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Porsche 996 caliper project is under way

Specific conversations and info for the BMW E28 M5 and M535i.
Philo
Posts: 2202
Joined: Feb 12, 2006 12:00 PM
Location: Long Beach, CA

Porsche 996 caliper project is under way

Post by Philo »

For months I've been contemplating how to get readily available Porsche calipers to fit my M5 since we can no longer find the e31 4 pots. Geez.., are beemer heads hording these things or what ? I looked at 928 calipers, 911 Turbo calipers, Boxter calipers and couldn't find any supporting information online regarding bracket fitment, brake bias numbers, etc.. , and not to mention what rotor would even work with big radial mount aluminum calipers. I even looked at the Brembo and Stoptech after-market kits and nothing was available for 16" wheels. Not to mention the cost was way out of wack. There are a few lesser known BBK companies that have a kit for the e28/e24, etc, but not sure if anyone will want to put these on their car. I mean.., we do have our standards.. right ? ;) Yes, Wilwood has parts that will work but that's not where I'm going with this project.

A few years ago I was given a pair of the e31 Brembo 4 piston calipers from my buddy who's in the brake business. I held onto them for a while with the intent of swapping them onto my daily driver. But at that time I was in the middle of building a custom S38 engine and the cost for parts was screaming out of control so I sold the 4 pots to Brooks R. Today, we can't find them at all.., and if you do find a pair you're gonna pay big!. So I decided to look into finding an alternative caliper that would bolt under the stock16" BBS wheel and would provide the same sexiness factor as the unattainable e31 Brembos. The goal was to build an enthusiast BBK using original equipment from Euro sport brands and engineered properly so the online know-it-alls wouldn't slam me for mixing and matching parts and confirming that I'm gonna kill myself.

So I started kicking this idea around with a friend that works at StopTech, he ran the numbers.., and decided that the Porsche 996 calipers off the 99-2008 model 911, 2000-2008 BoxterS and 2006-2008 CaymanS would be the perfect match *technically* along with the uprated rear e34 M5/540i calipers most of us run. My buddy engineer had been working on a Mazda Miata BBK utilizing the same 996 calipers so he had all the data on hand. Within an hour he confirmed that if I can make them fit under the 16" wheels using a 324mm e31 disc it would be the ultimate e24/e28 BBK for a stock wheel setup. Porsche 996 calipers can be purchased on Ebay for $500 to $700 depending on the seller.

http://forums.pelicanparts.com/uploads1 ... 002814.jpg

We are actually exploring two rotor possibilities., the e31 (324mm X 30mm) and the US e46 M3 (328mm X 28mm). This would allow enthusiasts to pretty much buy off the shelf stock rotors when the time comes for a brake job. We were also considering the Euro e46 M3 CSL (345mm X 28mm) but are pretty sure they wont fit under 16" wheels. We'll do a test fit but not holding our breath. Down the road I may consider building a bracket for the CSL rotors to fit under 17" wheels.., the CSL rotors are a really cool two piece floating design.

http://c1552172.r72.cf0.rackcdn.com/13085_x600.jpg

So why am I doing this ?? Well..., I actually read an online post about how the e36 M3 crowd was adapting the same 996 caliper using custom brackets by the guys at ralleyroad.net. http://www.rallyroad.net/content/bmw-e3 ... r-brackets I quickly contacted them to see if they would be willing to adapt their bracket design to the e24/e28 models but didn't hear back. So decided to go at it alone. Moose also has plans for a bracket design but not sure where he's at with getting them made. So again, decided to be proactive and pay for the prototyping myself. Maybe I'm nuts.. well see...

A test set of brackets will probably be ready by late Jan if all goes well. The brackets will be CNC machined and then coated or painted just like other after-market brackets. The end result should be pretty sweet though. Down the road I'll let you guys know what the Philo super special uber enthusiast cost will be to get your own set of brackets :)
Coldswede
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Post by Coldswede »

How much weight are we talking about for this conversion?
TurboChris
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Post by TurboChris »

Nice! I like it. Count me in as interested.
1st 5er
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Post by 1st 5er »

I'll watch as well to see the final outcome.
Das_Prachtstrasse
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Post by Das_Prachtstrasse »

Funny, I was just thinking about doing something like this the other day with Porsche brakes.. This works way better, as you can do all the hard work for me. Keep updating the thread as you make headway/hit problems, as i'm definitely interested in the developement and outcome.
S38Mike
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Post by S38Mike »

Subscribed.
Philo
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Location: Long Beach, CA

Post by Philo »

I already have an update. The prototype bracket for the e31 rotor that we are trying to fit is available off the shelf. This is really great news and will allow me to throw these brakes on my car and do some testing in early Jan. However.., to get the off the shelf brackets to fit the caliper mounts need to be shaved. Something the e36 M3 race guys do as well I'm told. Ultimately though I think it would be best to have a proper bracket made so we'll have a simple bolt-on BBK. Shaving mean sourcing a machine shop.., run the risk of having the machining improperly performed, etc.. This just adds to the cost of the BBK and adds a possible headache.

So.., I'm enlisting feedback from everyone. Are we ok with machining calipers or would we rather have a proper bracket for a direct bolt-on with the e31 324mm rotor ?
M5BB
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Post by M5BB »

Good work Philo.

I'm signed up.
:popcorn:

Have a Merry Christmas..........
Mab1957
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Location: Northern Virginia, USA

Post by Mab1957 »

I would rather have a proper bracket for a direct bolt-on with the e31 324mm rotor.

An all-in kit for the win. Purchase kit with bracket, rotors, calipers pads, lines, sensors. Oh, and the brake lighting upgrade kit so when these BIG BRAKES are applied the drivers behind will know the car is stopping right now!! :shock:
MShimon
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Location: Seattle, WA

Post by MShimon »

I am not for shaving the caliper mounts, a proper bracket should be produced. You are certainly welcome to do what you like for prototype testing, but I think the custom brackets are the way to go here. I am also for the kit idea, however pads and the lights should be optional since many have pad preferences and/or lights. This might also be true for the lines as some might have stainless already or prefer the rubber.

I like the progress updates, keep 'em coming! Be sure to let the Yahoo group know you've started a thread on mye28 too.
TurboChris
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Post by TurboChris »

Given a choice I'd far rather have a custom built bracket than having to customize the caliper. I suspect it could mean the difference between doing it or not for some.
Philo
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Location: Long Beach, CA

Post by Philo »

Here's some answers thus far..
Coldswede wrote:How much weight are we talking about for this conversion?
Not sure yet but will weigh the 996 calipers once I finish prototyping. The've got to be lighter though..., the stock M5 cast calipers are heavy pigs.., and the 7 series upgrade is even worse.
n all-in kit for the win. Purchase kit with bracket, rotors, calipers pads, lines, sensors. Oh, and the brake lighting upgrade kit so when these BIG BRAKES are applied the drivers behind will know the car is stopping right now!! Shocked
The plan as of now is to just provide the brackets and all the information needed to build your own BBK. I may have to include brake lines since they will be unique to the Brembo 996 setup. The nipple faces differently then the stock M5 calipers. Haven't looked into the pad sensor yet. Regarding pads I'm told there are countless pad choices. Another reason the 996 calipers is such a great unit for this BBK.
Be sure to let the Yahoo group know you've started a thread on mye28 too.
Thanks.., will post this evening.

I should have some mockup pics by tomorrow. I also asked my buddy to do the engineering for a custom bracket so the calipers do not have to be shaved.

Question, what do you guys think the percentage split is of e28 and e24s owners running 17" wheels ? There may be a minimum for machining the brackets so I may want to do both all at once.
alpinewhite
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Location: Jamaica Estates/Miami Shores

Post by alpinewhite »

Philo wrote:Here's some answers thus far..
Coldswede wrote:How much weight are we talking about for this conversion?
Not sure yet but will weigh the 996 calipers once I finish prototyping. The've got to be lighter though..., the stock M5 cast calipers are heavy pigs.., and the 7 series upgrade is even worse.
*e31/840Ci brembo = 7.183 lb.
http://bmwfans.info/parts/catalog/E31/C ... ad_sensor/

*e28/M5 e24/M6 mono block fixed calipers = 11.023 lb.
http://bmwfans.info/parts/catalog/E28/S ... sensor/#01

*e32/7 series e34/540 floating calipers = 8.025 lb. + 3.223 lb. with carrier
http://bmwfans.info/parts/catalog/E32/S ... sensor/#02

*e31/8 series floating calipers = 9.326lb. + 3.616lb. with carriers.
http://bmwfans.info/parts/catalog/E31/C ... ad_sensor/

*US e34/M5 e34/540 M sport floating calipers = 7.937lb. + 3.373 with carriers.
http://bmwfans.info/parts/catalog/E34/S ... se/brakes/

*EURO e34/M5(3.8) e31 850CSi Nürburgring(?) fixed calipers 14.784 lb.
http://bmwfans.info/parts/catalog/E34/S ... sensor/#01

*Porsche 996/Boxster S calipers = around 5lb. + 3lb. for e36 M3 CNC Machined Steel Brackets (according to Eric, from RallyRoad.net)
http://www.rallyroad.net/content/e36-an ... 6-calipers

*= for reference only

Philo:

IIRC the 996 calipers provide more clamping force than e31 brembo units as well. Ideally thats why one would want to do this upgrade/mod besides the aesthetics. I would try to make the brackets/adapters out high quality aluminum to save on weight too.

Porsche 996/Boxster S calipers with e31 LCAs and TI components from Rylee, should equate to significant amount reduction in unsprung weight that can be felt on the street and track... add to the equation high quality light wheels, Mooseheads UCA spherical bushings, 25/19 adjustable sway-bars, tower braces and a well sorted suspension and you'll have what imp will be a wicked street/track performer!

Also you may want to contact "igotbank" he had some Porsche calipers mounted to his old e28 M5 track car he may be able to help with some info regarding the bracket/adapters.


Links that you may find helpful:

http://teilecar.com/?1071,porsche-996-b ... e-calipers

http://forums.bimmerforums.com/forum/sh ... ?t=1649410

http://www.mye28.com/viewtopic.php?t=81 ... sc&start=0

Cheers,
mooseheadm5
Beamter
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Post by mooseheadm5 »

As Philo already knows, I already have a pair at George's shop. The logistics just haven't worked out for me to get them installed and tested yet. I'm interested to see what Philo comes up with, though, as I don't know when I'll be able to finish my project.
MShimon
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Post by MShimon »

Any exciting updates to report?
Philo
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Post by Philo »

I got a report back on Tuesday. The test calipers have been shaved and mounted to the hub. Clearance is tight but they say the fitment is pretty normal and works well with the 324mm E31 rotor. The hub and strut still had the splash shield mounted and I don't think it was removed prior to fitting. So it looks like no modifications are required to the splash shield, which was a concern of mine. I have some pics of the test fitting and will post them soon.

Still waiting to hear back about how the brackets will get made. Not sure if ST can make the custom brackets, one of their contractors, or if I'll have to find my own machine shop. I will have a digital file of the bracket design that I can take to a machinist and have them make a CNC file from. But the upfront cost will be rather pricey so not sure which way I will go just yet.

Things are progressing...:)
Philo
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Post by Philo »

OK.., here's the update and pics.

The brackets for 16" wheels will utilize a modified ST bracket. A slight clearance modification for the inner brake pad is required to get the calipers to fit on the bracket. To fit such a large caliper however under the stock 16" wheel there is no why to do this without trimming the caliper mounting area. I went around and around with the engineer and there is simply not enough room. Trimming the bracket down will not allow enough meat to hold the bracket mount pin securely. So the calipers on future installations will need to be cut as well. Sorry guys.., this is the only way.

Once I get the brakes on my car I'll post some more pics, performance data and parts list.

Here's a few pics of where we are at thus far.

Image


Modified StopTech Bracket

Image


Trimming the Porsche 996 Caliper

Image
Philo
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Post by Philo »

Hey guys.., so after a long debate with the engineer we've decided to explore other ways of making the 996 calipers fit the e28/e24 hub. Although using a standard bracket made adapting the 996 calipers to our hub easy.., the prospect of having to trim the calipers, and have you guys run the risk of having a mill operator screw up your set of brembos, was not getting me excited. I also noticed the lack of post to this thread after I posted the progress pics.., which tells me I need to push on and figure out how to make a proper custom bracket that allows for a simple bolt on approach.

The downside is the development costs will go up and the time it will take to produce the brackets will be greater. But in the end I'm hoping for a clean, simple bolt on approach. Simply buy a set of 996 calipers off Ebay and you're ready to rock :)

Any feedback / comments is appreciated. Oh yes.., brake lines are being engineered as well. From what I'm told the brake line configuration with Brembos and the e28/e24 requires a custom set. Already in the works though so not to worry.
Hffvdbl
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Post by Hffvdbl »

Very interested in your progress. Thanks for going through the trouble. Agree that this would be a better approach. Thanks for the update
MShimon
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Post by MShimon »

I love the progress, too bad you ruined(?) a caliper in the process; I suppose it's bound to happen though. I'm not sure that lack of response is due to lack of enthusiasm for your previous route. I just haven't checked the board lately. However I also think the bolt-on bracket is the correct route for more orders. I'm curious as to what needs to be engineered for the brake lines. The problem can't be rectified with just a different fitting on the end of the line to the caliper? Perhaps a higher pressure or volume is required to properly actuate the caliper? I would think if that was the case a new brake mc would be required.

How do you think this bbk will work with the e32 brake mc? Keep up the good work!
mooseheadm5
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Beamter
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Post by mooseheadm5 »

And now you know why it has taken me so long to get mine finished.
wkohler
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Post by wkohler »

Isn't this all you need? Bolt up calipers and go.

http://www.ebay.com/itm/BMW-E36-M3-Pors ... 0471351205

E36 M3 brakes bolt right up to E34/E28, etc...
ealoken
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Post by ealoken »

i have the same kalipper i tink.

i got a 345mm e34 m5 disc.

Image
Philo
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Post by Philo »

wkohler wrote:Isn't this all you need? Bolt up calipers and go.

http://www.ebay.com/itm/BMW-E36-M3-Pors ... 0471351205

E36 M3 brakes bolt right up to E34/E28, etc...
For 17" wheels yes.., my goal from the beginning is to design a bracket for the 16" wheels so we can retrofit 996 calipers to the car as we use to do with the e31 brembos.
Rich Euro M5
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Post by Rich Euro M5 »

Philo wrote:
wkohler wrote:Isn't this all you need? Bolt up calipers and go.

http://www.ebay.com/itm/BMW-E36-M3-Pors ... 0471351205

E36 M3 brakes bolt right up to E34/E28, etc...
For 17" wheels yes.., my goal from the beginning is to design a bracket for the 16" wheels so we can retrofit 996 calipers to the car as we use to do with the e31 brembos.
If you tread the eBay listing, they state you must also have the caliper shaved. They offer the service at an additional charge.

IMO, having a bolt-on solution for 16" wheels is ideal. The slightly smaller rotor means the E34 M5 / 540i rears will still provide proper bias.
EuroShark
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Post by EuroShark »

I like the idea of being able to run 16" wheels, but just for the sake of clarity, if I were using 17" wheels I could just shave the calipers 12mm and use those brackets... yes?
Philo
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Post by Philo »

IMO, having a bolt-on solution for 16" wheels is ideal. The slightly smaller rotor means the E34 M5 / 540i rears will still provide proper bias.
Yup.., that is my goal and is proving to be very challenging. Will see how it goes ;)
Philo
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Post by Philo »

EuroShark wrote:I like the idea of being able to run 16" wheels, but just for the sake of clarity, if I were using 17" wheels I could just shave the calipers 12mm and use those brackets... yes?
Sorry.., was out of town.

Yes, I think so.., the site says you can use them on e34s and e36s I recall. But you have to go with their rotor combo which is the e46. I like this combo but again I wanted to buil;d something as close to the e31 setup that the e24/e28 guys love so much but can't find calipers for.
Philo
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Post by Philo »

Here's an update. The Calipers are mounted and ready for testing. The prototype brackets needed to be shimmed to get the alignment perfect so this update will be added to the CAD drawing for final production.

Please excuse the obnoxious huge M logo. I had the calipers painted and the logo applied and not only did they blow the graphic up too large but they mounted it on an angle. Should have done this myself !

http://phil.files.infostreet.com/M5_Ima ... 300358.JPG

http://phil.files.infostreet.com/M5_Ima ... 300351.JPG

http://phil.files.infostreet.com/M5_Ima ... 300354.JPG

http://phil.files.infostreet.com/M5_Ima ... 123340.jpg

http://phil.files.infostreet.com/M5_Ima ... 123202.jpg

http://phil.files.infostreet.com/M5_Ima ... 300355.JPG
Matt
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Post by Matt »

Sweet.
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