Hey guys just a few questions? I have now modified the front suspension with coilovers as i said in a previous post but the new front suspension has brought to light some problems in the rear suspension. First of all I know a leaf sprung rear vechicle will never ride like a 4 link, 5 link or indepent suspension and i accept that as a fact of life. The rear of my car has 2 inch lowered reset springs reset profesionally apparantly by pedders using a big press with bilstein shock absorbers with the bumpstops chopped down. My problem is on hard driving it feels really loose in the rear end and bounces acroos the road for example i was taking a long sweeper at about 140kph with a small bump in it and my mate following in his bmw said the rear moved half a lane across this makes it scary when pushing hard around corners. It also has real poor ride quality in the rear at any speed. I think the rear leaves lost their springiness after being reset and this is causing the problem. I have read alot on this site about the anti tramp rear springs if i could have some feedback on them i would aprreciate it also any other ideas for the rear end such as 4 link designs or panhard rods or anything to make the rear better would be appreciated

Thanks guys

I can vouch for the JTS anti-tramp springs in a race car - they communicate very well with great feedback in more extreme conditions than normal road use. I would perservere with your springs in the meantime and investigate those Bilsteins - it sounds as though they may be incorrectly damped for your car. Also you should acknowledge that running 140kph through a public road corner is probably on the limit of a 1200's handling and a driver's good sense.

yes those springs are fantastic, and with the adjustables shocks, you can dial out most of those harsh bumps mid corner.
What the Datsun needs really is negative camber in the rear (about 1-2 degrees) and that is the achillies heal in rear live axles that it will twitch on fast sweepers if they hit a bump dus to lack of contact area of the loaded tyre to the road surface.
My new coupe has such a rear axle assy with 2.2 degrees negative camber built into the axle housing, JTS springs and Spax on-car adjustable shocks made in UK....
havent driven it yet but high speed sweepers will not be a problem.

Here is the picof the rear suspension showing the JTS leafs and Konis, note the reaf part of the leaf has been made less stiff to combat tramp (very effectively) and still is supple through sweepers.




Here is the rear working mid corner in a high speed sweeper at approx 140kph...




looking closely the rear contact patch is not perpendicular with the car as the front is which runs 4 degrees camber....
This would affect the cars handling substantially..especially if I was to hit a bump mid corner.

Also worth checking all the rear bushes for wear. If your leaf springs are actually OK the movement you experience when cornering can be caused by worn rear shackle bushes.

believe it or not, a small rear sway bar settles the rear of a 1200 down very nicely!

Make sure they havent over straightened your springs, they need some curve in them to work properly..

Also, if you've lowered the front of the car, chances are you've also lowered the front roll centre. Without some sort of lateral locating beastie at the rear, you wont have lowered the rear roll centre by a corresponding amout, which changes your roll axis, which will change the way it transfers weight in corners...blah blah...

Anyhoo, try a panhard, mounted as low as you can get it (somewhere below the centreline of the diff)and a tiny rear swaybar and see how it behaves. Any other nasties you should be able to dial out with the shocks...