89mm, Yep that sounds pretty good to me, and so you use the panhard to control the degree of roll steer by changing roll centre heights.

I change the amount of roll steer by varying the torsional stiffness on the rear stabiliser (You say tomateoes I say tomartoes) : )
It still works the same

On the sunny you can improve the 4 link rear suspension dramatically by lowering the rear of the top arm by 22mm and lowering the front of the lower arm 22mm. This changes the rear arm angles into a tighter V, tightening the rear end up. The major benefit is a reduction in roll centre with a slight increase in roll steer.

With a panhard as well, its a good rear end to set up. Very predictable handling and excellent adhesion levels that allow good approach, mid corner and exit speeds. This is where small cars flog big bangers.



An easy way to tell if you have it right, is when cornering hard you can change the steering input to tighten up in a corner and the car will four wheel slide but very controllably and easily turn in tighter with a little throttle steer or go wide with the boot of carefully.
In the corner it will pick up the front first (feel it go a bit light) , then the rear wheel (gets lighter again and a bit twitchy). To keep drive at this point you need a locker, LSD or spool or you start the dreaded single spinner howl and chew your diff up. Its a bit like cornering a well set up Kart.

Hey Feral!! How does this sound??

If you have (say) three different heights for the body end mounting point for your Panhard rod, you should have three corresponding roll centre heights.

Surely, by fiddling with the rear roll centre height, you should be able to increase (or decrease) the effect of the rear suspension to suit.

Waddoya reckon?

Cheers tsillay for the info!

With a stock 1200 setup, the only thing stopping the diff from moving side to side is the resistance of the leaf springs themselves. Once you bolt on your favorite brand of sticky donuts, the leafs themselves just aint up to the job, and the diff will cheerfully try and escape out thru the side of the car.
A panhard rod or watts linkage, or jacobs ladder are all devices which stop this movement. They all have their pros and cons, but for the limited suspension travel in tarmac work a panhard works just great...

Roll steer...
Imagine that as the car leans, the diff assumes some angle other than 90 degrees to the centreline of the car. This will cause the car to turn, without any steering input from the driver.. A Chassis is damn sensitive to rear steering input (you've all driven in reverse and flicked the steering wheel)...

I'm a big scaredy cat Feral, I run a little roll understeer when hillclimbing, but neutral steer on the circuit! Now the damn thing is sitting so much lower, I've run outa adjustment...

hey 1200rallycar the first thing i did was get rid of the original shocks and buy a full set of nolithanes. The panard rod stops the dif from moving sideways in corners the angled shocks in the coupe help alittle but as I said I was getting about 10-15mm sideways movement (both directions so 20-30mm all up) while racing this makes the rear of the car twichy and creates alot of 'false' movement.

can someone explain the need for the panhard rod and also exactly what roll over/understeer is and what causes it?

Interesting you mention the roll understeer in the 1200.

The B310 sunny with 4 link rear end (plus panhard) has the opposite with roll oversteer. This helps in setting up handling e(especially with a spool) as you can tune the response of the rear with an adjustable rear bar.

Quinn, In my experience, to get any effectiveness out of the tramp rods, they need to be above the diff, you just cant get them low enough underneath to get any real mechanical advantage...
It's a bit more hassle building boxes in your back seat to mount the top arms off, but worth it in the long run..

You still want the rods rougly as long as the front 1/2 of the springs, and the same comments about anti geometry still apply.

A panhard or watts linkage is a must, spread the mounting points out over a wide footprint!

The 1200 has masses of rear roll understeer as delivered from the factory, great for grandma and the groceries, but troublesome for us.

yeah but have you done the nolethane and good shocker thing, i mean i had that problem untill i replaced everything with stuff that wasnt 30 years old, so have you done that?

dont you want the traction (anti-tramp) bars to be the same lengh as the front half of the leaf so the have the same arch movement and therefore wont push/pull eachother? For example Im going to extend the front leaf eye bracket down and mount the bar from there to under the shock bracket (on the coupe). Havent decided where to run the pannard but it will obviously be mounted on the chasis rail (heard to many stories of them ripping out of floor-pans). What I find odd is there is a few 1200s in the ss2000 series running 200hp 4ages etc with lowering blocks and nothing else. SCARY! my outerwalls of my rear tires scrub on the guards (=10-15mm movement each way) going over the Johndeer hill and im carring half the speed they are.