Different front and rear track
 

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?

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

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?

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.

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

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

MR2 are different front to rear with no drama.

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

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.

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)