Steering Geometery
Discussion
I've recently had the Steering Geometery set on my car. It was done by a guy named Andy Turner, a Mechanic, not a Wheel allignment Centre, who is a former World Stockcar racing champion 3 years on the trot, who set his own cars up and now does a fair bit of set up work for race/performance cars, so he knows a bit about Steering geometery.
He set the front wheels on my car to a slight Toe-out, as opposed to the recomended Toe-In, assured me it would be better, and quoted me the 'Ackerman Principle', which is a bit over my head, but I've got to report that it has made a big improvement to the way the car feels and handles. Very stable at speed, turns in quickly, and feels much more planted and stable on fast sweeping bends than it did before.
Could be worth some of you trying it.
Ackerman
He set the front wheels on my car to a slight Toe-out, as opposed to the recomended Toe-In, assured me it would be better, and quoted me the 'Ackerman Principle', which is a bit over my head, but I've got to report that it has made a big improvement to the way the car feels and handles. Very stable at speed, turns in quickly, and feels much more planted and stable on fast sweeping bends than it did before.
Could be worth some of you trying it.
Ackerman
That's very interesting. The only (RWD) car I have run toe out on the front was my Elise - 1mm - but I used 6mm of toe in on the rear to keep the stability. Amazingly it wore the tyres evenly as well!
The problem with toe out on the front is that it can make the car feel nervous and twitchy around the straight ahead, but it can also help dial out understeer.
The main thing is that it works for you.
The problem with toe out on the front is that it can make the car feel nervous and twitchy around the straight ahead, but it can also help dial out understeer.
The main thing is that it works for you.
Hmmm, can't argue with the fancy diagrams as they are completely true.
However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
julian64 said:
Hmmm, can't argue with the fancy diagrams as they are completely true.
However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
That's why I had to run so much toe in at the rear on my Elise - 6mm! It did work though and the car turned in nicely without being at all nervous.However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
I've gone back to the standary factory settings on mine as I found it too hard to live with the "race" type settings for every day use.
It was way too oversteery (is that a word even ? ) at low speeds.
The factory settings are a better compromise for everyday use on relatively poor roads and occasional track days.
Just my two-pence worth.
It was way too oversteery (is that a word even ? ) at low speeds.
The factory settings are a better compromise for everyday use on relatively poor roads and occasional track days.
Just my two-pence worth.
julian64 said:
Hmmm, can't argue with the fancy diagrams as they are completely true.
However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens. On a roundabout at about 40 - Took my hands off the wheel and the wheel gave a very slight attempt to self centre, just a light touch on the wheel to carry on around the corner.However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens - Car immediately responds to the turning input, but immediately self centres when I let go.
On the motorway at 80 ish the car is rock steady.
JensenA said:
julian64 said:
Hmmm, can't argue with the fancy diagrams as they are completely true.
However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens. On a roundabout at about 40 - Took my hands off the wheel and the wheel gave a very slight attempt to self centre, just a light touch on the wheel to carry on around the corner.However I think tracking is a complete compromise, and your compromise is skewed heavily toward turing corners.
I would be interested in the answer to two questions though.
Performing tight circles at reasonable speed, not enough to lose grip at the rear but reasonable speed, let go of your steering wheel with your foot still on the gas and tell us what happens.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens.
I could be wrong, but I think the answer to those two questions is why I wouldn't be too keen to follow you.
Driving along at about twenty take your hands off the wheel, and then give a small tug to one side of the wheel or the other and tell us what happens - Car immediately responds to the turning input, but immediately self centres when I let go.
On the motorway at 80 ish the car is rock steady.
Sounds like you've got a good compromise there.
Personally I do like my steering wheel to centre promply.
As I see it if the car going round the roundabout doesn't centre promptly, then it shouldn't centre promptly on the straight. Not quite sure how you've managed that but sounds good that you have.
I had huge amounts of toe out on the 'skiboot' last season, it turned in with the slightest input of the steering wheel, but as a trade off the tyres only lasted a couple of track days and a season sprinting, that's less than 200 miles to you and me. 
A nightmare on the road, a joy on track.
Tim
A nightmare on the road, a joy on track.
Tim
TT Tim said:
I had huge amounts of toe out on the 'skiboot' last season, it turned in with the slightest input of the steering wheel, but as a trade off the tyres only lasted a couple of track days and a season sprinting, that's less than 200 miles to you and me.
A nightmare on the road, a joy on track.
Tim
Tim - The guy who set mine up has previously set up other TVR's with very similar settings, and not one car has reported any tyre wear problems at all. All I can say is that I am impressed and that the car feels really good, a lot better than before when it had the standard settings. A nightmare on the road, a joy on track.
Tim
An update on this topic which may help others - and at the risk of the "I told you So's" telling me 'I told you so'
I've gone back to having the Steering Geo back to almost standard with just a minute bit of toe-in at the front.
The previous Toe-out settings made the car really quick to turn in, but at higher speeds - which I happened to do one day, when by mistake I found myself on an unused airstrip - the car just felt a bit too twitchy.
So in summary, if you are predominantly a Track day or Back road user, Toe-out is good, but for everyday use stick with the Factory recomendations.
I've gone back to having the Steering Geo back to almost standard with just a minute bit of toe-in at the front.
The previous Toe-out settings made the car really quick to turn in, but at higher speeds - which I happened to do one day, when by mistake I found myself on an unused airstrip - the car just felt a bit too twitchy.
So in summary, if you are predominantly a Track day or Back road user, Toe-out is good, but for everyday use stick with the Factory recomendations.
Told you so.
No wait a minute, I prefer you gave it a try. I've been messing about with my geometry almost from the day I had my car. I had lots of advice and some has worked and some hasn't.
I'm running rear wheels straight as a die with 1 deg neg camber.
Front wheels 30mins toe in, with 1.5 deg neg camber and 0.2 deg castor angle.
I'm close but still not entirely happy.
running nitrons with now 500lb fronts and 450 rears, 6 clicks from soft all round. I have the lower whishbones completely straight while loaded but the car looks a bit too high in the arches.
Firstly I'm not convinced the Cerb should have a front bias in the shock department as the car is pretty much weight central when you do your corner weighting.
along the straights I can now go long periods with hands off, and still maintain hands off on acceleration or deceleration.
I do get bump steer though, and tight corners the steering still doesn't centre as fast as I would like but applying more toe in has a negative effect on the above.
No wait a minute, I prefer you gave it a try. I've been messing about with my geometry almost from the day I had my car. I had lots of advice and some has worked and some hasn't.
I'm running rear wheels straight as a die with 1 deg neg camber.
Front wheels 30mins toe in, with 1.5 deg neg camber and 0.2 deg castor angle.
I'm close but still not entirely happy.
running nitrons with now 500lb fronts and 450 rears, 6 clicks from soft all round. I have the lower whishbones completely straight while loaded but the car looks a bit too high in the arches.
Firstly I'm not convinced the Cerb should have a front bias in the shock department as the car is pretty much weight central when you do your corner weighting.
along the straights I can now go long periods with hands off, and still maintain hands off on acceleration or deceleration.
I do get bump steer though, and tight corners the steering still doesn't centre as fast as I would like but applying more toe in has a negative effect on the above.
Going to book mine in to get sorted hopefully next week. SP Matt sorted my back end out (ooh err missus) at Silverstone the other month, but didnt have the tools to hand to sort the front. Good job really as I t
tted a kerb going to Brands the other weekend, so if the front wasnt out before, it sure as hell must be now 
So, standard settings for the front, right?
tted a kerb going to Brands the other weekend, so if the front wasnt out before, it sure as hell must be now So, standard settings for the front, right?
Get the cheque and stickers Mike?I knew someone would say 'Told you so'
My Ride height was set with the front lower wishbones parallel to the ground. Agrred, at first it does look a bit to high but I think that was just because I was used to it being low, and coming from the world of 'normal' cars, lowering is the first thing you do to improve handling. But on the Cerb, it's already been lowered, so the parallel wishbone scenario is what you want to allow the suspension to work as it was designed to work.
The Toe-in at the rear is purely to aid traction. Brummie - If your reading this - increasing the Toe-in from the factory settings may be worth trying on your car, to try and get the power down better.
My Ride height was set with the front lower wishbones parallel to the ground. Agrred, at first it does look a bit to high but I think that was just because I was used to it being low, and coming from the world of 'normal' cars, lowering is the first thing you do to improve handling. But on the Cerb, it's already been lowered, so the parallel wishbone scenario is what you want to allow the suspension to work as it was designed to work.
The Toe-in at the rear is purely to aid traction. Brummie - If your reading this - increasing the Toe-in from the factory settings may be worth trying on your car, to try and get the power down better.
Edited by JensenA on Tuesday 12th May 13:38
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