Discussion
How bad do you rate the tram lining on your car?? I know that the wishbones are too short and the car was never designed to run 18" wheels, I cannot get my head round the tram lining I am getting and I would say that on the road is really bad,I have thought about fitting a wing but I do not think this will make a noticeable difference, I have had a full suspension setup, corner weight and bump steer dialled out all bushes and joints are good, I just hate the handling and cannot think of anyway to rectify it other than chop the chassis to bits at the rear!!! I have thought about changing the back wheels to the same as the front including tyre size and maybe going for a higher profile tyre so that there is more give in the side wall, but if I do this I will have traction trouble on accelleration,any thoughts?? I assume that the car handles well on a track with no bumps, seeing that my driving is 99% road use it needs to be right!! as someone said it is not a race car!! well if it doesn't handle well on the road what is it??? garden ornement!!! rant over, I'm a bit annoyedthat I have spent 40k on a car that has faults that nobody seems to discuss.
Is it not simply due to the width of the rear tyres...?
http://204.71.140.50/tires/tiretech/techpage.jsp?t...
http://204.71.140.50/tires/tiretech/techpage.jsp?t...
The gyometry of the front suspension is wrong. Basically and fundamentally to start with a line drawn from the top wishbone ball joint through the bottom wishbone balljoint should bisect the wheel rim in its mid point, ideally. The Ultima geometry does not do this. This is exhibited by the darting around on a 'b' road. The steering has a mind of its own and lacks steering wheel control!
The chassis is 'soft', very 'soft' and needs strategic bracing to stiffen it. Any setting of the suspension will be negated by the serious twisting of the chassis. Basically the car is not safe as it is.
The chassis is 'soft', very 'soft' and needs strategic bracing to stiffen it. Any setting of the suspension will be negated by the serious twisting of the chassis. Basically the car is not safe as it is.
Maybe you want to check the bump steer on your car... mine's be fine, and I regularly visit b roads...
If you put the KPI thru the center of the tyre contact patch, whilst this is the 'technical' ideal, you'll get bu99er all steering wheel feedback if you did so... I doubt many cars have the line thru the exact center... at least the KPI is within the tyre patch on the Ult, unlike some chaved up cars that are on the road...
If you put the KPI thru the center of the tyre contact patch, whilst this is the 'technical' ideal, you'll get bu99er all steering wheel feedback if you did so... I doubt many cars have the line thru the exact center... at least the KPI is within the tyre patch on the Ult, unlike some chaved up cars that are on the road...
There are a couple of things at work here. The KPI (scrub radius) is about 4". This along with very little castor causes the car to really give a lot of feedback to the wheel. You can lengthen the a-arms, but new wheel halves would need to be purchased. A bigger steering wheel, closer to the driver helps as well.
I've done both of these, and with a very good bumpsteer calibration, it's not too bad.
Bill
I've done both of these, and with a very good bumpsteer calibration, it's not too bad.
Bill
PeterSpeed said:
The gyometry of the front suspension is wrong. Basically and fundamentally to start with a line drawn from the top wishbone ball joint through the bottom wishbone balljoint should bisect the wheel rim in its mid point, ideally. The Ultima geometry does not do this. This is exhibited by the darting around on a 'b' road. The steering has a mind of its own and lacks steering wheel control!
The chassis is 'soft', very 'soft' and needs strategic bracing to stiffen it. Any setting of the suspension will be negated by the serious twisting of the chassis. Basically the car is not safe as it is.
I agree on the not safe bit, if it were a production car it would be taken off the line!!!The chassis is 'soft', very 'soft' and needs strategic bracing to stiffen it. Any setting of the suspension will be negated by the serious twisting of the chassis. Basically the car is not safe as it is.
PeterSpeed said:
The gyometry of the front suspension is wrong. Basically and fundamentally to start with a line drawn from the top wishbone ball joint through the bottom wishbone balljoint should bisect the wheel rim in its mid point, ideally. The Ultima geometry does not do this. This is exhibited by the darting around on a 'b' road. The steering has a mind of its own and lacks steering wheel control!
The chassis is 'soft', very 'soft' and needs strategic bracing to stiffen it. Any setting of the suspension will be negated by the serious twisting of the chassis. Basically the car is not safe as it is.
Sorry this is not rightThe chassis is 'soft', very 'soft' and needs strategic bracing to stiffen it. Any setting of the suspension will be negated by the serious twisting of the chassis. Basically the car is not safe as it is.
Zero scrub radius is only ideal in a book and is rarely used as it results in poor steering 'feel'. Not saying its not important and couldn't be better, in fact changing the wheels can make a big difference.... the problem of short wishbones is shared by many cars including the legendary prosport BTW.
and lets not start on the chasis again, could be better yes! but not safe? definately not!
Hi Dilley
I don't have a problem with my handling on road or track. (No wing on my Canam)
Rather than try to solve this problem yourself with lots of ideas and comments from the forum - why not get the car into the factory for their comments? Or did they do the pre-purchase check for you? It's got to be the best and cheapest way to get this resolved.
I don't have a problem with my handling on road or track. (No wing on my Canam)
Rather than try to solve this problem yourself with lots of ideas and comments from the forum - why not get the car into the factory for their comments? Or did they do the pre-purchase check for you? It's got to be the best and cheapest way to get this resolved.
Dilley
I had 17in wheels rear and 16in front and higher profile tyres on my canam and they were miles better controlled than the Genuine Ultima 18in wheels I fitted for the next owner.... ruined the car IMO and they added around 30kgs of weight.
They do tram line a bit though as they have huge tyres low weight and no power steering...... you wait till the thing aquaplanes.
I had 17in wheels rear and 16in front and higher profile tyres on my canam and they were miles better controlled than the Genuine Ultima 18in wheels I fitted for the next owner.... ruined the car IMO and they added around 30kgs of weight.
They do tram line a bit though as they have huge tyres low weight and no power steering...... you wait till the thing aquaplanes.
Dave Gallop at Track Developments has run a computer analysis of both the front and rear suspension on my car. Initially he suggested that I move the front suspension mounts and fabricate new wishbones. But I think we now have a compromise (its best to talk with him directly).
www.trackdevelopments.co.uk
www.trackdevelopments.co.uk
interesting this issue.... just got back from Lemans, driving on EMPTY roads, at "SAFE" speeds, and the car was solid at all times. Got back to england and drove home - My car had changed to another car..!!! it bounced all over the road, it tramlined, it was a real pain.. Strange.....! Nothing to do with the fact the french road are fantistic and the UK roads are really CRAP. ???? Honest - the change in the car was massive.
Still, got a tank of cheap 98 fuel in france - it was about 85p a litre there.
Still, got a tank of cheap 98 fuel in france - it was about 85p a litre there.
andygtt said:
Dilley
I had 17in wheels rear and 16in front and higher profile tyres on my canam and they were miles better controlled than the Genuine Ultima 18in wheels I fitted for the next owner.... ruined the car IMO and they added around 30kgs of weight.
They do tram line a bit though as they have huge tyres low weight and no power steering...... you wait till the thing aquaplanes.
what size tyres were you running, did you have any traction problems??I had 17in wheels rear and 16in front and higher profile tyres on my canam and they were miles better controlled than the Genuine Ultima 18in wheels I fitted for the next owner.... ruined the car IMO and they added around 30kgs of weight.
They do tram line a bit though as they have huge tyres low weight and no power steering...... you wait till the thing aquaplanes.
I suppose the question is can I can the car to handle where I am happy with it rather than putting up with it, Ultima have said that the gtr should handle 100% better than a 7 style car, at the moment my 7 would run rings around the ultima, The 7 has no rose jointed suspension and is adjusted with shims, built on a 1965 design and still works well!! with no tramlining!!
Hi Dilley , i always thought the tramlining was caused by the wide tyres as i have had a couple of cars that do it , have you tried altering the damping a bit i find the can-am is also better with a bit more front ride hieght i had to lift it a bit to get out of the drive at home and with the protech shocks its not too bad but to be honest on a bumpy back road my old westfield v8 would give me a kicking !!! but as soon as the road opens up i would be gone !!! i always look at it as being the character of the car and i also find it much easyer if i relax at the wheel and try not to fight it,perhaps it just a case of getting used to it they are so different to most cars .
I've never had any problems with tramlining on my Sports. It has 17" rears and 15" fronts, with 315x35 on the rear and 215x50 on the front. Not sure if the suspension geometry between a Sports and a GTR is similar enough for this to be a valid comparison?
Mind you I would much prefer larger front wheels as the 15" ones don't fill the front arches which looks rubbbish.
Mind you I would much prefer larger front wheels as the 15" ones don't fill the front arches which looks rubbbish.
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