Brake question
04-05-2011, 01:45 PM
#1
Rooting for Acura
Thread Starter
iTrader: (1)
Brake question
Just curious. I've noticed that brake calipers are positioned in different positions on rotors, even on the same car from front to rear. Anyone know what the relevance of the caliper position is? Just curious.
Thx,
kr
Thx,
kr
04-05-2011, 03:35 PM
#5
Good question. I don't really know why the placement on some cars are different than others, but I would assume packaging and cooling are definitely considerations. I wouldn't think calipers would be located at the top or bottom of a disc because of accessibility (or lack thereof) or potential for damage. Placement of calipers at these locations would also probably interfere with suspension compents (top), or longevity due to road debris (bottom).
Still another consideration may be inertia. Yes, you can all laugh, but I've often wondered about this when I look at caliper placement on high performance cars. Most times they are located behind the front disc and forward the rear one. In other words, closer to the center of the car. Brake components, including calipers and pads can be very heavy. If they were located to the outside of the rotors (in other words towards the end of the car), there is that much more weight being pushed towards the end of the car. Any weight distributed towards the ends of a car can have a negative effect on it's handling.
Again, I'm just making assumptions here.
Terry
Still another consideration may be inertia. Yes, you can all laugh, but I've often wondered about this when I look at caliper placement on high performance cars. Most times they are located behind the front disc and forward the rear one. In other words, closer to the center of the car. Brake components, including calipers and pads can be very heavy. If they were located to the outside of the rotors (in other words towards the end of the car), there is that much more weight being pushed towards the end of the car. Any weight distributed towards the ends of a car can have a negative effect on it's handling.
Again, I'm just making assumptions here.
Terry
04-05-2011, 05:03 PM
#6
I've googled this question before & to date, this thread gives out a lot of amazing insight.
http://www.f1technical.net/forum/viewtopic.php?t=2444
A few quotes.
And a pretty definitive answer.
Although most of what they are talking about is referring to how F1 cars work, a lot of it can be applied to how engineers work with consumer sports cars.
http://www.f1technical.net/forum/viewtopic.php?t=2444
A few quotes.
Because of the locations of the upper and lower joints on the steering knuckle, you really are left with two locations, in front of, or behind the axle, usually located almost level with the axle. There's not much room in there, and the places are limited. Also, because most steering linkages attach in front of the knuckle, that really leaves just one place, directly behind the axle. You could fit the caliper in beside the steering joint, but all of a sudden you would have a ball joint very close to a high level of heat, which increases the risk of seizing or failure.
If the brake caliper is for lighter use, it can be smaller and you have more choices for location. But for a large racing caliper, there's not many choices where it can go.
If the brake caliper is for lighter use, it can be smaller and you have more choices for location. But for a large racing caliper, there's not many choices where it can go.
I think I understand you Ciro. I am fairly sure the caliper location has an effect on how the loads are sent through the chassis.
The braking loads are transmitted via. the inboard suspension mounts. If viewed from side on these converge towards the CofG (parallel effectively means ground level), you get anti-dive geometry - going through the CofG is 100% anti-dive and a lower converging point is less than 100%, right down to 0% @ ground level. I don't know how much anti-dive is used in F1 cars (or anti-squat for that matter) as too much anti-dive can work to make the suspension "tie up" under braking.
Because the wheels rotate, if the caliper is behind the upright any braking force will try and lift the wheel off the ground (how much effect this has I don't know) - a caliper in front of the upright will try and drive the wheel into the ground. I expect these effects are minimal otherwise I'm sure we would see more calipers in front of the upright.
As it is, for packaging reasons it is probably better to get your steering rack where you want it before the calipers. Also, calipers behind the upright must reduce the MOI of the car.
The braking loads are transmitted via. the inboard suspension mounts. If viewed from side on these converge towards the CofG (parallel effectively means ground level), you get anti-dive geometry - going through the CofG is 100% anti-dive and a lower converging point is less than 100%, right down to 0% @ ground level. I don't know how much anti-dive is used in F1 cars (or anti-squat for that matter) as too much anti-dive can work to make the suspension "tie up" under braking.
Because the wheels rotate, if the caliper is behind the upright any braking force will try and lift the wheel off the ground (how much effect this has I don't know) - a caliper in front of the upright will try and drive the wheel into the ground. I expect these effects are minimal otherwise I'm sure we would see more calipers in front of the upright.
As it is, for packaging reasons it is probably better to get your steering rack where you want it before the calipers. Also, calipers behind the upright must reduce the MOI of the car.
Just in case anybody wanted an update...
Last week during Friday's practice, Steve Matchett answered this question. He was talking about the position of the caliper on a Honda, and he said that ideally, teams would put it as close to the ground as possible, to keep the CoG as low as possible.
So, manchild, you were the first one to say that...and you were right!
Last week during Friday's practice, Steve Matchett answered this question. He was talking about the position of the caliper on a Honda, and he said that ideally, teams would put it as close to the ground as possible, to keep the CoG as low as possible.
So, manchild, you were the first one to say that...and you were right!
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04-05-2011, 06:57 PM
#8
AZ Community Team
I think you and the F1-Technical site from Rick-TL-S are both correct. I've seen a number of F1 cars with the wheels off and they mostly put the calipers on the rear side of the front uprights and the front side of the rear uprights. The reason I think is for mass centralization. The cars are pretty light and every little bit of mass away from the Cg helps.Good question. I don't really know why the placement on some cars are different than others, but I would assume packaging and cooling are definitely considerations. I wouldn't think calipers would be located at the top or bottom of a disc because of accessibility (or lack thereof) or potential for damage. Placement of calipers at these locations would also probably interfere with suspension compents (top), or longevity due to road debris (bottom).
Still another consideration may be inertia. Yes, you can all laugh, but I've often wondered about this when I look at caliper placement on high performance cars. Most times they are located behind the front disc and forward the rear one. In other words, closer to the center of the car. Brake components, including calipers and pads can be very heavy. If they were located to the outside of the rotors (in other words towards the end of the car), there is that much more weight being pushed towards the end of the car. Any weight distributed towards the ends of a car can have a negative effect on it's handling.
Again, I'm just making assumptions here.
Terry
Still another consideration may be inertia. Yes, you can all laugh, but I've often wondered about this when I look at caliper placement on high performance cars. Most times they are located behind the front disc and forward the rear one. In other words, closer to the center of the car. Brake components, including calipers and pads can be very heavy. If they were located to the outside of the rotors (in other words towards the end of the car), there is that much more weight being pushed towards the end of the car. Any weight distributed towards the ends of a car can have a negative effect on it's handling.
Again, I'm just making assumptions here.
Terry
04-05-2011, 09:20 PM
#9
Senior Moderator
Like said above, for street cars it really comes down to where they can place it due to the other suspension/steering components.
04-05-2011, 10:39 PM
#10
On super cars, on the other hand, every gram matters. When the Carrera GT came out 5 years ago, I remember reading an article. Porsche said that to keep the point of inertia toward the center of the car as much as possible, the calipers are positioned on the "inside".
In other words, the wheel/tire is the center of pivot. Putting weight on the outside of this point increases the inertia forces, which doesn't help the stability and handling of the car.
04-06-2011, 08:25 PM
#13
01-23-2016, 12:09 PM
#15
Rooting for Acura
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iTrader: (1)
I didn't want to start a new thread on this. This video made me remember this thread I started years ago.
https://www.youtube.com/watch?v=HEIk0hJ7eGk#t=355.641
https://www.youtube.com/watch?v=HEIk0hJ7eGk#t=355.641
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