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Coilover height for track
- Thread starter imprezaworks
- Start date
NorthloopCup
ClioSport Moderator
I'm with @Tony Hunter on this and I disagree. A corner weighted car won't be as unbalanced with a passenger as a car that some hooray henry has set up with his ruler on a uneven floor.
Granted Trackdays aren't racing, but you still want to get maximum enjoyment out of your car vs £'s spent surely?
Granted Trackdays aren't racing, but you still want to get maximum enjoyment out of your car vs £'s spent surely?
imprezaworks
ClioSport Club Member
Mk5 Golf GTI :)
Mmm not sure what to think now lol
Track 172 Cup
I was going to have mine setup as I was in the same line of thinking to what Tony and Northloop said about it being set up, but to be fair mine looks pretty well setup and was used for sprints by the person who had I before me so maybe its already been done and the guy was just on about my car not being worth spending the money having it corner weighted as like said above if anyone has just thrown a set of coil overs on or adjusted them it could cause a problem with the handling.
imprezaworks
ClioSport Club Member
Mk5 Golf GTI :)
Did the car feel better afterwards?
JamesBryan
ClioSport Club Member
That toe in or out on the rear? Minus sounds like toe out.
Track 172 Cup
@imprezaworks yeah it felt better to me and my dad said it did feel better to him as we both drove it at Oulton last week and again this week, but the weather was better this week so may have been difference with the tyres and heat etc and just being more confident.
JamesBryan
ClioSport Club Member
Quite a bit of toe out that then. Is it tail happy?
I'm sure these are set to toe in as standard.
I'm sure these are set to toe in as standard.
Peoples views on Corner Weighting a car are quite interesting - I will try to explain in a brief response here to help people have an understanding:
Corner weighting a car will not improve the handling of that car! - There you go - bit of a bombshell to start with!
Now let me explain the above statement;
The amount of grip the car generates is dependant on the vertical load placed on the tyre. A tyre has a performance curve and the more vertical load you place on it the more grip it will generate but it becomes less efficient (hence a lighter car can generate more cornering G force).
When a car is travelling around a circuit there are various amounts of weight transfer happening around the vehicle; note- you can never change the total amount of weigh transfer but you can effect the rate of the weight transfer.
Most weight transfers in a correctly driven vehicle happen diagonally across the vehicle. eg. entering a left hand turn the weight transfers from drivers side rear wheel to passenger side front wheel and vice versa.
Going back to the statement "The amount of grip a tyre has depends on its vertical load" we can now see that is is important we are transferring the same weights onto each of the loaded tyres so they have the same grip when cornering.
As previously stated the majority of weight transfers during circuit driving (there are very few steady state corners in the UK) happen diagonally across the vehicle so it is important you get the weights across each diagonal the same and this is called a 50% cross weight.
If the cross weights are NOT equal then your car will have either more grip when turning left or turning right.
A good indication that the corner weights of a vehicle are not correct is when a driver will come into the pits and say to us " The car is perfect in left handers but understeers in right handers" - unfortunately there is no adjustments you can make to the chassis to improve this situation - if you remove the understeer from the right hand corners the car will oversteer in the left hand corners.
If the corner weighting is correct the driver will say that the car is good or it either understeers or oversteers in both directions and this is then easy to correct changing set-up such as ride heights or roll bar stiffness etc.
So.............Corner weighting will make the car handle the same in left and right hand corners but it's main advantage is that it allows the chassis tuner to effectively delete the handling characteristic (understeer or oversteer) effectively - it does not improve the handling on its own.
Now.................. as stated previously we can not change the total weight transfer but the rate of that transfer depends on the dampers and springs fitted (plus to a varying degree other components). Unfortunately even the best dampers are not matched and if you are serious about your corner weighting then you need to get the dampers matched otherwise you might as well have different springs on every corner of your car.
We dyno the dampers in house for the various Clio Cup cars we set up prior to them being Corner weighted; this ensures that the dampers are matched across each axle and the weight transfer rates will be the same - these are not cheap dampers either; they are supplied by Ohlins but still require matching. If the rate of the weight transfer is not the same then, again the car will have different levels of grip at each phase of the corner.
Below is an example of a damper dyno plot taken from our damper dyno showing the range of adjustment on a Force Vs Velocity graph:
Having a set-up done to this level becomes expensive - yes it will ultimately improve your car but the returns are diminishing! We like to be honest with our customers and offer a service we think is best suited to their needs - we could quite easily say you need this and that doing and take your money for corner weighting but we think you should make this decision on an informed basis.
We offer bespoke chassis set-ups at all levels so we are prepared to do whatever you want - Its your car in the end of the day but we like to discuss these matters with you - usually a good Geo will get you 85% of the performance and for the occasional track day attendee we personally feel you should use the extra money towards another track day and have more fun, if you compete at a very high level then you would need everything doing as the various race teams that use our services do.
We do have a certified 'flat floor' for all our geo and Corner weighting and this is level to within 0.5 mm across it's full plane - this is vital for this level of vehicle set-up. We are always willing to show callibration certificates for this equipment and they are on display at out workshop.
This is very brief and complete books could/have been written on it but I hope it gives an understanding as to why we recommend certain levels of Geo.
Thanks for reading
Fraser
Corner weighting a car will not improve the handling of that car! - There you go - bit of a bombshell to start with!
Now let me explain the above statement;
The amount of grip the car generates is dependant on the vertical load placed on the tyre. A tyre has a performance curve and the more vertical load you place on it the more grip it will generate but it becomes less efficient (hence a lighter car can generate more cornering G force).
When a car is travelling around a circuit there are various amounts of weight transfer happening around the vehicle; note- you can never change the total amount of weigh transfer but you can effect the rate of the weight transfer.
Most weight transfers in a correctly driven vehicle happen diagonally across the vehicle. eg. entering a left hand turn the weight transfers from drivers side rear wheel to passenger side front wheel and vice versa.
Going back to the statement "The amount of grip a tyre has depends on its vertical load" we can now see that is is important we are transferring the same weights onto each of the loaded tyres so they have the same grip when cornering.
As previously stated the majority of weight transfers during circuit driving (there are very few steady state corners in the UK) happen diagonally across the vehicle so it is important you get the weights across each diagonal the same and this is called a 50% cross weight.
If the cross weights are NOT equal then your car will have either more grip when turning left or turning right.
A good indication that the corner weights of a vehicle are not correct is when a driver will come into the pits and say to us " The car is perfect in left handers but understeers in right handers" - unfortunately there is no adjustments you can make to the chassis to improve this situation - if you remove the understeer from the right hand corners the car will oversteer in the left hand corners.
If the corner weighting is correct the driver will say that the car is good or it either understeers or oversteers in both directions and this is then easy to correct changing set-up such as ride heights or roll bar stiffness etc.
So.............Corner weighting will make the car handle the same in left and right hand corners but it's main advantage is that it allows the chassis tuner to effectively delete the handling characteristic (understeer or oversteer) effectively - it does not improve the handling on its own.
Now.................. as stated previously we can not change the total weight transfer but the rate of that transfer depends on the dampers and springs fitted (plus to a varying degree other components). Unfortunately even the best dampers are not matched and if you are serious about your corner weighting then you need to get the dampers matched otherwise you might as well have different springs on every corner of your car.
We dyno the dampers in house for the various Clio Cup cars we set up prior to them being Corner weighted; this ensures that the dampers are matched across each axle and the weight transfer rates will be the same - these are not cheap dampers either; they are supplied by Ohlins but still require matching. If the rate of the weight transfer is not the same then, again the car will have different levels of grip at each phase of the corner.
Below is an example of a damper dyno plot taken from our damper dyno showing the range of adjustment on a Force Vs Velocity graph:
Having a set-up done to this level becomes expensive - yes it will ultimately improve your car but the returns are diminishing! We like to be honest with our customers and offer a service we think is best suited to their needs - we could quite easily say you need this and that doing and take your money for corner weighting but we think you should make this decision on an informed basis.
We offer bespoke chassis set-ups at all levels so we are prepared to do whatever you want - Its your car in the end of the day but we like to discuss these matters with you - usually a good Geo will get you 85% of the performance and for the occasional track day attendee we personally feel you should use the extra money towards another track day and have more fun, if you compete at a very high level then you would need everything doing as the various race teams that use our services do.
We do have a certified 'flat floor' for all our geo and Corner weighting and this is level to within 0.5 mm across it's full plane - this is vital for this level of vehicle set-up. We are always willing to show callibration certificates for this equipment and they are on display at out workshop.
This is very brief and complete books could/have been written on it but I hope it gives an understanding as to why we recommend certain levels of Geo.
Thanks for reading
Fraser
Last edited:
imprezaworks
ClioSport Club Member
Mk5 Golf GTI :)
Can't say fairer than that, great post
182cup & 172 racecar
Good post Frasr, and agree, as mine still isn't perfect, but what I was saying is, that if somebody just chucks a set of coilovers on, and they are all different heights, this will effect how the car handles.
I know there is more to it than that, as everything, and it's a right minefield.
Not belittling your expertise or company in any way at all.
Good for in not just taking the money.
But still like to get it roughly right.
Tony.
I know there is more to it than that, as everything, and it's a right minefield.
Not belittling your expertise or company in any way at all.
Good for in not just taking the money.
But still like to get it roughly right.
Tony.
MicKPM
ClioSport Trader
Clio16v/Zoe Z.E.50
Remember that BC springs are factory pre-loaded so you don't adjust ride height by altering the compression on the spring with the upper collars, this changes the spring rate on each corner. Set the lower collars so they're just taking the springs and then use the bottom collar near the hub to adjust ride height to preference. Corner weighting is indeed a HUGE benefit especially on a race car but you need to remember, you will never achieve a perfect CWP on a road car that has different people in with you or sometimes, just yourself. It's a highly contentious subject depending on who you speak to. I personally set the following ride heights on our Clios with BCR's before sending them off for corner weighting:
NSF - 600mm : 595mm - OSF
NSR - 615mm : 610mm - OSR
NOTES:NSR - 615mm : 610mm - OSR
A: Measurements above are taken along the center line of hub and the ride heights are measured from floor level to underside of wheel arch when resting (So check your tyre pressures to).
B: It is also worth noting our floor is floated concrete so pretty level and this job NEEDS to be done on a level surface to work. Without a flat patch though it still isn't 100% accurate.
You can level the above heights up to 600mm front Vs 610mm rear if you like but I always find each corner needs tweaking slightly when the car is finally on the scales and those figures seem to put it about "there" for a road vehicle which see's track time rather than a full on race car with a consistent driver.
I'm pleased the previous post helped explain matters.
Adding pre-load to a spring does not change it's rate - a spring's rate is constant unless it is a special variable rate spring.
Adding different amounts of pre-load effects the Bump/rebound ratio of the damper rod; if you add pre-load you remove some of the droop travel from the suspension but increase the bump travel.
This is the advantage of the dual perch (BC coilovers/Meister and Ohlins) damper units - altering the ride heights does not effect this Bump/rebound Ratio.
HTH
Fraser
Adding pre-load to a spring does not change it's rate - a spring's rate is constant unless it is a special variable rate spring.
Adding different amounts of pre-load effects the Bump/rebound ratio of the damper rod; if you add pre-load you remove some of the droop travel from the suspension but increase the bump travel.
This is the advantage of the dual perch (BC coilovers/Meister and Ohlins) damper units - altering the ride heights does not effect this Bump/rebound Ratio.
HTH
Fraser
