Nir

Hello guys,
There's a question that is running in a local forum that lacks experts:
What is, really, the mechanical difference in cars' "hot" versions versus the "settled" version from the chassis point of view?
think like, Seat Ibiza GTI, 206 GTI, Polo GTI, Punto GTI, Golf GTI, Rover 620Ti, Clio Sport, BMW M3 and so on.
Ok, they all got wider tyres, we know that, some of them have 4x4, we know that too, but do they have a difference in, say, wheel fork? suspensions? shape of the chassis?
The argument comes from the question whether is it any good to install lower-profile, wider tyres; the opponents claim that it's best to keep the car as the manufacturer set it, and keep the right balance between all chassis component; the other school reckon that since GTIs are not seriously any different than the cars' normal version, it only proves that various tyre sizes can be utilized freely.
What do you think? any options and data is more than welcomed - as these chassis differences were very hard to track on internet searches!!
Nir.



[This message has been edited by Nir (edited 29 September 2000).]

I Stancer

usualy there are differences in spring rates and damper rates ( and also quality sometimes ) also anti roll bars can be different as well as all sorts of bushes and geometry settings , some good basic designs can take good advantage of better tyres others could be made worse , depends on the car

TonyC-Evo Lurker

Yes, shoving big tyres ona basic car will not make it handle like the GTi version.
The basic car will have a higher ride height. It will have softer springs and dampers. And it will have a softer anti-roll bar, or no anti-roll bar. If that suspension then has to work with a tyre generating twice the grip as the one it was designed for it will overload those settings. The car will roll more, wallow more, and generally feel horrible.
All the suspension has to work together. Tyres are just a factor in a bigger equation.

TonyC

Diablo

Hi,

No easy answer and it all depends on the car.

The Golf GTi for instance has the same (exactly) suspension as lesser models, but has bigger wheels and tyres. Only the GTi Turbo has a different (lower and stiffer) set up.

Think the same applies for the polo, but not sure as for the rest.

Within certain limits, changing to lower profile/wider tyres with the appropriate change in wheel size to maintain the same rolling radius will usually generate more outright grip, but may not improve overall handling (which may be subjective anyway)

D

BarryK

I presume Peugeot continue to change the assorted settings and parts in their GTi models.

We had a 205 Junior and a 205 1.9 GTi on an E plate some years ago and there was simply no comparison between the setup of the "standard" car and the GTi.

Steve Perriam

i had a rover 216 gti prior to getting my new scoob.

my ex wife had a rover 214 sli and the difference in ride and handling was amazing.

the 214 wallowed around on any corner whilst the gti would go around them so muuch better, more quickly and feel safe and composed.(no comparison to the scoob of course)

steve

AWD

This totally depends on the car. With some the GTI version has better brakes, tweaked suspension, more power etc. However, for other cars the GTI can mean as little as special edition colour scheme, top spec brakes, different alloys, etc. (but no different from getting the top options on a normal car). It has become the naming standard for the sportier version of a car so it really does depend on the manufacturer.

By the way, what is a BMW 328 GTI I have never heard of this. As far as I know the only option for the 328 is coupe, saloon or estate (touring).

Carolyn T-S

Had a 206 GTI prior to the scoob - and it was pants. It just did not want to go round corners at speed (very scary). Hubby had a 306 GTI prior to his 206 GTI prior to his scoob and there was no contest between the pugs. The 306 was great fun (even stayed on the road going round corners)

We both put up with the 206 GTIs for 2 months and finally they had to go. Lost shed loads of money trading them in (fortunately got £2.5k each off list to start with) but we are having a ball with the scoobs

I've no idea about the technical reasons for the differences - I just drive them

[This message has been edited by Carolyn T-S (edited 28 September 2000).]

Bright Kar

As well as the Scoob Ive got an Escort SI. When I bought it I was considering the Escort GTi. Apparently the only difference between the SI and the GTi is the bodykit and a trimings. In fact all the Escorts were actually the same expect differences in wheel size and trim. Appart from the GTi which was a tad more, a whole bunch of the Escorts we the same cost too - you could buy a 1.6 for the price of the 1.8 ...dough...

bkar

Nir

Ok, thanks to anyone who answered
If I get it right now, there is a point in TRYING.
That's is, if the manufacturer decided on a specific size for the tyres, it doesn't necessarily mean that this is the best possible size, and trying to uprate them to get sportier chassis might be beneficial.
Right?

[This message has been edited by Nir (edited 30 September 2000).]

I Stancer

Deffinately maybee

dsmith

A couple more examples.

Many years ago my Dad's Cavalier SRi (At the time top of the range) had significantly different susupension to the base models. The front wishbones had additional links and the anti-roll bars were visibly thicker.

My Civic VTi (3Dr) had a rear brace between the rear suspension turrets which intruded into the boot area - which is why VTi's have a nasty plastic boot box (moulded around the brace) and lesser Civics have a proper hatch type cover over the boot area.

GTis also have the obligatory spoiler for downforce at high speeds of course

simes

My Almera GTI too had a rear strut brace.

Never mentioned in the tests or by the dealer, so imagine my surprise the first time I converted it to a hatch and tried to put a large bulky object into it...

Still, I grew to love it cos it was one fine handling car, in some aspects better than the scoob, but of course minus the power and grip.

Cheers

Simon

JasonM

Most performance versions of cars can have any of the following over the standard version. But then it really depends on the car.

Higher compression engine
Close Ratio Box
Steering Damper
Lower & higher poundage springs
Stiffer dampers or even Gas dampers over oil dampers
Bigger Brakes or ABS
Fast Steering Rack

Also wider tyres don’t always work, as it means that there’s less downforce per square inch of tyre, which can result in less grip. However lower profile tyres reduce tyre flex.