Ongoing issue with numb steering at speed

[1991 Corvette ZR-1]

Hello all. I have had my ZR-1 for a few years now and one thing that has always been present is the loose steering feel. I have replaced the loose factory rag joint with a solid aluminum disc and also had the rack rebuilt by Turn One. I also rebuilt the factory power steering pump. No difference in road feel. The car feels fine at highway speeds up to about 65. Anything above that with WOT and the steering feels very numb and does not inspire confidence. I only have two other options that this could be:

1) somehow, I was charged a rebuild fee for my rack but it was not rebuilt. I did note that the exterior had not been cleaned / sand blasted as they have done for another rack I sent them years prior.

2) The tilt sphere assembly in the column is worn and WOT shifts magnify the disconnected steering feel past 65 mph.

I am going to say it is number two, as the column is up there in age and it may be time for a rebuild. Has anyone experienced what I can only describe as numb disconnected steering at speed? I feel like I have touched everything possible that could be causing this but the column. Upper ball joints were replaced not long ago, while the lowers still appeared good upon inspection.

[secondchance]

I too had the steering rack rebuilt by Turnone, perhaps the most reputable rebuilder of steering components for GM cars.
I also rebuilt front control arms and ball joints as well as installing a new steering shaft and yet feel the vagueness in steering.
Only component that could be responsible for the vague steering feel are front hubs (I have about 120,000 miles on them) scheduled to be replaced soon.
I am hoping replacing hubs will resolve the steering feel.
At the same time, I am wondering crisper steering of recent vintage cars (such as a new C8 I am driving) is creating a sensation of C4 ZR-1 steering of having degraded.

[richarde]

You haven't mentioned tires - are they up to the job?


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[secondchance]

Originally Posted by richarde

You haven't mentioned tires - are they up to the job?


Sent from my iPad using ZR-1 Net Registry

I?m running Michelin pilot sport. Wear pattern (or lack of) tells me alignment is good.

[conesare2seconds]

It could help to update the alignment to get a bit more caster up front and a smidge of negative camber front and rear. Hib used to have a good alignment guide on the action center, I think.

Other than that, check tie rods, wheel bearings and control arm bushings. As you mention, play in the tilt mechanism could have some effect.

[1991 Corvette ZR-1]

Originally Posted by conesare2seconds

It could help to update the alignment to get a bit more caster up front and a smidge of negative camber front and rear. Hib used to have a good alignment guide on the action center, I think.

Other than that, check tie rods, wheel bearings and control arm bushings. As you mention, play in the tilt mechanism could have some effect.

Everything you mentioned, I have replaced in the last two years. Even post alignment, the disconnected feel at speed seems to remain. Part of me wonders if Second Chance is on to something and we may be spoiled by more modern steering. I do have all the parts for a column rebuild, maybe I will make this the thread that I update with build pics when I do it. I fixed the column wobble with an oversized tilt pin from previous owners or people hanging off the wheel getting in and out of the car. I guess it would not be unreasonable to think at some point along the way someone manhandled the wheel without PS assist and jacked up the tilt sphere assembly.

I will ask this: for those of you who feel you have pretty sharp steering in your Z, how does the slop feel left to right when gently turning the wheel with the car off? I feel like my wheel can turn left and right more than it should be able to with the car off but the column lock not engaged. I feel like this slop is getting amplified the higher the speeds climb on a less than perfectly flat road.

[conesare2seconds]

What you are describing with excessive play off-center doesn?t sound normal. Based on what you?ve done so far, last thing I can think of would be check the rack mounts and make sure the rack is secure.

With luck, someone else will have a solution for you.

[Mikey]

interesting comment you made that it feels fine up to 65mph but then vague after that.. is vague = non-responsive play in the system or does it mean the steering feels too "light" or too easy to turn?

one culprit could be in the rebuilt p/s pump and rack, if the flow control valve is of the wrong size (this valve is easily changed with the pump out of the car and should be selected to match the requirements of the R&P in the car.)
in this case, the steering would feel too "light" and you can confirm by going 75mph on a straight section of highway and turning the wheel only slightly to see if the car responds (even though it may feel vague or disconnected at the steering wheel).

in the garage, there should be virtually zero play in the steering wheel. on my car for example, I can turn the wheel 5-10 degrees max, with some slight resistance, while the engine is off. After that it becomes much harder to turn. Note the initial 5 degrees is not actually "play", it is just compliance in the system that is easy to overcome such as tire flex, rag joint, etc. If I watch the tire closely it starts moving IMMEDIATELY in conjunction with the steering wheel, even as I go through the 5-10 degree initial turning.

subsequently, any slight movement of the steering wheel while driving does result in response from the car.

on the other hand, if your issue is with lack of control, as in the car may go right or left on its own even while you maintain a steady 0 degree steering input, if you are sure it is not being induced by grooves or ruts in the road, then suspect ball joints or rod ends. these can be checked in your driveway, simply raise the tire off the ground and then grab it from the left and right side and attempt to move it, and again at top and bottom.

report back on your findings.

Cheers,
Mikey