Interesting. I always thought they were the same. One thing that Dave did for the Lotus rotors to save weight was to reduce the dimensions in the rear to match the path of the pads (+1mm) which is about 5mm less than the full inside and outside diameters.
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Interesting. I always thought they were the same. One thing that Dave did for the Lotus rotors to save weight was to reduce the dimensions in the rear to match the path of the pads (+1mm) which is about 5mm less than the full inside and outside diameters.
I had a discussion with Martin Eberhard some time back where I mentioned how bad the Roadster's braking was, saying they're borderline dangerous. He indicated that the Roadster's braking system was beefed up/bigger than the Elise. I was perplexed since the pads/calipers were the same and the rotor's didn't seem that much larger. But now I guess he was talking about the larger rear discs. Makes sense now, however still not adequate to stop safely. Kinda silly going larger on the rear rotors with such skimpy rear calipers and pads. Surprised they didn't go 1" larger in the front as well where the pads and calipers are acceptable in their size. I personally have seen warping on the rear rotors of the Roadster and this makes sense if the calipers are working as hard as possible, but with such a small foot print they'll generate more heat. Hence where the slotted rotors with the aluminum hats will help dissipate and expunge the heated gasses better than stock.
Thanks for letting us know!
Thanks for letting us know!
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I've had my Roadster about 6 weeks. Have rad many negative posts about the brakes. I've tried many rapid stops on quiet streets and freeway off ramps, going from 60 to zero as quickly as possible. Brakes seem good to me compared to my most recent Porsche, an '09 Cayman. As far as I know my Roadster has the stock pads. It has just under 14K miles on it.
The brakes on the Roadster don't bite with the stock pads, they rather gracefully glide it to a stop. They also won't be there for you when a hard stop is needed. The CarboTech AX6 pads feel like airbrakes in a sense on an F-15. They bite hard when you need them to. I love having confidence I have much improved stopping power over stock while driving in traffic.
A true test on the braking system is to go 60-80mph, put the Roadster in neutral and then try bringing it to a full stop. That'll give you a pretty clear picture of how well or not those brakes bring you to a stop.
I do notice when I use the brakes hard and longer such as on windy roads pushing it, I feel the rotors are the next limiting factor and feel the braking system is still not functioning up to par. Especially compared to the Roadster's performance and handling. I feel a proper sports car must have brakes that are at least comparable but realistically should be better than the performance of the engine/motor/handling of the vehicle. Proper braking is fundamental to the handling and safety of both the driver and the vehicle itself.
As for comparison, the brakes on the Roadster are far worse than the Cayman in terms of true stopping distance.
The 2010 Roadster stops from 80mph to 0mph in: 210ft.
The 2006Cayman S stops from 80mph to 0mph in: 190ft.
That's a 20 foot difference!!! 20 feet can easily allow you avoid or create a collision.
The 2009 Lotus Exige S 260 Sport stops from 80mph to 0mph in: 196ft.
*Note that the 2009 Lotus Exige S 260 is lighter than the Elise (which the Elise is lighter than the Roadster).
2006 Cayman stat (can't find an '09 spec):
http://www.roadandtrack.com/cm/roadandtrack/data/RT_2006-Porsche-Cayman-S_data.pdf
2010 Roadster stat:
2010 Tesla Roadster Sport - Road & Track
2009 Lotus Exige S 260 Sport stat:
Lotus Exige S 260 Sport vs. Nissan Nismo 370Z - Road & Track
A true test on the braking system is to go 60-80mph, put the Roadster in neutral and then try bringing it to a full stop. That'll give you a pretty clear picture of how well or not those brakes bring you to a stop.
I do notice when I use the brakes hard and longer such as on windy roads pushing it, I feel the rotors are the next limiting factor and feel the braking system is still not functioning up to par. Especially compared to the Roadster's performance and handling. I feel a proper sports car must have brakes that are at least comparable but realistically should be better than the performance of the engine/motor/handling of the vehicle. Proper braking is fundamental to the handling and safety of both the driver and the vehicle itself.
As for comparison, the brakes on the Roadster are far worse than the Cayman in terms of true stopping distance.
The 2010 Roadster stops from 80mph to 0mph in: 210ft.
The 2006Cayman S stops from 80mph to 0mph in: 190ft.
That's a 20 foot difference!!! 20 feet can easily allow you avoid or create a collision.
The 2009 Lotus Exige S 260 Sport stops from 80mph to 0mph in: 196ft.
*Note that the 2009 Lotus Exige S 260 is lighter than the Elise (which the Elise is lighter than the Roadster).
2006 Cayman stat (can't find an '09 spec):
http://www.roadandtrack.com/cm/roadandtrack/data/RT_2006-Porsche-Cayman-S_data.pdf
2010 Roadster stat:
2010 Tesla Roadster Sport - Road & Track
2009 Lotus Exige S 260 Sport stat:
Lotus Exige S 260 Sport vs. Nissan Nismo 370Z - Road & Track
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Jaff
Active Member
Have you tried "emergency style" stops in wet weather?...I found the stock pads incredibly bad when it's raining...
Worst-case scenario... Drive in the rain, let the car sit overnight so you have nice rusty rotors, and THEN try to do an emergency stop. With the stock pads you'll be in trouble. This is the biggest advantage of AX6. One braking operation and the rotors are cleaned off.
adiggs
Well-Known Member
That squishy slidey feel the first time or 2 hitting the brakes when the rotors have had an opportunity to get wet is just miserable. I've learned to plan for it, what with driving the car through the winter in Portland, but that doesn't mean I remember every time. That's entirely the wrong feel to get back from the brakes.
Ok, will keep you in the loop about the progress.
As MAUTO indicated, you can look at the drilled holes (5 of them) in the rotor and notice the front has more rotor than the back which shows the front is bigger than the back.
Bump in the thread and another confirmation that slotted rotors are better than drilled:
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He expressed an opinion, "slotted better than drilled", without actually saying WHY he has that opinion.
Doug_G, this comment goes back to a conversation earlier in this thread where I was asking if this gentleman could drill and slot, and he provided pictures of cracks through the drilled holes. His opinion was that slots alone are superior as holes crack and fill with dirt, making them dangerous and useless.
I'm not sure I agree, but I hope this makes things clearer about where he is coming from.
Best,
T
Yes, it would be better if he actually stated why they were better. For me, I believe I mentioned this before, slotted allows heat as well as other elements to off-gas, it also allows brake dust to be taken into the slot then blown away after it exits the pad and makes the revolution around. As for drilled, I've seen many pics of drilled rotors cracking which appear to be mostly from the larger drilled holes. As for the Roadster the drilled holes offer a place for the brake dust to collect, they block, and then become very limited for offgassing. And my theory when its raining is that all this dust turns to muck / slime which then pours all over your rotor limiting the braking ability when wet.
I'll try to find some metrics if any on slots vs. drilled performance.
I've also put slotted rotors on my Dodge truck which I also increased the rotor size and placed better pads on. Before the truck could barely stop itself, faded hard upon heavy breaking with no load in the truck. I now feels bite and stop better with my 2300 pound camper loaded, then another 600+ pounds of camping weight/food/water. No fading and pure bite. When braking if feels like I could have the camper fly off! However in that case there were 3 things I did change out. But all three I feel are essential for proper braking of a vehicle. Also it was a standard disc brake upgraded to slots on my truck.
[Update]
Here's a good link / write-up on the comparison between flat, slotted, drilled, slotted + drilled, as well as floating rotors. Its interesting they note that drilled rotors are best in rainy / wet conditions:
http://www.zeckhausen.com/How_to_select_brake_rotors.htm
Smooth rotors offer the quietest operation, lowest dust and longest pad life. If you have a luxury car that is not driven aggressively, this may be your best choice. Often used by endurance racers who need to survive a 24-hour race without a pad change and are willing to give up some performance to achieve that. Typically these are the lowest cost option. Some premium products, such as Centric Parts High Carbon rotors, are available with directional internal cooling vanes (there's a left and a right side part number), even though the factory rotors may use straight vanes. See "Which Way? How to properly install plain, slotted or drilled brake rotors" for more details.
Slotted rotors offer improved bite (initial onset of braking) and slightly higher friction level than smooth rotors. Slots prevent reduction in friction due to pad outgassing or brake dust trapped between pads and rotors. Pad coefficient of friction is maintained over the lifetime of the pads, since slots shave away glaze formation and expose fresh pad surface each time brakes are applied. Slotted rotors are by far the number one choice for cars used in competition or open track events. Best choice for heavy trucks and SUVs, particularly when extra bite is needed for towing. Disadvantages include slightly reduced pad life, some low frequency rumble and pedal flutter when braking hard from high speeds. If the slots are improperly machined all the way to the outside edges, then rotors may develop cracks sooner than plain or properly slotted rotors.
Drilled rotors offer slightly more bite and friction than slotted rotors. As with slotted rotors, pad coefficient of friction remains consistent over their lifetime. Wet bite is improved over plain and slotted rotors, so these may be the best choice for areas with heavy rainfall, like Seattle or Singapore. Weight is reduced by about 0.2 pounds per rotor, depending on size and drill pattern. Disadvantages include possible uneven rotor wear, typically concentric groove formation, although this is mostly an aesthetic concern. A major disadvantage is accelerated formation and spreading of cracks under racing conditions. For this reason, drilled rotors should be avoided for track cars, unless required by the rules. A common piece of misinformation is that they have lower performance than smooth rotors, due to reduced surface area and are for looks only. This is false.
Slotted & Drilled rotorsoffer a compromise, midway between the benefits of slotted rotors and drilled rotors. These are fine for street applications, but should be avoided for track cars. For the first time, slotted & drilled rotors are starting to appear on some cars as delivered from the factory, including models from BMW and Mercedes.
2-Piece Floating rotorsconsist of an iron "friction ring" assembled with float hardware to an aluminum hat or mounting bell. These are available slotted or drilled. 2-Piece rotors offer substantial weight savings over the 1-piece rotors described above, as much as 10 pounds per rotor, depending on the specific application. The design allows the outer friction ring to expand as it's heated, without being constrained by the center section. This prevents rotor "coning" and subsequent tapered pad wear and spongy pedal. Because the center section and friction ring are fabricated from dissimilar materials, conductive heat transfer is reduced, lowering wheel bearing temperatures dramatically. Outer friction rings may be replaced when worn, while reusing the center hat, at substantial cost savings. Click HERE for more details on the hardware and assembly of StopTech floating rotors. For track cars, these are absolute best choice and should be used when available. A disadvantage is significantly higher initial cost. For street cars driven in high-salt/chemical environments, corrosion between the iron friction rings, aluminum hats, and float hardware may lead to reduced product lifetime. This can be mitigated by flushing the brakes with water frequently or swapping back and forth between "summer" and "winter" brakes.
I'll try to find some metrics if any on slots vs. drilled performance.
I've also put slotted rotors on my Dodge truck which I also increased the rotor size and placed better pads on. Before the truck could barely stop itself, faded hard upon heavy breaking with no load in the truck. I now feels bite and stop better with my 2300 pound camper loaded, then another 600+ pounds of camping weight/food/water. No fading and pure bite. When braking if feels like I could have the camper fly off! However in that case there were 3 things I did change out. But all three I feel are essential for proper braking of a vehicle. Also it was a standard disc brake upgraded to slots on my truck.
[Update]
Here's a good link / write-up on the comparison between flat, slotted, drilled, slotted + drilled, as well as floating rotors. Its interesting they note that drilled rotors are best in rainy / wet conditions:
http://www.zeckhausen.com/How_to_select_brake_rotors.htm
Smooth rotors offer the quietest operation, lowest dust and longest pad life. If you have a luxury car that is not driven aggressively, this may be your best choice. Often used by endurance racers who need to survive a 24-hour race without a pad change and are willing to give up some performance to achieve that. Typically these are the lowest cost option. Some premium products, such as Centric Parts High Carbon rotors, are available with directional internal cooling vanes (there's a left and a right side part number), even though the factory rotors may use straight vanes. See "Which Way? How to properly install plain, slotted or drilled brake rotors" for more details.
Slotted rotors offer improved bite (initial onset of braking) and slightly higher friction level than smooth rotors. Slots prevent reduction in friction due to pad outgassing or brake dust trapped between pads and rotors. Pad coefficient of friction is maintained over the lifetime of the pads, since slots shave away glaze formation and expose fresh pad surface each time brakes are applied. Slotted rotors are by far the number one choice for cars used in competition or open track events. Best choice for heavy trucks and SUVs, particularly when extra bite is needed for towing. Disadvantages include slightly reduced pad life, some low frequency rumble and pedal flutter when braking hard from high speeds. If the slots are improperly machined all the way to the outside edges, then rotors may develop cracks sooner than plain or properly slotted rotors.
Drilled rotors offer slightly more bite and friction than slotted rotors. As with slotted rotors, pad coefficient of friction remains consistent over their lifetime. Wet bite is improved over plain and slotted rotors, so these may be the best choice for areas with heavy rainfall, like Seattle or Singapore. Weight is reduced by about 0.2 pounds per rotor, depending on size and drill pattern. Disadvantages include possible uneven rotor wear, typically concentric groove formation, although this is mostly an aesthetic concern. A major disadvantage is accelerated formation and spreading of cracks under racing conditions. For this reason, drilled rotors should be avoided for track cars, unless required by the rules. A common piece of misinformation is that they have lower performance than smooth rotors, due to reduced surface area and are for looks only. This is false.
Slotted & Drilled rotorsoffer a compromise, midway between the benefits of slotted rotors and drilled rotors. These are fine for street applications, but should be avoided for track cars. For the first time, slotted & drilled rotors are starting to appear on some cars as delivered from the factory, including models from BMW and Mercedes.
2-Piece Floating rotorsconsist of an iron "friction ring" assembled with float hardware to an aluminum hat or mounting bell. These are available slotted or drilled. 2-Piece rotors offer substantial weight savings over the 1-piece rotors described above, as much as 10 pounds per rotor, depending on the specific application. The design allows the outer friction ring to expand as it's heated, without being constrained by the center section. This prevents rotor "coning" and subsequent tapered pad wear and spongy pedal. Because the center section and friction ring are fabricated from dissimilar materials, conductive heat transfer is reduced, lowering wheel bearing temperatures dramatically. Outer friction rings may be replaced when worn, while reusing the center hat, at substantial cost savings. Click HERE for more details on the hardware and assembly of StopTech floating rotors. For track cars, these are absolute best choice and should be used when available. A disadvantage is significantly higher initial cost. For street cars driven in high-salt/chemical environments, corrosion between the iron friction rings, aluminum hats, and float hardware may lead to reduced product lifetime. This can be mitigated by flushing the brakes with water frequently or swapping back and forth between "summer" and "winter" brakes.
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I can certainly agree that drilled rotors are problematic for track use. The drill holes are where the cracks start. In fact it takes just a couple of track days with my C6 for hairline cracks to start forming around the drill holes.
Here's an informative video on the benefits of a 2 piece floating rotor which these rotors are we're looking to have fabricated. He also goes into describing about what a full floating rotor is which is used in supercars. Interesting seeing the slotted not drilled rotor used in the supercar rotor design( drilled not used due to cracking I'm sure). It appears they went smaller in size with the slots, more of them, not as deep but wavier. The two piece rotor offers the benefit of preventing warping of the rotor since the heat becomes more evenly distributed across the disc as well as the benefit of keeping heat away from the wheel bearings. Slotted rotors are recommended for vehicles that are carrying more weight. I can contest on the improvement it makes with my truck. I do believe the Roadster will benefit from its design, since I feel we're pushing the braking system of the Roadster WAY too hard.
The Roadster's braking system is based on the Elise which so much lighter. 739 pounds lighter! Every pound of weight counts when to stopping, it has lots of energy moving forward that needs a counter-action. So we're trying to stop 739 more pounds with basically the same braking system as what's spec'd in a lighter equipped car! The CarboTechs helped out a good bit, but there still needs much improvement in this area. Rain is an issue, at least for me. Stopping in the rain does not match the car's acceleration. Also when you really do drive the Roadster spirited the rotors do show significant signs of needing improvement. With braking its money well spent.
tesla roadster weight - Google Search
2,723lbs-1,984lbs=739lbs
The Roadster's braking system is based on the Elise which so much lighter. 739 pounds lighter! Every pound of weight counts when to stopping, it has lots of energy moving forward that needs a counter-action. So we're trying to stop 739 more pounds with basically the same braking system as what's spec'd in a lighter equipped car! The CarboTechs helped out a good bit, but there still needs much improvement in this area. Rain is an issue, at least for me. Stopping in the rain does not match the car's acceleration. Also when you really do drive the Roadster spirited the rotors do show significant signs of needing improvement. With braking its money well spent.
tesla roadster weight - Google Search
- 2011 Tesla Roadster
Luxury vehicle - Body style: Convertible
- Horsepower: 288 HP
- Curb weight: 2,723 lbs
- Payload: 550 lbs
- 2006 Lotus Elise
Luxury vehicle - Engine size: 1.8L
- Horsepower: 190 HP
- Curb weight: 1,984 lbs
- MPG: 24 city / 29 highway
- Fuel tank capacity: 10.6 gal
2,723lbs-1,984lbs=739lbs
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adiggs
Well-Known Member
Wiztecy - put me on the list, rather than just thinking about it. My wife and I've been talking about it and what with driving the Roadster daily through the winter rains here in Portland, we've decided this moves from nice-to-have to must-have 
Thanks Adiggs!
So I have the following who're committed to the rotor set:
-Hcsharp
-Tobash
-Dsm363
-Adiggs
-Wiztecy (me)
Anyone else? Once these are being made its a done deal and I'm sure we won't be making any more hats. We can however have more disc's needed as they need to be replaced.
Honestly, this is the best place to put your money. When it comes that you can't brake in time, its done and the damage easily will exceed the cost of upgrading your braking system.
Also these rotors should remedy the rear warped rotors of setting / pulling the emergency brake when parking the Roadster while the rotors are hot.
Lastly look at the benefits of having a reduction in "unsprung" weight, the weight we're saving by making the hats aluminum. Some benefits are better response from the suspension since less weight has to be dampened as the wheel comes up, improved acceleration and braking since the rotating weight has significantly been reduced.
So I have the following who're committed to the rotor set:
-Hcsharp
-Tobash
-Dsm363
-Adiggs
-Wiztecy (me)
Anyone else? Once these are being made its a done deal and I'm sure we won't be making any more hats. We can however have more disc's needed as they need to be replaced.
Honestly, this is the best place to put your money. When it comes that you can't brake in time, its done and the damage easily will exceed the cost of upgrading your braking system.
Also these rotors should remedy the rear warped rotors of setting / pulling the emergency brake when parking the Roadster while the rotors are hot.
Lastly look at the benefits of having a reduction in "unsprung" weight, the weight we're saving by making the hats aluminum. Some benefits are better response from the suspension since less weight has to be dampened as the wheel comes up, improved acceleration and braking since the rotating weight has significantly been reduced.
Wiztecy:
Will Tesla install these in one of their SCs, or will everyone be doing themselves or using their local garage? I'd be interested, but, over here in Hong Kong, I'll be relying on the local Tesla SC to help me install. I will also ask them direct, but wondered what other folks will do.
Appreciate input/thoughts.
Thanks.
Volta.
Will Tesla install these in one of their SCs, or will everyone be doing themselves or using their local garage? I'd be interested, but, over here in Hong Kong, I'll be relying on the local Tesla SC to help me install. I will also ask them direct, but wondered what other folks will do.
Appreciate input/thoughts.
Thanks.
Volta.
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Hi Volta,
I would have to say to be safe that Tesla won't install any aftermarket part on Tesla. However it can happen, such as with the Carbotech brake pads. So you'd have to first inquire to see if they'd do both the pads and rotor. If not, the next best place to take the Roadster is to a Lotus Elise mechanic that has a good reputation. The brake system is basically identical. Feel free to PM me if you have any more questions.
At this point it would be more of a distraction, but possibly in the future after these have rolled off. I don't think there's an issue with braking on the S, at least not like the Roadster. The S's braking system was designed for the S's weight from the beginning, the Roadster's braking system was not, it was for a car that was 740 pounds lighter hence the need for the rotors in order to stop safely in all types of driving conditions.
