Wow... that's just not good. 

Strangely I have a " dead "  feeling just off center with my 1976 280Z New Poly Rack bushings, Poly steering shaft coupler ( old ) and 225/50 x 16 Conti Tires. Very heavy steering an car just doesn't respond to initial movement of steering wheel, then it takes a big bite. Very disconcerting. I've had the front end checked a couple of times but nothing has been found. I'm going to replace the Lower Control arm bushes and Lower Ball joints just for good measure. It actually feels like the rack is moving just like Daves car. But it shouldn't with the Poly bushings... at least I would think it wouldn't.

If memory serves me correct, the 240Z bushings were a lot thinner. Perhaps the 280Z rack bushes just have too much material and deflect too much with wide sticky tires. Even with Poly bushinsg?  I'm going to have to put it up on an Alignment rack and load up the front end while turning the steering wheel. Something is not right. 

 

 

Edited April 1, 20177 yr by Dave WM

delete dupe

Edited April 1, 20177 yr by Dave WM

Wow. Not good. Don't know what's going on there, but I can tell you that mine (with poly bushings) doesn't do that.

I assume you already saw this, but here's my experiences with the steering rack. Bunch of bushing info towards the beginning of the thread:
http://www.classiczcars.com/topic/48621-steering-rack-disassembly-and-refurb/

 

This is not looking good... I was hoping not to have to rebuild mine (wishful thinking I know) but it looks like it will be inevitable. Almost wish there was an aftermarket or exchange service for this one!

I don't see how it is possible for it to move that much. The bushings fit inside that track that is welded to the rack.   Is it possible that the brackets are from another car (240 perhaps) which allows too much play? 

All stock, understand the wheels are on the ground and the car is not moving (obviously) so the rubber mount is fighting max friction of tire on ground (carpeted garage no less), you can clearly see the tires moving in the video. I suspect this is normal, which is why I would love to see someone else do the same test, tires on ground turning the steering wheel 45-60 degrees each way and document the movement. My guess is the rubber functions to isolate road vibration transmission into the frame, and therefore MUST have movement, only real question is how much. So if there is anyone else interested in this, please post up some video.

FYI from what I can tell there is no play just the rubber being compressed on the side load.

Edited April 10, 20177 yr by Dave WM

I've got poly bushings, so I'm not sure if it would add any useful data, but I can try to take a video off mine if that would help at all.

LMK and I'll see if I can figure out how to use my camera for that.

I think that would be very useful, if nothing else a direct comparison of poly vs OE Nissan rubber. See if you can note the amount of tire movement in my video, I cant say for sure exactly how much I was turning the steering wheel but you can kind of get the idea by seeing how far you are actually moving the tires.

OK, I'll see what I can do. Give me a couple days to find someone else to move the wheel while I man the camera.

As an alternative... Have you got any public domain video editing software that I can use to clip the unnecessary parts of a longer video off? I could brace the camera into position like you did and do the rest of it alone, but I'd need to clip that out of the video (again, like you did). I clearly don't do much of this kind of thing.

I can already tell you from just casually viewing the system from topside while moving the steering wheel... I don't have anything near the amount of motion you do.

I just use the youtube editor for any clipping that I do.

2 hours ago, Captain Obvious said:

OK, I'll see what I can do. Give me a couple days to find someone else to move the wheel while I man the camera.

As an alternative... Have you got any public domain video editing software that I can use to clip the unnecessary parts of a longer video off? I could brace the camera into position like you did and do the rest of it alone, but I'd need to clip that out of the video (again, like you did). I clearly don't do much of this kind of thing.

I can already tell you from just casually viewing the system from topside while moving the steering wheel... I don't have anything near the amount of motion you do.

Windows Movie Maker - With the caveat that I used the Windows 8 version in Windows 10, and it works fine. My old Win7 machine choked and puked on editing videos.