the 120& bar is 20mm solid.

swaybars should really be used as a fine tuning device after getting the majority of the balance with springs shocks and geometry. I used a really big rear bar because of the locked diff, but there are better ways of achieving the same end result with roll centres or roll axis tuning.

i did some research harry and found that whiteline make a sway bar for the front and rear being part numbers
and are for both 120Y and 1200 coupes

front= BDF29
rear= BDR33

Hi Nick, and welcome to the club.

It's easy to think of a sway bar as trying to hold the body of the vehicle flat relative to the road, but the sway bar is mounted to the axle and the chassis. So in effect, the mass off the vehicle's body is so much greater than the mass of the suspension that the sway bar is attached to, the real effect it that the sway bar is holding the axle (in this case) level with the chassis.

It is pulling up on the inside rear wheel with as much force as it is pushing down on the outside rear wheel. It will unweight the inside rear.

This is where it gets interesting...
While a swaybar is only effective cross axle - that's where the links to the body or suspension are, and therfore where the forces are generated, there is an effect felt at the diagonal opposite corner. In order to keep more weight on the inside rear, the front roll couple must be increased. So fitting a front sway bar will keep more weight on the inside rear wheel when cornering, as it will reduce the amount of yaw and pitch to the outside front. The rear sway bar will try and hold the inside rear down, but as I said before, that is only ever going to result in lifting that wheel rather than holding the body in place. Not sure if that's going to make any sense when its read back...

Anyway, fitting a rear bar will keep more weight on the inside front wheel by pushing down on the outside rear. That's the diagonally opposite effect you've heard of, but I don't think I'm explaining it very well...

What we have found is that our race cars actually went quicker when we removed the rear sway bars. (this was at Eastern Creek)

We found that we were having rear end traction issues exiting corners, so we removed the rear bar to effectively "soften" it up. By doing this we were significantly quicker, but it did induce some understeer on the really slow corners - nothing we couldn't live with though.

As L18 said though...it's unlikely that you'll ever notice the difference on the street.

I run a locked diff, so the unweighting of the inside rear wheel is not a problem for traction exiting corners, and helps eliminate the the normal turn-in understeer lockers are infamous for. My car does not demonstrate that understeer tendancy at all.

I might post a pick showing the amount of positive camber the swaybar creates on the outside rear to illustrate the problem. If I can get rid of this 17mm rear bar, and increase the rear roll couple with a different set of springs to get the balance back, and maybe some adjustment of the roll centre axis, with a much lighter sway bar for final tuning/adjustment, I think I could pick up even more mid corner speed. But it would compromise start-line traction.

I've had the sway bar so long, I can't remember if it was listed for a 1200 or a 120Y... but it was definitely listed for one of them and fits without modification to the bar. You have to weld on 2 little 'L' brackets to the chassis to mount the link pins to.

I would like to get rid of the sway bar and stiffen up the leaves a bit to balance it out, because on the racetrack the sway bar tried to hold the axle parellel to the body instead of leaving it level to the road. This effectively gives you positive camber on the outside rear tyre when cornering - not exactly ideal. I have some pics that show this pretty graphically.

That's not such an issue on the street where you won't ever get close to those kind of lateral forces. The big issue for road cars with rear swaybars (of this size!) is they unweight the inside rear tyre when cornering, leaving you with no traction/drive out of the corner - just lots of wheelspin.