Gauging Interest: Model S Front Caliper Upgrade Kit

[MasterC17]

I purchased my P3D+ with the intent of tracking it at HPDE's. It became pretty clear that the stock PUP brakes were not up to the task of track driving; at the very least new pads and brake fluid would be needed. However, pad selection was poor and the stock rotors are pretty thin at 25mm. So I began investigating ways to retrofit the Model S Calipers without it costing an arm and a leg.

I sourced Centric (StopTech) Rotors and had them custom machined and drilled to accommodate the Model S Calipers with some supporting hardware. Paired with Hawk DTC-70's and Motul RBF-600 they performed flawlessly at VIR.

I wanted to share my retrofit with the community and see if others would be interested in purchasing my kit. This kit will also work on non-performance Model 3's and those without the PUP. I am not ready to release them yet (still making some tweaks), but I also don't want to invest a bunch of time and money if no one is interested. I am guessing the kit will be in the $500-$600 range (rotors and supporting hardware, I can help source Calipers if needed, you can source pads of your choice).

Pro's:

• Rotors are 32mm thick compared to the stock 25mm, a 28% increase in thermal capacity!
• Fit's under the Stock 18" Wheel, PUP Caliper requires Stock 19" Wheels
• Pads can be changed without removing the caliper, unlike the Model 3 Calipers (PUP or not)
• Pad selection is much better
• Cost is reasonable, you don't have to spend an arm and a leg to get a factory-feel/look BBK

Con's:

• They are hefty at 28lbs each (compares to 21lb stock rotors), though I doubt you would notice any difference in most scenarios.

Without further ado, here are some photo's!

 

[Glamisduner]

I'm assuming at that price I would still need to also buy the S calipersm What do those cost? How much weight are we considering adding to the rotor?

 

[juanmedina]

Can we use 18" wheels?

 

[MasterC17]

I'm assuming at that price I would still need to also buy the S calipersm What do those cost? How much weight are we considering adding to the rotor?

Yes, you would need to source calipers. New with pads they are $440 each. You can find them used for about $200 a piece. The rotors weigh an additional 7lbs each, however the calipers are slightly lighter (I need to weigh them to get an exact # which I will do).

Can we use 18" wheels?

Yes, I will take a photo this weekend with a stock 18" mounted up.

 

[Orwell]

There are carbon ceramic options for Model S rotors that are significantly lighter (to your car and wallet).

And also 2-piece rotors are available with aluminum hats.

 

[Orwell]

I assume this kit would include an caliper adapter bracket and machined rotors?

Can we just buy the adapter bracket by itself?

I really like that you can change the pads for track days without removing the calipers.

 

[MasterC17]

There are carbon ceramic options for Model S rotors that are significantly lighter (to your car and wallet).

And also 2-piece rotors are available with aluminum hats.

The point of this kit was to be economical - I am offering 2 rotors and the required hardware for $500-$600. I highly doubt there are any carbon ceramic or 2-piece rotors available for less than $600. If so, please provide the link.

I assume this kit would include an caliper adapter bracket and machined rotors?

Can we just buy the adapter bracket by itself?

I really like that you can change the pads for track days without removing the calipers.

There is no adapter bracket needed. This kit includes the appropriately machined and drilled rotors along with some hardware bits.

 

[vletnguyen]

So its basically BBK for under $1,000. Not bad, considering it fits 18" and OEM.

 

[MasterC17]

So its basically BBK for under $1,000. Not bad, considering it fits 18" and OEM.

Precisely! I think this is a nice upgrade and a great value for those without the PUP brakes, and if you already have the PUP brakes but want better thermal capacity it serves a need there as well.

 

[Orwell]

Did you compare the piston sizes between the 3P+ brakes the Model S brakes?

I never said you can get carbon ceramics or 2-piece rotors for less than $600. I was merely stating an option for lighter Model S rotors since the kit you are offering uses heavier rotors than OE Model 3 rotors.

Nice to know that the Model S and Model 3 uses the same caliper mounting position. I appreciate that you did the work to find this out.

 

[MasterC17]

Did you compare the piston sizes between the 3P+ brakes the Model S brakes?

I never said you can get carbon ceramics or 2-piece rotors for less than $600. I was merely stating an option for lighter Model S rotors since the kit you are offering uses heavier rotors than OE Model 3 rotors.

Nice to know that the Model S and Model 3 uses the same caliper mounting position.

Ah, gotcha, sorry I did not understand. There are lighter rotors available as you mentioned, but they come with a significant premium.

I am fairly certain the piston size is the same. I am going to measure them as soon as I have an opportunity.

 

[Orwell]

Are any modifications required to the OEM knuckles?

Did braking feel change at all?

I would be interested if you offered 2-piece rotors.

 

[MasterC17]

Are any modifications required to the OEM knuckles?

Did braking feel change at all?

I would be interested if you offered 2-piece rotors.

No modification to the knuckles or calipers is needed. Brake feel is effectively the same, no noticeable difference as long as it is properly bled. I am not planning to offer 2-piece rotors at this time but that may come in the future depending on demand.

 

[YisSerL]

I am mildly interested, but I would need your help in sourcing the Model S calipers.

 

[MasterC17]

I am mildly interested, but I would need your help in sourcing the Model S calipers.

I am planning to have a few sets of re-manufactured calipers available at any given time. They would be a bit cheaper than new ones.

 

[Lucky13]

I almost did this when I first got my car and was going to have MPP make me a two price rotor but it was a bit pricey. I still have model s calipers if anyone is interested in buying them. Slide into my DM. Nice work by the way.

 

[dfwatt]

No modification to the knuckles or calipers is needed. Brake feel is effectively the same, no noticeable difference as long as it is properly bled. I am not planning to offer 2-piece rotors at this time but that may come in the future depending on demand.

Racing Brake is offering a range of 2 piece rotors (S, 3 with big brakes, 3 with standard brakes), admittedly at a premium, with convergent vane design that reportedly increases cooling air flow. Big plus for those with deeper budgets is that the rotors save significant unsprung weight. I suspect that the convergent vane design, on the 3 PUP brakes, will be roughly comparable to the stock S brakes, at a cost premium but with a weight reduction instead of weight gain. Here is a white paper written by numerous PhDs, explaining the technical details on how various design and structural parameters effect heat dissipation. I doubt anyone would want to read this (I sure didn't) but you can surf to the conclusions on page 109. The curved convergent vane design of these rotors appears to be the smart way to reduce weight, and get better management of thermal stresses - for a price of course. It's all tradeoffs. While putting on S calipers and rotors might be the best value for increasing braking thermal capacity/per $, the weight difference between S brakes and rotors vs. PUP brakes with these lighter weight rotors might be as much as 20-25 lbs/corner. That's a lot of weight, and its importance is magnified if you are tracking the car, as weight for sure is your main enemy for all aspects. I'm reminded of Colin Chapman's aphorism, "do your best design, and then add lightness!"

I've ordered a set of four, due to arrive in a week. I'll post pictures, and impressions, although at this point, I'm not tracking the car.

 

[MasterC17]

Racing Brake is offering a range of 2 piece rotors (S, 3 with big brakes, 3 with standard brakes), admittedly at a premium, with convergent vane design that reportedly increases cooling air flow. Big plus for those with deeper budgets is that the rotors save significant unsprung weight. I suspect that the convergent vane design, on the 3 PUP brakes, will be roughly comparable to the stock S brakes, at a cost premium but with a weight reduction instead of weight gain. Here is a white paper written by numerous PhDs, explaining the technical details on how various design and structural parameters effect heat dissipation. I doubt anyone would want to read this (I sure didn't) but you can surf to the conclusions on page 109. The curved convergent vane design of these rotors appears to be the smart way to reduce weight, and get better management of thermal stresses - for a price of course. It's all tradeoffs. While putting on S calipers and rotors might be the best value for increasing braking thermal capacity/per $, the weight difference between S brakes and rotors vs. PUP brakes with these lighter weight rotors might be as much as 20-25 lbs/corner. That's a lot of weight, and its importance is magnified if you are tracking the car, as weight for sure is your main enemy for all aspects. I'm reminded of Colin Chapman's aphorism, "do your best design, and then add lightness!"

I've ordered a set of four, due to arrive in a week. I'll post pictures, and impressions, although at this point, I'm not tracking the car.

Racing Brake does have a nice solution here but I am not sure where you are finding 20-25lbs/corner? RB says right on their website that their front Model S Caliper Retrofit rotors are 21lbs/pc - exactly the same as the stock PUP and 7lbs/corner lighter than my solution. This comes with, as you stated, a hefty premium over what I am offering ($700-$800).

If, instead, you opted to keep the PUP Calipers and replace the rotors with the RB Solution ($1,140) you do save more weight, nearly 12lbs compared to my solution (which I admit is quite a bit, though still nowhere near 20-25lbs).

Ultimately, I think the solution I have proposed is best for those without PUP brakes looking for an upgrade (cosmetic and functional) and those with PUP brakes that are budget-conscious (function only).

 

[dfwatt]

Racing Brake does have a nice solution here but I am not sure where you are finding 20-25lbs/corner? RB says right on their website that their front Model S Caliper Retrofit rotors are 21lbs/pc - exactly the same as the stock PUP and 7lbs/corner lighter than my solution. This comes with, as you stated, a hefty premium over what I am offering ($700-$800).

If, instead, you opted to keep the PUP Calipers and replace the rotors with the RB Solution ($1,140) you do save more weight, nearly 12lbs compared to my solution (which I admit is quite a bit, though still nowhere near 20-25lbs).

Ultimately, I think the solution I have proposed is best for those without PUP brakes looking for an upgrade (cosmetic and functional) and those with PUP brakes that are budget-conscious (function only).

I was assuming that the stock caliper was significantly lighter than the S one (and admittedly didn't crunch the numbers properly). You're suggesting it's not - but how's that possible? Aren't they both made from the same material? In any case, if you do RB convergent vane rotors, those are 15 lbs, which is 13 lbs less than the 28 lbs rotor that the S caliper mandates. That's still a boatload of unsprung weight - perhaps not as bad as tire tread weight in terms of impact on braking and acceleration, but it's still a lot. It's an open empirical question how much additional thermal dissipation their design promotes over simply a larger surface area.

Would be nice to get some input on that from RB as I suspect they must have testing data. It's all about air flow over a heated surface area, and contrary to widespread assumptions, the extra mass doesn't hold a lot of heat, as metals have a very poor specific heat (roughly one tenth of the SH compared to water, which is the gold standard). The bigger brake rotor does provide more total internal and external area to dissipate that heat, although again the internal vane structure of the RB disks may make that closer, and then there is the air flow question, which is not simply outside the disk area, but inside flow as well. Bottom line, hard to know how much a smaller but better designed disk compares with a standard straight vane larger disk in heat dissipation ability. In any case, all of this is beyond both our pay grades, and would be a question for RB and their design team.

 

[MasterC17]

I was assuming that the stock caliper was significantly lighter than the S one (and admittedly didn't crunch the numbers properly). You're suggesting it's not - but how's that possible? Aren't they both made from the same material? In any case, if you do RB convergent vane rotors, those are 15 lbs, which is 13 lbs less than the 28 lbs rotor that the S caliper mandates. That's still a boatload of unsprung weight - perhaps not as bad as tire tread weight in terms of impact on braking and acceleration, but it's still a lot. It's an open empirical question how much additional thermal dissipation their design promotes over simply a larger surface area.

Would be nice to get some input on that from RB as I suspect they must have testing data. It's all about air flow over a heated surface area, and contrary to widespread assumptions, the extra mass doesn't hold a lot of heat, as metals have a very poor specific heat (roughly one tenth of the SH compare to water, which is the gold standard). The bigger brake does provide more total internal and external area to dissipate that heat, although again the internal vane structure of the RB disks may make that closer, and then there is the air flow question, which is not simply outside the disk area, but inside flow as well. Bottom line, hard to know how much a smaller but better designed disk compares with a standard straight vane larger disk in heat dissipation ability. In any case, all of this is beyond both our pay grades, and would be a question for RB and their design team.

I concur that the RB replacement rotor for the stock PUP brakes is a great upgrade, but again, it comes with a cost and is not available to those without the PUP brakes.

I will weigh the S calipers and the PUP 3 calipers this weekend and post my results, but I don't think there is much or any weight difference between the two.

Ultimately, what I am offering is targeted to those without the PUP brakes and those with PUP brakes that are looking to track the car and are budget-conscious.