Bill Verburg

997.1 has the same brakes as a 996, static bias is 1.811

997.1 S static bias is 2.021

997.1 PCCB static bias is 2.084

all of the above go much more front in hard braking because of the p/v

Matt Romanowski

Why does Mark never use center of gravity height and location when doing these calculations?

mark kibort

sounds a little extreme for 1:1, but 2:1 as you metioned sounds about right. maybe 1:1 if most of the wear is around town and to and from the track. going from laguna seca , where i can measure a weakend wear in seveal mm, vs willow springs where i saw no measurable wear for the weekend, Willow might be a poor example for pad wear comparisons, or certainly up the parity of front to rear wear based on the bias settings

yes, they go much more to the front under threshold breaking, as a 911 can use 50% more rear brakes than a similar front engine car and 15% less front brakes than a front engined car at the limit.. However, around town, all bets are off and more determined by the bias settings

matt, its ok, i wont bite...............to answer, i absolutely use CG height in these calculations............why wouldnt I?

The calculation is simple

decel weight transfer =
decel (g) x (weight lbs x cg height in inches/wheelbase in inches.)

HINT: Cayman for example , has a cg height of very close to 20" in stock form.

Have fun!


here is what happens with braking bias valves with proportioning.
plug in the weight transfer during any decel rate and see what happens.

morsini

Because with his human torque wrench physique and his seat of the pant gyroscopic *** clenching he doesn't need to account for anything but his opinion, which is wrong about 85% of the time. And, yes, I did use his math there.

Slakker

Being toxic adds no value to the forum.

morsini

Lol, you don't know the history, if you did you'd feel similarly.

Slakker

Actually I do. I was the OP of the thread that the torque wrench ridiculousness took place in.

This is a racing and DE forum. Bashing someone who is trying to constructively add to the conversation is juvenile, non-productive, and just plain annoying to have to skim through. Luckily, most people have realized this and the stupidity has become minimal.

So I would ask you kindly to either stick to the topic or move on to the next thread.

morsini

So you're the thread police? Please. MYOB as you've got no skin in this. Mark, in all his infinite wisdom, can defend himself and doesn't need your help. So, take your non-productive [sic], self and bugger off.

mark kibort

I think he is saying what many of us would think of your post. often, you rarely provide a contribution and only shoot out insults. as Slacker mentioned, im ONLY trying to add information to help others here.

You must be a little insecure about being on a racing thread . are you acting out? what i posted is "Mathematically" sound, is backed up with 20 years of "real " racing experience, evidence and data. So, if you disagree, this is the place. after all its a discussion board. if you dont think that weight bias of a race car doesnt shift wear and rear brake capability to the rear, i think many of us would be interested in your "MATH" to prove otherwise!

as a note:
Maybe if you used your brakes a little more, you wouldnt end up off track down the corkscrew as much doing your best imitation of Zanardi.. Big difference, He did that on purpose.
Cheers Pal,
look forward to seeing you out at the track this season!

and by the way.. this was your 6th insultive post.. ill respond to you every 6th time in an order to keep the toxicity down


Thank you Slakker.....i didnt want to respond as i HAVE learned from the past that responding , only fuels the fire for those that feel it nessary to insult someone for their contibution that either thretens their perceptions or just to make themselves feel better by putting down someone.

mark kibort

Matt, lets have some fun...why dont YOU ever do some of the calculations?
Why dont you plug in your cars weight and use the CG height and show what the difference of your cars weight transfer vs a BMW of the same weight. (maybe use the same CG height just for simplicity) and see what the answers become.

decel weight transfer =
decel (g) x (weight lbs x cg height in inches/wheelbase in inches.)

If you dont have your CG, you can use the Cayman for example , has a cg height of very close to 20" in stock form.

From my perspective, brake pad wear is a HUGE indicator of driving style. If you are wearing the fronts near the same as the rears, you are no where at the limits of the decel rates of the car, or you are driving in rain a lot.

as i mentioned, if you go through the exercise as i have done before in another thread, you will clearly see that a 911 vs a front engine car in most cases will us 50% more rear brakes and 15% less front brakes just based on weight transfer for the same decel rates. So, if you are 4:1 on a front engine car, that will drop to near 3:1 on a Porsche 911. (approx, and based on similar sized pads front to rear)

Matt Romanowski

I'm not interested in an argument Mark, but your formula is wrong from the start. The change in weight transfer is (total weight x long g x COG height) / wheel base

Then, you have to consider the load sensitivity of the tire, anti-dive in the front suspension, and a myriad of other things to figure out the proper brake balance.

Back to your regularly scheduled rants. Hopefully people see what is important and don't listen to the noise.

mark kibort

Not an argument, just thought it would be interesting ... i think it is you that wanted to start the argument, for one, saying that i didnt incorporate CG height, which i have! (its a very dominant factor) or saying that anti dive is a factor worth mentioning.. (actually, just alters the CG height slightly)

well, you know more than Carrol's Book, where i quoted the equation..
why dont yhou tell us how is your equation and the one quoted from carrol's book different?
Yours :
(total weight x long g x COG height) / wheel base

Carrol's
decel weight transfer =decel (g) x (weight lbs x cg height in inches/wheelbase in inches.)

All the other factors are very small.... we are not trying to get a very preciece answer, just relative scale.

Its not noise Matt... its on topic and directly answering the OP's question with some ways to understand what is really happening and what the predicted outcome might be for a myriad of factor changes.

morsini

My racing record is out there - I would have thought with your superior intellect you would have found it by now. Guess you're not as smart as you think you are.
Everyone, makes mistakes when learning a new track (except you). Especially, when trying out new things. I was playing with braking points and went a little too deep. The fact that I can put it out there and laugh about all while also helping others to lean, what not to do, disproves your idiotic point about my contributions. You on the other hand pass out so much useless and incorrect information it's astounding.
Lastly, I am not your pal. You don't have any pals here. Everyone, I mean everyone has tried to help you but you fall back into the same old routines and it's been going on for well over 15 years. Do you even know how many people have you on ignore? You need serious psychological help.

mark kibort

Mike,
Ill only respond with this. Try and stay on topic and cut out the juvenile insults..
Im sure everyone appreciates your examples of what not to do...as long as it helps, i have no criticism of that.
Its not about knowing it all, its about exchange of information.
If you dont think brakes will wear faster in the rear on a 911 vs BMW, lets hear why.
Thats all.

(and by the way, you said, "everyone" and "I mean everyone".. guess you dont mean the 10s of people that have contacted me privately, so they wont get blasted by guys like you on the list). so, everyone , but them. gotcha!

mark kibort

Well Matt,

Ill take your pause or science to maybe be a time where you are thinking about it. But, here is a quote, right from Carrol's book, where the formula is clear and ironically enough, he talks about "anti-dive" or other elements as not a significant factor to worry about in our discussion here.

Paraphrasing: "Not all the kings horses or men or all the anti dive or squat technologies will change load transfer much".

the point is, we have MORE than enough information with weight, decel rates and wheel base to see the effects or change of effects on the brake load.

we already went over the load sensitivities of the tire in another thread.
also a very small factor here.

Now, lets do a comparison of a BMW with 50-50 weight distribution at a 100" wheel base and CG at 20" height. decel rate of 1.0g (using "my equation")
1G x (3000 x 20/100) = 600lbs of weight transfer

this means your BMW would now have instead of 1500lbs fr 1500rear, it would change to 2100lbs front and 900lbs rear ,( 1050fr tire each/ 450rear tire each)

Now, lets use YOUR formula, because i start out being "wrong" by using the wrong formula..... OH, i forgot, your formula and mine are basically the same..
(3000 x 1 x 20)/100= ALSO equals 600 .................Matt, 600=600...............so how is my formula, "wrong"?

Matt.... and (Mr math mike orsini) you guys, before you correct me, you might want to check your work. just a thought.
thanks!

anyway, hopefully its clear to all who look at this to see what a 45/55 (cayman) 40/60 (997) weight distribution would do to weight transfer proportions and why more rear brake and less front brake forces would be possible, likely,and cause more wear in the rear and less in the front vs a front engine'd racer that is more like 55/45 distributed.