I am busy with the front end,going for adjustable strut tops that will give me camber and castor with coilovers and custom shocks.
I was thinking as i am busy with the front i might aswel find out what i can do at the back.
I am running 2 yokohama semis in front and firestone semis at the back

are whiteline still selling rollbars for the 1200/120y? i tried getting some to the uk and was told they don't do them anymore?

Does it have a rear sway bar currently? If not you could try adding one, or stiffening (closer pickup point on the swaybar if multiple holes, or alternately a thicker bar) the rear. I'd tend to do this over and above stiffening the leaves.

Something not mentioned yet (I totally agree - get as much neg camber as you can in there) which might help turn-in enough to make a noticeable difference is deliberately running front toe-OUT This will stuff the tyres quick smart on a streeter, but on short tight courses, turn in will be improved bigtime, and potentially (though I've never measured it on a datto 1200, it occurs in a lot of cars I've played with) improves ackerman issues (i.e. at tight turns, the inside wheel turns in a tighter radius than the outside wheel, so as the steering turns, it ideally needs to turn the inside wheel further/more degrees of rotation than the outside wheel. On streeters this usually happens ok for moderate speed turns, but for motorkhana/autocross style stuff it's often in need of improvement..

On the toe-out thing, I'd try as much as 1/8" (approx 3mm) then try 2mm and so on, but it should produce a difference (whether it's a helpful difference? can't say for sure, but it should be)

no rear sway bar,what sway bar do i use and how do i fit it?
(I use the diff out of an old alfa ,its LS unit)

is it a one piece diff or indipendent suspention type???


mustang for example still use a diff that is one piece even in the new gt500 and the following image show the sway bar instalation of the 2005 gt500




taken from the following website

i tend to disagress, if the front is already stiffened, the rear would need a slight tweaking and stiffening to match.
I found with max neg camber from my s13 camber tops and castor rod mods, the front felt responsive and flat through corners, even off camber turns.

The stockish rear however was rubbish, felt like it wanted to trip over the front, not over steering at all and had a heap of under steer in a corner.

By adding one leaf(a shorter one, and the flipping of one to lower slightly from stock, the car now feels balanced, responsive and corner speed is more consistant in the dry... no wet in melbourne for a long time now.

I would recomened a rear sway over this mod, or even properly reset rear leaves, but for an trial attempt of if it would be an improvement, it sure has improved the handeling of the car, with slight oversteer if provked, but its a progressive shift, not violent snap oversteer.

I made some assumiptions from the word gymkhana about the likely corner entry speeds and general conditions, so I may be off on it, but the toe-out option is about 1-2 minutes adjustment and an instant test/result. It is one of the few things that has an effect right from teh getgo as far as starting the corner, well before there is any weight transfer or roll (or lack or roll!) starting to happen.

The idea of the rear bar is to allow either a softer front bar, or the same front bar, but with some of the resistance to roll (and roll and weight transfer aren't necessarily the same thing) by the rear tyres, so the fronts can keep better contact with the road, and concentrate on lateral grip, not resisting roll. I realise that it's not a static situation and many variables play a part (meaning that depending on corner speeds, the same 'tweak' can have oppositve effects.

I also made the assumption that even though caster is generally 'the more the better' it might not get enough steering angle to make as much difference as is needed,, I think the static camber has to be tweeked a lot

Running a stiffer rear doesn't absolutely have to reduce rear grip. The car is understeering so in a sense, the rear isn't getting it's fair share of the workload, and the addition of a rear bar (doesn't have to be massive) might help. I guess it's a case of getting it to do more, without going to the point that rear grip itself is actually compromised.

Like anything else I post, none of it is written in stone, it's just suggestions, that seem to makle sense to me. I hope I haven't come across any different!

I have chopped the top leaf and put in the front section upside down afetr cold bending it up the other way. This seemed to get good results. We also ran on dirt with NO front swaybar and this was excellent for rear grip as the body rolled more and got the rear wheels on the ground more. I know this seems crazy but as soon as you lift a wheel you get less traction and tend to understeer. For motorkhana you don't want a very stiff car setup like a track or rally car, you want traction and wheels on the ground. The soft setup makes the car horrible to drive on the road though!!!
Handbrake turns always work well!!