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Making adapters for Boxster brembo calipers
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Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Fri Dec 29, 2023 7:42 am    Post subject: Making adapters for Boxster brembo calipers Reply with quote

Hi

Im doing a little side project while waiting for parts to finish my engine stuff. Not that im in direct need, Ive had the std brakes work well on track, and could step up a few levels in pad compound with the new power level. But instead Im doing this, mostly for fun, but also to be able to run less hardcore compounds since its also a road car, and still handle the heat.

The choice is 4 piston Boxster front calipers from the non S, they have pretty much exactly the same piston area as the original calipers, so no shift in balance. the plan is to combine them with the Carrera 3.2 discs, which are 24mm wide, instead of 20,5. That will also give some additional heat capacity. I hope i can still fit with 15" wheels with these ones, thats the plan.

Weight wise they weigh ca 3.2kg complete with pads, i couldnt weigh the std caliper since it maxed my little scale at 5kg. So even with adapters and heavier discs it will cut some weight.

Im fine tuning the fitment now, and waiting for brake discs (cost me about 65usd /each, so very reasonable. when the discs arrive i will conclude the design and order them machined.

Btw, they will be sturdy fairly heavy pieces made of steel, i dont want to rely on treads in aluminum on a track car.

Anyone else interested in a set? Could be fun to get someone else on the project






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Mclaren924  



Joined: 13 Oct 2021
Posts: 171
Location: California

PostPosted: Fri Dec 29, 2023 2:33 pm    Post subject: Re: Making adapters for Boxster brembo calipers Reply with quote

Cedric wrote:
Hi

Im doing a little side project while waiting for parts to finish my engine stuff. Not that im in direct need, Ive had the std brakes work well on track, and could step up a few levels in pad compound with the new power level. But instead Im doing this, mostly for fun, but also to be able to run less hardcore compounds since its also a road car, and still handle the heat.

The choice is 4 piston Boxster front calipers from the non S, they have pretty much exactly the same piston area as the original calipers, so no shift in balance. the plan is to combine them with the Carrera 3.2 discs, which are 24mm wide, instead of 20,5. That will also give some additional heat capacity. I hope i can still fit with 15" wheels with these ones, thats the plan.

Weight wise they weigh ca 3.2kg complete with pads, i couldnt weigh the std caliper since it maxed my little scale at 5kg. So even with adapters and heavier discs it will cut some weight.

Im fine tuning the fitment now, and waiting for brake discs (cost me about 65usd /each, so very reasonable. when the discs arrive i will conclude the design and order them machined.

Btw, they will be sturdy fairly heavy pieces made of steel, i dont want to rely on treads in aluminum on a track car.

Anyone else interested in a set? Could be fun to get someone else on the project







Very interested in a set for my 77 Restoration that I want to 5 lug swap.
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morghen  



Joined: 21 Jan 2005
Posts: 8868
Location: Romania

PostPosted: Fri Dec 29, 2023 6:27 pm    Post subject: Reply with quote

I need to check my disks and pads condition, if i need to replace them i'll also want a pair of adapters.
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Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Sat Dec 30, 2023 11:33 pm    Post subject: Reply with quote

Work has been progressing, and protoypes has been tested, adjusted and tested again, its very small changes to get everything perfectly centered up. And I also got my 24mm discs, so i could sort out the final measurments.

Pretty happy with the location of the caliper now, so I think im gonna work a bit on the design to prepare for ordering of the steel ones.

The thicker discs has significantly more flow are in the cooling ducts, this looks vert promising for the heat management.

20,5 vs 24mm disc


difference in cooling channels



with the thicker disc installed

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Joma  



Joined: 28 Nov 2016
Posts: 18
Location: Netherlands

PostPosted: Sun Dec 31, 2023 5:34 am    Post subject: Reply with quote

sign me up
i got a set of calipers left over from my 987 that i upgraded to 330mm.

any plans for the rear brakes?
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Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Sun Dec 31, 2023 7:52 pm    Post subject: Reply with quote

Joma wrote:
sign me up
i got a set of calipers left over from my 987 that i upgraded to 330mm.

any plans for the rear brakes?


Just had a quick google and the base Cayman seems to have the same calipers as the base 986 Boxster, so it should work.

Regarding the rear brakes i have no plans, theres much less thermal load on them, would be nice to shed some weight though, but finding a fancier caliper with such a small caliper area is not so easy. Balance is important for me since im performance oriented, dont want to make the braking worse than the std system:) a re route of the braking system to f/r and reducer valve for the rear would of course make it easier to find calipers, but i want to keep it simple.

Caliper part numbers:
986351422
986351421
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Carrera RSR  



Joined: 08 Jan 2010
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Location: Somerset, UK

PostPosted: Wed Jan 03, 2024 11:16 pm    Post subject: Reply with quote

Isn't there one or two bolt on 944/968/Boxster Brembo solutions for the rear of a 931? I can't recall exactly without searching, but it was always the front where mounting needed a 944 hub or mounting adapters.

But, if you have lost decent weight out of the rear, the stock rear caliper easily locks up before the fronts on my car.....especially trail braking which once used to the movement helps pivot the car in sharper corners.
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Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Thu Jan 04, 2024 12:08 am    Post subject: Reply with quote

Carrera RSR wrote:
Isn't there one or two bolt on 944/968/Boxster Brembo solutions for the rear of a 931? I can't recall exactly without searching, but it was always the front where mounting needed a 944 hub or mounting adapters.

But, if you have lost decent weight out of the rear, the stock rear caliper easily locks up before the fronts on my car.....especially trail braking which once used to the movement helps pivot the car in sharper corners.


I haven't found much on the rear that have close to the right piston area, almost every caliper has to much of it, maybe if i used a different front caliper. The boxster/cayman one is the same area as the std caliper up front, which is one of the reasons i chose it, and the compact size. 2 piston 36mm Brembos from an impreza sti would have the same area though as the std ones But its not something i will look at now. At the moment im finalising the order of two sets, one for me and a spare set for someone that wants to try them

I found std brake bias to work very well, and i always trail brake deep to the apex, Hence i want to keep the balance as it is and not shift it, according to logs my braking looks really good compared to other similar track cars,. i hope it will continue like that
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barnwerks  



Joined: 28 Oct 2022
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Location: Northeast and southeast US

PostPosted: Thu Jan 04, 2024 3:49 am    Post subject: Reply with quote

I am also interested in a set of these adapters. Do you have an estimate of cost? Are you willing to ship to US?
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Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Thu Jan 25, 2024 7:43 pm    Post subject: Reply with quote

The parts just arrived from machining, made in steel with nickel plating. Everything seem to line up great. So time to gets some proper pads and put everything together. The fitment with cookie cutters 15" for example still needs to be checked. I have some 15" BBS wheels around aswell that i could try. With some help of a friend we did some half decent FEM calculations, and updated the design to be sure they outlast me and the car

The spare set might be up for grabs if someone have plans to try this mod, and could drive their car sooner than i can drive mine


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morghen  



Joined: 21 Jan 2005
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PostPosted: Thu Jan 25, 2024 11:43 pm    Post subject: Reply with quote

These look amazing! And really cool with those cutouts in the midle.
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Cedric  



Joined: 27 Aug 2004
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PostPosted: Fri Jan 26, 2024 12:04 am    Post subject: Reply with quote

morghen wrote:
These look amazing! And really cool with those cutouts in the midle.


It was a good way to cut some weight, but I also did it for them to look cool just for fun
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Mike9311  



Joined: 14 Dec 2004
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PostPosted: Fri Jan 26, 2024 3:23 am    Post subject: Reply with quote

Cedric wrote:
morghen wrote:
These look amazing! And really cool with those cutouts in the midle.


It was a good way to cut some weight, but I also did it for them to look cool just for fun


Sooo nice!! This is why I come here. There are more of us out there

Really nicely done. They look wicked!
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Joma  



Joined: 28 Nov 2016
Posts: 18
Location: Netherlands

PostPosted: Sat Jan 27, 2024 8:54 pm    Post subject: Reply with quote

Cedric wrote:
The parts just arrived from machining, made in steel with nickel plating. Everything seem to line up great. So time to gets some proper pads and put everything together. The fitment with cookie cutters 15" for example still needs to be checked. I have some 15" BBS wheels around aswell that i could try. With some help of a friend we did some half decent FEM calculations, and updated the design to be sure they outlast me and the car

The spare set might be up for grabs if someone have plans to try this mod, and could drive their car sooner than i can drive mine



They look really nice.

i still want them, but i will be a while before i can test fit them
currently working on the outside of the car.
and need to have the callipers rebuild and repainted.

so i want them but cant immediately fit them
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Cedric  



Joined: 27 Aug 2004
Posts: 2600
Location: Sweden

PostPosted: Sun Jan 28, 2024 8:05 am    Post subject: Reply with quote

Joma wrote:
Cedric wrote:
The parts just arrived from machining, made in steel with nickel plating. Everything seem to line up great. So time to gets some proper pads and put everything together. The fitment with cookie cutters 15" for example still needs to be checked. I have some 15" BBS wheels around aswell that i could try. With some help of a friend we did some half decent FEM calculations, and updated the design to be sure they outlast me and the car

The spare set might be up for grabs if someone have plans to try this mod, and could drive their car sooner than i can drive mine



They look really nice.

i still want them, but i will be a while before i can test fit them
currently working on the outside of the car.
and need to have the callipers rebuild and repainted.

so i want them but cant immediately fit them


What wheels do you intend to use?

Today I had some wheel fitting tryout, i tried 15" BBS mahle, 16" Fuchs (Maxilite), 16" D90. The BBS wheels and especially D90s had plenty of room. the Fuchs were much tighter now that i moved the caliper out to accommodate the wider brake disc, but it fits, i just have to relocate the balancing weights to be sure they doesnt touch
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