Steering Effort Differences Between Years

[Captain Obvious]

So my local Z buddy @GGRIII got his 74 260Z on the road and we drove that to Zcon. During the short shake down testing, one of the things we noticed was that the steering effort was significantly lighter in his 260 compared to my 77 280. And then (thanks to other forum members @Zup and @wal280z ), I got the pleasure to drive a 240 and another 77 280 at Zcon for a larger sample size.

The steering effort was consistent, meaning that the 77 280 took way more steering effort than the earlier years. Now, some of this could be attributable to suspension mods and tire choice, but it's stark. Once you're moving, it's no big deal, but maneuvering in a parking lot at a crawl, the earlier years are waaaaay easier to steer than the 77. I don't know about 75 and 76 280s, but by the time they got to 77, it seems something had changed.

I took a look at the specs in the FSM's and according to the documentation, the alignment specs are pretty much the same. Maybe some minor tweaks to the right of the decimal places, but certainly nothing that would explain the difference. I was expecting some large change in caster or something, but no. It's the same.

Can anyone else confirm my findings? Anyone with seat time jumping back and forth between one of the late models and one of the early?

And if so, does anyone have an explanation? Is it just my imagination, or did something change?

[Patcon]

Did you look at tire width per car? That would make a big difference

[siteunseen]

I have thought the same, Captain.  Having both I think it's the weight difference.  The steering wheel on my 240 also seems bigger which makes turning seem easier.  My $.02.

[Dave WM]

agree with the steering wheel, I notice it seemed lighter with the 240 style. I attributed it to my tendency to turn by grabbing the spokes on the foam wheel (not wanted to damage the fragile foam covering). This is on a 75 280z

[SoCalJim]

My old ‘78’s steering was heavy at low speeds with the stock tire size.  

[Captain Obvious]

It's not tire width as the 260's tires were even wider (and stickier) than what I have on my 280. I've got 195 "touring" tires, and the 260 has 205 "summer" tires. Point is, the 260 tires should be grabbier than mine both due to the compound and the width.

And I'm not sure about steering wheels... I'm running a wheel from the 1990 300ZX, but it's pretty much the same size as my original 280 steering wheel. Was there a change in wheel diameter from 240 to 280?

Also, I do believe that the weight went up over the years, but it's not by that much. Couple hundred pounds maybe? Not a big change in percent.

[Zed Head]

Tire air pressure?  Probably have to swap wheels to be sure it's a car difference and not a tire/wheel difference.

[Captain Obvious]

I don't think it's tire pressure. They were all within the same general range of "general use". No severely deflated mud bog tires were used for the eval.

So I was looking at the steering specs thinking that maybe I missed the most obvious answer... Maybe there was a change in the steering ratio over the years? Well it's hard to tell... The specs in the FSM's are all confused.

First, the spec for the number of turns lock-to-lock in 74 is given in both meters and feet. WTF is that all about?   And then in 75, they dropped the units for lock-to-lock (which is a good thing), but the number changed.

And then the spec for steering ratio changed in 75, going from 18 to 15. That would surely make a difference, right. But then in 77, it went back up to 18.

And I can't get any of the numbers to line up... If you have rack stroke, ratio, and turns lock-to-lock, you should be able to use any two to calculate the third. But none of them work out...

In 74, they said there were seven teeth on the pinion, and from that point forward, they stopped listing that spec. I've got pics of my pinion gear from when I had my rack all pulled apart, but it's hard to determine the number of teeth. It's clearly either six or seven....

[siteunseen]

Not an "obvious" answer it seems?  You'll figure it out, I'm sure of that. 8^)

[rturbo 930]

Yes, the steering racks are different, someone on hybrdZ measured the travel per revolution on both racks, and the 240 rack was a little faster. However, to me, that would mean that the 240 would have heavier steering, but the opposite is true.

[wal280z]

6 hours ago, Captain Obvious said:

.....and @wal280z ), I got the pleasure to drive .... another 77 280 at Zcon for a larger sample size.

The steering effort was consistent, meaning that the 77 280 took way more steering effort than the earlier years. Now, some of this could be attributable to suspension mods and tire choice, but it's stark. Once you're moving, it's no big deal, but maneuvering in a parking lot at a crawl, the earlier years are waaaaay easier to steer than the 77.

....Is it just my imagination, or did something change?

Awwwwww, did my car stress your biceps @Captain Obvious ??

Interesting topic. For the record, my specs for comparison, in case it is attributable.

Tires: Bridgestone RE-11, 205/50 R15, UTOG of 200 A A, tires mfr date of 2009 (maybe?) with approximately 60% wear at the time of testing at ZCon.

Larger front sway bar (although that should not effect the steering tension in a parking lot)

Lowering springs with KYB standard struts.

[wheee!]

All good information and reasons I am using the AZC Shortened steering knuckles along with the Silvermine Power Steering kit on my rebuilt 76 280Z rack.