Hello all, I am looking at building a caterham size locost. And I was curious to know what the pivot to pivot length is on the steering rack. I have an escort 2.4 quick rack but just looking at it compared to the lotus 7 S2 chassis dimensions (which I am lead to believe is a very similar size to the caterham) it just doesnt seem to fit.

Any help, suggestions would be great

Also, I am curious to know the roll center heights, I know it may be hard, but general pointers would be nice.

Thanks

OK.. You WILL NOT be able to aquire ALL the necessary dimensions to build a Caterham blindly.
Get the basics down and learn to adapt as you go.
Otherwise best stop right now.
Don't ask :0)

I am not trying to 'copy' a caterham. That is near impossible for what I want to do. I have drawings for the S2 and I am using that as the basis for build and work from there.

But considering the caterham is in the same ball park for size, I am curious about a few dimensions of the vehicle (cause the info I have for the series 2 is incomplete), hense the questions

You might be better off starting from a locost, there is a lot of info on here about the chassis, mod's ect, very similar size the the cater-van...

Ideal width of the rack between ball ends depends on the front suspension design, if using Triumph front end parts I would use an MG Midget or Triumph rack.
If using Cortina parts I would sugest a narrowed Sierra rack.

Bump steer is much more sensitive to vertical placement of the rack than to how close you can get the rack pivots to the line between the upper and lower wishbone pivots. I was able to achieve negligable bump steer with careful vertical placement even with a MK2 escort rack that has its pivots at least an inch or so (if I recall) outside of the line between the wishbone pivots of my similar-to-locost suspension geometry.

When selecting rack width an built in Ackerman in the steering arms has to be considered, with the rack & steering arms mounted ahead of the axle centre line this would mean the rack inner ball joints would be expected to be located outside the line joining the upper and lower wishbone pivots.