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Those batteries sure take up a lot of space. I wonder what their physical volume is -- compared to a 15 gallon gasoline tank. The slide-out brake pads are a ne

Those batteries sure take up a lot of space. I wonder what their physical volume is -- compared to a 15 gallon gasoline tank. The slide-out brake pads are a neat idea, but I'm wondering why, as the caliper still has to be removed during a brake change to pull off the rotor. Those aluminum pieces can't be cheap. Neither can the 4-piston brake calipers. Nor the armored underbelly. It's definitely performance-oriented.

grecy 14y ago
> The slide-out brake pads are a neat idea Every car I've ever worked on with calipers has slide out pads just like that... > as the caliper still has to be removed during a brake change to pull off the rotor Although pad changes are much more frequent than rotor changes, so it makes sense.
- stephengillie 14y ago
  I've worked on many domestic and foreign cars, and I've never seen slide-out calipers. Most have a window so you can check pad and rotor thickness, but none have a slide-out section. Even if you don't replace the rotor, you still have to remove have it turned (grinding the contact surfaces flat again), so the new pads make good contact, instead of being pressed against the ridges and valleys left in the rotor from the worn-out pad. It just seems like a bit of over-engineering.
  - sbierwagen 14y ago
    This isn't quite my field, but I've been told you only need to have a rotor turned if it's warped or scored; otherwise you can just change out the pads, then apply the brakes heavily to conform them to the rotor surface.
    - grecy 14y ago
      That's exactly what I have always done.
      - stephengillie 14y ago
        I've never seen brake pads wear out without scoring the rotor.
        sbierwagen 14y ago
        Some pads have a thin piece of soft spring steel that drag on the rotor when the pad is thin, producing horrible screeching noises without damaging the surface.
  - duck 14y ago
    It isn't over-engineering because they are just Brembo calipers with Telsa stamped on them. Brembo has a huge share of the performance/racing brake market. On a regular car you might have to have your rotors turned, but on something like this the rotors are more heavy duty and I think resist warping. Plus, on something like this you could run a lot softer pad (for track days) and need to change them out after a single weekend of use. It is still a good idea to sand the rotor surface, by hand, just so the pads will seat correctly. Edit: And I do agree, I've never seen a "normal" car with the slide out pads... although they always look like you can do that until you get close and realize it is going to be a little more work than you thought. :)
  - goofygrin 14y ago
    Almost all performance brakes have this easy drop in pads to make changes faster at the track (I'd change pads 2-3x a track day in my evo). They bought an off the shelf brake setup from brembo. Nothing special here for people in the know.
CapitalistCartr 14y ago
"Those batteries sure take up a lot of space. I wonder what their physical volume is -- compared to a 15 gallon gasoline tank." Its more realistic to compare the volume and weight of the ICE, transmission, driveshaft, rear end, and fuel tank with the electric motors, drive train, and batteries for two cars of similar range and performance.
peterwwillis 14y ago
About 26,472 cubic inches. Fifteen gallons is 3,465 cubic inches. (Taking the wheels off, if the car were rectangular its dimensions would result in around 696,581 cubic inches of volume, so the battery pack takes up about 3.8% of that) Rotors don't have to be changed as frequently as pads. It's probably a lot easier this way vs dismantling the whole thing.
- stephengillie 14y ago
  Thanks for that info! So the batteries take up about 9 times as much space as a gas tank? If you do not replace the rotor when you replace the pads, a machine shop has to grind the rotor, so its surface will be flat to work effectively with the new pads. If you don't, the pads won't make full contact with the rotor, and maintaining the brakes would make them operate worse until they wore in.
  - peterwwillis 14y ago
    Ah, you're right. I'm cheap and lazy but this car deserves doing it right. Perhaps the pads are slipped in after the assembly is put together so you don't have to juggle with them while putting it on? Alternate idea: a chunk of the caliper missing reduces unspring weight?
  - ricardobeat 14y ago
    I thought this was absurd so looked it up. Apparently most cars these days have metal pads, so both the pads and rotor wear equally. I'd never heard of that, all the small city cars I've had always had pads made of rubber/ceramic material.
    - peterwwillis 14y ago
      A lot of manufacturers sell cars with ceramic because it's less annoying to the driver. Performance brake pads are going to be metal (or a combination of alloy and something else) because they bite harder and pull heat away from the rotor.
  - 14y ago

grecy 14y ago

> The slide-out brake pads are a neat idea Every car I've ever worked on with calipers has slide out pads just like that... > as the caliper still has to be removed during a brake change to pull off the rotor Although pad changes are much more frequent than rotor changes, so it makes sense.

stephengillie 14y ago
I've worked on many domestic and foreign cars, and I've never seen slide-out calipers. Most have a window so you can check pad and rotor thickness, but none have a slide-out section. Even if you don't replace the rotor, you still have to remove have it turned (grinding the contact surfaces flat again), so the new pads make good contact, instead of being pressed against the ridges and valleys left in the rotor from the worn-out pad. It just seems like a bit of over-engineering.
- sbierwagen 14y ago
  This isn't quite my field, but I've been told you only need to have a rotor turned if it's warped or scored; otherwise you can just change out the pads, then apply the brakes heavily to conform them to the rotor surface.
  - grecy 14y ago
    That's exactly what I have always done.
    - stephengillie 14y ago
      I've never seen brake pads wear out without scoring the rotor.
      - sbierwagen 14y ago
        Some pads have a thin piece of soft spring steel that drag on the rotor when the pad is thin, producing horrible screeching noises without damaging the surface.
- duck 14y ago
  It isn't over-engineering because they are just Brembo calipers with Telsa stamped on them. Brembo has a huge share of the performance/racing brake market. On a regular car you might have to have your rotors turned, but on something like this the rotors are more heavy duty and I think resist warping. Plus, on something like this you could run a lot softer pad (for track days) and need to change them out after a single weekend of use. It is still a good idea to sand the rotor surface, by hand, just so the pads will seat correctly. Edit: And I do agree, I've never seen a "normal" car with the slide out pads... although they always look like you can do that until you get close and realize it is going to be a little more work than you thought. :)
- goofygrin 14y ago
  Almost all performance brakes have this easy drop in pads to make changes faster at the track (I'd change pads 2-3x a track day in my evo). They bought an off the shelf brake setup from brembo. Nothing special here for people in the know.

CapitalistCartr 14y ago

"Those batteries sure take up a lot of space. I wonder what their physical volume is -- compared to a 15 gallon gasoline tank." Its more realistic to compare the volume and weight of the ICE, transmission, driveshaft, rear end, and fuel tank with the electric motors, drive train, and batteries for two cars of similar range and performance.

peterwwillis 14y ago

About 26,472 cubic inches. Fifteen gallons is 3,465 cubic inches. (Taking the wheels off, if the car were rectangular its dimensions would result in around 696,581 cubic inches of volume, so the battery pack takes up about 3.8% of that) Rotors don't have to be changed as frequently as pads. It's probably a lot easier this way vs dismantling the whole thing.

stephengillie 14y ago
Thanks for that info! So the batteries take up about 9 times as much space as a gas tank? If you do not replace the rotor when you replace the pads, a machine shop has to grind the rotor, so its surface will be flat to work effectively with the new pads. If you don't, the pads won't make full contact with the rotor, and maintaining the brakes would make them operate worse until they wore in.
- peterwwillis 14y ago
  Ah, you're right. I'm cheap and lazy but this car deserves doing it right. Perhaps the pads are slipped in after the assembly is put together so you don't have to juggle with them while putting it on? Alternate idea: a chunk of the caliper missing reduces unspring weight?
- ricardobeat 14y ago
  I thought this was absurd so looked it up. Apparently most cars these days have metal pads, so both the pads and rotor wear equally. I'd never heard of that, all the small city cars I've had always had pads made of rubber/ceramic material.
  - peterwwillis 14y ago
    A lot of manufacturers sell cars with ceramic because it's less annoying to the driver. Performance brake pads are going to be metal (or a combination of alloy and something else) because they bite harder and pull heat away from the rotor.
- 14y ago