Steering Effort Differences Between Years

[SoCalJim]

1975 - 3.1 turns L-to-L, as recorded by my calibrated eyeballs.

[Captain Obvious]

Yup, That helps! Thanks! 72 manual says 2.7 (assuming the units in the FSM are incorrect), so you are right on.

Doesn't answer the question about why my 280 (with harder compound touring tires and a higher steering ratio) would be harder to turn than an earlier year, but it's confirmation that something is different!

[Captain Obvious]

So we got a 72 at 2.7 and every year 280 comes in at 3.1 (assuming 78 is the same as the rest).

Thanks for the data points guys.

[Zed Head]

Lock to lock could be separate from ratio, maybe.  Not sure exactly where the stops are but aren't they on the hubs?  280Z hubs different from 240Z.  Different knuckles.  Shouldn't we just measure the ratio?  Not sure how to make that a one man operation.

[siteunseen]

Me too SoCalJim!  Eyeballs.

[Captain Obvious]

Oh, and you guys are the best!  

[Captain Obvious]

3 minutes ago, Zed Head said:

Lock to lock could be separate from ratio, maybe.  Not sure exactly where the stops are but aren't they on the hubs?  280Z hubs different from 240Z.  Different knuckles.  Shouldn't we just measure the ratio?  Not sure how to make that a one man operation.

Yes, lock to lock can be different from ratio. The stops are on the rack. The rubber washers bottom out on the ends of the rack housing at each lock.

I was just doing lock-to-lock because it's so easy and clean. It's nowhere near the whole story, but one that I can do now without getting under the car or taking anything apart.

Edited December 5, 2018 by Captain Obvious

[dmorales-bello]

My '78 280 is 3 and a bit. I guess 3.1 as well. That completes every year 280.

[Captain Obvious]

Thanks for the confirmation on the 78.

So according to the parts breakdown, all of the 240's used the same rack gear and pinion gear set from inception until summer 73 (7307) when both the rack and pinion gears changed part numbers. And then from that point forward until the end of the run in 78, everything used a new pair.

In other words... The 240's used one set of rack and pinion gears, and the 260s and 280s used a different pair. At the same time is when they changed the whole rack housing to the newer style with the wider bushing groove. That could certainly explain differences in steering ratio or L-L between 240 and everything later.

But based on the part numbers, I think the 75 and 76 steering is identical to the the rest of the bunch from 74 through 78 and there are some documentation issues that make it seem like they are different. I don't think they are.

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

[wheee!]

Could it be something as simple as your tension adjuster on the steering rack is set too tight?

[Captain Obvious]

I really don't think so. I don't think that tension adjuster really adds that much friction. More just to keep the rack loaded under all conditions so it's not so floaty? Mine is adjusted according to the manual and the spring is not binding. Other than that, I don't think it's that much of an impact.

To be honest, it really feels like a caster change from the previous years. Like I'm really having to lift the front end weight when I get the wheel cranked off straight ahead.

I know they changed a lot of the sheet metal stuff in 77 and the 77-78 cars look similar from the outside, but are very different cars underneath the skin. I wonder if some of those changes affected the steering feel. The FSM's say the caster and king pin angle and all that is pretty much identical to the previous years, but I'm skeptical.

I need to find a 76 close by to compare it to.

[HS30-H]

37 minutes ago, Captain Obvious said:

...all of the 240's...

The 240's used one set of rack and pinion gears, and the 260s and 280s used a different pair.

As has been pointed out, this is not the case. We need to qualify the market/model/production date if we want to be accurate.