2 hours ago, Captain Obvious said:

None of this explains why my steering is so much heavier than my buddy's 260.

Too many variables and sample size too small to draw any conclusions, it seems.  As I noted above my steering was very light and loose in my garage on a dry smooth cold level concrete slab.  But my memory says that it's been much more difficult out on the rough driveway or the pavement of a road.

Add the height of the car, lowered or stock, to the variable list.  And rake, nose down is typically harder steering than nose up.

There is tension, especially on center provided by ball joints and tie rod ends.  Different brands may provide more or less on center feel and steering weight.

I know what you need!  

4 hours ago, Zed Head said:

Too many variables and sample size too small to draw any conclusions, it seems.  As I noted above my steering was very light and loose in my garage on a dry smooth cold level concrete slab.  But my memory says that it's been much more difficult out on the rough driveway or the pavement of a road.

Add the height of the car, lowered or stock, to the variable list.  And rake, nose down is typically harder steering than nose up.

  When I changed my springs (Mulholland) and shocks (Bilstein) on my early 71, it dropped the car a bit as anticipated but one of the first things I noticed was the heavier steering at low-speed (parking lots). I did run a bit more negative camber than stock. I drove Jai's 76 at ZCON and it was definitely easier than my modified 71.

Well my sample size is definitely too small to be reliable. I'm comparing two 77's to one 74 and one 73.

I've got one of those cheap digital angle gauges... Should be good enough to check for castor differences between my car and my buddy's 260. Maybe I'll do that next time the two cars are together.

Thanks for the input guys.

Not quite on topic, but my car was very hard to steer at low speed. The tires were low. Put some air today and now it's steering easy again.

My 76 280Z with 225/50 x16 Continental Extreme Contacts DW's has VERY heavy steering.  This was on Eibach springs. Front camber was about Zero if memory serves me correct.

Installed coil overs and Camber plates. Have a small amount of negative Camber now. Maybe -1.0 to -1.5 degrees by eyeball. Haven't had a chance to take it in for an alignment yet. But holy cow... did that little bit of Negative camber lighten up the steering. 

I've found in the past that different brands of tires, even in the same size, have a very different steering feel and effort. It part of the construction of the tires ( Self Aligning Torque ). Had some Michelin X's on my 1971 240z . 195/60 x 14. ( We're talking mid 70's here ). Car steered like a dump truck. Oh lord was the steering heavy. Then I switched to some Vredestein 195/60 x 14's and it felt like 300 lbs had come off the front. Crisp and light steering. Just with a tire brand change. 

https://en.wikipedia.org/wiki/Self_aligning_torque

 

 

 

 

Edited December 31, 20186 yr by Chickenman

To bring this one back, wheel offset plays a large role in low-speed steering loads, potentially more so than tire width or compound, since it controls scrub radius. A lower offset wheel, i.e. wheel center pushed outboard, will increase the lever arm between the contact patch and the steering axis. This will exacerbate the lifting effects of caster and kingpin offset. Additional weight over the axle will also contribute to an increase in steering loads. So this begs the question of whether the
as-tested" 280Z wheels were lower offset than 240Z wheels.

If the kingpin inclinations differ by even a degree between 240Z and 280Z, which the FSM's imply may be the case, then that could lead to significant increases in scrub in the 280Z's case.