Different front and rear track

[Talonmotorsport]

My chassis is 1218mm wide at Br11+12 and standard width at the front. I'm using standard width RS3+6 and standard wishbones. Now I know I'm going to need either bolt-on spacers or some deep dished alloys on the rear so the tyres clear the chassis, but how much difference will it make if the front and rear track are different by 100mm? Should I be making 2 or 4 bolt on spacers?

[fabbyglass]

Spacers are not a good idea as will knock hell out of your wheel bearings..Also if the front of the car is book width and the cockpit is wider the car will look odd in my opinion...any nosecone you buy will look odd as the angles are all wrong.

Why don't you just make the whole chassis wider and adjust you suspension to suit, at least that way you create a "new car" and one that won't look so weird.

All my own opinion but based on playing with these type of cars over the last few years....skinny 7's look better than fat ones:D

[Talonmotorsport]

I thought about the spacer Vs wheel bearing problem and came to this conclusion, the donner sierra weighs 1100kg (ish) was made to carry 5 people, with 120kg of luggage towing a caravan weighing 1000kg. The roadster will prob weight not much more than 750kg (steel panels and lardy me) and will prob not do more than 3000 miles a year. So if the wheel bearings last 2-3 years so be it.
As for the shape of it looking odd you should see some of the heaps I've taxed over the years. I don't realy care what it looks like to be honest as long as it's road legal ,drives in a straight line and passes an MOT.

So front to rear track being different any body know the answer, will I need more camber and caster?

[AshG]

if you alter the rear track too much without doing the front you will have high speed stability issues, have seen it on a 7 that was jiggled around with. simplest way i can put it is think robin reliant.

[Talonmotorsport]

So what happens when you put 185 tyres on the front and 205's on the rear?

[AshG]

that should not be as detrimental as you are not changing the pivots/geometry of the suspension just the diameter of the wheel.

[flyerncle]

MR2 are different front to rear with no drama.

[fabbyglass]

I would imagine the car would be a bit twitchy in the corners with a wider rear track. Plus i still think it will look odd.:o

[mikemph]

Someone has got to be first to try these things. In general most configrations can be made to work with minot tweaking.

My VX220 turbo is wider at the back than the front by 20mm

My Mini is about 1" wider at the front than the back and that is also fine but did take a few goes getting geo setup nice. Although I will be fitting spacers to the rear. The front are wider as I have metro 4pot calipers on the front. No option but to fit spacers to the rear to get the look right.
http://i7.photobucket.com/albums/y296/madmike81/cc4d58b0.jpg

[mr henderson]

The Tiger Avon is substantially wider at the back that the front, and doesn't have any known issues. I can't rememeber the actual difference, but it is a lot, well over 100mm IIRC

Thing is, what really counts is the distance between the insides of the rear wheels. A lot of 7s I've seen have a fair bit of clearance between the inside of the wheel and the outside of the chassis, so you may not need much spacing (or offset if you change the wheels)

[fabbyglass]

The Tiger Avon aint much to shout about though ...:rolleyes:

[mr henderson]

The Tiger Avon aint much to shout about though ...:rolleyes:

Who's shouting, it was only an example of a perfectly acceptable kit car with different track widths. :rolleyes:

[MikeB]

the change in track width will just change the load transfer between the front and rear axle. If I remember right a wider track would give more load transfer on that axle.
So in theory you'll just need to adjust front rear spring rates to get the balance right again.
(lowering rear spring rate or increasing the front spring rate would bring the balance back for a wider rear track, think i have that the right way round)

[Tony]

from my experience wider front track gave better handling in the wet

[fabbyglass]

I think you would be best making the car wider at the front to compensate the extra rear track...longer wishbones perhaps?

[deezee]

Is all this track malarkey going to affect the positioning of your headlights and indicators? I know the headlights on a standard chassis are getting quite close to the front wings on full lock. This is because the light distances are taken from the widest point of the chassis (The rear wings). So your headlights are going to have to be 2 inches closer to the front tyres / wings.

Just something to think about.

[alga]

I think you would be best making the car wider at the front to compensate the extra rear track...longer wishbones perhaps?

If the front track is widened, the wheelbase must be increased proportionally in order to maintain the Ackermann steering geometry.
http://en.wikipedia.org/wiki/Ackermann_steering_geometry

I think the Roadster already has the standard Sierra front track with a shorter wheelbase, making the front wider will throw it further out of tune.

Albertas

[fabbyglass]

..........:d :d :d

[flyerncle]

Forgotten the words Mark ?:p

[fabbyglass]

Forgotten the words Mark ?:p


something like that yeah.......:rolleyes:

[mr henderson]

Personally, if it was me, I would choose rear wheels that gave as little clearance agaisnt the chassis as possible, and I would leave the front end as it is in the book, knowing I could always make some adjustments later if any problems showed up (which I bet they won't).

[RAYLEE29]

Wider track at the rear causes understeer wider track at the front causes oversteer.
Ray:)

[fabbyglass]

Most sensible thing to do is ditch building a kit car and buy a vw camper, transport and a roof over yer head at the same time..because next year the powers that be will ban houses along with thinking for yourself;)

[tex]

the dax rush i had had huge 255x40x15 tyres on the back and the track was if i remember right about 50mm or more wider EACH SIDE than the front. there was no handling problems with it at all - the only thing that you really have to watch for is remembering you have a wider rear end than the front! reason - your blasting along a country road - in this instant kirkstone pass in the lakes - narrow road - car comes other way - you gotta squeeze over to the left a bit - the front wheels miss the big rocks on the left but does the rear? naaaaa of course not - it can stop the car dead from moving..

so iv heard.. baaaaaah... :rolleyes:

[7ishNZ]

Why not make the car with equal front and rear track... perfect time to do it while you are building it..?

[Talonmotorsport]

to late for that the wheels are nearly on. I am using 7j rims which will need 2" spacers as they currently lock solid to sb1 and d11 when bolted on.

[aerosam]

Ford Capri wheels on the front will increase your track width considerably as they have a negative offset.

Easier than making different suspension, and fit straight on the sierra hubs.

I even have a pair you can have for nowt if you want them.

[dogwood]

Someone has got to be first to try these things.


Hmmmm....
I got a Tee shirt as well;)
http://i129.photobucket.com/albums/p212/muddypaws4x4/006.jpg