Tuscan front suspension facts and experiment
Discussion
OK, consider that the front end could be OK, according to Martin's measurements and the fact that the majority of mods seem to be of little reported benefit? What about the rear??
I say this as a certain Tuscan I know has a lot of camber on the rear and it does stay put. I pushed along in my Elise last year on French twisty roads and it was a tough call to stick with him. The earlier comment re less control on hard acceleration further prompted my thoughts.
What toe and camber have we tried back end???
Still high on axle stands so I know not how the beast will behave....
J
I say this as a certain Tuscan I know has a lot of camber on the rear and it does stay put. I pushed along in my Elise last year on French twisty roads and it was a tough call to stick with him. The earlier comment re less control on hard acceleration further prompted my thoughts.
What toe and camber have we tried back end???
Still high on axle stands so I know not how the beast will behave....
J
Fwiw I went with these settings...
FRONT
toe-in per wheel NIL
toe-in total NIL
camber -1.5 degrees
REAR
toe-in per wheel -12 minutes
toe-in total -24 min.
camber -2.5 degrees
Car handles brilliantly, excellent turn-in, steering very precise, directionally stable and feels well planted. Steering might be a touch sensitive for some peoples liking.
FRONT
toe-in per wheel NIL
toe-in total NIL
camber -1.5 degrees
REAR
toe-in per wheel -12 minutes
toe-in total -24 min.
camber -2.5 degrees
Car handles brilliantly, excellent turn-in, steering very precise, directionally stable and feels well planted. Steering might be a touch sensitive for some peoples liking.
dvs_dave said:
I thought the changes to the suspension coincided with the launch of the Tuscan S in late '01? At the time it was billed as having revised suspension geometry to account for the 18" spiders that were standard on the S.
The early cars were designed for the 16" spiders which had different offsets. Anyone with a standard early car try it on 16" spiders? How did it handle?
Hi Dave, just to answer question from my experience, my 2000 Tuscan had 16" spiders. It had everything, bump steer, tram lining and all.The early cars were designed for the 16" spiders which had different offsets. Anyone with a standard early car try it on 16" spiders? How did it handle?
Tried geo set up but decided to replace shocks and go to SP12's.
Not saying the 16" and original set up were the problem as it had been around a while before me but my changes made a huge difference and she became a pleasure to drive.
Basil Brush said:
bananaface said:
ive had a chimp, cerb, griff, tuscan mk1 and finally a t350.
nothing scared me like the tuscan.
the only one that ever span me off the road without reason or warning and the only one that ever changed lanes in the time it took to blink.
I wonder why the Cerbs don't have the same issue as the front end setup is identical to the early Tuscans AFAIK.nothing scared me like the tuscan.
the only one that ever span me off the road without reason or warning and the only one that ever changed lanes in the time it took to blink.
We could go on for ages taking about this topic with no real conclusions! My car with the standard set up is now on the road and feels ok to me. As I get familiar with it, I will push it more, but the engine needs running in and so I'm not going bonkers.
Looking at the comments about the suspension behaviours, it appears obvious that people who've posted about their car's driving charteristics, they have a similar situation to the graphs/traces I recorded. High speed instability I think is more down to aero causing the front to lift, which in turn causes the suspension to sag and point the wheels outwards. The overtaking and B road instability is a simple fact the the steering arm is not matched to the geo of the wishbones. This can be minimised as I have done, by adding spacers below the rack, but one can not get away from the differential between these critical components and where the pivot on the chassis (pivot points in line, upper, lower and track rod inner ball joint).
To achieve this alignment a spacer can be fabricated and the use of shorter track rod arms could be used. Ill try this next.
The next step will be to go to the later setup with the longer upper wishbones and moving the upright upper ball joint outboard. (This requires my father to make use of his new hobby lathes nod pillar drill). This all takes time and money.
As I said, I'm happy with the way it drives for now.
I was wondering if perhaps those people that have discussed the options and experiences on here would like to meet up at Burleigh house and have a sharing of experiences and things they've tried? I'd be happy to coordinate a time and location and bring along a whiteboard
Looking at the comments about the suspension behaviours, it appears obvious that people who've posted about their car's driving charteristics, they have a similar situation to the graphs/traces I recorded. High speed instability I think is more down to aero causing the front to lift, which in turn causes the suspension to sag and point the wheels outwards. The overtaking and B road instability is a simple fact the the steering arm is not matched to the geo of the wishbones. This can be minimised as I have done, by adding spacers below the rack, but one can not get away from the differential between these critical components and where the pivot on the chassis (pivot points in line, upper, lower and track rod inner ball joint).
To achieve this alignment a spacer can be fabricated and the use of shorter track rod arms could be used. Ill try this next.
The next step will be to go to the later setup with the longer upper wishbones and moving the upright upper ball joint outboard. (This requires my father to make use of his new hobby lathes nod pillar drill). This all takes time and money.
As I said, I'm happy with the way it drives for now.
I was wondering if perhaps those people that have discussed the options and experiences on here would like to meet up at Burleigh house and have a sharing of experiences and things they've tried? I'd be happy to coordinate a time and location and bring along a whiteboard
Edited by MPETT on Tuesday 18th March 23:20
Walford said:
Because the Cerb suspension was designed for that chassis, thats why it did,nt work on a narrower T chassis 2 inches is quiet a lot, may as well been 2 feet for the effect it has
From looking at parts, the front end is identical. same rack, track rods, wishbones, uprights etc.900T-R said:
In the tech specs the Tuscan seems to have a narrower front and rear track than the Griffith/Chimaera/Cerbera though...
According to web....Cerbera 4.2: Front track 1464 mm, Rear track 1470 mm.
Tuscan 4.0: Front track: 1445 mm, Rear track: 1500 mm.
As measured on my 2000 car...
Tuscan front: 1680mm and rear was 1700mm
measured from rim edge to rim edge)Not sure how else I could measure it to make it tie in with the figures on the web?
p.s. I've got the 3mm spacers either side, so I should take off 6mm from the front track.
Edited by MPETT on Wednesday 19th March 19:35
Need a while to comment... just got all my poly bushes last weekend and engine to rebuild yet.
Anyone else got camber figures for the rear??? Think rack extensions are available on line, are the rods Mk3 Escort? Anyone know where the bottom part of the steering column is from, rack to second UJ ??? Vauxhall?
My Sag has an odd feel when not "loaded" in a corner and despite putting more toe in on it still has it slightly. It feels almost fluid until you get weight transfer. No bush problems or any thing else, had geo twice as well and I've been over this car many times so nothing hanging off. Played with tyre pressures and wheel/tyre combos. Not scary just odd.
Anyone else experience this or similar?
J
Anyone else got camber figures for the rear??? Think rack extensions are available on line, are the rods Mk3 Escort? Anyone know where the bottom part of the steering column is from, rack to second UJ ??? Vauxhall?
My Sag has an odd feel when not "loaded" in a corner and despite putting more toe in on it still has it slightly. It feels almost fluid until you get weight transfer. No bush problems or any thing else, had geo twice as well and I've been over this car many times so nothing hanging off. Played with tyre pressures and wheel/tyre combos. Not scary just odd.
Anyone else experience this or similar?
J
MPETT said:
According to web....
Cerbera 4.2: Front track 1464 mm, Rear track 1470 mm.
Tuscan 4.0: Front track: 1445 mm, Rear track: 1500 mm.
Weird, I get 1445 front and rear in 'my' onlne databases. Cerbera 4.2: Front track 1464 mm, Rear track 1470 mm.
Tuscan 4.0: Front track: 1445 mm, Rear track: 1500 mm.
MPETT said:
As measured on my 2000 car...
Tuscan front: 1680mm and rear was 1700mm
measured from rim edge to rim edge)Not sure how else I could measure it to make it tie in with the figures on the web?
Minus the width of 1 tyre (because you measure track from center to center) would mean 1445 mm for both front and rear assuming you have 235 mm wide tyres at the front and 255 mm ones at the rear, database ses 225 front and 225 rear...Tuscan front: 1680mm and rear was 1700mm
measured from rim edge to rim edge)Not sure how else I could measure it to make it tie in with the figures on the web?
aerospoke said:
The wheel where the tyre sits on. If the spiders are 8 inch wide you would have to deduct 203 mm if TVR built them exactly.
If you measure from outside rim to outside rim yes - measuring from outside tyre to outside tyre seems more practical to me unless the tyres are 'stretched' on the rim Dub-style... I would assume the tyre sits centered on the rim.
My Cerbera was a ditch finder when I first got it, it's now like a "normal" car.
Stiff sidewall tyres are terrible, so a pliable sidewall with around 25psi seems about right.
I fitted a later rack with shorter tie bars, this on its own is WORSE, because of the arms being shorter it goes through more radical angle changes.
So this forced me to look a rack location, we flipped the tie bars/track rods and raised the rack as high as it would go, the pas pipes foul after you go so high, this gave me angles that were very similar to the wishbones.
I don't know the angles as I just drove it, I can now drive it as I want down fun roads!
As we have now done many of our 330 disc conversions, older Tuscans can be hit and miss on what upright you have, as early Cerbera.
Post 2001 with later caliper an easier guess for bolt and spacer combo!!
Stiff sidewall tyres are terrible, so a pliable sidewall with around 25psi seems about right.
I fitted a later rack with shorter tie bars, this on its own is WORSE, because of the arms being shorter it goes through more radical angle changes.
So this forced me to look a rack location, we flipped the tie bars/track rods and raised the rack as high as it would go, the pas pipes foul after you go so high, this gave me angles that were very similar to the wishbones.
I don't know the angles as I just drove it, I can now drive it as I want down fun roads!
As we have now done many of our 330 disc conversions, older Tuscans can be hit and miss on what upright you have, as early Cerbera.
Post 2001 with later caliper an easier guess for bolt and spacer combo!!
Edited by Brummmie on Friday 21st March 12:23
Right then. I've been around the cars at TVR Power to measure the overall width of a Tuscans and Cerberas using Spider wheels and the results (measured from what I can best judge as being the outside edge of the rim) are as follows:
My 2000 Tuscan:
Front: 1680mm, Rear: 1700mm
Cerbera Speed 6:
Front: 1680, Rear 1680mm
I spoke with Powers and they confirmed the front geo is the same between the Tuscan and the Cerbera. I asked about upgrading to the later geo, upright, rack, tie rods etc, and his advice was don't bother. He responce was that Cerberas, early Tuscans and later T series cars can all be made to handle. I agree that the inner ball joint on the tie rod/rack is not right and to be perfect it should be pushed outwards, but the book I've been reading on sport car suspension and the chap at powers both said, a small amount toe out can be useful in hard/tight cornering. Most of the time you're pointing straight ahead, with minor steering input, and my 2mm rack spacer mod makes the wheels point in the right direction for all but full bump (beyond where the bump stop would allow) and full droop, which you only really going to get when you're airborne or on appalling road surfaces with ditches/pot holes etc... when you're not going to be giving it some.
After this discussion with Powers, I went and had my geo checked/adjusted at a garage using the Hunter alignment system. I had my geo tweeked slightly (my eye, a spirit level and some string wasn't far out!)to the following settings and it feels great.
(FYI: there are 60 Mins of arc in a degree)
Front:
Toe: +10mins of arc per wheel (toe in)
Camber: -45mins of arc per side (wheel top is leaning into the car)...= -0.75degs
Caster: 1 Shim on both sides.
Rear:
Toe: +30mins of arc per wheel (toe in)..1 degree overall
Camber: -1deg&30mins per side (wheel top is leaning into the car)...= -1.5degs
Powers said to set the front wheels dead ahead, but I feel, given the nature of the suspension movements I've measured and should the suspension go to full droop, this small amount of toe in should counteract it and prevent the suspension pulling one way or the other.
On the drive home, I have to say it felt great, stable and very much under control. Smooth roads were obviously great, but the bumpy b roads all around my area, did not unsettle the car and I felt more and more confidence growing in the car.
So, I feel happy. I don't feel tempted to go further with modifications for now and I believe that it is stable and can be driven enthusiastically.
Of course I will go on evaluating the set up and report back with any new information that may be of use to the PH community and I plan to do some track days. Unfortunatley, 2nd gear is popping out so the next job is getting that fixed. I've seen positive things about Redman Racing.
Cheers,
Martin
My 2000 Tuscan:
Front: 1680mm, Rear: 1700mm
Cerbera Speed 6:
Front: 1680, Rear 1680mm
I spoke with Powers and they confirmed the front geo is the same between the Tuscan and the Cerbera. I asked about upgrading to the later geo, upright, rack, tie rods etc, and his advice was don't bother. He responce was that Cerberas, early Tuscans and later T series cars can all be made to handle. I agree that the inner ball joint on the tie rod/rack is not right and to be perfect it should be pushed outwards, but the book I've been reading on sport car suspension and the chap at powers both said, a small amount toe out can be useful in hard/tight cornering. Most of the time you're pointing straight ahead, with minor steering input, and my 2mm rack spacer mod makes the wheels point in the right direction for all but full bump (beyond where the bump stop would allow) and full droop, which you only really going to get when you're airborne or on appalling road surfaces with ditches/pot holes etc... when you're not going to be giving it some.
After this discussion with Powers, I went and had my geo checked/adjusted at a garage using the Hunter alignment system. I had my geo tweeked slightly (my eye, a spirit level and some string wasn't far out!)to the following settings and it feels great.
(FYI: there are 60 Mins of arc in a degree)
Front:
Toe: +10mins of arc per wheel (toe in)
Camber: -45mins of arc per side (wheel top is leaning into the car)...= -0.75degs
Caster: 1 Shim on both sides.
Rear:
Toe: +30mins of arc per wheel (toe in)..1 degree overall
Camber: -1deg&30mins per side (wheel top is leaning into the car)...= -1.5degs
Powers said to set the front wheels dead ahead, but I feel, given the nature of the suspension movements I've measured and should the suspension go to full droop, this small amount of toe in should counteract it and prevent the suspension pulling one way or the other.
On the drive home, I have to say it felt great, stable and very much under control. Smooth roads were obviously great, but the bumpy b roads all around my area, did not unsettle the car and I felt more and more confidence growing in the car.
So, I feel happy. I don't feel tempted to go further with modifications for now and I believe that it is stable and can be driven enthusiastically.
Of course I will go on evaluating the set up and report back with any new information that may be of use to the PH community and I plan to do some track days. Unfortunatley, 2nd gear is popping out so the next job is getting that fixed. I've seen positive things about Redman Racing.
Cheers,
Martin
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