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1983 280ZX Turbo ; floating on highway

280ZX Turbo (1983) floating on the highway; we’ve had it in the shop for 3 months and have completely rebuilt the front end. All new parts, tires, everything…still floating… HELP

How old are the struts/shocks?
Has the rear suspension been evaluated?

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The struts and shocks and every other thing they can think of has been replaced, even as going as far as replacing the new struts with another set just in case the first set of new one had a defect. I’m not sure about the rear suspension being evaluated but I would venture to guess after 3 months in the shop they have. I’ll check with them about the rear suspension though just to be sure.

Thanks for your input, maybe I’ll come back with more info on what they’ve done to help more in your guess what it could be. By the way, the floating didn’t happen until we had new tires, new paint job, new leather seats, new muffler/exhaust system, and shocks put on.

Your vehicle doesn’t have rack & pinion steering. Instead it has a steering gear.

Has the steering gear been replaced? And if not, has anyone checked to see if the gear is out of adjustment/worn out?


It’s dificult to understand exactly what you mean by “floating” but I will suggest that you measure the distance from the pavement to the rocker panel at the front and rear wheel wells to determine if the rear end is lower than the front. If the “floating” occurs at highway speeds it may be the result of the car being lifted by air flowing under the car.

If it turns out all the parts involved are ok, it’s still possible there’s a problem with the front-end alignment, esp check the caster angle. Too steep will make it hard to keep the car going straight down the road without the driver having to constantly make steering corrections.

Steering Float = The vehicle does not respond to steering wheel inputs at high speeds.


Again, “floating” is very ambiguous. When the steering fails to return to center when moving forward then caster and/or toe in are suspect but when the OP didn’t mention those problems I moved on to my best guess based on similar complaints on an early model Camaro. I worried with the Camaro for several days and finally it occurred to me to raise the rear end on shackles and give it a try and temporarilly solved the problem. The leaf springs were sagging. I forget how much lower the rear was relative to the front but it was not noticeable until measured. The owner had paid for more than one front end alignment with no success.

I agree with the others, I’d want a great alignment shop to align it, front AND rear.

Thank you so much. I’ve printed off all your suggestions and taken them down to the shop. They will be taking my car over to a front end specialist.

A better description of floating: Loading way to much weight in the back of a pick-up and driving down the highway with the front end barely off the pavement (which my dad was really bad about doing!). Does that help my description easier to understand?

Are you absolutely certain the rear shocks have been replaced and there are no issues with sway bars?

Back in the 80s and 90s I worked on a bunch of Z cars as there was a ton of them around here. It seems that most of the single pilots at the Air Force base had to have a Z car or a Corvette.

I also replaced a lot of rear shocks and struts on those cars. There was seldom any issues with the fronts but the rears were a different story altogether.

At this point, the front and rear have been completely rebuilt with even some of the shocks, struts, bearings, etc. have been replaced twice just to make sure. I have had the car moved to a front end alignment specialist to see if he can figure it out. This is so frustrating for me. I am very, very fortunate that the mechanic has only charged me the original quote he gave me of $1,800. He has tried for almost 6 months to figure this out and has spent a lot of his time and parts at his expense to find the problem.

Is this vehicle configured w/ one of those side-ways shock-absorber gadgets in the front? My truck has one, situated horizontally, sort of goes from one tie rod to the other as I recall. When that gadget malfunctions it can cause a symptom where it feels like when you are going pretty fast & turn the steering wheel you don’t seem to get the expected amount of change in direction. Then when you turn the steering wheel a little further you get too much change in direction, and the vehicle sort of quickly jumps to the left or right. There’s a name for this but forget what it is called. “Jump steering” or “Bump steering” or something like that.

That’s a “steering damper”. The condition you describe is called “bump steer”. It’s a situation wherein any vertical movement in the steering knuckle causes a horizontal movement of the tie rod end. This occurs because of the dynamics of the steering geometry. As the knuckle moves up and down, it moves in an arc. If the arc at the end of the tie rod, being drawn up and down with the steering knuckle, doesn’t track well with the arc in which the steering knuckle is moving, it induces a horizontal movement in the tie rod end… a steering input. Since vertical movement of the steering knuckle is caused by a bump, it’s referred to as “bump steer”. The damper mitigates the effect much as a shock absorber mitigates the bump-induced movement of the wheel.

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Maybe OP could do an experiment, carefully watch to see if the steering wheel rotates by itself when going over bumps. Might provide a clue anyways.

I would check control arm bushings and look for broken frame sections. The steering column shaft may have the rubber bushing and it may be gone. The steering box may have worn out recirculating ball bearings which can look really gone when removed and brought into view.

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I define “floating” in a car as being kind of a gentle rolling sensation while going down the road. Much like a boat on gentle swells at the lake. Does that sound like your symptom?

The Z cars definitely do not have a floating ride as normal. As a matter of fact, the normal ride on a Z car is somewhat stiff and possibly even a little harsh. They’re solid and heavy in feel; at least normally.

As for a steering dampener, the Z cars do not have them.

HELLO TO EVERYONE THAT RESPONDED WITH SUGGESTIONS! All of your suggestions were taken to the shop doing the work. He finally gave up after 6 months and recommended a specialist just 2 miles from him. This man was able to find the problem in one day and had it fixed and on the road again in one week!! Turns out the car had a bent “stub axle” and he installed a new one with new bearings, etc. He found that when the “name brand store” put our new brakes on they jammed a part on crooked and tightened the part down in order to “make it work”. The specialist actually put the car up on the rack and took a video of the underneath while the car was running. He showed the video to my husband and it clearly showed the rear left wheel “doing the princess contestant wave”. This man also completely restores old cars (inside and out) for car shows and hot rods. He has found a client for life.

Sincere thanks for taking the time to let us know the ending. It’s always great to hear of success, and we rarely hear back. Sounds like you found yourself a good shop.

Sincere best.