MyE28.com

Finally got around working a little more on potential pricing and summarizing all the options.
The question is now, what would you guys be interested in?
Curious to see what everybody thinks!
If at some point there is high interest in one particular version, I am willing to negotiate with Suppliers for rotors, pads and rebuild kits to get a lower price. Maybe even have a whole batch of calipers powder coated.



Assumptions:
Prices include calipers, caliper rebuild (new seals & powdercoating) for used ones, rotors, pads and adapter where necessary. No SS brake lines included yet which might be necessary for the connection.
Costs for V, VII & VIII are for the complete BBK from Turner / ECS.
Estimated caliper costs:
- Cayenne $200 per set of fronts
- 996 Front $200 per set of fronts
- 996 Rear $200 per set of rears
- 986 Rear $150 per set of rears
- ATS Front $250 per set of new fronts, no rebuild costs (for customer powdercoating) applied
- E31 Brembo Fronts $500 per set of fronts
Rebuild costs for Porsche calipers about 300 for a set of 4. (45 for seals per caliper, 30 for powdercoating per caliper)
Rotors are priced off ECS for Zimmermann, Meyle or Brembo, whatever was the cheapest.
Pads are priced off ECS for Pagid, Jurid or Textar (factory replacement options).
E23s require different rotors in the rear (Different Offset), E32 750i or F10 528i seem to be potential options.

I am interested in buying ATS front adapters only. Is that an option?

BenGerman wrote: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.

What's the word on 16" wheel fitment here? Your latest didn't make the answer clear (to me anyway). Great work on this, regardless!

T_C_D wrote:I am interested in buying ATS front adapters only. Is that an option?

It for sure will be!
I'm not looking into offering the whole kits all the time. So the adapters will most likely be the only thing I will offer for sale.
This is more of an overview how much the total costs for an upgrade would be to evaluate what kits that make sense.

cek wrote:

BenGerman wrote: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.

What's the word on 16" wheel fitment here? Your latest didn't make the answer clear (to me anyway). Great work on this, regardless!

From what I found out, there is huge differences in the fitment of different wheels.
For example: Style 42 17x8 has about the same room as a Style 5 16x8.
At this point I'm very confident that all the options with 324mm front rotors and 328mm rear rotors (close call there) will clear the Style 5 16x8 wheels. I should be able to confirm for sure in the next 2 weeks.
Individual fitments will have to be discussed.

I'm still most interested in the VIII.3 with ATS calipers front and 986 rear. I would likely just buy the adapters from you and slowly build/rebuild the rest of the kit to spread out the cost and use up my track pads in my current 540i setup.

Thanks for the continued effort.

Adam

I would just be interested in 986 rear adaptors. I would source my own disks and calipers.

It’s been a rough day in the shop.

Good news first: the ATS calipers seem to work good, no big adapter required.

The bad news: there is no way to make the 1st Gen Cayenne rotors work. the mounting holes are in the way, no matter which way we tried to move the caliper. It would require at least a 14” rotor. And that requires 18” wheels.
So it won’t happen. I was really confused first, as the calipers are being used on E30s, but the E30 strut (mounting position for the factory calipers) is a lot smaller, giving enough room for an adapter.

But: I hate giving up and just ordered a set of 2012 Panamera 6-piston calipers.
They are top mount and I still see a chance to make those work. Plus they are lighter and take up less space in the wheel.

BenGerman wrote:

Am I reading this incorrectly? It seems like 745i's brakes are rather decent and upgrades don't make much sense from price/performance perspective? Or the upgrades fade way less or something?

Thradya wrote:

BenGerman wrote:

Am I reading this incorrectly? It seems like 745i's brakes are rather decent and upgrades don't make much sense from price/performance perspective? Or the upgrades fade way less or something?

You are reading it correctly in regards of the brake torque.
There is a couple of factors influencing the brake torque.
The explanation for the high torques for the E23 system are based on the small diameter of the master cylinder.
The E23 only runs a 22.2mm Mc, while E28s have 23.8 and E34s have 25.4mm.
The smaller the surface Area of the MC piston, the higher the pressure in the brake like, the higher the pressure on the caliper pistons, the higher the brake torque.

The question is now: why not just run the 22.2mm MC in every setup?
Ultimately the stopping of your car is defined by a couple of things. If you just reduce the diameter of your Mc, your pedal travel will increase significantly. The feeling you get when braking is basically the amount of brake fluid that you move through the lines at the same time, trying to displace the volume of the caliper piston(s).

That’s why a lot of people like to do the upgrade to the 25.4mm Mc on the E28. The ultimate brake torque is decreased, but the brakes can be modulated way better by the driver.
The same thing is being done by a lot of Porsche Track Guys that upgrade the factory MC with 25.4mm ( for 911 Turbo, Cayman, Boxster and so in) to the MC of the 911 GT3 which is 27mm in diameter.

The more piston area you have, the more you will have to compensate the increased fluid flow with a bigger MC.

In regards of the E23 brakes you are right. The rotors are only 284mm in diameter, the pads have a very small surface area. Both of these factors are mayor contributors to brake fading.
Also the available pad choice is very limited.

Which brings me to the last point: friction coefficient of pads.
This is one of the main contributors to increase brake torque.
All my calculations are based on a friction coefficient of 0.4, which according to my research is an average number for factory brake pads.
If you choose to go with a full blown race pad (let’s take the Hawk DTC-70) your friction coefficient at temperature can be as high as 0.85. With that being said, the friction coefficient under normal operating temperatures (street driving) is even lower than 0.4, which is reached at around 370 F pad temperature.

Now if I take the friction coefficient of 0.85 and combine it with the cayenne calipers and 324mm rotors I can increase the brake torque from 638kNmm (yes, I just realized the error with my list, using the wrong units, i didn’t convert mm to m, therefore we will go with Nmm for now) to 1,355kNmm. That would be almost triple the original torque of a 535i front brake. Imagine what that feels like, given everything else stays constant.

The Brake torque number is mainly there to compare the front to rear Bias, as it is based on the assumption of a 1000N input force on the MC, which is defined by the operator and pedal leverage. This can also be affected by the MC size, which defines the position your pedal stiffens up and therefore the position of the pedal where you are appliying the pressure.

Hope that helps to clarify the technical background a little bit.

BenGerman wrote:You are reading it correctly in regards of the brake torque.
There is a couple of factors influencing the brake torque.
The explanation for the high torques for the E23 system are based on the small diameter of the master cylinder.
The E23 only runs a 22.2mm Mc, while E28s have 23.8 and E34s have 25.4mm.
The smaller the surface Area of the MC piston, the higher the pressure in the brake like, the higher the pressure on the caliper pistons, the higher the brake torque.

The question is now: why not just run the 22.2mm MC in every setup?
Ultimately the stopping of your car is defined by a couple of things. If you just reduce the diameter of your Mc, your pedal travel will increase significantly. The feeling you get when braking is basically the amount of brake fluid that you move through the lines at the same time, trying to displace the volume of the caliper piston(s).

That’s why a lot of people like to do the upgrade to the 25.4mm Mc on the E28. The ultimate brake torque is decreased, but the brakes can be modulated way better by the driver.
The same thing is being done by a lot of Porsche Track Guys that upgrade the factory MC with 25.4mm ( for 911 Turbo, Cayman, Boxster and so in) to the MC of the 911 GT3 which is 27mm in diameter.

The more piston area you have, the more you will have to compensate the increased fluid flow with a bigger MC.

In regards of the E23 brakes you are right. The rotors are only 284mm in diameter, the pads have a very small surface area. Both of these factors are mayor contributors to brake fading.
Also the available pad choice is very limited.

Which brings me to the last point: friction coefficient of pads.
This is one of the main contributors to increase brake torque.
All my calculations are based on a friction coefficient of 0.4, which according to my research is an average number for factory brake pads.
If you choose to go with a full blown race pad (let’s take the Hawk DTC-70) your friction coefficient at temperature can be as high as 0.85. With that being said, the friction coefficient under normal operating temperatures (street driving) is even lower than 0.4, which is reached at around 370 F pad temperature.

Now if I take the friction coefficient of 0.85 and combine it with the cayenne calipers and 324mm rotors I can increase the brake torque from 638kNmm (yes, I just realized the error with my list, using the wrong units, i didn’t convert mm to m, therefore we will go with Nmm for now) to 1,355kNmm. That would be almost triple the original torque of a 535i front brake. Imagine what that feels like, given everything else stays constant.

The Brake torque number is mainly there to compare the front to rear Bias, as it is based on the assumption of a 1000N input force on the MC, which is defined by the operator and pedal leverage. This can also be affected by the MC size, which defines the position your pedal stiffens up and therefore the position of the pedal where you are appliying the pressure.

Hope that helps to clarify the technical background a little bit.

That was an excellent explanation! Thank you!

After the frustration with the 1st Gen Cayenne calipers, there was only one way: go even bigger.
I ordered another caliper, this time off a 2012 Cayenne (92A). The main difference is the mounting style, while the older Cayenne caliper has a bolts that mount sideways, the newer ones are bolted down from the top, just like the 911 caliper. This will hopefully allow me to design a bracket that works on the E28 struts.

First impression: that thing is huge!
But, it seems like it is shaped less bulky, allowing for easier Fitment in the wheels.
And indeed, the 16” Style 5 fit with 334mm rotors the way it seems.

Now it’s time to sell some of the old cayenne calipers. (I have 10 Porsche, 2 Brembo E31 and 2 Cadillac calipers in my basement )







Edit: Fits like a glove!
A couple slight mods to the caliper and it will be a perfect match to the 334mm E38 rotors or the 330mm 2-piece rotor solution.
It's crazy how BIG that caliper is in person.

adam_poll wrote:I'm still most interested in the VIII.3 with ATS calipers front and 986 rear. I would likely just buy the adapters from you and slowly build/rebuild the rest of the kit to spread out the cost and use up my track pads in my current 540i setup.

Also voting for ATS front, 986 rears!

Amy updates ?

Still working on it. Sorry there hasn’t been a lot of updates lately.

I’m still confident I will have a car at the vintage showing a set. At this point it is more realistic that I will have a set of Cadillac calipers mounted to my car. Ultimately I will run the Cayenne calipers, but I’d like to show the combination that everybody here is interested in (Cadillac + 986).

I got 2 more rotors in today (324x30 --> E23, E24, E28, E34 Front & 336x22 --> E23, E32 rear).



The combination above will be mounted to my car at the Vintage with ATS and 996 Turbo Calipers.
Even though it's slightly suboptimal for now, it is only an intermediate step before the Cayenne calipers will be mounted with 2 piece 345x32 rotors.

BenGerman wrote:... at the Vintage.

See ya there.

The 336x22 E30 rotor fits great. Unfortunately there is not a lot of options on the E23 for the rear.
Most cars use an offset similar to the E28 on the rear axle. The “deeper” E23 and E32 is uncommon and it’s hard to find options larger than 300mm.

Nevertheless, this one should work great in combination with 324, 334 and 345mm rotors in the front, allowing some variation with the brake Bias to personal taste.

I had 2006 Viper brembo's with 348mm E60 550i rotors on my E28. Great stopping power and looks really good:

Any updates on this new kit being sold as a package ? My e23 could use a better braking system.

Sorry that there hasn't been any updates lately.
I had some great conversations at the Vintage with some of you!
I had the samples with me, but nothing mounted on a strut yet, as we are still fighting clearance issues for the front adapters.
Unless all of you are willing to run 18" wheels, I will have to go back and do a little more brainwork on this one.

Due to the other projects in line, we will move this back a little further and tackle it again later this summer.
I have about $2,000 invested in it, I'm not giving up that easy!

Having failed to get my E23 to The Vintage, I plan to drive it to O'Fest in Pittsburgh. Just found LF caliper has 3 seized pistons. I apologize for jumping in on the thread, but if anyone has a good LF caliper to sell, please shoot me a PM.

Shoot me a PM

funfunfer wrote:Having failed to get my E23 to The Vintage, I plan to drive it to O'Fest in Pittsburgh. Just found LF caliper has 3 seized pistons. I apologize for jumping in on the thread, but if anyone has a good LF caliper to sell, please shoot me a PM.

Now that I'm awake, I found closeout re-manufactured calipers at RockAuto.
Still following this thread 'cause big Brembos.

BenGerman wrote:
I had the samples with me, but nothing mounted on a strut yet, as we are still fighting clearance issues for the front adapters.
Unless all of you are willing to run 18" wheels, I will have to go back and do a little more brainwork on this one.
:

Benny, You mean that ATS caliper wont fit 17" wheel ? damn..

No, not at all!
I think at this point the only thing that is dead is the 6 piston Cayenne caliper.
There is no realistic solution under 18”.

For everything else I have to go back to the drawing board.

Any new progress on this E23 brake upgrade ?

Sorry there hasn't been any updates.
Got a little frustrated before the Vintage, when rotors and calipers wouldn't clear what I wanted them to clear, especially considering I have about $800 in rotors sitting in my basement and more than that in calipers.

BUT! I'm not giving up. After the clutch spring project and a couple other small projects have been done, I promise to get back to it. Most likely a little streamlined though. 1-2 caliper & rotor choices, everything else can be made custom if anyone needs it.

BenGerman wrote:Sorry there hasn't been any updates.
Got a little frustrated before the Vintage, when rotors and calipers wouldn't clear what I wanted them to clear, especially considering I have about $800 in rotors sitting in my basement and more than that in calipers.

BUT! I'm not giving up. After the clutch spring project and a couple other small projects have been done, I promise to get back to it. Most likely a little streamlined though. 1-2 caliper & rotor choices, everything else can be made custom if anyone needs it.

Thanks for the update ! Im excited about what product comes out of this.

I keep checking in on a rear solution! Take your time, no rush, but I'll be waiting : )

I assume your bias values all coming from the weight of a US e28 M5. If that is true, I hope your comparisons are all based on this single vehicle weight distribution.

I applaud you for your research and efforts in putting all of this together. It really is good data and helps to further the informed decisions for brake setup. I had come to my current brake setup after reviewing the big brake detail of mye28 and m535i.org back in about 2013-14. My biggest concern was rotor weight as we have so much power loss at elevation that adding rotor weight was only going to hurt vehicle performance.

After reviewing all your charts and tables, I am now wondering why you are looking to use these expensive calipers on your build at all. Is it for looks or just for a fun project? In the charts, I see that a budget solution exists with the existing factory options. Maybe your project is planning a high HP build? Lucifer's Hammers runs the E31 Brembo's and I'm sure it has all the brakes it needs with off the shelf (europe) parts. Granted those parts are expensive and maybe you are just trying to emulate or improve on that setup for a cheaper price with more availability?

I have to say after reviewing the tables, I really came out with the impression that the current setup I have really is ideal for my purpose. That purpose is a 535is with turbo for road course use (2 miles long). Say not quite 300hp due to altitude, but a street-able setup driven year round and anticipating some level of wear and replacement in the future. IMO, it is overkill for any sort of street duty and decidedly up to the task for for any application of extreme temperatures and hard use.
Weight: 3300lbs (lighter than M5 slightly)
Front: E34 540/740i Rotors and Calipers. Street or race pads depending
Rear: E34 540i Rotors and Calipers. Street or race pads depending
E32 Master Cylinder (although I think I may have preferred the feel of the E28 master)

This includes overall cost, weight/lightness, pad selection, brake bias, stopping force, heat dissipation, minimum wheel size, accessibility for spare parts and consumable parts cost (pads/rotors/caliper rebuilds). When I had these parts in my E24, I noticed that bias was too much rear and had installed a bias valve to adjust. At this point, no bias valve on the E28 and the fronts do lock up first.

If I were to build a stock weight 535i for autocross, I would go with stock e28 pads and rotors with aggressive pads
If I were to build a stock weight 535i for road course use I would go with the E34 535i calipers and rotors (nonvented rears)
both of these options chosen to minimize overall weight.

For M5 setups, I used E32 740i Front Rotors with stock calipers.
I used 540i rear rotors calipers and pads.
It seemed like I had a bit of extra rear bias, but I never checked it for sure by disabling ABS. Either way, this was a street setup for me and was more than acceptable. I did not want to go with the heavier E34 M5 rotors and the upgrade was to eliminate front brake rotor warping issues.

I have to admit 'bling' factor is not a criteria of mine, so I have no preference on 2 pot vs 4 pot calipers, or the size/color/brand. Cost is more a driving factor for me as the brakes are consumable parts in a sense.