How much can I influence my handling with basics ?
Discussion
So I just tried my new VXR8 around my usual local, Cadwell Park, an excellent chassis testing track.
Surprisingly the VXR8 had quite some horrible entry understeer into the mid speed corners, and in general the car tends to squat a lot accelerating out of the slower corners creating massively more grip than I was expecting.
As standard the car comes with a LSD and 245's up front and 275's on the arse end, so my gutt feeling initially is to try some smaller tyres at the rear first off, maybe 255's if they will fit my rims, and also of course tyre pressures
The Dilemma ?
On track road tyres will overheat for sure, if you drive hard enough, and sure enough my tyres seem to go off after 3 to 4 laps at most.
Thing I can't figure is am I running the pressures too high, thus having the heated pressures causing the lack of grip, or is the compound simply overheating, again more air pressure should slightly cool the tyre no ? (very slightly) ? or ? Maybe I need to start my sessions with lower pressures to accomodate the heating up etc ? Advice welcomed because im starting to get confused which way to go ?
Are there any other simple things I can do to get the basic balance to change a little without having to spend out on suspension systems which in the past have not supplied me with the feel I still desire ? I had a full KW V3 kit on my old 3 series and suffered huge understeer it never had on standard suspension before hand for example........makes me nervous, even tho I adjusted it all up correctly.
Gut instinct says geometry and ARB's are a simple effective sollution ? over and above the tyre stuff ?? maybe get some blades made up etc ?
Again advice welcomed.........
You can see the understeer and general chassis balance here in this vid......sideways is very possible (and at end of vid), but your really having to force the issue as you can see in the vid, despite the understeer the car was still awesome fun and very capable, would just like to dial it into my personal driving style which is smooth when the car is behaving nicely, and overly agressive when understeer comes to play !!!
http://www.youtube.com/watch?v=84ZbM06_qkI
Surprisingly the VXR8 had quite some horrible entry understeer into the mid speed corners, and in general the car tends to squat a lot accelerating out of the slower corners creating massively more grip than I was expecting.
As standard the car comes with a LSD and 245's up front and 275's on the arse end, so my gutt feeling initially is to try some smaller tyres at the rear first off, maybe 255's if they will fit my rims, and also of course tyre pressures
The Dilemma ?
On track road tyres will overheat for sure, if you drive hard enough, and sure enough my tyres seem to go off after 3 to 4 laps at most.
Thing I can't figure is am I running the pressures too high, thus having the heated pressures causing the lack of grip, or is the compound simply overheating, again more air pressure should slightly cool the tyre no ? (very slightly) ? or ? Maybe I need to start my sessions with lower pressures to accomodate the heating up etc ? Advice welcomed because im starting to get confused which way to go ?
Are there any other simple things I can do to get the basic balance to change a little without having to spend out on suspension systems which in the past have not supplied me with the feel I still desire ? I had a full KW V3 kit on my old 3 series and suffered huge understeer it never had on standard suspension before hand for example........makes me nervous, even tho I adjusted it all up correctly.
Gut instinct says geometry and ARB's are a simple effective sollution ? over and above the tyre stuff ?? maybe get some blades made up etc ?
Again advice welcomed.........
You can see the understeer and general chassis balance here in this vid......sideways is very possible (and at end of vid), but your really having to force the issue as you can see in the vid, despite the understeer the car was still awesome fun and very capable, would just like to dial it into my personal driving style which is smooth when the car is behaving nicely, and overly agressive when understeer comes to play !!!
http://www.youtube.com/watch?v=84ZbM06_qkI
Phantom Mark said:
So I just tried my new VXR8 around my usual local, Cadwell Park, an excellent chassis testing track.
Surprisingly the VXR8 had quite some horrible entry understeer into the mid speed corners, and in general the car tends to squat a lot accelerating out of the slower corners creating massively more grip than I was expecting.
As standard the car comes with a LSD and 245's up front and 275's on the arse end, so my gutt feeling initially is to try some smaller tyres at the rear first off, maybe 255's if they will fit my rims, and also of course tyre pressures
The Dilemma ?
On track road tyres will overheat for sure, if you drive hard enough, and sure enough my tyres seem to go off after 3 to 4 laps at most.
Thing I can't figure is am I running the pressures too high, thus having the heated pressures causing the lack of grip, or is the compound simply overheating, again more air pressure should slightly cool the tyre no ? (very slightly) ? or ? Maybe I need to start my sessions with lower pressures to accomodate the heating up etc ? Advice welcomed because im starting to get confused which way to go ?
Are there any other simple things I can do to get the basic balance to change a little without having to spend out on suspension systems which in the past have not supplied me with the feel I still desire ? I had a full KW V3 kit on my old 3 series and suffered huge understeer it never had on standard suspension before hand for example........makes me nervous, even tho I adjusted it all up correctly.
Gut instinct says geometry and ARB's are a simple effective sollution ? over and above the tyre stuff ?? maybe get some blades made up etc ?
Again advice welcomed.........
You can see the understeer and general chassis balance here in this vid......sideways is very possible (and at end of vid), but your really having to force the issue as you can see in the vid, despite the understeer the car was still awesome fun and very capable, would just like to dial it into my personal driving style which is smooth when the car is behaving nicely, and overly agressive when understeer comes to play !!!
http://www.youtube.com/watch?v=84ZbM06_qkI
Tyre pressures can be played with and you get different results for different cars and profiles etc. Each car will work its tyres slightly differently, but usually its a simple case of sticking to the manufacturers quoted pressure and leave them at that. Then after a few laps reduce the pressure only slightly..... but this again depends on the track and the car and how it is working the tyres....also driving style plays a big part.Surprisingly the VXR8 had quite some horrible entry understeer into the mid speed corners, and in general the car tends to squat a lot accelerating out of the slower corners creating massively more grip than I was expecting.
As standard the car comes with a LSD and 245's up front and 275's on the arse end, so my gutt feeling initially is to try some smaller tyres at the rear first off, maybe 255's if they will fit my rims, and also of course tyre pressures
The Dilemma ?
On track road tyres will overheat for sure, if you drive hard enough, and sure enough my tyres seem to go off after 3 to 4 laps at most.
Thing I can't figure is am I running the pressures too high, thus having the heated pressures causing the lack of grip, or is the compound simply overheating, again more air pressure should slightly cool the tyre no ? (very slightly) ? or ? Maybe I need to start my sessions with lower pressures to accomodate the heating up etc ? Advice welcomed because im starting to get confused which way to go ?
Are there any other simple things I can do to get the basic balance to change a little without having to spend out on suspension systems which in the past have not supplied me with the feel I still desire ? I had a full KW V3 kit on my old 3 series and suffered huge understeer it never had on standard suspension before hand for example........makes me nervous, even tho I adjusted it all up correctly.
Gut instinct says geometry and ARB's are a simple effective sollution ? over and above the tyre stuff ?? maybe get some blades made up etc ?
Again advice welcomed.........
You can see the understeer and general chassis balance here in this vid......sideways is very possible (and at end of vid), but your really having to force the issue as you can see in the vid, despite the understeer the car was still awesome fun and very capable, would just like to dial it into my personal driving style which is smooth when the car is behaving nicely, and overly agressive when understeer comes to play !!!
http://www.youtube.com/watch?v=84ZbM06_qkI
If you have a temp gauge to record tyre temps along with the usual pressure readings then you can get a good idea of which tyres are being over worked at that particular pressure.
You'll probably find that most manufacturers will engineer this understeer you mention on mid-speed corners on most cars they sell to the public. They have to set a car up so that it meets their perceeved safety level for a typical public wet road. So that Jeo Bloggs doesn't buy the car in middle of winter and take it round a wet bend and stuff it through oversteer.
If you were to lift-off mid-bend in the wet I am guessing you might find the car happily have enough bite on the front to cause some correction attention on the steering wheel.
Stiff and lower suspension can easily cause more understeer so maybe as you mentioned leave this until you've tried other things.
Changing tyre widths again is not necessarily going to give you your desired results. Although if you are just looking for track day fun then a harder compound tyre on the back would considerably alter the balance of grip of your car. But for general road use this would have to be done very wisely and with much care taken.
You've already mentioned ARBs and fitting one to the rear would dial out an amount of understeer....how much I can not tell on your model of car as I am not experienced in VXR8s.
It may well be that a more agressive 4-wheel alignment could be enough to sort out your handling issues. If you can get the front to turn in hard enough and the rear to have less initial bite on a corner then you would certainly see a more tail happy car.
Phantom Mark said:
The Dilemma ?
On track road tyres will overheat for sure, if you drive hard enough, and sure enough my tyres seem to go off after 3 to 4 laps at most.
Thing I can't figure is am I running the pressures too high, thus having the heated pressures causing the lack of grip, or is the compound simply overheating, again more air pressure should slightly cool the tyre no ? (very slightly) ? or ? Maybe I need to start my sessions with lower pressures to accomodate the heating up etc ? Advice welcomed because im starting to get confused which way to go ?
It's not entirely clear from your post what you actually want to achieve - obviously better handling, but for what? Drifting or optimum pace? If you start spending money on modifications where do you stop? What I can tell you from watching the video is, you're inducing some of the understeer with your steering technique.On track road tyres will overheat for sure, if you drive hard enough, and sure enough my tyres seem to go off after 3 to 4 laps at most.
Thing I can't figure is am I running the pressures too high, thus having the heated pressures causing the lack of grip, or is the compound simply overheating, again more air pressure should slightly cool the tyre no ? (very slightly) ? or ? Maybe I need to start my sessions with lower pressures to accomodate the heating up etc ? Advice welcomed because im starting to get confused which way to go ?
Before I go on, I should point out that I was paid to do drift rides in Monaro's for one of the Vauxhall race teams, so I am speaking from experience.
Remember the Monaro/VXR8 is a heavy car, so it won't turn like single-seater or even a 3 series BMW, and if you are too aggressive (which you are in the video) you will induce understeer.
The trick to reducing (even eliminating) the understeer is smooth. progressive steering coupled with a smooth transition from braking to applying power, which should be done as early as possible.
In the video you appear (difficult to judge accurately without actually being in the car) to be carrying a tad too much speed into the corners, particularly the slower ones, and then owing to the resultant understeer, struggling to get on the throttle until quite late.
When I had to drift a Monaro on Sliverstone's Stowe circuit (5 corners, 1 fast(ish), 1 medium speed and three relatively tight, slow(ish) one's) I found that by slowing the car enough and 'hinting' by rolling the steering progressively into the corner, starting slowly (this 'slowly' being relative of course) and speeding the 'roll' up progressively, while simultaneously trailing off the brakes, there was minimal (if any) understeer, quickly changing to mild oversteer. This is all well before the apex of the corner! So by now the car is turning - there's a turning moment induced causing the car to yaw...
At this point there is a choice, and that choice is whether you want to accelerate out of the corner fast or put the car wildly sideways. It's already turning and the front tyres are gripping; the turning moment is helping to push the car round and is causing the back end to gently slide, assisting the turn. If you want to exit the corner quicker start very progressively adding power and reducing the steering lock, balancing one against the other, to keep the back end in line and managing the traction to ensure that all the power being delivered is transmitted to the road. If you want the car to drift (and hold the drift through the corner), just add more power... so long as the car is already turning and the front end is gripping, you should be able to hold the drift,again by balancing the throttle against the steering input. Make fine, smooth adjustments to both throttle and steering where necessary and try not to over-correct with the steering - which you do a couple of times in the video.
This is probably best practiced on an airfield rather than the tight confines of Cadwell.
Drifting does cost in tyres though. I managed to shave a brand new set of rears to nothing in less than 45 minutes of actual track time!
Of course you will make the car handle/grip better with stiffer dampers/springs/roll bars and stickier/wider tyres; but it will still do bad things if you drive it incorrectly.
Edited by timarnold on Tuesday 25th August 21:20
Edited by timarnold on Tuesday 25th August 21:22
ALl points taken on thanks, and yes I was being overly aggressive with the car on turn in, basically cocking around to be truthfull.
I will be uploading another clip from that evening where im simply going for pace rather than messing around, more managed smoother steering.
One of my worst habbits at Cadwell is overdriving the entry to several of the bends, but to be honest even when I drove the car smoother whilst it was a better drive I still had the understeer to a point which did not satisfy me greatly, if your familiar with Cadwell Charlies 2 and the entry to the goosneck especially were problem areas, felt the car had much more to give but was being spoilt with understeer, in similar situations and speeds even my BMW E60 530d M-Sport felt slightly more composed and better balanced, both a simlar size with similar tyres and weight, the front tyres really did feel overworked even with the smoother style.
I do not want a pure drift machine, fun whilst it may be, I do however want a more pointy car which I can drive more on the throttle, I drove the car on a wet rockingham trackday with VXR events (one of their VXR8's) and the balance was wonderful, a really nice drive it by the throttle and seat of your pants experience, I know Rockingham is like Ice compared to most other tracks in the wet but I was hoping the dry balance to be more comparable.
I will live with it a little first, and give it some more time to try and understand how to get the most from this machine before making any wild changes
, I will however try and do the basics and see what gives, style and pressures etc.
Its also worth a mention its my first time out with this car driving at any serious speeds, let alone on track so the whole session was a learning curve for sure, just my gutt feeling impressions of the car so far.
I will be uploading another clip from that evening where im simply going for pace rather than messing around, more managed smoother steering.
One of my worst habbits at Cadwell is overdriving the entry to several of the bends, but to be honest even when I drove the car smoother whilst it was a better drive I still had the understeer to a point which did not satisfy me greatly, if your familiar with Cadwell Charlies 2 and the entry to the goosneck especially were problem areas, felt the car had much more to give but was being spoilt with understeer, in similar situations and speeds even my BMW E60 530d M-Sport felt slightly more composed and better balanced, both a simlar size with similar tyres and weight, the front tyres really did feel overworked even with the smoother style.
I do not want a pure drift machine, fun whilst it may be, I do however want a more pointy car which I can drive more on the throttle, I drove the car on a wet rockingham trackday with VXR events (one of their VXR8's) and the balance was wonderful, a really nice drive it by the throttle and seat of your pants experience, I know Rockingham is like Ice compared to most other tracks in the wet but I was hoping the dry balance to be more comparable.
I will live with it a little first, and give it some more time to try and understand how to get the most from this machine before making any wild changes
, I will however try and do the basics and see what gives, style and pressures etc.Its also worth a mention its my first time out with this car driving at any serious speeds, let alone on track so the whole session was a learning curve for sure, just my gutt feeling impressions of the car so far.
Edited by Phantom Mark on Tuesday 25th August 23:20
If you have put it down to driving style then as Tim hints above you could try going into corners with more brake.
Start braking later but carry the braking more to the apex of the corner which will load up the front tyres and give them much more grip compared to the rear. Tim explains how the car feels when doing this above.
And yes smoothness is the key.
Nice vid by the way, looks like you were having fun.
Start braking later but carry the braking more to the apex of the corner which will load up the front tyres and give them much more grip compared to the rear. Tim explains how the car feels when doing this above.
And yes smoothness is the key.
Nice vid by the way, looks like you were having fun.
I did vary my approach a little through the evening, and of course smoother felt the best, the main aim of the session was only to learn a little about the car and have some fun, the biggest surprise was actually how easy the car was to drive quickly and how little it bit when overdriving it.
Like said I think I need to get onto a different kind of track maybe like Silverstone where I can really experiment properly with my driving style and this car, if you check out my other tube vids you can see I was quite comfortable with my 3 series as it generally did everything I asked (until I fitted coilovers that is), that chassis really suited my style and allow smooth 4 wheel drifts through Charlies and the Gooseneck whenever you wanted it, slightly more aggressive turn in saw oversteer whenever you please, this is something I was hoping the VXR would be a bit more like.
Thanks again for the comments.
Like said I think I need to get onto a different kind of track maybe like Silverstone where I can really experiment properly with my driving style and this car, if you check out my other tube vids you can see I was quite comfortable with my 3 series as it generally did everything I asked (until I fitted coilovers that is), that chassis really suited my style and allow smooth 4 wheel drifts through Charlies and the Gooseneck whenever you wanted it, slightly more aggressive turn in saw oversteer whenever you please, this is something I was hoping the VXR would be a bit more like.
Thanks again for the comments.
Buy this book: http://www.amazon.co.uk/exec/obidos/ASIN/184584207... which will explain a lot.
Apart from the driving as above, you have a couple of options:
1. Get the geometry altered - all cars come from the factory with "safe" understeer as default - perhaps even a little more negative camber on the front is all thats required.
2. Get wider front tyres - I wouldn't ever reduce the amount of rubber on the road, as thats detrimental for all reasons - you want to improve balance while increasing grip overall, not decreasing it. This would definitely improve turn-in.
3. Anti-roll bars - I'd imagine your car should have them, see if the settings car be adjusted, maybe the front is too firm - this would be the most straightforward way of altering handling. Also if the car is squatting on acceleration thats possibly lifting the front and reducing grip and introducing understeer on the way out - firming up the rear bar should help this.
Apart from the driving as above, you have a couple of options:
1. Get the geometry altered - all cars come from the factory with "safe" understeer as default - perhaps even a little more negative camber on the front is all thats required.
2. Get wider front tyres - I wouldn't ever reduce the amount of rubber on the road, as thats detrimental for all reasons - you want to improve balance while increasing grip overall, not decreasing it. This would definitely improve turn-in.
3. Anti-roll bars - I'd imagine your car should have them, see if the settings car be adjusted, maybe the front is too firm - this would be the most straightforward way of altering handling. Also if the car is squatting on acceleration thats possibly lifting the front and reducing grip and introducing understeer on the way out - firming up the rear bar should help this.
Phantom Mark said:
I did vary my approach a little through the evening, and of course smoother felt the best, the main aim of the session was only to learn a little about the car and have some fun, the biggest surprise was actually how easy the car was to drive quickly and how little it bit when overdriving it.
Like said I think I need to get onto a different kind of track maybe like Silverstone where I can really experiment properly with my driving style and this car, if you check out my other tube vids you can see I was quite comfortable with my 3 series as it generally did everything I asked (until I fitted coilovers that is), that chassis really suited my style and allow smooth 4 wheel drifts through Charlies and the Gooseneck whenever you wanted it, slightly more aggressive turn in saw oversteer whenever you please, this is something I was hoping the VXR would be a bit more like.
Thanks again for the comments.
Mark, Like said I think I need to get onto a different kind of track maybe like Silverstone where I can really experiment properly with my driving style and this car, if you check out my other tube vids you can see I was quite comfortable with my 3 series as it generally did everything I asked (until I fitted coilovers that is), that chassis really suited my style and allow smooth 4 wheel drifts through Charlies and the Gooseneck whenever you wanted it, slightly more aggressive turn in saw oversteer whenever you please, this is something I was hoping the VXR would be a bit more like.
Thanks again for the comments.
Cadwell Park is on your doorstep, and is a far better circuit to hone your driving style. Trailbraking & correct corner entry as in turning in earlier, rather than late, is a very important part of mastering that circuit. Everyone makes very hard work of driving around there, but it is so easy to carry a lot of speed, smoothly & safely, just by understanding the physics of what the car is doing, and more importantly, how to prevent it misbehaving! I'm assuming your car is an automatic, and it is a very heavy car, which will reward you, by not overdriving it!
If you want help, just PM me.
Regards, Howard
I drive Cadwell all the time but this was the first time with the VXR8, its actually a manual.
I have driven hundreds of laps around that track in BMW's in the past and only suffered handling problems in the past with an E46 3 series which was fitted with an aftermarket coilover kit and poly bushes (Badly setup) and mis matched tyres.....prior to that the chassis was wonderful.
In the past I have been able to jump in the car and concentrate fully on driving style, lines, apex's etc, not having to do much work to extract the best from the chassis, however on this occasion in the VXR8 I was over driving the car because I was basically just trying out different things after finding the car basically wanted to understeer in places I was expecting oversteer, the underlying tone of the car was understeer however when you really pushed on (no doubt exaggerated by my style at times)
I was turning 1:47.xx at the very best which is pretty reasonable, previous visits I have managed 1:49.xx in a BMW 530d M-Sport Auto, and 1:53.00 in a BMW E46 320d SE Manual (Stock except pads/discs and remap)
I only mention lap times not for bragging rights but purely to quantify relative chassis ability vs expectation, my best lap that day was certainly in the right ball park for my expecations given that I was not pushing the braking zones.
The reason for starting this thread was to see if I was missing the obvious with the car, tyre pressures, style, expectations etc, I do know for sure there is more to be extracted from this car in the way I turn in and manage the weight transfers especially from the transitions from brake to steering/throttle, I just need some more laps I guess.
I work in the simulation industry and do the vehicle dynamics physics so understand plenty how things should be, even if I do still overdrive my cars sometimes, I did do much cleaner laps earlier on in the day without all the aggression, its a bad habbit of mine which I recognise, I find the my limit/car limit and then basically start messing around which is really a reflection of what the vid shows.
I have driven hundreds of laps around that track in BMW's in the past and only suffered handling problems in the past with an E46 3 series which was fitted with an aftermarket coilover kit and poly bushes (Badly setup) and mis matched tyres.....prior to that the chassis was wonderful.
In the past I have been able to jump in the car and concentrate fully on driving style, lines, apex's etc, not having to do much work to extract the best from the chassis, however on this occasion in the VXR8 I was over driving the car because I was basically just trying out different things after finding the car basically wanted to understeer in places I was expecting oversteer, the underlying tone of the car was understeer however when you really pushed on (no doubt exaggerated by my style at times)
I was turning 1:47.xx at the very best which is pretty reasonable, previous visits I have managed 1:49.xx in a BMW 530d M-Sport Auto, and 1:53.00 in a BMW E46 320d SE Manual (Stock except pads/discs and remap)
I only mention lap times not for bragging rights but purely to quantify relative chassis ability vs expectation, my best lap that day was certainly in the right ball park for my expecations given that I was not pushing the braking zones.
The reason for starting this thread was to see if I was missing the obvious with the car, tyre pressures, style, expectations etc, I do know for sure there is more to be extracted from this car in the way I turn in and manage the weight transfers especially from the transitions from brake to steering/throttle, I just need some more laps I guess.
I work in the simulation industry and do the vehicle dynamics physics so understand plenty how things should be, even if I do still overdrive my cars sometimes, I did do much cleaner laps earlier on in the day without all the aggression, its a bad habbit of mine which I recognise, I find the my limit/car limit and then basically start messing around which is really a reflection of what the vid shows.
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