Brembo Big Brake retrofit kits for E28/E23/E24

[BenGerman]

Here are the fronts:

Thanks for the measurements, really appreciated!!
As soon as I'm done with all the math, I will see if it makes sense to get a set of those in.

That's awesome. Enough room for balancing weights?

From a brief look, yes. But then again, I need to get it bolted down to a strut to evaluate details like that.
Good point though, I didn't think of that yet!

After figuring out the Master cylinders, we can now start to look into the factory and known working combinations of Porsche calipers with different rotors.
I'm sure other combinations have been tried, I'm willing to update the list if you have more references.



So this leaves me with the final list (Factory options in grey):




Filtered by Brake Bias, Min. = 65% (not recommended for street applications), Max. = 71% (Trying to get away from the front heavy M5 breaking at 73%).
Plus we know that the E34 540i setup Bias works pretty decent at around 68%.



Which leads me to the final table of the weights (-pads, just because I couldn't find any for the Porsche stuff), (-adapters, count on approx. 300g for rear, 200g for fronts).



Discuss!
Most interesting fact to me: not one of the 996 front calipers made it to the final selection. They were all below 65% front Bias.

[BenGerman]

Doing some more research, I will introduce another option here shortly.
I was kind of disappointed with the results of the 996 caliper calculations.
Unfortunately the 996 Turbo set seems to be very pricey on the market. I only paid $300 for mine which is not the normal price, as I had to find out.

Newer generation GM vehicles have some very interesting options, where calipers can be had for $160-$250 a set (!) rebuild and ready to go.
The specs are basically the same as the E31 Brembo caliper (4x42mm pistons).

The only disadvantage found so far: They are a two piece design, where the BMW und Porsche Brembos are one piece.
This will take some of the caliper stability away under heavy breaking situation. Nevertheless, I would consider them a very interesting option in combination with the Brembo 986 rears and a cheap alternative to the E31 Brembos.

I will have a set on my desk this weekend.

[T_C_D]

I would like to have some GM 4 piston brakes on my GM powered BMW for Vintage.

[Karl Grau]

Most interesting fact to me: not one of the 996 front calipers made it to the final selection. They were all below 65% front Bias.

That is interesting. I wonder if has something to do with the engine/trans location in the Porsche.

[BenGerman]

Most interesting fact to me: not one of the 996 front calipers made it to the final selection. They were all below 65% front Bias.

That is interesting. I wonder if has something to do with the engine/trans location in the Porsche.

That's what I believe. A car with a rear engine will behave completely different in hard braking situations than an car with the engine in the front.

I would like to have some GM 4 piston brakes on my GM powered BMW for Vintage.

No idea if I will have any before the Vintage. Be we can swap them in the Hotel parking lot. Would be the first brake job there.


Picked up the Cadillac ATS calipers today.
It's crazy how cheap they are. For $131 a piece you get them brand new from Summit racing.
Of course, they are a 2 piece design instead of the 1 piece Porsche Brembo. Also, they are not perfect in all the casting details.
But, at that price new it's hard to complain about details like that.
I need to confirm the piston diameters tomorrow. But in order to do that, the pistons will have to come out a little bit.
They can only be used with 324mm rotors. As seen in the pictures below, the 334mm E38 rotor would not be covered by the pads completely.

https://www.summitracing.com/parts/ado-172-2768

The other option would be 04-07 CTS-V calipers which are not a lot more expensive but supposedly have 40/44mm pistons.

https://www.summitracing.com/parts/ado-172-2287

The 6 piston CTS-V / Z06 calipers do not make sense, as their piston surface area is smaller than the Cayenne 6 piston caliper and they are made for 370mm rotors, which will not fit under any wheel that makes sense on the E28.

Pictures (compared to 996T Fronts):







The goal is to have all the options and combinations lined up by the end of february. We are already working on the rear 986 brackets.

[T_C_D]

I definitely want the ATS brakes! What about ATS rears?

[BenGerman]

Verified the ATS piston diameters: 4x42.
Therefore: It is mechanically equal to the E31 Brembo caliper.
Weight is 3860g, about 400g heavier than the E31 Brembos. But at $160-250 for a set of rebuild or brand new calipers, who is going to complain.



I will confirm the offered combination of calipers and post the expected technical datas.

I believe this should be the final list. There is no plans for the Cadillac rears ATM, but we can talk about that once the rest is completed.
From what I saw online, they should be 28/30mm pistons in the rear. Pads will be comparable to the Porsche 996T rears.

Update: now with the weights (4 calipers, 4 rotors, adapters where necessary):



I did leave the factory options in the list to compare.
Some of the wheel sizes still have to be confirmed.
The list would require 3 different rear adapters and 5 different front adapters.

[adam_poll]

It looks like the Cadillac calipers also share a common brake pad with a bunch of other cars including some Mustangs (GT, GT500, BOSS 302) and later WRX STi's so getting decent brake pads shouldn't be too bad. The Caddilac 324x30 with 986 300x20 is the package I am most interested in.

Thanks for all the effort you are putting into this!

Adam

[BenGerman]

I definitely want the ATS brakes! What about ATS rears?

Just checked the parts catalog. The ATS has a normal 1 piston floating caliper in the rear.
It does not make sense to adapt that solution, as there is a bolt on solution with the 540i rear caliper that would match the ATS fronts.

The Boxster 4 pistons rears are available as re manufactured models for about $86 a piece and would match the ATS fronts as well.

The only thing that could potentially be negative with that combination is the different lettering of both calipers. I'm not really concerned about that...

It looks like the Cadillac calipers also share a common brake pad with a bunch of other cars including some Mustangs (GT, GT500, BOSS 302) and later WRX STi's so getting decent brake pads shouldn't be too bad. The Caddilac 324x30 with 986 300x20 is the package I am most interested in.

Thanks for all the effort you are putting into this!

Adam

Yes, that's another advantage. The same goes for the Porsche calipers as well. Plenty of different pads available to play with, in case the stopping power is not enough with standard ATE, Akebono, Pagid, Textar, or whatever pads.

[T_C_D]

I definitely want the ATS brakes! What about ATS rears?

Just checked the parts catalog. The ATS has a normal 1 piston floating caliper in the rear.
It does not make sense to adapt that solution, as there is a bolt on solution with the 540i rear caliper that would match the ATS fronts.

I would just use 540 rears and paint them to match. Thanks!

[q20v]

I have nothing meaningful to contribute other than please keep this going. You have me hooked on 986 rear calipers to match the E31 brembos I just picked up so I'm impatiently waiting for you to finish the brackets : ) Seriously though, no rush since I'll be doing this in the summer.

[BenGerman]

I'm glad to see the great feedback, in this threads and in the multiple PMs! The only way to make this happen is with a good community!

So here is some updates:

[q20v]

Oh very nice! 6061? How is everything attached? Zip ties, elastic bands? DIY rivets?

I know what goes into making parts like this so I appreciate the effort you're putting into it. I'm in the process of machining my own bump steer spacers on a lathe with milling attachment. Do you work in a machine shop or have your own CNC mill?

[BenGerman]

Yes, that's 6061 for prototyping, test fitting and maybe some test laps around the blocks is absolutely fine. It's probably fine for everything else as well.
But with brakes I much rather over engineer than realize a problem too late. So the serial models will most likely be 7075, potentially even hardened.
So far, everything is holding up by its weight.

I do work in the automotive industry during the day. But the machining is done at a good friends shop.
Moving on forward, we will potentially market these products in form of a small online shop.
The group buy style, like I've done it so far will not work for the variety of components necessary in this project.

More pics, because that's what everybody likes:





The location of the ABS sensor is a pain, compared to E30 trailing arms. But we will get that worked out as well.

[q20v]

Looking good. I checked out some pictures of the E34 trailing arm and the ABS sensor is in the same spot (not sure if you're considering marketing these for E34's as well?)

[BenGerman]

Since the E34 Big brake kit is a direct fit on the E28, I would assume that my adapter should fit the E34 as well.
This is something I will have to confirm in details once we are further down the road.

[q20v]

If you want to sell me a set before your website is up and running I'd love to help out in that respect. You've invested a ton already, I don't mind investing in your brackets if it helps confirm another platform. I've been eyeing 986 rear calipers on eBay lately and there's definitely no shortage!

[skeeter_nohustle]

Im in Cincinnati and im the proud owner of beautiful 1985 BMW 735i E23 if you need a donor car for test fitment let me know i can make the drive to you sir. Besides i would love to upgrade my brake system lol

[scarey013]

I’m glad this thread came up. I’ve had a set of 996 calipers for a few years and have been planning on putting them on my e28. A good friend of mine pointed out that the bias would likely be way off, so I started making spreadsheets. Oh joy.

Yes, the bias was off. So I started reading threads, mostly in the E36 M3 section, knowing that at least the commonly available Brembo brackets would be a direct fit on the front and I speculated on the rear. What I came to find is that the front is the same, rear is different.

E36 M3 rotors fit the rear of the E28 and are reasonably priced, but are directional. In my attempts to install on them on my car, E36 M3 carriers placed the carriers/calipers not far enough out (radially) to mount the 312mm disc. They fit the 300mm e34 disc, though. Since there is a mounting distance difference between e24/28/32/34 VS e36 carriers, means rear commonly available (for the E36) brackets wouldn’t fit the standard upgraded disc size of 328mm without turning down the outer diameter.

So to make a short story long, I’ve often thought that a bracket that would allow 300mm in the rear would be fantastic. Since the Brembo rears are similar in bias to the M5/M3/540/740 40mm calipers.

I’ve got a full set of e34 M5/e36 M3 brakes, a full set of 996 and a set of e31 Brembos sitting on the bench. Looking at the bias charts, I’m tentatively interested in a rear set-up for 996 calipers with 300, 312 or 328 rotors.

Thank you for your diligent work. Looking forward to seeing the outcome. PM me if I can help in any way.

[Philo]

Great work and really happy that someone picked up on this project. Looks familiar - http://phil.infostreet.com/M5_Images/99 ... lipers.JPG

I'm running the Porsche 996 fronts with E34 M5 rears on a 528e vacuum booster. Visually I like the look of the big calipers and rotors but to be honest I had better stopping power with the original M5 brakes on hydro-boost. I think my issue is not enough vacuum, currently using a 528e booster. Any ideas on how to up the vacuum let me know.

Thanks Ben, keep it up !

P.

[BenGerman]

Sorry I'm just getting back to everybody. Real life has caught up and I spend most of the nights this week at my real job.

I purchased a 6 piston caliper of ebay but got the wrong part delivered.
Already bought another one which should arrive some time next week.
I still need to confirm the physical differences between the 330 and 350mm setup. The pads are different, the bolt locations are different, but potentially the housing might be the same.

I'm still aiming to have the M7 equipped with Cayenne calipers, E34 MC, 348/345mm rotors and the vacuum booster setup at the Vintage.
I would also like to bring some of the other sets as showcases.

If you want to sell me a set before your website is up and running I'd love to help out in that respect. You've invested a ton already, I don't mind investing in your brackets if it helps confirm another platform. I've been eyeing 986 rear calipers on eBay lately and there's definitely no shortage!

Agreed, they are easily available.
There is also a nice set of Turbo calipers all around for about $400 OBO! Still a very good deal. The last set of used E31 calipers sold for double that.

It will be a while before I have those brackets ready for serious testing.
I really want to take the first set out myself and give them some good testing. Again, we are not talking about some fancy add on.
This is brakes. Failure of this product can cause serious harm to people on the road.

I’m glad this thread came up. I’ve had a set of 996 calipers for a few years and have been planning on putting them on my e28. A good friend of mine pointed out that the bias would likely be way off, so I started making spreadsheets. Oh joy.

Thanks for sharing all your infos, it's great to see that I'm not the only one out there with those thoughts.
I hope at some point this can be the go-to thread for big brake upgrades on our platform.
My spreadsheet by now has about 15 worksheets with different calculations.

Good information in the M3 rear rotors. At this point, I don't see a good use for them but I'll add them to the list for sure!

Im in Cincinnati and im the proud owner of beautiful 1985 BMW 735i E23 if you need a donor car for test fitment let me know i can make the drive to you sir. Besides i would love to upgrade my brake system lol

Sounds good, I'll keep you in mind. I have an E23 myself. At this point I would hate to tear a strut out of the car, but I have a good lead to a spare set of struts to take my measurements outside the car.

Great work and really happy that someone picked up on this project. Looks familiar - http://phil.infostreet.com/M5_Images/99 ... lipers.JPG

I'm running the Porsche 996 fronts with E34 M5 rears on a 528e vacuum booster. Visually I like the look of the big calipers and rotors but to be honest I had better stopping power with the original M5 brakes on hydro-boost. I think my issue is not enough vacuum, currently using a 528e booster. Any ideas on how to up the vacuum let me know.

Thanks Ben, keep it up !

P.

Thanks again for all your inspiration. I went through your thread a couple of times to get everything that you already collected.
Too bad your project died after your car!

Vacuum is something I would consider switching over too as well. How did you make it fit in your M5, do you have detailed pictures?
From my measurements it would be extremly tight.
One option could be the E34 booster?

Edit: I believe the ITB setup might be the culprit. It is known to cause lower vacuum pressure than the single TB setup if I'm not mistaken.
Where do you get your vaccuum?

I will try to call you next week.

[BenGerman]

328x20 in the rear with Turbo calipers will be awfully tight in 16" wheels. The dust shield will need the edges trimmed all around.
Once the brackets are completed, I will test again.
But it might stay a 17" only option and I will have to investigate more towards the 315mm M3 E36 rears with 996 calipers.

Time will tell.

[BenGerman]

Added the last missing piece to the caliper collection today. Cayenne aka the anchor. Almost scary how huge that thing is.
And still lighter than most of the factory options (basically every option besides the E31 Brembos).









As seen in the pictures, I'm not happy with the pad and rotor surface area combination.
It is insane how much surface those 334mm rotors have compared to modern rotors.
For example E46 M3 CSL rotors in 345mm are fully covered by the same caliper / pad combo.

Therefore: the 334mm rotors have been dropped from the equation at this point.

But: I'm already working on another possible solution to maximize rotor surface area just a little more. It would also drop the weight below most of the factory options. That's what I'm leaving it at right now. More details later on.

Also clearly visible:
There is no way to make a 348mm rotor fit a 17" (Style 42 17x8 pictured) wheel at this point.

[skeeter_nohustle]

Thank you for your commited R&D im excited to see the out come with a modern brake ,rotor and pad set up for my beloved E23

[q20v]

Hey, how are things going?

[BenGerman]

Not a lot of progress in the last couple days, real life kept me busy.
But, I now a have spare E28 strut and we are working on the front adapters.
Still aiming for driving a car with the big brake setup (Cayenne) to the vintage.

[1st 5er]

... real life kept me busy.

[skeeter_nohustle]

Any new updates ?

[BenGerman]

It will be at least another week before any more updates will be posted.
The front adapters are in the works.

[skeeter_nohustle]

Sounds ..thanks !