New plaid rear brake caliper looks like it may be open pot with a cover.

[Sam1]

klwtts posted a pic of a new model X plaid (yes I know this is an S forum, but they should have the same setup) rear caliper and it appears to be a caliper cover with an open pot caliper underneath it, like the MYP has now.

If you zoom in, you can see a bar on the inside close to the wheel (open pot caliper) and the red part looks has a ledge in the middle of it, and what looks like a bolt probably to hold it on.

 

[WilliamG]

klwtts posted a pic of a new model X plaid (yes I know this is an S forum, but they should have the same setup) rear caliper and it appears to be a caliper cover with an open pot caliper underneath it, like the MYP has now.

If you zoom in, you can see a bar on the inside close to the wheel (open pot caliper) and the red part looks has a ledge in the middle of it, and what looks like a bolt probably to hold it on.

View attachment 909778

I think you're right. It was pretty shameful on the Y to do this, and even more embarrassing on the S/X.

 

[Zuikkis]

klwtts posted a pic of a new model X plaid

The picture is from Model S, not X...

 

[Sam1]

The picture is from Model S, not X...

Sorry, he mixed that in with his MXP photos.

 

[Visionary]

Looks definitely like a cover. I guess the only change was the pads.

 

[TLLMRRJ]

I wouldn't be against a caliper cover that doesn't look like a caliper cover, but this one definitely looks like a poorly executed caliper cover.

 

[SoCal Buzz]

I think you're right. It was pretty shameful on the Y to do this, and even more embarrassing on the S/X.

What is inherent issue with an open pot caliper for those of us that don’t know brakes?

 

[lowtek]

What is inherent issue with an open pot caliper for those of us that don’t know brakes?

There's not, necessarily. Everybody is assuming because it's a cover it's been cheapened to save money, which could be true, but it could also be true that just swapping to a better set of pads makes a huge difference in performance. We'll see

 

[ninefiveone]

What is inherent issue with an open pot caliper for those of us that don’t know brakes?

It’s the unfortunate “feature list more is better” mentality without an understanding of how things work.

You can make a fair argument that an open pot caliper is worse than a monoblock multi-piston caliper but usage is the real consideration. Open pot calipers typically have smaller brake pads, less even application of force, less mass to manage heat, etc.

All of that sounds bad except that 75% of braking work is done by the front brakes because of weight shift, etc. Some traction/stability control systems use the rear brakes but under normal usage that isn’t going to be a problem. For light track use you would need to manage it. For heavy track use you should be upgrading the entire brake system anyway. Also brakes that are good on track are not good on the street. Brake pads that work well at track temperatures work poorly at street temps.

Improved rear braking is vanity 90% of the time.

That said… for a car as expensive as the plaid is… a little vanity should be part of the deal.

 

[TLLMRRJ]

What is inherent issue with an open pot caliper for those of us that don’t know brakes?

It's worth mentioning that the term "open pot caliper" appears to be the sole invention of some Tesla fan's imagination.

If you google that term, nothing comes up. And I have been a gearhead for many decades and this is the first time I have heard that term.

 

[SoCal Buzz]

It's worth mentioning that the term "open pot caliper" appears to be the sole invention of some Tesla fan's imagination.

If you google that term, nothing comes up. And I have been a gearhead for many decades and this is the first time I have heard that term.

Yeah, I googled before asking the question here to avoid looking too dumb

 

[E90alex]

It's worth mentioning that the term "open pot caliper" appears to be the sole invention of some Tesla fan's imagination.

If you google that term, nothing comes up. And I have been a gearhead for many decades and this is the first time I have heard that term.

Yep. It’s a called a floating caliper.

Edit: actually looks like the S/X has had floating rear calipers since 2018. So this may just be a cheaper/uglier design of the floating caliper thereby needing a beauty cover for aesthetics. Performance wise should be a negligible difference since it’s the same type of caliper.

 

[Visionary]

Yeah all current plaids have the floating rear one piston caliper. My GT-R had 4 pistons in the back and that's a car with 1/2 the Plaid's Power.

 

[vcor]

Selecting brake components shouldn't be compared with ICE cars. We have regen which I'm sure has an effect, particularly since the brakes are rarely used. I expect both the lack of usage and regen changes the optimal brake design over ICE cars. I think it was Munro Associates that thought we might be better off with drum brakes in the rear on EVs, and not due to cost differences. I'm not sure of the reasons though. I did notice the latest Audi eTron uses rear drum brakes.

I'm not advocating for drums, as the eTron is far from a sports car, but I wish I knew more about why different options are better for our specific EVs.

 

[Nickos]

Yeah all current plaids have the floating rear one piston caliper. My GT-R had 4 pistons in the back and that's a car with 1/2 the Plaid's Power.

BMW's M-division historically did the single pot or floating rear too...always struck me as a poor choice especially as I took both my M3s and M5s to the track on occasion. Certainly Porsche make the best brakes, I've never had anything but superb stopping power (a few squeaks!) and they've historically put much more expensive rivals like F-cars to shame in that department.

 

[E90alex]

BMW's M-division historically did the single pot or floating rear too...always struck me as a poor choice especially as I took both my M3s and M5s to the track on occasion. Certainly Porsche make the best brakes, I've never had anything but superb stopping power (a few squeaks!) and they've historically put much more expensive rivals like F-cars to shame in that department.

The majority of heavy braking load is handled by the front brakes so the rear brake calipers likely don’t make much of a difference in practice. The fixed 2/4 piston rear calipers on some cars are largely for aesthetics. The rotor diameter and thickness will have more of an effect on braking performance than single floating vs dual piston fixed caliper.

Porsches tend to have great stopping power because their weight distribution is more rear biased. So under braking, there’s still more weight retained over the rear axle so the rear brakes can contribute more to the braking load. For example a 911 might be 35/65 F/R static but under heavy braking more like 70/30.

In an already front heavy 65/35 car or even 50/50 car, even more weight is shifted forward under heavy braking so the rear brakes don’t need much force before they’re already locking up the wheels. A 50/50 car might be like 80/20 under braking. Some front heavy cars can end up lifting the whole rear end off the ground in some braking situations so you get 100/0. The rear brakes end up doing very little work in such scenarios.

 

[TLLMRRJ]

Also worth noting that even though the brakes are universally panned, the current Model S has outstanding braking performance out of the box of 60-0 in 104 feet, which is outstanding for such a heavy car.

The only downside to the brakes is that they overheat quickly from repeated back to back hard braking stops.

A higher temp brake fluid would probably go a long way to improving that issue. Next would be to add some air cooling ducts that could probably be adapted from another car. But that's really all for track use, and not to many of these are bought for serious track use.

 

[lowtek]

Would any of you buy the $20,000 brake upgrade kit if they release it?

 

[Sam1]

It's worth mentioning that the term "open pot caliper" appears to be the sole invention of some Tesla fan's imagination.

If you google that term, nothing comes up. And I have been a gearhead for many decades and this is the first time I have heard that term.

It's what we call them in dirt track racing.

Would it make you happier if I referred to them as an open frame floating caliper?

 

[TLLMRRJ]

It's what we call them in dirt track racing.

Would it make you happier if I referred to them as an open frame floating caliper?

Got me curious. Please post a link where they call it that in dirt track racing?