struts.

We (craig downs and I) had to mill 3" struts and make custom adapters to fit....
http://www.914world.com/bbs2/index.php?sho...=77197&st=0


Where did you find those Jim? (IMG:style_emoticons/default/bye1.gif)

[jim_hoyland]

Just after reading the Boxster caliper update thread, I came across a pair of adapters to mount the Boxster front calipers on the stock 914 spindle ( 3" )

Wondering if anyone else has made this conversion. I'm probably not gonna do it at this point and will be listing in the classifieds shortly

I've never seen 3" M struts to Boxster adapters. They all are 3.5" A/S caliper struts.

We (craig downs and I) had to mill 3" struts and make custom adapters to fit....

Where did you find those Jim? (IMG:style_emoticons/default/bye1.gif)

I remember the thread where you and Craig did that. The adapters were made by Mark--the machinist that made the billet hubs for Brad. Bought them from Mark at the G & Rswapmeet

[Aaron Cox]

Just after reading the Boxster caliper update thread, I came across a pair of adapters to mount the Boxster front calipers on the stock 914 spindle ( 3" )

Wondering if anyone else has made this conversion. I'm probably not gonna do it at this point and will be listing in the classifieds shortly

I've never seen 3" M struts to Boxster adapters. They all are 3.5" A/S caliper struts.

We (craig downs and I) had to mill 3" struts and make custom adapters to fit....

Where did you find those Jim? (IMG:style_emoticons/default/bye1.gif)

I remember the thread where you and Craig did that. The adapters were made by Mark--the machinist that made the billet hubs for Brad. Bought them from Mark at the G & Rswapmeet

Right ON! I'm curious how he did it? Can you post a pic? Will they also work with 15" wheels?

Thanks Jim!

[jim_hoyland]

Her ya' go... (IMG:style_emoticons/default/smile.gif) I'm not sure the pic where the adapter is mounted is oriented correctly...

[okieflyr]

pretty sure they're lighter than the front M-calipers i replaced them with...

The rear is a toss up. Heavier rotor (vented), and 911 ebrake hardware to make up for the lack of integrate p-brake.

Like Andy stated, I know I saved weight up front coming from the Carrera Tank calipers up front, but the back end gained weight in my case. I like the modern calipers for several reasons and they are effective stoppers, but I can't say for sure that I have any more shear stopping power than any other P-car. It could be pad related for all I know, but my suby forester with it's vac assist can stop just as hard if not harder.

But then again it could be perception of modulation.

(IMG:style_emoticons/default/popcorn[1].gif)

[Aaron Cox]

Wow, Jim.

Those look scary thin at the corners of the mounting hole. Interesting!

[SirAndy]

Wow, Jim.
Those look scary thin at the corners of the mounting hole. Interesting!

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/blink.gif)

[seanery]

It's been 2 months now, Andy. How do you like them?

[seanery]

Wow, Jim.
Those look scary thin at the corners of the mounting hole. Interesting!

(IMG:style_emoticons/default/agree.gif) (IMG:style_emoticons/default/blink.gif)

I was excited about them, but yeah, that's scary!

Aaron, what's your front setup?

[SirAndy]

It's been 2 months now, Andy. How do you like them?

They work great! (IMG:style_emoticons/default/piratenanner.gif)

[Steve]

I love mine!! They work great and they don't squeak like the 944 Turbo brakes I had before.

[timothy_nd28]

Hey, I'm no engineer by any means, but these mounting brackets scare the hell out of me. Typically, you would see the 2 caliper thru bolts situated so that the bolts are seeing shear forces. These bolts do pretty well with this force, in excess of 5000lbs or so. Now you're putting these bolts in tensile mode, which seems somewhat shady. Every bolt i have seen on a caliper, has always been designed for shear. Is this the new trend by the automotive engineers? Moreover, this mounting bracket, is it comprised of aluminum? If so, are these thru bolts, with nuts on the back end?
Maybe I'm overthinking this, but I would like to hear some input from a Mechanical engineer.
In the mean time, you could cut a square hole in your floor boards and do some Flintstone braking as a last resort if the calipers snap off. (IMG:style_emoticons/default/beerchug.gif)