Castor or caster.
More caster will improve on-center "feel" and make the car track better. In other words, it will go straight ahead with hands off wheel -- without wandering. This will make the steering effort heavier, but the 1200 is arguably too light in this area to start with, so no worries.
More caster will also give the car a negative camber change while cornering, which is desirable.
Increase caster up to 3 degrees for a street 1200. Use at least 2 degrees for good tracking. Stock specification is as low as 0 degrees 20 minutes, which makes the 1200 wander on the road.
Increase caster up to 4 degrees for racing. The tension rods may be modified to provide an increase in caster. See Datsun 1200 Competition Suspension Manual
See discussion Negative Camber (Page 2, for caster)
- To increase caster, shave the Tension Rod bushings and pull the wheels forward
- To decrease caster, insert spacers (washers) on the tension rod
Another way to use adjustable radius rods.
See main article: Custom Caster Rods
Tension Rod and Bushing Modification
High speed stability can be enhanced by increasing the caster. On a Datsun 1200, this is accomplished by remachining the tension rods .600 of an inch as shown in Fig. 17. This shortens the rod and pulls the bottom of the strut foreward to obtain approximately 4° of additional caster.
Discussion: Moar Castor
Datsun 1200 came with very antiquated Wheel alignment settings. They didn't drive very straight even when new.
A little more caster will fix that!
Cut the Tension Rod rubber bushings in half, and shorten the metal spacer and put it back together. It will pull the wheels forward just enough to track well, with no wandering. Even with hands off the wheel it will drive straight.
1. Park on a level surface and measure the toe-in. Mine was right on spec, 3mm closer at front of tire compared to rear of tire (or 4mm measured from tread centerline, but as you can see I measured closer to the hub)
I used the long stick to go clear across the car and measured front tape to rear tape.
4. Insert back through the Tension Rod Bracket and tighten bolts to specification. Remember this is suspension parts, you life depends on them, so do not weaken the fasteners by overtightening. 5.5 to 6.5 kg-m (40 to 47 ft-lb)
5. Re-measure the Toe-in, and if out of spec (4-6mm) then evenly rotate the side-rod ends until Toe-in is correct.
- Before: two hands gripping the steering wheel, making frequent steering adjustments on straight roads
- After: two hands lightly holding the steering wheel, making occasional steering adjustment