Handling setup
Discussion
Can anyone point me to a book/website or any sort of information on how making different changes to a car's suspension affects the handling, or more importantly, how to get it handling right?
At the moment, I have an MX5 which has the following options for adjustment and I have very little idea how to do so to get the handling right:
Spring rates
Ride height
Caster, camber, toe front
Camber, toe rear
Low speed damping all around
Tyre pressures
Anti-rollbar stiffness front and rear
I've no idea how you know when you've got one right and to adjust another or if one incorrect adjustment masks another, or, or...
And on top of all that, the instructor at Donington yesterday helped me diagnose that the bushes are shot (slight oversteer on turn in but settles in place rather than carrying on - "interesting" through Craner
)
Any help would be greatly appreciated.
At the moment, I have an MX5 which has the following options for adjustment and I have very little idea how to do so to get the handling right:
Spring rates
Ride height
Caster, camber, toe front
Camber, toe rear
Low speed damping all around
Tyre pressures
Anti-rollbar stiffness front and rear
I've no idea how you know when you've got one right and to adjust another or if one incorrect adjustment masks another, or, or...
And on top of all that, the instructor at Donington yesterday helped me diagnose that the bushes are shot (slight oversteer on turn in but settles in place rather than carrying on - "interesting" through Craner
) Any help would be greatly appreciated.
Jsut look up the "lanny" settings on the MX5 forums, pretty easy to find.
The bush will be the lower outside crossbolt worn through.
If its a track car then.
Front 1.5-2.3deg camber 0.deg toe
Rear 1.5-2.0 deg camber 0.3deg toe in (always run slight rear toe on MX5's)
That'll have you sorted on the geometry
What shocks & springs you got? I assume they are adjustable for ride height/preload not spring rate
The bush will be the lower outside crossbolt worn through.
If its a track car then.
Front 1.5-2.3deg camber 0.deg toe
Rear 1.5-2.0 deg camber 0.3deg toe in (always run slight rear toe on MX5's)
That'll have you sorted on the geometry
What shocks & springs you got? I assume they are adjustable for ride height/preload not spring rate
Thanks for that Declan. I've seen (and tried) the lanny settings. Although at the moment, it's set up with pretty much standard settings as recommended by Tony at WiM.
It's getting more and more track use, but does still need to be road useable as it will be doing more road work than track. Don't want to compromise it too much.
I've got the Absolutely Shocks / Gaz springs/dampers. They are ride height adjustable rather than spring rate, but were different spring rates required, getting hold of them isn't a problem.
Sorry for the ignorance - what's the lower crossbolt? Is that the bolt through the hub and lower wishbone or the alignment bolt? Or something completely different... I know that the front balljoints need replacing so I plan to polybush all round at the same time.
Thanks again!
It's getting more and more track use, but does still need to be road useable as it will be doing more road work than track. Don't want to compromise it too much.
I've got the Absolutely Shocks / Gaz springs/dampers. They are ride height adjustable rather than spring rate, but were different spring rates required, getting hold of them isn't a problem.
Sorry for the ignorance - what's the lower crossbolt? Is that the bolt through the hub and lower wishbone or the alignment bolt? Or something completely different... I know that the front balljoints need replacing so I plan to polybush all round at the same time.
Thanks again!
This is general set up advice but will work for all cars. First of all you can adjust pretty much everything there.
Start with the simple stuff and move on to the more important aspects.
Tyre pressure...Measure tyre temps accross the tyre to determine the correct pressure, average of outside should equal the centre.
Castor.. Set it to standard and ensure its the same on the left and right.
Toe.. front straight or slight toe in. Rear..always slight toe in.
Spring rates..Your springs want to be as soft as possible so the suspension does not hit the bump stops all the time and at critical moments and the chassis does not scrape the road all the time and at critical moments.
Ride hieght..The lower the better however you need suspension travel to absorb the bumps. The smoother the surface the lower you can go. I actually favour more suspension travel and a slightly higher ride height with softer springs. Generally this is easier to drive than a super stiff skittery setup for people who are not pro drivers.
Damping.. Experiment. Too soft and it will feel like a 2CV, too hard and it will shake your teeth out and the car will jump around. It really is a matter of try and see.
ARB..These are your strongest tool and on my car are tweaked at every race meeting. I do not favour a rear bar as it can make power on oversteer worse. The front bar needs to be as soft as possible so it controls body roll to keep wheel camber in check when at max cornering. However running more static negative camber can mean you can run less bar. Also the front bar is used to balance the car for under / oversteer. So I balance my car with the front bar (moving the drop link 20mm along the bar can completly change my car from over to under steer) Now its balanced I look at how much it is rolling. If its rolling too much I increase spring rate all round. I prefer this to running a harder front bar and balancing it with a rear bar.
So there is no simple answer and you will have to try various setups. Keep notes of every change you do and then note how the car feels. The feel in the first lap is important as you will adapt your driving after that.
On my car that I designed from scratch it took 3 changes of springs and 3 new ARB`s until I was happy enoegh to race. However now I want to try some stiffer springs.
Books......All of Carroll Smiths books (especially Tune To Win) and Miliken / Miliken. You can borrow them from a libarary (remember them!!??) to see which is the most use.
I hope this helps,
John
Start with the simple stuff and move on to the more important aspects.
Tyre pressure...Measure tyre temps accross the tyre to determine the correct pressure, average of outside should equal the centre.
Castor.. Set it to standard and ensure its the same on the left and right.
Toe.. front straight or slight toe in. Rear..always slight toe in.
Spring rates..Your springs want to be as soft as possible so the suspension does not hit the bump stops all the time and at critical moments and the chassis does not scrape the road all the time and at critical moments.
Ride hieght..The lower the better however you need suspension travel to absorb the bumps. The smoother the surface the lower you can go. I actually favour more suspension travel and a slightly higher ride height with softer springs. Generally this is easier to drive than a super stiff skittery setup for people who are not pro drivers.
Damping.. Experiment. Too soft and it will feel like a 2CV, too hard and it will shake your teeth out and the car will jump around. It really is a matter of try and see.
ARB..These are your strongest tool and on my car are tweaked at every race meeting. I do not favour a rear bar as it can make power on oversteer worse. The front bar needs to be as soft as possible so it controls body roll to keep wheel camber in check when at max cornering. However running more static negative camber can mean you can run less bar. Also the front bar is used to balance the car for under / oversteer. So I balance my car with the front bar (moving the drop link 20mm along the bar can completly change my car from over to under steer) Now its balanced I look at how much it is rolling. If its rolling too much I increase spring rate all round. I prefer this to running a harder front bar and balancing it with a rear bar.
So there is no simple answer and you will have to try various setups. Keep notes of every change you do and then note how the car feels. The feel in the first lap is important as you will adapt your driving after that.
On my car that I designed from scratch it took 3 changes of springs and 3 new ARB`s until I was happy enoegh to race. However now I want to try some stiffer springs.
Books......All of Carroll Smiths books (especially Tune To Win) and Miliken / Miliken. You can borrow them from a libarary (remember them!!??) to see which is the most use.
I hope this helps,
John
Fantastic! So much more here than I could have hoped for. Now, if you'll indulge me, I've got one more mind-block to get through I think:
Softer gives more grip - this I think threw me because race cars always always seem to have a much stiffer setup than road cars. If I've got it right, then yes you want it softer, but you need stiffer spring rates (and therefore harder damping) to be able to run lower ride height without bottoming out the suspension. Also, as most road cars don't have adjustable anti roll bars, people will stiffen the damping if that is adjustable to compensate and reduce roll.
One of these days I might be able to get my car to handle AND learn how to drive it properly!
Softer gives more grip - this I think threw me because race cars always always seem to have a much stiffer setup than road cars. If I've got it right, then yes you want it softer, but you need stiffer spring rates (and therefore harder damping) to be able to run lower ride height without bottoming out the suspension. Also, as most road cars don't have adjustable anti roll bars, people will stiffen the damping if that is adjustable to compensate and reduce roll.
One of these days I might be able to get my car to handle AND learn how to drive it properly!
Its a compromise. Do you run the car low with stiff springs or higher with softer springs? If you go too low then you will run the wishbones at compromised angles......But this is what testing is for and makes it fun.
The basics of all this comes down to the coeffeicent of friction of the tyres. The important fact is that a tyre has a higher coeffeicent friction the less it is loaded. So if you double a load on a tyre you will NOT double the grip. This means that 4 equally loaded tyres will give more grip than just 2 tyres carrying the same load. Softer springs give less load transfer so softer springs will mean the tyres are more equally loaded.
Tune To Win by Carroll Smith explains very well.
John
The basics of all this comes down to the coeffeicent of friction of the tyres. The important fact is that a tyre has a higher coeffeicent friction the less it is loaded. So if you double a load on a tyre you will NOT double the grip. This means that 4 equally loaded tyres will give more grip than just 2 tyres carrying the same load. Softer springs give less load transfer so softer springs will mean the tyres are more equally loaded.
Tune To Win by Carroll Smith explains very well.
John
jwb said:
Softer springs give less load transfer so softer springs will mean the tyres are more equally loaded.
Less variation in the sense of varying over time (contact patch load variation) especially; the benefits in terms of other forms of load transfer are less clear cut (softer may result in bigger transients as well as poorer steady state geometry so a bit of an own goal).try 'high performance handling handbook' by Don Alexander. It explains roll centres, roll raes, how to calculate effective spring rates, the roll of damping, ARBs, and helps you address all sorts of different handling issues. There's a VERY comprehensive setup guide as well.
www.amazon.co.uk/High-Performance-Handling-Handbook-Alexander/dp/0760309485/sr=8-2/qid=1162380487/ref=sr_1_2/203-2609515-2453523?ie=UTF8&s=books
JWB - any more 'Minor' projects on the back burner?! Pretty impressive build diary for your current minor - a lot of thought and work gone into that. For everyone else - John's site is well worth a read to see what can be done in a single garage! Puts a lot of 'tuning shops' to shame!!
www.amazon.co.uk/High-Performance-Handling-Handbook-Alexander/dp/0760309485/sr=8-2/qid=1162380487/ref=sr_1_2/203-2609515-2453523?ie=UTF8&s=books
JWB - any more 'Minor' projects on the back burner?! Pretty impressive build diary for your current minor - a lot of thought and work gone into that. For everyone else - John's site is well worth a read to see what can be done in a single garage! Puts a lot of 'tuning shops' to shame!!
The lower crossbolt can be seen when looking from the rear, its the lower outer pivot point that joins the susp arm to the hub, its about 10" long from memory & rather than the bush moving the the bush moves on the bolt, wearing the bolt out & you get a geometry wobble of sveral degrees!!. Jack the car up & wobble the wheel, its easy to tell you have it.
[quote=ELAN+2]try this www.carbibles.com/suspension_bible.html
should explain all you want to know!!
regards
Mark[/quote]
er, apart from setup!
should explain all you want to know!!
regards
Mark[/quote]
er, apart from setup!
Hi
I have been playing with geo on the 5 and have come up with a toned down trackday set-up that works well on the road, there is much discussion on the forums about front/rear camber and my set-up vears towards the Lanny spec.
Front
1.5 degrees neg camber
0 Toe in
4.5 degrees of caster
Rear
1 degree neg camber
1.5mm toe in per side
On the trackday I increased the front camber to 2 degrees neg.
I like this set-up
I have been playing with geo on the 5 and have come up with a toned down trackday set-up that works well on the road, there is much discussion on the forums about front/rear camber and my set-up vears towards the Lanny spec.
Front
1.5 degrees neg camber
0 Toe in
4.5 degrees of caster
Rear
1 degree neg camber
1.5mm toe in per side
On the trackday I increased the front camber to 2 degrees neg.
I like this set-up
Declan - thanks again. I thought that might have been the part you meant. I shall replace them all when I put everything back together.
Thanks Derek. It's your design of shocks and springs I've got on the car so it's good to hear from the horses mouth.
And of course, thanks to everyone that's contributed.
Thanks Derek. It's your design of shocks and springs I've got on the car so it's good to hear from the horses mouth.
And of course, thanks to everyone that's contributed.
The only way you can accurately setup your camber is with the aid of a tyre pyrometer. The camber guage is then used to check this setting for repeatability. Setting camber to a static setting will mean that if people are using different tyres, with different side wall stiffnesses, they will encounter varying levels of grip as all the different tyres are working are varying degress of optimality.
Anyone who claims to be able to give someone a load of setings over the internet is talking out of their ar5e! A baseline setup maybe, but even then unless the car has been cornerweighted, the tyres will still be being under/over utilised.
Anyone who claims to be able to give someone a load of setings over the internet is talking out of their ar5e! A baseline setup maybe, but even then unless the car has been cornerweighted, the tyres will still be being under/over utilised.
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