XRAY - Model racing cars

I am currently running Mike Dumas' set up and it is awsome - but I have a question - I need to up the ride height to 5mm to comply with our clubs 5mm minimum ride height rule. If I do this and do not want to change the behaviour of the car I am I right in thinking the first thing I need to do is maintain the same ammount of droop - i.e. reduce the downstop at the rear to a 3mm reading?

What other changes to the cars handling can I expect?

Hi projectmnt

New to the Xray chassis and this forum myself, but notice no-on has responded to your post so I'll give it a go!

I guess this is a carpet set-up if you are raising to 5mm ride height (us tamarc boys don't get down below 5mm generally). As you suggest, if you don't alter the downstops but raise the ride height then you are taking droop out of the car. If you want to retain the front/rear weight transfer properties of a set up then a good starting point might be to increase the droop setting (i.e. allow the arms to sit lower) relative to the increase in ride height. I.e. if you raise by a mm then increase the droop by a mm. This doesn't actually work out identically in theory as you are putting the suspension arms at a different angle by raising the ride height and therefore moving the roll centre down relative to the CoG, and therefore providing more traction and body roll, but it's a good starting point for some further tweaking. If you're only moving by, say 0.5 mm then it won't make a massive difference. Probably better to err on that side and dial the traction out rather than have the inside wheels off the floor!

Projectnmt :

Thinking about your set up question again, in practical terms, I think it really depends upon by how much you are raising the ride height over the set up you would like to use, but at 5mm.

Let's say you are raising from 4mm to 5mm, I would try the following if it was me (and I'm open to contradiction from more experienced racers here) :-

1) raise the ride height by 1mm - what you need to do
2) increase the amount of wishbone drop (i.e. arms hang lower when car off the floor) by 1mm - maintains the droop setting
3) shim the camber link under the ball stud at the hub end by, say, 0.5mm - keeps the distance from the centre of gravity to the roll centre similar
4) see if it drives the same and if not try something else!

Best of luck

Rob