Fine Tuning Rear Brake Bias
06-04-2009, 08:31 AM
#61
Rennlist Member
Thread Starter
Brian, the different track/street setup changing of adjustable brake proportioning is why some use adjustable camber plates and adjustable shocks. I don't think that is what they are intended for.
If you are into Formula 1 and have followed Michael Schumacher, he is the King of braking. He not only uses brakes to slow the car for corners, but all the way thru the corner and thru the first couple of gears exiting. Once he enters a corner he doesn't come completely off the brakes or throttle for that matter until the car is going straight again. There are several charts on the internets showing the difference in the telemetry between Schumacher and Barracello that show the differences in their braking, throttle, and speed. Michael gets on the brakes much later, slows down faster and is faster up to the apex of the corner. Barrachello does exit corners faster, but Michael is faster thru the corner overall. Watching some of the in-car video he can be seen changing brake bias several times each lap just before he goes into a corner.
If you are into Formula 1 and have followed Michael Schumacher, he is the King of braking. He not only uses brakes to slow the car for corners, but all the way thru the corner and thru the first couple of gears exiting. Once he enters a corner he doesn't come completely off the brakes or throttle for that matter until the car is going straight again. There are several charts on the internets showing the difference in the telemetry between Schumacher and Barracello that show the differences in their braking, throttle, and speed. Michael gets on the brakes much later, slows down faster and is faster up to the apex of the corner. Barrachello does exit corners faster, but Michael is faster thru the corner overall. Watching some of the in-car video he can be seen changing brake bias several times each lap just before he goes into a corner.
Last edited by RKD in OKC; 06-04-2009 at 09:28 AM.
06-04-2009, 10:56 AM
#62
Rennlist Member
I'm wondering where the disconnect is here.
WORF, re-read my post and get back to me.
the weight distribution we are discussing here is front to rear. This cannont be changed to any worth mentioning amount by changing suspension settings.
When you lower or raise ride height on a corner, it trades off the weight change with all the other corners, and DOES NOT change weight distribution front to rear, and that was what we are talking about. So yes, each wheel can have different weight adjustments, but this doesnt change the weight distribution front to rear. Make sense??
I origially said:" (a quicky of "How") However, this doesnt change front to rear weights (to any real measureable degree). "
Then you said worf: " When you change ride height the change in weight distribution isn't measurable to any degree? Huh?
Ok, so if you can't measure the change in weight distribution, I ask again: how do you corner balance (if you can't measure the change?)
This knot you continue to tie is rooted in what you wrote many posts ago:"
Let me ask you something. Do you not know the differnce between weight distribution front to rear and changing the individual corner weight??
SO, Ill ask you again. why dont you tell us how you can change weight distribution front to rear with suspension settings.
FRONT TO REAR!! in case you missed this salient point.
mk
WORF, re-read my post and get back to me.
the weight distribution we are discussing here is front to rear. This cannont be changed to any worth mentioning amount by changing suspension settings.
When you lower or raise ride height on a corner, it trades off the weight change with all the other corners, and DOES NOT change weight distribution front to rear, and that was what we are talking about. So yes, each wheel can have different weight adjustments, but this doesnt change the weight distribution front to rear. Make sense??
I origially said:" (a quicky of "How") However, this doesnt change front to rear weights (to any real measureable degree). "
Then you said worf: " When you change ride height the change in weight distribution isn't measurable to any degree? Huh?
Ok, so if you can't measure the change in weight distribution, I ask again: how do you corner balance (if you can't measure the change?)
This knot you continue to tie is rooted in what you wrote many posts ago:"
Let me ask you something. Do you not know the differnce between weight distribution front to rear and changing the individual corner weight??
SO, Ill ask you again. why dont you tell us how you can change weight distribution front to rear with suspension settings.
FRONT TO REAR!! in case you missed this salient point.
mk
I don't need to as you did it yourself:
Ah! So, changing ride height does change weight distribution.
When you change ride height the change in weight distribution isn't measurable to any degree? Huh?
Ok, so if you can't measure the change in weight distribution, I ask again: how do you corner balance (if you can't measure the change?)
This knot you continue to tie is rooted in what you wrote many posts ago:
Ah! So, changing ride height does change weight distribution.
When you change ride height the change in weight distribution isn't measurable to any degree? Huh?
Ok, so if you can't measure the change in weight distribution, I ask again: how do you corner balance (if you can't measure the change?)
This knot you continue to tie is rooted in what you wrote many posts ago:
06-04-2009, 11:30 AM
#63
Rennlist Member
Agreed, but as I have pointed out, what is the effectiveness of the rear brakes on a decel of 1.3 g's from 140 to 0? What is the weight transfer? If you have 2500lbs over the front wheels and 500lb over the rear wheels and have some braking already in the rear, how much can it be improved? say you are only getting the effectiveness of a rear limit of braking for a 250lb rear end. by totally utilizing the other 250lbs of potential, what would that increase the g's of decel to? Keep in mind that any increase effectivenss further increase the weight transfer the front. To increase decel g rate from 1.3 to 1.35, the weight transfter would be:
1.3g x (3000LBS x 24"/100"=936 lbs of weight transfer
1.35g x ( 30000lbs x 24" /100" = 972 lbs of weight tranfer
With my race car of 1700 /1300 lbs front to rear, the weight transfer goes to :
2672lbs / 328lbs at 1.35g'. that's less than 175lbs per rear tire. Not much!
You see if in reality you were near capacity in the rear brakes and suddenly you were able to create 1.35g more brakng from the rear, the rear would be lighter by near 50lbs. If you are trail braking or braking into a set of transision turns, you could have rear lock up and some control issues.
mk
1.3g x (3000LBS x 24"/100"=936 lbs of weight transfer
1.35g x ( 30000lbs x 24" /100" = 972 lbs of weight tranfer
With my race car of 1700 /1300 lbs front to rear, the weight transfer goes to :
2672lbs / 328lbs at 1.35g'. that's less than 175lbs per rear tire. Not much!
You see if in reality you were near capacity in the rear brakes and suddenly you were able to create 1.35g more brakng from the rear, the rear would be lighter by near 50lbs. If you are trail braking or braking into a set of transision turns, you could have rear lock up and some control issues.
mk
As a new 928 owner still at the getting to know my car stage I have great
respect for owners with more experience and who compete in their cars
BUT
surely if you want to vary the brake bias you don't work around it by using
different brakes pad types front to rear and so on.
The obvious answer is to fit a variable brake proportioning valve.
It is the correct component designed to do that very job.
(http://www.tiltonracing.com/content....ist2&id=36&m=b).
This is the "across the board" method used in just about every type of
motorsport I have had any involvement with. Look under the bonnet of
just about any race or rally car and you will find a twin brake master cylinder
set up with an adjustable balance bar. As a cheaper alternative you will
find a variable brake proportioning valve. For a car used for occasional
track/ DE days such a set up is ideal since you can turn it up to get maximum
braking from all four wheel on the track then adjust it down to get less to the
rears for safer braking on the road with little chance of the rear locking up first.
Remember even on a 928 with a highly modified engine the brakes will be much more
powerful than the engine, i.e. 140-0 will be much faster than 0-140, so it makes sense
to optimise your braking.
respect for owners with more experience and who compete in their cars
BUT
surely if you want to vary the brake bias you don't work around it by using
different brakes pad types front to rear and so on.
The obvious answer is to fit a variable brake proportioning valve.
It is the correct component designed to do that very job.
(http://www.tiltonracing.com/content....ist2&id=36&m=b).
This is the "across the board" method used in just about every type of
motorsport I have had any involvement with. Look under the bonnet of
just about any race or rally car and you will find a twin brake master cylinder
set up with an adjustable balance bar. As a cheaper alternative you will
find a variable brake proportioning valve. For a car used for occasional
track/ DE days such a set up is ideal since you can turn it up to get maximum
braking from all four wheel on the track then adjust it down to get less to the
rears for safer braking on the road with little chance of the rear locking up first.
Remember even on a 928 with a highly modified engine the brakes will be much more
powerful than the engine, i.e. 140-0 will be much faster than 0-140, so it makes sense
to optimise your braking.
06-04-2009, 12:12 PM
#64
Rennlist Member
Thread Starter
Here is one of those F1 comparison charts I mentioned...
They don't mention any data on front to rear bias, but it seems to me Michael is using throttle to modulate the rear brake bias. This allows him to maximize total braking because he can apply as much rear brake as whatever weight ends up in the rear at any given time can handle. Does seem to give him a bit of an advantage using more rear brake what.
Mark, please ignore the last sentence in bold.
They don't mention any data on front to rear bias, but it seems to me Michael is using throttle to modulate the rear brake bias. This allows him to maximize total braking because he can apply as much rear brake as whatever weight ends up in the rear at any given time can handle. Does seem to give him a bit of an advantage using more rear brake what.
Mark, please ignore the last sentence in bold.
06-04-2009, 12:33 PM
#65
Rennlist Member
Hard to really see what is going on here without g loading graphs, but I see your point. certainly, there is a place for bias changes, whether settings or by throttle and brake techniques. However, what you are seeing below, are style diffferences where michael usually wins. However there are plenty of drivers that have turned the same or better lap times a Michael in a given race on a given lap. His style and techniques are thought to be of the best out there.
Does the author really mean michael wants to reduce weight transfer? Thats like saying he wants to reduce decelleration gs. . He is probably talking about rate of weight transfer.
mk
Does the author really mean michael wants to reduce weight transfer?
Thats like saying he wants to reduce decelleration gs. . He is probably talking about rate of weight transfer. mk
Here is one of those F1 comparison charts I
They don't mention any data on front to rear bias, but it seems to me Michael is using throttle to modulate the rear brake bias. This allows him to maximize total braking because he can apply as much rear brake as whatever weight ends up in the rear at any given time can handle. Does seem to give him a bit of an advantage using more rear brake what.
Mark, please ignore the last sentence in bold.
They don't mention any data on front to rear bias, but it seems to me Michael is using throttle to modulate the rear brake bias. This allows him to maximize total braking because he can apply as much rear brake as whatever weight ends up in the rear at any given time can handle. Does seem to give him a bit of an advantage using more rear brake what.
Mark, please ignore the last sentence in bold.
06-04-2009, 12:35 PM
#66
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Great stuff on braking techniques! I'll speculate that Shu' uses the light brake application on exit as a form of traction control.
housekeeping: MK, please thread your responses with the original quoted test above your comments. It's a chore to go up and down on the page trying to figure out what you are commenting on. My old eyes and feeble pea-brain have a lot of trouble keeping the train of thoughts on a single track these days. Thanks!
housekeeping: MK, please thread your responses with the original quoted test above your comments. It's a chore to go up and down on the page trying to figure out what you are commenting on. My old eyes and feeble pea-brain have a lot of trouble keeping the train of thoughts on a single track these days. Thanks!
06-04-2009, 04:17 PM
#67
Rennlist Member
Thread Starter
I told you to ignore the last sentence in bold 
MS is using less brakes so, decelerating slower over a longer time so, therefore transferring less weight.
What everyone would like to see is side by side comparisons between Michael Schumacher and Ayrton Senna. MS is smooth left foot braking where AS is on/off on/off on/off. I've seen in-car film of AS where he basically slides ***** to the wall sideways into the corners then pumps the throttle on/off all the way through until he can go full throttle on exit, anything but what would be considered smooth. I think those two are considered the ultimate opposites in driving style.\
I've tried left foot braking. I either hit my head on the windshield because i didn't move my foot over to the clutch to upshift after the corner, or lock up the front and push till I give up and lift off the brakes. A couple of times, both on the same corner.
MS is using less brakes so, decelerating slower over a longer time so, therefore transferring less weight.
What everyone would like to see is side by side comparisons between Michael Schumacher and Ayrton Senna. MS is smooth left foot braking where AS is on/off on/off on/off. I've seen in-car film of AS where he basically slides ***** to the wall sideways into the corners then pumps the throttle on/off all the way through until he can go full throttle on exit, anything but what would be considered smooth. I think those two are considered the ultimate opposites in driving style.\
I've tried left foot braking. I either hit my head on the windshield because i didn't move my foot over to the clutch to upshift after the corner, or lock up the front and push till I give up and lift off the brakes. A couple of times, both on the same corner.
06-04-2009, 05:17 PM
#68
Rennlist Member
I knew you were going to come back with that.
Actually, it gets really more complicated because you can enter a turn at a faster speed, and still be decelerating during the turn, even if he is off the brakes. Its one of the advantages of trail braking. Let's not go there. all these graphs show is braking force. there could be lower braking forces (on the pedal) that translate to higher Gs on the car. Also, look at the graphs. michael is on the brakes much later, but seems to get to near the same cornering speed in a fraction of the time. dv/dt tells me he has more decelleration g's in that period and would have more weight transfer there too. Again, we dont know as we are only getting the braking pedal graphs, which only tell a fraction of the story. But, we do have speed changes vs tiime and that is very telling as well.
Anyway, points well heard.
Nice visual of your left foot braking experience.
mk
Actually, it gets really more complicated because you can enter a turn at a faster speed, and still be decelerating during the turn, even if he is off the brakes. Its one of the advantages of trail braking. Let's not go there. all these graphs show is braking force. there could be lower braking forces (on the pedal) that translate to higher Gs on the car. Also, look at the graphs. michael is on the brakes much later, but seems to get to near the same cornering speed in a fraction of the time. dv/dt tells me he has more decelleration g's in that period and would have more weight transfer there too. Again, we dont know as we are only getting the braking pedal graphs, which only tell a fraction of the story. But, we do have speed changes vs tiime and that is very telling as well.
Anyway, points well heard.
Nice visual of your left foot braking experience.
mk
I told you to ignore the last sentence in bold
MS is using less brakes so, decelerating slower over a longer time so, therefore transferring less weight.
What everyone would like to see is side by side comparisons between Michael Schumacher and Ayrton Senna. MS is smooth left foot braking where AS is on/off on/off on/off. I've seen in-car film of AS where he basically slides ***** to the wall sideways into the corners then pumps the throttle on/off all the way through until he can go full throttle on exit, anything but what would be considered smooth. I think those two are considered the ultimate opposites in driving style.\
I've tried left foot braking. I either hit my head on the windshield because i didn't move my foot over to the clutch to upshift after the corner, or lock up the front and push till I give up and lift off the brakes. A couple of times, both on the same corner.
MS is using less brakes so, decelerating slower over a longer time so, therefore transferring less weight.
What everyone would like to see is side by side comparisons between Michael Schumacher and Ayrton Senna. MS is smooth left foot braking where AS is on/off on/off on/off. I've seen in-car film of AS where he basically slides ***** to the wall sideways into the corners then pumps the throttle on/off all the way through until he can go full throttle on exit, anything but what would be considered smooth. I think those two are considered the ultimate opposites in driving style.\
I've tried left foot braking. I either hit my head on the windshield because i didn't move my foot over to the clutch to upshift after the corner, or lock up the front and push till I give up and lift off the brakes. A couple of times, both on the same corner.
06-04-2009, 05:54 PM
#69
Rennlist Member
Thread Starter
Ah, but it does show their speed over time!!! MS slows at generally the same rate where RB slows, keeps the same speed a bit then slows again.
06-04-2009, 06:12 PM
#70
Rennlist Member
I mentioned that. Look at the speed right around the shumacher "M" to the "H". (that vertical speed reference line) . The angle (slope) of that line is deceleration. Those can be considered equal gs at the same speed range, right, so, Michael has the same max g loading at those same speeds, even though he started his braking a lot later. (edit) In actually, it still is a little less than Borechello's greater speed decel, right up until the "RR"s in Borrechellos name. there is a blip and that looks to be a pretty rapid change in speed. That really is the best graph, as it is showing vehicle speed. same change in any speed, will cause the same g loading and weight transfer. Now, weight tranfer rates are different.
Bottomline, thats one turn, lots of factors and micheal was faster that day.
mk
Bottomline, thats one turn, lots of factors and micheal was faster that day.
mk
06-04-2009, 06:25 PM
#71
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The first turn at Suzuka is a tough place to make comparisons in braking style because the first half of it is nearly flat out in an F1 car. They're really on the limit on entry and factors like bravery come into play.
A better comparison would be the straightline braking for the hairpin at Montreal:
A better comparison would be the straightline braking for the hairpin at Montreal:
06-04-2009, 06:37 PM
#72
Rennlist Member
Well, there you go. faster rate of deceleration, more g's to the slowest speed and thus more weight transfer. the author gets it a little wrong, in that if Michael has a greater rate of deceleration, even though he is using some throttle on decel, the g loading and weight transfer will still be greater than Borrechello's flatter decel line. The reason for the mix of gas could be to counteract rear brake bias to be able to use more front brake % and increase decel rate. I dont know. Interesting though. Maybe his LHjetronic idle switch cuts off fuel and he doesnt want the engine to die when he puts the clutch in. Oh, no clutch?? nevermind.
mk
mk
The first turn at Suzuka is a tough place to make comparisons in braking style because the first half of it is nearly flat out in an F1 car. They're really on the limit on entry and factors like bravery come into play.
A better comparison would be the straightline braking for the hairpin at Montreal:
A better comparison would be the straightline braking for the hairpin at Montreal:
06-04-2009, 10:22 PM
#73
Rennlist Member
Have attended the Montreal F1 GP twice...............there's no comparrison no matter what corner you sat at..............MS ruled RB.
Again just my opinion based on real life experience.
Again just my opinion based on real life experience.
06-04-2009, 11:25 PM
#74
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06-04-2009, 11:34 PM
#75
What book is that?