Handling affected by old rubber bushings?

[Mikes Z car]

Right after I bought my current 1970 240Z in 2008 I noticed when driving it that it would twitch left and right slightly seemingly randomly and I could not feel any of that in the steering wheel indicating to me the problem was coming from bad rubber suspension bushings. My previous 240Z, a 1971 model I had 30 years ago did not do that. I considered putting a video camera under the car aimed at the suspension to see where a bushing might be flexing but couldn't figure out good placement for the camera. Maybe a magnet mount would have worked. I had noticed the T/C rubber bushings were very cracked so I replaced them and the handling returned to normal with no twitchiness. I have noticed threads regarding replacing the LCA and spindle rubber bushings. My two related questions are:

1. Is there any way to tell which rubber bushing needs to be replaced if there is a handling issue?

2. How do I know I have a bad bushing if the car is handling okay (if there is an answer for this question)?

My car is handling fine now but I have been wondering about the spindle pin and LCA bushings since others are going to a great deal of effort to replace them.

[EuroDat]

You can check them using a tyre lever or something like that to move it up and dowm. The rubber will flex a bit, but if there is a bad one you will notice the differance.

Just remember the the wheel and spring are trying to push the arm downwards. So you have to lever it upwards to check play.

It just works like a simple counter lever. Wheel pushes up, spring pushes down and the bush end "pushes" up.

IMO if any are suspect, I would just replace the lot. They have done well for 40 years, time for retirement. Spindle pins are a PITA. Every Z owners nightmare. Tools have been invented to make it easier.

This link show how to replace step by step.

Z Tech Tips Suspension (AtlanticZ.ca) || |  |   |    |      |        |          |

Chas

[Wade Nelson]

Get an expert to drive your car. Chances are if your car twitches side to side you've got insufficient toe-in. Just a fraction of an inch of toe-out and the thing will absolutely LURCH into the other lane if you even THINK about it. How are your tires? Matched front and rear? In good shape, matched wear? If you've got uneven wear, replace them. Attempting to do an alignment on anything but almost new tires is a waste of effort! Replace your tie rod ends, for starters. And something very simple, check how tight your axle nuts are on. Mine were loose! After that I"d do sway bar ends and bushings, a very easy (and cheap) job. Front and rear. If your twitching is coming from the rear end you've got some work to do. With less than $300 in parts and labor my 280ZX went from twitchy, nervous, seemingly trying to kill me to smooth and controllable.

[Mikes Z car]

EuroDat,

Thanks for the idea of using a lever to pry on the suspension to move the bushings. Good article on spindle pins, thanks for the link, looks like Blue's car. Replacing all bushings seems like a great idea, a sure fix for any problems instead of guessing.

Wade,

I do know someone here who races Z cars, he may know how my car is supposed to handle. Thanks, I hadn't thought of toe in or loose wheel bearing nuts causing twitching. Those things I can check myself too. Tires don't look worn at a glance though I will take a closer look at them. I will start collecting replacement bushings.

Sigh, I was hoping for an easy fix, there isn't one. I was hoping to avoid the spindle pin hall of fame scenario.