Finally developed my own GPL setup...

Having used other people's setups for the last year, I thought it was about time to develop my own. It really is fantastic to be able to have a car setup with which you can truly be committed, know what it is going to do, and how it is going to react to your input. The motivation was that I have a few tracks (Spa, Zandy, Mosport and Silverstone) where I could not find a setup that I was very happy or comfortable with. I have now got Zandy down to a 1:27.22 which although not super fast, I was quite happy with it! Especially since I have only really been driving there about a month on and off. Silverstone was always a killer at Abbey, every single lap....Finally able to nail it properly, lap time drop by 4 (!!!!) seconds to 1:30.9. All down to the confidence my own setup allows. I found that shock absorber tuning made a huge difference to the turn- in characteristics of the car, I've got it down very nicely. Nunnini's theories on ride height vs. spring rate worked very well, as did setting the spring rates to the exact weight distribution of the car. However, it would be interesting to be able to adjust the damper rates in smaller increments. If the weight dist. - spring rate theory is valid (which it is) then as the weight is transferred when entering a corner would also require a 38%/62% (Lotus) damping rate, with some small adjustments to get a nice turn in or oversteer. I tried something as best I could with such coarse adjustment, which was alright, but an exact 38/62 rate would be very interesting. If this was possible using the setup editing tools... I have also found that my style tends to leave the rear tyres generally hotter than either fronts, generally because I tend to always hang the back out and use a bit too much throttle. Is this a common situation for others? I know that the cars are tail-happy, but I have read often about the outside front consistently overheating being a big problem for most. My setup generally yields 180-200 on the inside front, 200-220 outside front, and 210-230 on the rears. Any other setup development thoughts or experiences? Rafe Mc

I have found, using Nunnini's concepts for spring rates, that I consistently heat the rear tires to 25-40 degrees higher than the fronts. I differ, however, with his reverse-weight-distribution concept on the arb's. Makes the setup way to pushy for me. I prefer to set the arb's so that both the front and rear have the same roll rate when the arb rate is added to the spring rate. For example: If the rear has a 100 lb/in spring rate and a 50 lb/in arb rate, the total rate resisting suspension compression due to lateral weight transfer for the rear is 150 lb/in. Now, if the front has a 62 lb/in spring rate I need an 88 lb/in arb rate so that the front end has the same total 150 lb/in roll rate as the rear. Makes for a nicely balanced car IMHO. I have wondered the same as you how the car would behave if the damping rates could be adjusted to the weight distribution percentages (i.e. 61% of range rear bump damping vs. 39% of range front bump damping). Maybe the gentleman who made the setup editor that enabled us to change the spring rates in 1 lb increments would be kind enough to enable us to adjust the damper settings in 0.1 step increments vs. the 1 step increments we currently have. -Chris-

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> Having used other people's setups for the last year, I thought it was > about time to develop my own. It really is fantastic to be able to > have a car setup with which you can truly be committed, know what it > is going to do, and how it is going to react to your input. The > motivation was that I have a few tracks (Spa, Zandy, Mosport and > Silverstone) where I could not find a setup that I was very happy or > comfortable with. I have now got Zandy down to a 1:27.22 which > although not super fast, I was quite happy with it! Especially since I > have only really been driving there about a month on and off. > Silverstone was always a killer at Abbey, every single lap....Finally > able to nail it properly, lap time drop by 4 (!!!!) seconds to 1:30.9. > All down to the confidence my own setup allows. > I found that shock absorber tuning made a huge difference to the turn- > in characteristics of the car, I've got it down very nicely. Nunnini's > theories on ride height vs. spring rate worked very well, as did > setting the spring rates to the exact weight distribution of the car. > However, it would be interesting to be able to adjust the damper rates > in smaller increments. If the weight dist. - spring rate theory is > valid (which it is) then as the weight is transferred when entering a > corner would also require a 38%/62% (Lotus) damping rate, with some > small adjustments to get a nice turn in or oversteer. > I tried something as best I could with such coarse adjustment, which > was alright, but an exact 38/62 rate would be very interesting. If > this was possible using the setup editing tools... > I have also found that my style tends to leave the rear tyres > generally hotter than either fronts, generally because I tend to > always hang the back out and use a bit too much throttle. Is this a > common situation for others? I know that the cars are tail-happy, but > I have read often about the outside front consistently overheating > being a big problem for most. My setup generally yields 180-200 on the > inside front, 200-220 outside front, and 210-230 on the rears. > Any other setup development thoughts or experiences? > Rafe Mc

Sent via Deja.com http://www.deja.com/ Before you buy.

> I differ, however, with his reverse-weight-distribution > concept on the arb's. Makes the setup way to pushy for me. I prefer > to set the arb's so that both the front and rear have the same roll > rate when the arb rate is added to the spring rate. Sounds like you run an 85/30 diff? The diff setting makes a huge difference to teh car's balance. I use a 60/60 and having the 150/80ish ARBs helps balance the car properly for that diff setting. the 60 power side setting makes the car somewhat more oversteery on corner exit so the understeer helps, the 60 coast side is also much more oversteery on entry, so the understeer helps. Grant.

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> > I differ, however, with his reverse-weight-distribution > > concept on the arb's. Makes the setup way to pushy for me. > > I prefer to set the arb's so that both the front and rear > > have the same roll rate when the arb rate is added to the > > spring rate. > Sounds like you run an 85/30 diff? The diff setting makes > a huge difference to teh car's balance. I use a 60/60 and > having the 150/80ish ARBs helps balance the car properly for > that diff setting. the 60 power side setting makes the car > somewhat more oversteery on corner exit so the understeer > helps, the 60 coast side is also much more oversteery on > entry, so the understeer helps. > Grant.

Actually, I use a 45/85-1 or -2 diff. I like to throttle steer. :) -Chris- Sent via Deja.com http://www.deja.com/ Before you buy.

He has actually updated his site recently, and renounced his earlier theories on arb settings. He now suggests that you set the front arb to obtain the right grip, temp and camber to work, and then use the rear to get your own preference for over/understeer. I was trying to follow this, but couldn't really get what he was trying to say! I just set the front to reduce the body roll nicely, then balanced the car with the rear. Interesting idea, I'll have to try it out. I feel that it would be a great way to fine tune the handling of the car. It's just too coarse by adjusting in 20% increments. However, in reality such fine adjustments were not possible, that is why the settings are so coarse. But if Chapman was designing his Lotus for a specific set of damping rates, he would be able to get exactly what he wanted. So why shouldn't we?? What kind of toe in/out settings do you use? Currently using -0.075 deg on the front, which gives a nice turn in and grip, but makes the car a bit twitchier. I know that more toe out would be faster, but that makes the setup difficult and uncomfortable - so I actually go slower and less consistently. Rafe Mc

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> What kind of toe in/out settings do you use? Currently using -0.075 > deg on the front, which gives a nice turn in and grip, but makes the > car a bit twitchier. I know that more toe out would be faster, but > that makes the setup difficult and uncomfortable - so I actually go > slower and less consistently. > Rafe Mc

I currently use -0.125 at the front and 0.075 at the rear. I find if I use too much toe in at the rear, I actually end up with too much on-throttle oversteer. It resists throttle-steering too much and I end up oversteering by simply trying to force the car to steer with the throttle on exit. I'll probably end up with different settings in another month, though. One of the things I really like about GPL is the ability to play with the setups. I end up with a different setup philosophy about every two months or so. :) -Chris- Sent via Deja.com http://www.deja.com/ Before you buy.

Doesn't sound like the best way to balance a car's handling - by compensating for the power oversteer by dialling in more understeer. The reason the 60 deg diff is so oversteery is because the outside rear locks too easily when power is transferred from the slipping inside rear. You don't get that gradual transfer of torque via the clutches that you do with an 85 deg diff. Just seems to be compensating for a lack of rear end grip with reducing the front end grip. I always found it so difficult to be consistent with the lower angle diffs - yourself? I guess I'm too heavy with the throttle to be able to control a more locked diff - I usually use an 85/45 with 5 clutches in the Lotus. Rafe Mc

<snip> I agree. I spent piles of time trying to get a 60 power-side ramp to work well. I was actually getting some decent response in training but the Eagle was too much of a handfull during the pressure of a race. I'm currently settling in on 85/45 with 5 clutches as my sweet spot.

<snip> I change my philosophy every other lap :-) but I think I've reached a more stable phase. I am more comfortable (and faster) with my current setups than ever before (a 1:27.48 freak lap at Monza the other day <vbg> ). Some of the more experienced drivers might chuckle at my setups but they suit my style, for now anyway. My current obsession is massive amounts of toe-out at the front and major amounts of toe-in at the rear (eg. -0.500F, +0.475R at Zandvoort). It doesn't seem to slow me down at all and it provides a lot of grip. Also I am using positive cambers on the front and rear tires. After reading G. Tifosi's comments on R. Nunnini's site re. keeping the unloaded (inside) tire flat in the corners, I tried positive cambers and was very pleased with the increased grip. I'm using less positive camber now then I needed with negative settings (0.00LF, 0.75RF, 0.00LR, 0.75RR at Zandvoort). I'm also using a quite stiff rear bar and a relatively soft front bar (100F, 200R at Zandvoort) which I was reluctant to do as the GPL guide recommended running stiffer bars in the front versus rear. The change has really helped the mid-corner performance. B.t.w. I run an 85/45 diff with 5 clutches on most of my setups. I find that I can really toss the Eagle into the corners with this setting (coupled with the setups above). I would welcome comments.

Wow, I don't think I've ever seen a setup with that much toe-in at the rear. What is the reason and effect of that much? It won't change the rolling resistance in GPL, as that is one of the few things that is not modelled. Unusual to have zero camber on the left at Zandy. Currently using -0.5 and 0 (front), -0.5 and +0.25 rear. I get a nice even temperature spread, good corner speed and turn in. I don't think I'd ever be able to control the car with twice the arb on the rear. Goes to show how much the style must suit the setup. (and vice versa). I've found I get the best speed and control using either 4 or 5 clutches, depending on the circuit. Confidence at throwing the Lotus into corners is paramount with me, my setup really lets me get stuck into it when I want to. Has a nice wide slip angle, and can get REALLY sideways and still be caught easily. Something I tend to need....! One thing that helped my setup was to adjust the tyre pressures to get 24-25 psi hot, something Nunnini is not in favour of. I found that I get good grip and control at this pressure, nice even temps, etc. What pressures do you run at when hot? Rafe Mc

:>My current obsession is massive amounts of toe-out at the front :>and major amounts of toe-in at the rear (eg. -0.500F, +0.475R :>at Zandvoort). It doesn't seem to slow me down at all and it :>provides a lot of grip. :> : Wow, I don't think I've ever seen a setup with that much toe-in at the : rear. What is the reason and effect of that much? It won't change the : rolling resistance in GPL, as that is one of the few things that is : not modelled. The book that came with GPL strongly suggests that rolling resistance IS modelled. -- Richard G. Clegg Only the mind is waving Networks and Non-Linear Dynamics Group Dept. of Mathematics, Uni. of York www: http://manor.york.ac.uk/top.html

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> :>My current obsession is massive amounts of toe-out at the front > :>and major amounts of toe-in at the rear (eg. -0.500F, +0.475R > :>at Zandvoort). It doesn't seem to slow me down at all and it > :>provides a lot of grip. > :> > : Wow, I don't think I've ever seen a setup with that much toe-in at the > : rear. What is the reason and effect of that much? It won't change the > : rolling resistance in GPL, as that is one of the few things that is > : not modelled. > The book that came with GPL strongly suggests that rolling > resistance IS modelled. > --

I don't know if it was mentioned this way or not so I won't agree or disagree with you. However, I will say that a -5.0 Toe has no difference in top speed or acceleration to that top speed in Time or distance witch suggests that it's not modeled correctly. I will say that the tire temps are altered by the toe though. I don't know how Toe is measured in GPL. I'll just assume that (if the car was a physical car, one that you could touch) If you took a string and laid it across the center of the tire horizontally and parallel to the center of the car (front to rear), the Toe would be measured as the distance from the string to the edge of the wheel..

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| |a/-/ \-\ |/ /---|---\ \ |- | - | | | | | |

(hope this graphic displays right) Where "a" is is the measuring area. The Left line is the string, then there's the +toe tire, Then axle, then Center line of the chassis. Then the same thing for the Right hand side. This is one way to measure Toe but is it the way GPL measures and displays Toe? If so, then a + or - 5.0 Toe would be a very bad setup. -- ========================================= Mike Barlow Current GPVL points Champion =========================================

If so, then a + or - I should have reread the original post.. A + or - 5.0 is a bad setup, but a 0.5 like mentioned is ok. -- ========================================= Mike Barlow Current GPVL points Champion =========================================

I'm not really an expert on the physics behind toe settings but I knew that -'ve front toe would help the car into the turn. I wasn't really sure how rear toe-in could help in a turn but I knew it provided stabilty. One day I just got tired of losing grip in the corners and having the back end slide out so I figured the more rear stability in the corner the better. So I cranked in lots of toe-out in front and toe-in on the rear and never looked back. Now that I have my times down a bit I'll try backing off the toe settings and see if I pick up any straight line speed. Actually the zero camber tires have higher temps on the outside due to factors other than camber. So when I go into a left turn the temps even out, indicating that the inside tire is flat on the track. I don't have to work too much at controlling the car. It's nice and stable, dive under braking is not a problem, and it turns quite nicely in mid-corner. I think the other setup items contribute to stability and allow for a loose front bar. I'm using R. Nunnini's table for my spring settings b.t.w. I run 24-25 psi hot too. His tire pressure page quotes some cold pressures (is that what you were thinking of ?) but recommends 24-25 psi hot.

On Tue, 22 Feb 2000 22:04:56 -0500, "Jim Allison" <[email hidden]> wrote: Do you have any views on Lotus setups at all, or do you not drive it? Mauricio.

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> >Chris Cavin <[email hidden]> wrote in message >news:88u4v2$udr$[email hidden]... >> [email hidden] (Rafe McAuliffe) wrote: >> > > ><snip> > >> >> I'll probably end up with different settings in another month, though. >> One of the things I really like about GPL is the ability to play >> with the setups. I end up with a different setup philosophy about >> every two months or so. :) >> >> -Chris- > >I change my philosophy every other lap :-) but I think I've reached >a more stable phase. I am more comfortable (and faster) with my >current setups than ever before (a 1:27.48 freak lap at Monza >the other day <vbg> ). Some of the more experienced drivers >might chuckle at my setups but they suit my style, for now anyway. > >My current obsession is massive amounts of toe-out at the front >and major amounts of toe-in at the rear (eg. -0.500F, +0.475R >at Zandvoort). It doesn't seem to slow me down at all and it >provides a lot of grip. > >Also I am using positive cambers on the front and rear tires. >After reading G. Tifosi's comments on R. Nunnini's site >re. keeping the unloaded (inside) tire flat in the corners, I tried >positive cambers and was very pleased with the increased >grip. I'm using less positive camber now then I needed with >negative settings (0.00LF, 0.75RF, 0.00LR, 0.75RR at >Zandvoort). > >I'm also using a quite stiff rear bar and a relatively soft front >bar (100F, 200R at Zandvoort) which I was reluctant to do >as the GPL guide recommended running stiffer bars in the front >versus rear. The change has really helped the mid-corner performance. > >B.t.w. I run an 85/45 diff with 5 clutches on most of my setups. >I find that I can really toss the Eagle into the corners with this >setting (coupled with the setups above). > >I would welcome comments. > >

Michael Barlow wrote:

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> I don't know how Toe is measured in GPL. I'll just assume that (if the > car was a physical car, one that you could touch) If you took a string > and laid it across the center of the tire horizontally and parallel to > the center of the car (front to rear), the Toe would be measured as the > distance from the string to the edge of the wheel.. > > | > |a/-/ \-\ > |/ /---|---\ \ > |- | - > | | > | | > | | > (hope this graphic displays right) > > Where "a" is is the measuring area. The Left line is the string, then > there's the +toe tire, Then axle, then Center line of the chassis. Then > the same thing for the Right hand side. This is one way to measure Toe > but is it the way GPL measures and displays Toe? If so, then a + or - > 5.0 Toe would be a very bad setup. >

No, we've done some "shade-tree" toe adjustments on the big busses at work in the past. How it's measured is you measure from tire centerline to tire centerline, both at the front & rear of the tire. Half that distance difference is the amount of toe. Much more accurate, as you can run across individual wheels with different amounts of toe with your method, but you must remember that toe tends to equalize when the vehicle is in motion. -- /Chuck Kandler #70 /ChuckK on Won.net & WinVROC /K&S Racing http://www.fortunecity.com/silverstone/thepits/195 /The box said "Windows 0x5f or better", so I installed LINUX!

Chuck Kandler wrote:

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> > Michael Barlow wrote: > > > I don't know how Toe is measured in GPL. I'll just assume that (if the > > car was a physical car, one that you could touch) If you took a string > > and laid it across the center of the tire horizontally and parallel to > > the center of the car (front to rear), the Toe would be measured as the > > distance from the string to the edge of the wheel.. > > > > | > > |a/-/ \-\ > > |/ /---|---\ \ > > |- | - > > | | > > | | > > | | > > (hope this graphic displays right) > > > > Where "a" is is the measuring area. The Left line is the string, then > > there's the +toe tire, Then axle, then Center line of the chassis. Then > > the same thing for the Right hand side. This is one way to measure Toe > > but is it the way GPL measures and displays Toe? If so, then a + or - > > 5.0 Toe would be a very bad setup. > > > > No, we've done some "shade-tree" toe adjustments on the big busses at > work in the past. How it's measured is you measure from tire centerline > to tire centerline, both at the front & rear of the tire. Half that > distance difference is the amount of toe. Much more accurate, as you > can run across individual wheels with different amounts of toe with your > method, but you must remember that toe tends to equalize when the > vehicle is in motion. >

You are right, that is another way to measure Toe. There are many different ways to measure Toe-in/out and none are more accurate then the others unless you count in the digital meters.. :) -- ========================================= Mike Barlow Current GPVL points Champion =========================================

> > You are right, that is another way to measure Toe. There are many > different ways to measure Toe-in/out and none are more accurate then the > others unless you count in the digital meters.. :) oops, I thought about it just after I sent that massage.. Your way will give a Track for the Front or rear wheels (Dog Tracking), as well as giving a good indication of Toe in/out but not accurate for the alignment of the chassis -to- wheels toe. Unless you boo-boo'ed with your typing and meant to say that you measure from center (front then rear) of the wheel to the center of the chassis. If so, then both of our ways are identical only I move the center chassis line to the out side for easy access. -- ========================================= Mike Barlow Current GPVL points Champion =========================================

BendsMaster <[email hidden]> wrote in message news:[email hidden]...

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> On Tue, 22 Feb 2000 22:04:56 -0500, "Jim Allison" > <[email hidden]> wrote: > > Do you have any views on Lotus setups at all, or do you not drive it? > > > Mauricio. > > >

I drove the Lotus when I first started GPL and I tried some other car but later on I decided to use the Eagle all the time. I found that for me using one car made learning how to do setups easier. Now that I have a better feel for setting up a race car I think I'll try the Lotus again. I expect that I'll be able to use much the same philosophy as I did with the Eagle. I'll just need to use the Lotus numbers on R. Nunnini's setup tables. And of course I'll need to adapt to the more nimble response of the Lotus.

Rafe McAuliffe wrote:

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> > Doesn't sound like the best way to balance a car's handling - by > compensating for the power oversteer by dialling in more understeer. > The reason the 60 deg diff is so oversteery is because the outside > rear locks too easily when power is transferred from the slipping > inside rear. You don't get that gradual transfer of torque via the > clutches that you do with an 85 deg diff. Just seems to be > compensating for a lack of rear end grip with reducing the front end > grip. >

probably :) But it seems to be getting relatively predictable. If I apply too much power the rear will definitely step way too far out, that's when the outside rear gets loose, but if I'm applying the power very carefully and smoothly it tends to just step around a little and feels like it's really biting and taking off. > I always found it so difficult to be consistent with the lower angle > diffs - yourself? I guess I'm too heavy with the throttle to be able > to control a more locked diff - I usually use an 85/45 with 5 clutches > in the Lotus. > yes, i agree completely, these lower power side diff angles are much less consistant :) I tried using a 45 at one point, but I just can't apply power predictably, the rear WILL come around on me. the 30 was the same but worse. I think my older driving habits involved using too much throttle, and 85 doesn't punish you for doing that. I don't really like using 85's because of the inside rear wheelspin, but normally I don't use 5-6 clutches either. I autocross my road car (which is a mid engined rear wheel drive 2 seater) so I want to if possible set up my GPL cars in such a way as to teach me the correct habits, not bad habits - such as using too much throttle on exit because the 85 diff lets me get away with it. I'm having proper clutch type diff in it soon, (an improvement over the viscous fluid type one in there now) so I really want to have my driving habits tuned for cars that lock the rear wheels together somewhat under acceleration :) Also, I've been reliably setting PBs lately with these 60/60 setups. So they must be doing something right :) Grant.

Exactly what I was referring to, the lack of effect on top speed with toe in/out. Rafe Mc

What are you referring to, by "factors other than camber"? Do you mean that the left tyres are hot on the outside in a right hander, but then even out for a left hander? If so, then you seem to be sacrificing the loaded tyres for when they become the unloaded tyres in the next corner. Obviously it is ideal to get the most from all 4 tyres, but since the loaded tyres are doing the majority of the work, I have put most attention to the loaded ones. Like cutting the apex over the grass is no big deal, usually quicker. Get the loaded tyres on the grass though, and wham! Same here, great resource. Currently using his ideas on linking ride height with spring rate, seems to work a treat. No, what I was referring to was developing a setup, and then adjusting tyree pressures later to suit. He recommends setting pressures, then altering the setup to get the right temp and pressure combo. Rafe Mc

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> >Actually the zero camber tires have higher temps on the outside due to > >factors other than camber. So when I go into a left turn the temps even > >out, indicating that the inside tire is flat on the track. > What are you referring to, by "factors other than camber"? Do you mean > that the left tyres are hot on the outside in a right hander, but then > even out for a left hander? If so, then you seem to be sacrificing the > loaded tyres for when they become the unloaded tyres in the next > corner. Obviously it is ideal to get the most from all 4 tyres, but > since the loaded tyres are doing the majority of the work, I have put > most attention to the loaded ones. Like cutting the apex over the > grass is no big deal, usually quicker. Get the loaded tyres on the > grass though, and wham!

um, Don't quote me but I think he's talking about "Thrust Camber". I haven't a clue how accurate the math is in GPL but I do know it is modeled -- ========================================= Mike Barlow Current GPVL points Champion =========================================

Michael Barlow <[email hidden]> wrote in message news:[email hidden]...

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> Rafe McAuliffe wrote: > > > > > > > >Actually the zero camber tires have higher temps on the outside due to > > >factors other than camber. So when I go into a left turn the temps even > > >out, indicating that the inside tire is flat on the track. > > > > > What are you referring to, by "factors other than camber"? Do you mean > > that the left tyres are hot on the outside in a right hander, but then > > even out for a left hander? If so, then you seem to be sacrificing the > > loaded tyres for when they become the unloaded tyres in the next > > corner. Obviously it is ideal to get the most from all 4 tyres, but > > since the loaded tyres are doing the majority of the work, I have put > > most attention to the loaded ones. Like cutting the apex over the > > grass is no big deal, usually quicker. Get the loaded tyres on the > > grass though, and wham! > > > > um, Don't quote me but I think he's talking about "Thrust Camber". I > haven't a clue how accurate the math is in GPL but I do know it is > modeled > > -- > ========================================= > Mike Barlow > Current GPVL points Champion > =========================================

Sorry Rafe and Mike, I should have been more specific. I was referring to the temperatures on the straight and I wasn't thinking of camber thrust. As an aside, I understand that camber thrust provides extra grip in a similar way to a pencil eraser dragged across a desk but tilted away from its direction of travel. To get this effect on a tire you would need to set the camber to get even temperatures in a turn (indicating the tire is flat on the track) and then increase the camber a little further so that the tire is actually tilted away from the outside of the turn. I hope this is the correct interpretation. I'm aiming to get the unloaded (inside) tire flat in the turns (as indicated by even temperatures). My 0 degree camber on the front and rear left side tires at Zandvoort result in a higher temperature on the outside of those tires on the straight. So when I enter a left hand bend the temperatures even out and give me a flat tire (so to speak). Now, the preceding discussion seems a little strange since along the straight you would expect a 0 degree camber to give you even temperatures across the tire. This is where my use of 'factors other than camber' comes from. I'm not sure what accounts for the uneven temperatures. Perhaps the large front toe-out and large rear toe-in may account for this.

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> Rafe McAuliffe wrote: > > > > > > > >Actually the zero camber tires have higher temps on the outside due to > > >factors other than camber. So when I go into a left turn the temps even > > >out, indicating that the inside tire is flat on the track. > > > > > What are you referring to, by "factors other than camber"? Do you mean > > that the left tyres are hot on the outside in a right hander, but then > > even out for a left hander? If so, then you seem to be sacrificing the > > loaded tyres for when they become the unloaded tyres in the next > > corner. Obviously it is ideal to get the most from all 4 tyres, but > > since the loaded tyres are doing the majority of the work, I have put > > most attention to the loaded ones. Like cutting the apex over the > > grass is no big deal, usually quicker. Get the loaded tyres on the > > grass though, and wham! > >

Rafe, re. your question in the 2nd paragraph above: yes, I run hot on the outside left of the loaded tire in a right hander and thus the temps even out in a left hander. I think Giovanni Tifosi's explanation is better than what I can cobble together. See "Keeping the Unloaded Tire Flat" in his Guru Meditations on R. Nunnini's site.

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> > Sorry Rafe and Mike, I should have been more specific. I was referring > to the temperatures on the straight and I wasn't thinking of camber thrust. > > As an aside, I understand that camber thrust provides extra grip in a > similar > way to a pencil eraser dragged across a desk but tilted away from its > direction of travel. To get this effect on a tire you would need to set the > camber to get even temperatures in a turn (indicating the tire is flat on > the > track) and then increase the camber a little further so that the tire is > actually > tilted away from the outside of the turn. I hope this is the correct > interpretation. > > I'm aiming to get the unloaded (inside) tire flat in the turns (as indicated > by > even temperatures). My 0 degree camber on the front and rear left side > tires at Zandvoort result in a higher temperature on the outside of those > tires on the straight. So when I enter a left hand bend the temperatures > even out and give me a flat tire (so to speak). > > Now, the preceding discussion seems a little strange since along the > straight > you would expect a 0 degree camber to give you even temperatures across > the tire. This is where my use of 'factors other than camber' comes from. > I'm not sure what accounts for the uneven temperatures. Perhaps the large > front toe-out and large rear toe-in may account for this.

Again, I may be wrong but.. At 0 camber you do have even temps (to a point) what gives a higher temp at one edge is your toe + or -. -- ========================================= Mike Barlow Current GPVL points Champion =========================================

Quoted text (28 lines)

>Sorry Rafe and Mike, I should have been more specific. I was referring >to the temperatures on the straight and I wasn't thinking of camber thrust. > >As an aside, I understand that camber thrust provides extra grip in a >similar >way to a pencil eraser dragged across a desk but tilted away from its >direction of travel. To get this effect on a tire you would need to set the >camber to get even temperatures in a turn (indicating the tire is flat on >the >track) and then increase the camber a little further so that the tire is >actually >tilted away from the outside of the turn. I hope this is the correct >interpretation. > >I'm aiming to get the unloaded (inside) tire flat in the turns (as indicated >by >even temperatures). My 0 degree camber on the front and rear left side >tires at Zandvoort result in a higher temperature on the outside of those >tires on the straight. So when I enter a left hand bend the temperatures >even out and give me a flat tire (so to speak). > >Now, the preceding discussion seems a little strange since along the >straight >you would expect a 0 degree camber to give you even temperatures across >the tire. This is where my use of 'factors other than camber' comes from. >I'm not sure what accounts for the uneven temperatures. Perhaps the large >front toe-out and large rear toe-in may account for this. >

To quote R Nunnini: Don't bother to keep the inside temperature higher than the outside - to take advantageof the legendary camber thrust - because it doesn't appear to be modelled in GPL. In any case, Carroll Smith reckons that you need to keep the inside of the tires about 15�F hotter than the outside to take full advantage of it - which would require unacceptable amounts of static camber in GPL. I think an important point is " doesn't appear to be modelled in GPL". Anyone know if it is or not? My guess is that Nunnini's point is valid - that you would need too much -ve camber to achieve it, which would make the car hard to drive. Maybe possible in real life, but a bit too tough for GPL. Rafe Mc

Rafe McAuliffe wrote:

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> To quote R Nunnini: > > Don't bother to keep the inside temperature higher than the outside - > to take advantageof the legendary camber thrust - because it doesn't > appear to be modelled in GPL. In any case, Carroll Smith reckons that > you need to keep the inside of the tires about 15�F hotter than the > outside to take full advantage of it - which would require > unacceptable amounts of static camber in GPL. > > I think an important point is " doesn't appear to be modelled in GPL". > Anyone know if it is or not? My guess is that Nunnini's point is valid > - that you would need too much -ve camber to achieve it, which would > make the car hard to drive. Maybe possible in real life, but a bit too > tough for GPL. > > Rafe Mc

It appears to be modelled. Try setting the left tyres with negative and the right ones with positive camber, and then see how much steering you require to keep the car straight. Another interesting point is, if you are using lots of positive camber, then you should also use some toe out to stop the wheels fighting each other (this is taken from the Millikens' 'Race Car Vehicle Dynamics').

What would be neat is if our resident track building genius would constuct a GPL skid pad, with painted lines, built in lap timer, and tire temp readout. Just dreaming out loud. -- Don Scurlock Vancouver,B.C.