Improved Handling
Discussion
Thats an interesing set up. I suppose somtimes what you learn isn't right for everything.
The toe in seems a lot too and especially on the fronts.
A couple of years ago i had an e36 m3 which was almost completly stripped (1280KGS), 335bhp, was a very quick car (nothing like the tuscan mind).
I had numerous geometry set ups by various people, all of which i never liked, it never felt right to me, steering too light, not stable enough, turn in no good for me.
Eventually i had it set up by some guys who raced in britcar and my god they sorted the car into an amazing tool.
I cant remember the actual settings but it had a fair bit of toe out on the front, a bit of toe in on the rear, about 2.5deg negative camber all round and a little more than standard castor on the fronts. Rear was quite soft as it allowed the rear end to dig in and grip. The funny thing was that tyre wear actually wasn't that bad either.
It was so predictable and imo about as good as you could ever get a road/track m3.
The difference with the tvr is that the tuscan is naturally sooooo much stiffer due to the spaceframe design chassis. I believe it could handle as good as any other car as the basics are there. For one the turn in is spectacular, similar to a go kart, which for a road car is unbelievable imo.
The toe in seems a lot too and especially on the fronts.
A couple of years ago i had an e36 m3 which was almost completly stripped (1280KGS), 335bhp, was a very quick car (nothing like the tuscan mind).
I had numerous geometry set ups by various people, all of which i never liked, it never felt right to me, steering too light, not stable enough, turn in no good for me.
Eventually i had it set up by some guys who raced in britcar and my god they sorted the car into an amazing tool.
I cant remember the actual settings but it had a fair bit of toe out on the front, a bit of toe in on the rear, about 2.5deg negative camber all round and a little more than standard castor on the fronts. Rear was quite soft as it allowed the rear end to dig in and grip. The funny thing was that tyre wear actually wasn't that bad either.
It was so predictable and imo about as good as you could ever get a road/track m3.
The difference with the tvr is that the tuscan is naturally sooooo much stiffer due to the spaceframe design chassis. I believe it could handle as good as any other car as the basics are there. For one the turn in is spectacular, similar to a go kart, which for a road car is unbelievable imo.
Just like GT TVR, whom I met in Spain last month ( nice guy ) on the TVR trip.......I too had independently of him come to the rear rate of 400lbs and a front rate now of 375lbs on the springs. I use Gaz Gold Pro shocks.
I do however run 255/40 18 Toyo R1R's front and rear.
I have raised my steering rack by 15mm and I run a lot of front castor angle. ( see my thread for exact details in major mods section ) My Tuscan was lethal, it really was. It is now pin sharp and a joy to drive at any speed.
I have now fitted the "S" splitter and yet to test it. I hope that this will prove to be a further improvement. Although in what area I do not know as my Tuscan as I say is very well sorted now. But I had the splitter for 4 years and thought what the heck I will fit it on anyway.
Getting the rake angle as I now have it, front lower than rear, and the corner weights to work with it was a big step forwards. Also I see that I run my Tuscan very low compared to a lot of others. I have measured them from wheel arch apex to road and they all seem higer than mine.
I still see quite a few Tuscan's with nose up at rest attitude.
I do not believe that the Tuscan is a bad handling car at all. It left the factory as one, but if you persist then it can be sorted.
I will enjoy testing it against JG and his Sagaris at Gaurdix next time.
Regards.
Speed eight.
I do however run 255/40 18 Toyo R1R's front and rear.
I have raised my steering rack by 15mm and I run a lot of front castor angle. ( see my thread for exact details in major mods section ) My Tuscan was lethal, it really was. It is now pin sharp and a joy to drive at any speed.
I have now fitted the "S" splitter and yet to test it. I hope that this will prove to be a further improvement. Although in what area I do not know as my Tuscan as I say is very well sorted now. But I had the splitter for 4 years and thought what the heck I will fit it on anyway.
Getting the rake angle as I now have it, front lower than rear, and the corner weights to work with it was a big step forwards. Also I see that I run my Tuscan very low compared to a lot of others. I have measured them from wheel arch apex to road and they all seem higer than mine.
I still see quite a few Tuscan's with nose up at rest attitude.
I do not believe that the Tuscan is a bad handling car at all. It left the factory as one, but if you persist then it can be sorted.
I will enjoy testing it against JG and his Sagaris at Gaurdix next time.
Regards.
Speed eight.
My advice would be to take it a well known TVR specialist with a good reputation when it comes to setting suspension up for UK roads/tracks.
I'm no expert in the field but some of the settings being touted in this thread are a little extreme for road use. Remember that roads here in the UK are fairly bumpy so you need a complaint set-up for optimum results. Also, the Tuscan has limited suspension travel so running too low doesn't do the handling any favors over the bumps.
I'm no expert in the field but some of the settings being touted in this thread are a little extreme for road use. Remember that roads here in the UK are fairly bumpy so you need a complaint set-up for optimum results. Also, the Tuscan has limited suspension travel so running too low doesn't do the handling any favors over the bumps.
dvs_dave said:
My advice would be to take it a well known TVR specialist with a good reputation when it comes to setting suspension up for UK roads/tracks.
I'm no expert in the field but some of the settings being touted in this thread are a little extreme for road use. Remember that roads here in the UK are fairly bumpy so you need a complaint set-up for optimum results. Also, the Tuscan has limited suspension travel so running too low doesn't do the handling any favors over the bumps.
The geo settings above are not extreme and perfectly suitable for fast road use. And they help to reduce tramlining/nervousness. They come from Derek form Abshocks and he has done quite some testing.I'm no expert in the field but some of the settings being touted in this thread are a little extreme for road use. Remember that roads here in the UK are fairly bumpy so you need a complaint set-up for optimum results. Also, the Tuscan has limited suspension travel so running too low doesn't do the handling any favors over the bumps.
Indeed the greatest weakness of a Tuscan is the lack of suspension travel. So agree that you shouldn't set them too low; leave some space and don't set the dampers too hard so that the springs can do their work.
GT TVR said:
The geo settings above are not extreme and perfectly suitable for fast road use. And they help to reduce tramlining/nervousness. They come from Derek form Abshocks and he has done quite some testing.
Indeed the greatest weakness of a Tuscan is the lack of suspension travel. So agree that you shouldn't set them too low; leave some space and don't set the dampers too hard so that the springs can do their work.
I've found this hard to believe before, but now that I have given it thought, I think I understand why this set up seems to 'work' on a Tuscan. It is still NOT what I would recommend for a modern TVR, but I'll go into that later...Indeed the greatest weakness of a Tuscan is the lack of suspension travel. So agree that you shouldn't set them too low; leave some space and don't set the dampers too hard so that the springs can do their work.
GT TVR/ Speed Eight, can you get a photo of your rear dampers with the car on the ground (so loaded) - I would like to see the amount of travel to the bump stops of the Gaz/ Nitron set ups. Also, what ride heights are you both running?
You see my set-up is the one from Nitron and it's stiff at the front and quite soft at the back, with a slight nose down attitude. My car was set-up by Joolz from Track Car Solutions (now amalgamated with Raceproved) and he's done a lot of race TVR's so knows how to make a TVR handle.
My car doesn't tramline at all (even before the spacers). Only times it has was when the geo was out. I can drive it at 150mph and it tracks perfectly straight and true and you can happily drive it with one hand on the wheel at normal speeds.
If the back end was stiff the car would be a bucking bronco tail happy mess anywhere near some bumps and it would have trouble putting its power down due to the wheels not maintaining even pressure on the ground. With my current set-up, it's actually quite hard to light up the rear wheels unless you're being deliberate.
My car doesn't tramline at all (even before the spacers). Only times it has was when the geo was out. I can drive it at 150mph and it tracks perfectly straight and true and you can happily drive it with one hand on the wheel at normal speeds.
If the back end was stiff the car would be a bucking bronco tail happy mess anywhere near some bumps and it would have trouble putting its power down due to the wheels not maintaining even pressure on the ground. With my current set-up, it's actually quite hard to light up the rear wheels unless you're being deliberate.
I'll try to take a pic but I'm guessing the travel to the bump stops is about 4 cm.
I used the Nitron settings before too and it was very good. But I found the rear a bit unstable in higher speed corners which could be cured by setting the dampers harder, but this made the overal ride too hard.
So had a talk with various experts and some suggested to use harder springs on the back and softer on the front. This really helped and now the car is more stable in the same sort of corners and the ride is still quite comfortable. Haven't tried this set up on the track yet.
I used the Nitron settings before too and it was very good. But I found the rear a bit unstable in higher speed corners which could be cured by setting the dampers harder, but this made the overal ride too hard.
So had a talk with various experts and some suggested to use harder springs on the back and softer on the front. This really helped and now the car is more stable in the same sort of corners and the ride is still quite comfortable. Haven't tried this set up on the track yet.
GT TVR said:
I'll try to take a pic but I'm guessing the travel to the bump stops is about 4 cm.
I used the Nitron settings before too and it was very good. But I found the rear a bit unstable in higher speed corners which could be cured by setting the dampers harder, but this made the overal ride too hard.
So had a talk with various experts and some suggested to use harder springs on the back and softer on the front. This really helped and now the car is more stable in the same sort of corners and the ride is still quite comfortable. Haven't tried this set up on the track yet.
I need to see photos, but that has already semi-confirmed my theory for it. I used the Nitron settings before too and it was very good. But I found the rear a bit unstable in higher speed corners which could be cured by setting the dampers harder, but this made the overal ride too hard.
So had a talk with various experts and some suggested to use harder springs on the back and softer on the front. This really helped and now the car is more stable in the same sort of corners and the ride is still quite comfortable. Haven't tried this set up on the track yet.
If you could possibly get a measurement or photo of your cars ride height at the same time that would be very helpful.Hello there.
I can do this next week for you.
Right now it is in bits because I am still "futsing" around with other things.
While I was at Guardix race track last month I was able to measure a lot of things on a lot of TVR's.
Such as track widths, ride heights, wheel base lengths and so on. It was very interesting.
I took away a lot of knowledge and new ideas which I have now incorperated into my Tuscan.
The deal with the springs is very interesting in itself. It does have a direct effect with the type of damper that one uses and the rate of bump and rebound ie, the valving of the damper unit.
I was using Intrax units and their springs. I have also used Nitrons. But I find the Gaz units much better than either of those choices. I have also run through many spring rate combinations. What I have now actualy enables one to feel and imagine the effect of the wheels followinng the road surface. It also produces a silky smooth ride. But on the circuit it is superb also. For me it has never been set up better than it is now. I did let a friend of mine drive my Tuscan, a very rare event that, and he was amazed at the way it rode so well and how it encouraged confidence in its ability.
Regards.
Speed eight.
I can do this next week for you.
Right now it is in bits because I am still "futsing" around with other things.
While I was at Guardix race track last month I was able to measure a lot of things on a lot of TVR's.
Such as track widths, ride heights, wheel base lengths and so on. It was very interesting.
I took away a lot of knowledge and new ideas which I have now incorperated into my Tuscan.
The deal with the springs is very interesting in itself. It does have a direct effect with the type of damper that one uses and the rate of bump and rebound ie, the valving of the damper unit.
I was using Intrax units and their springs. I have also used Nitrons. But I find the Gaz units much better than either of those choices. I have also run through many spring rate combinations. What I have now actualy enables one to feel and imagine the effect of the wheels followinng the road surface. It also produces a silky smooth ride. But on the circuit it is superb also. For me it has never been set up better than it is now. I did let a friend of mine drive my Tuscan, a very rare event that, and he was amazed at the way it rode so well and how it encouraged confidence in its ability.
Regards.
Speed eight.
GT TVR said:
Springs: yes, firmer on the rear. On a Tuscan all the weight is behind the front axle (with a big *ss sticking out) so this will help to stabilize it. And set the dampers softer so it absorbs the bumps in stead of jumping off them.
Tyres: if you have 225/40 and 245/40 that's OK, don't change them.
Geo:
FRONT
toe-in per wheel-4 min
toe-in total -8 min
camber -1
REAR
toe-in per wheel-12 min
toe-in total -24 min
camber -1,5
I went down to a place yesterday with a hunter machine and had mine done, front camber had been set to -1 deg and rear was -1.3 so was left as pretty damn close.Tyres: if you have 225/40 and 245/40 that's OK, don't change them.
Geo:
FRONT
toe-in per wheel-4 min
toe-in total -8 min
camber -1
REAR
toe-in per wheel-12 min
toe-in total -24 min
camber -1,5
Rear toe was iirc a total of 8mins so that was adjusted to 24. Not driven at any real speed yet but initially it does feel more stable which the toe in should do on the rear.
However the front was actually slightly toeing out. So we set it to 4 each wheel. When i drove it though i hated it, the steering was really light and i felt like the beautiful turn in had gone
so i went back and set the front to 0 toe and now it feels pretty damn good, not quite as much 'feel' as when it was toeing out but much better than the toe in and generally feels quite a bit more stable.The guy reckoned that castor could not be adjusted, must admit i couldnt see where to adjust from either. Does anyone know and does anyone know what effect max castor would give? its currently 4.
Btw how hard is it to set a steering wheel straight? Every car i have ever owned has always always sat slightly to one side, even when the car tracks perfectly straight, it bugs the s
t out of me.This bloke was nice enough to let me sit in the car though and every so often he would tell me to give the steering a little wiggle and make sure the wheel was straight. Result was i now drive with a steering wheel which is 100% straight which makes me very happy
I suppose that every steering rack no matter how new has a very slight bit of play in the centre and as such its very difficult to set it perfectly.
Top wishbone. Top joint. Two bolt set up.
You will most probably see each side of the joint a thick shim.
If so move both shims to the front of the wishbone side of said joint, so that caster is introduced, about 5.6 degrees on a MK1 Tuscan
These shims alone should get you sorted. Unless you want to experiment in which case you will have to make others up.
Caster (Castor...USA)
Caster is the inclination of the steering axis from vertical in side view.
Positive caster causes caster trail, which is force imbalance at the tyre contact patch.
This force twists the tyre tread and creates a torque around the point where the steering axis intersects the tyre contact patch.
The greater the caster, the more caster trail is present. The torque increases with caster and so does the steering effort. The self centring effect of the tyres caused by this torque also increases, which improves straight line stability and driver feel.
Less caster reduces tyre scrub while cornering, but also reduces straight line stability and feel.
If you are going away from the standard 16" diameter wheel of the MK1 Tuscan by more than 1", you will need to increase the caster angle. This is also true of wheel offsets. And radical suspension changes. Too much caster will hurt traction, but as with most things a compromise has to be drawn by the owner. I would say that for the street the 5.6 degrees in this case is spot on.
Regards,
Speed eight.
You will most probably see each side of the joint a thick shim.
If so move both shims to the front of the wishbone side of said joint, so that caster is introduced, about 5.6 degrees on a MK1 Tuscan
These shims alone should get you sorted. Unless you want to experiment in which case you will have to make others up.
Caster (Castor...USA)
Caster is the inclination of the steering axis from vertical in side view.
Positive caster causes caster trail, which is force imbalance at the tyre contact patch.
This force twists the tyre tread and creates a torque around the point where the steering axis intersects the tyre contact patch.
The greater the caster, the more caster trail is present. The torque increases with caster and so does the steering effort. The self centring effect of the tyres caused by this torque also increases, which improves straight line stability and driver feel.
Less caster reduces tyre scrub while cornering, but also reduces straight line stability and feel.
If you are going away from the standard 16" diameter wheel of the MK1 Tuscan by more than 1", you will need to increase the caster angle. This is also true of wheel offsets. And radical suspension changes. Too much caster will hurt traction, but as with most things a compromise has to be drawn by the owner. I would say that for the street the 5.6 degrees in this case is spot on.
Regards,
Speed eight.
Thanks speed eight. I'll go back down there and get them to have a look again, they are quite friendly and will try a couple of settings so if i don't like it they will re do it.
The guy down there did say though that changing the caster would alter camber as well but im not sure it would as surely you are just moving the wheel backwards or forwards and not to the side.
The guy down there did say though that changing the caster would alter camber as well but im not sure it would as surely you are just moving the wheel backwards or forwards and not to the side.
As you know, with IRS, rear toe in is mandatory, toe out is unsafe.
I think that you should introduce more toe in at the rear. I would say if you are going to increase your caster at the front then go for a partial toe at the rear of +2.5 to +3.0.
On the front try a partial toe of +0.5
This will increase your straight line stability (and turning in to a corner) even more, and slow down your turn in, making the car less twitchy at the higher speeds of motorway driving.............. I am assuming that this is for road use.
If you have wheel spacers to try to rectify "bump steer"..........get rid of them!
Raise your steering rack 15mm instead. Don't start messing around with the wheel offset. This is not the answer.
If you really get into your suspension/steering geometry settings and experiment with them, then you will be amazed at how good the Tuscan really is.
I have seen people say............."Oh well we all know that the Tuscan does not handle well"......
Don't believe it! Have these people owned a Tuscan? Keep a detailed record of all their settings and pushed for the optimum set up. Well, if they have I have never seen their findings. I report all of what I am doing and I can tell you that the Tuscan on the street is just fine. And really rather good on the track also.
If I was setting my car up for the track then it would be spot on. Mine is set up for very fast street use and some track use.
It is also a very smooth ride with compliant suspension. Not some kind of house brick with wheels.
My Tuscan was a shockingly bad drive before I set it all up.
I went to "experts" and the upshot was like a hospital that treated everyone for a broken arm regardless of their needs.
You have to keep pushing forwards to a point where it all starts to go wrong, and then back off. It is time demanding and frustrating. But the end result is worth it. I would say that they all need to be a bit different of course.
But I would be surprised if you did not like these settings.
I will try to sort out a picture of my steering rack modification and post it up.
Regards.
Speed eight.
I think that you should introduce more toe in at the rear. I would say if you are going to increase your caster at the front then go for a partial toe at the rear of +2.5 to +3.0.
On the front try a partial toe of +0.5
This will increase your straight line stability (and turning in to a corner) even more, and slow down your turn in, making the car less twitchy at the higher speeds of motorway driving.............. I am assuming that this is for road use.
If you have wheel spacers to try to rectify "bump steer"..........get rid of them!
Raise your steering rack 15mm instead. Don't start messing around with the wheel offset. This is not the answer.
If you really get into your suspension/steering geometry settings and experiment with them, then you will be amazed at how good the Tuscan really is.
I have seen people say............."Oh well we all know that the Tuscan does not handle well"......
Don't believe it! Have these people owned a Tuscan? Keep a detailed record of all their settings and pushed for the optimum set up. Well, if they have I have never seen their findings. I report all of what I am doing and I can tell you that the Tuscan on the street is just fine. And really rather good on the track also.
If I was setting my car up for the track then it would be spot on. Mine is set up for very fast street use and some track use.
It is also a very smooth ride with compliant suspension. Not some kind of house brick with wheels.
My Tuscan was a shockingly bad drive before I set it all up.
I went to "experts" and the upshot was like a hospital that treated everyone for a broken arm regardless of their needs.
You have to keep pushing forwards to a point where it all starts to go wrong, and then back off. It is time demanding and frustrating. But the end result is worth it. I would say that they all need to be a bit different of course.
But I would be surprised if you did not like these settings.
I will try to sort out a picture of my steering rack modification and post it up.
Regards.
Speed eight.
m3jappa said:
I went down to a place yesterday with a hunter machine and had mine done, front camber had been set to -1 deg and rear was -1.3 so was left as pretty damn close.
Rear toe was iirc a total of 8mins so that was adjusted to 24. Not driven at any real speed yet but initially it does feel more stable which the toe in should do on the rear.
However the front was actually slightly toeing out. So we set it to 4 each wheel. When i drove it though i hated it, the steering was really light and i felt like the beautiful turn in had gone so i went back and set the front to 0 toe and now it feels pretty damn good, not quite as much 'feel' as when it was toeing out but much better than the toe in and generally feels quite a bit more stable.
The guy reckoned that castor could not be adjusted, must admit i couldnt see where to adjust from either. Does anyone know and does anyone know what effect max castor would give? its currently 4.
I'd go for more camber at the rear. I'm running 1.7.Rear toe was iirc a total of 8mins so that was adjusted to 24. Not driven at any real speed yet but initially it does feel more stable which the toe in should do on the rear.
However the front was actually slightly toeing out. So we set it to 4 each wheel. When i drove it though i hated it, the steering was really light and i felt like the beautiful turn in had gone
so i went back and set the front to 0 toe and now it feels pretty damn good, not quite as much 'feel' as when it was toeing out but much better than the toe in and generally feels quite a bit more stable.The guy reckoned that castor could not be adjusted, must admit i couldnt see where to adjust from either. Does anyone know and does anyone know what effect max castor would give? its currently 4.
Toe in at the front helps for high speed stability but indeed a trade off for turn in. I'm running sticky Toyo R1-R's so have plenty of turn-in anyway so sacrafied a bit for higher speed stability. Now my steering feels a bit light for a few minutes till the tyres heat up, then it's great and meaty.
Toe out is great for trackdays but not for the public road.
glow worm said:
I never noticed the difference with wheel spacers, I'll take them off next time the wheels are off.
I defintely notice a difference on my early Mk1. I thought the change to the top ball joint alignment on later cars was made to correct the set up so spacers aren't needed?When the front suspension moves through bump and rebound travel over bumps and so on, it swings in an arc that is deternmined by the instant center location. The steering tie rod also moves in an arc when the suspensetion moves up and down. If the arc of the tie rod does not match the arc of the suspension the difference will cause the wheel to be steered. The effect, there is a change in toe in or toe out at the wheel.
This will cause an unwanted steering motion...... "bump-steer".
Zero bump steer occurs when the tie rod ends fall on the lines the upper and lower inner pivots and the upper and lower outer ball joints scribe.
By raising the rack on the "MK1 Tuscan"...........I do not speak for the others......you will eliminate this problem.
I attach a photograph which shows my journey to this goal by way of 5mm thick shims. I reached "zero" at 15mm on my Tuscan, ie 3 x shims.
Regards.
Speed eight
This will cause an unwanted steering motion...... "bump-steer".
Zero bump steer occurs when the tie rod ends fall on the lines the upper and lower inner pivots and the upper and lower outer ball joints scribe.
By raising the rack on the "MK1 Tuscan"...........I do not speak for the others......you will eliminate this problem.
I attach a photograph which shows my journey to this goal by way of 5mm thick shims. I reached "zero" at 15mm on my Tuscan, ie 3 x shims.
Regards.
Speed eight
Edited by Speed eight on Thursday 26th May 13:24
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