handling characteristics

[pro2]

I have only driven my 71 vette and would like to know if others have the same oversteering characteristics as mine. I have completed a body off and everything was replaced. An alignment was performed and within spec. The oversteering is to the point of being dangerious. I have the stock sway-bar in the front, none in the rear. New GM shocks and fiberglass rear spring. Is this handling characteristic normal?

 

[BBB454]

What oversteering?

If you can explain what you mean by oversteering, I might be able to give you a comparison to my '71. I just had a 4-wheel alignment too, and didn't really notice any difference from the way it handled before (it was about 12 years since the last alignment, about 15,000 miles). I was told that it needs work on the front end (needs bushings but the shocks are OK).
Give me an example of what you mean... Thanks!

 

[1979toy]

Sit in the drivers seat, look at your feet. The pedel under your right foot is the throttle. If you are smashing the throttle like you're smashing grapes for next years wine then you are going to get some oversteer!:L
Your car should have netural steering if you are not braking or accelerating hard at that time. The most likely cause is a problem in the rear suspension. Look for loose hardware. Check the shims to see if any have moved or fallen out since your alignment. Have your alignment varified by the shop that did the work. If all of that checks good, then you might think about maybe the differnical isn't unlocking if you have postraction.
Most of all get it fixed before you wreck a fine classic.

 

[Eric]

Like 1979Toy said, if you're taking corners like a bat out of hell, that's exactly where you're going to end up. I have a 71 too and have pretty sticky tires that have only given in to oversteer twice and it scared the heck out of me the first time; the second time was intentional. If your car has that familiar old age rear-end squat theat sharks get, oversteer will be more prevalent due to worn rear components. If all of the suspension and alignment issues check out, make sure you have tires that are built for the kind of driving you appear to be doing. I know their name is mudd right now but firestone firehawk ss20 is a really inexpensive yet sticky tire. Threre are plenty of others too that I'm sure other users will recommend

All of this may just be the result of getting used to the feel of driving a car when your butt is resting on the rear wheel wells as opposed to dead center of the car. That took me some getting used to.

 

[redmist]

Get a rear sway bar and don't use the stock settings. You need to have more toe-in on the rear and a little more negative camber.

I still have, for the moment, the stock wheels and regular old T/A radials 245/60/15s. I have no oversteer problem unless as someone else said I mash it around a tight turn.

Give the folks at Vette Brakes and Products a call.

 

[Hib Halverson]

Wow!
A 71 with no rear bar that's loose. That's a new one on me.

What is the spring rate of the fiberglass rear spring?

 

[rpounds]

Oversteer?

I agree with the previous writer that mentioned sitting on the rear axle. The single most difficult thing for most people to get used to is the relationship of the driver's seat to the rear axle. I have experienced what you are talking about - on purpose. I wanted to see how much the car would take before it let go. This was done in a safe area, not on public roads and with no other vechicles around to bump into. What did I find out? Well, if you are actually getting your car to the point of oversteer, you push it way too hard . . . so, I hope you don't drive in Califonia!!

Just my two cents.

 

[pro2]

Thanks for the comments, The oversteering concern starts to happen at just moderate speeds. I would be scared to go any faster with the way it handles. It drives straight has 1500 miles since the restoration. It oversteers even while coasting through a turn. Maybe I'm explaining it incorrectly, it does have power steering and it feels touchy at a certain point. The steering wheel has free play in the centered position"straight" but then the power steering really kicks in. I have a new rag joint and all new steering components. The comment about sitting on the rear tires is very interesting.

Thanks,
Phil

 

[silver 80]

steering?

It could be that your steering valve is not properly balanced.
tom

 

[Eric]

Silver has a good point. If you have play in your wheel, replacing all of the components should have fixed it. Was your steering box rebuilt or did you get a new one?

 

[pro2]

I rebuilt the steering box, by replacing the seals and also installed wheel bearing grease in place of the less viscous oil. I visually inspected the two gears and it appeared to be OK, i also adjusted the preload. Is there anyway to check if the steering box needs work?

 

[silver 80]

Steering II

Yes 71 shark has a good point about the Box. I was refering to the steering valve, its hydraulicly controled from the pump. when ever you replace the steering valve it has to be calibrated or balanced, so that when you turn your steering wheel one direction it doesn't take off and slam the steering to one side and then you will be fighting it to get it back to center.
does that make sense?
tom

 

[Hib Halverson]

Ok, so when we're talking "oversteering" in this thread we are talking about power steering that lacks sensitivity on-center but feels over boosted or too sensisitive off-center. The car seems to suddenly lurch into a turn after you've cranked in more than normal steering lock as you move through the poorly responding, on-center area.

First of all, poor steering feel on-center is a trademark of the linkage assisted power steering that was used on Corvettes from the 1950s until 1982. This is true even when the system is in perfect condition.

Wide tires and aggressive front end alignment make the problem worse.

It sounds to me like not only may this car's steering box be worn (as are many C2/3 steering boxes at this point in time) but there may be a problem with he car's power steering control valve. It may need to be adjusted or replaced. There also might be worn steering linkage parts such as tire rod ends, idler arm or the relay rod.

Also, it was said that this steering box has been filled with grease. Be careful doing that because, over time, grease tends to pack at the ends of the box and leave the center of the steering gears unlubricated. IMO, one of the best mixes for steering boxes is Red Line synthetic bearing grease mixed 1:1 with (believe it or not) STP.

 

[pro2]

thanks for all the great advise!
It's difficult to explain the problem, the steering is touchy. When in a turn it feels like the rear wants to come around. This occurs even at moderate speeds. If the steering box was worn what affect would that have on the steering?
I have completely rebuilt this vehicle, new ball joints, tie-rod ends, idler arm, rag joint, and steering control valve. (the valve has been adjusted, per manual).

Thanks,
Phil

 

[Hib Halverson]

Well, it sounds like you've done most of the right stuff as far as rebuilding the steering.

What are the front and rear alignment specs on this car? What stabilizer bars are you using? And, the springs? What kind and size of tires?

 

[Doug78]

Whoa, I lost track!!!

Understeer is when the front tires are sliding making it feel like the car is plowing forward rather than turning.

Overstreer is when the rear tires are sliding and the tail of the car is coming out - similar to sprint car racing.

Over-assisted steering means you have no feel for the road and very little streering effort - like a fullsize Chevy truck.

Steering ratio is related to the number of turns of the steering wheel from 'lock to lock' at the wheels.

Which of these items are we discussing?

 

[pro2]

Doug78,
I'm not sure anymore!
My 71 conv has a nasty oversteering problem, the rear wants to come around IN A HURRY!
Now I'm not talking about driving hard and getting a power oversteer, I'm just driving around some back roads at 30 to 40mph taking some moderate turns and after turning, the rear end really wants to swing, the tires don't screech, but if your not carefull it feels like you could loose control. Every system has been rebuild and I don't know if this is just a shark handling characteristic or not as I have never driven another vette of the same vintage to compare it to. Any thoughts Doug?
Once again thanks to all who have responded.
Phil

 

[Doug78]

What size are your rear tires? How old are they? What brand?

I doubt that the handling of your 71 differs that much from my 78. I have BFG Radial T/A 255/60R15 all around. My 78 will hold a curve at 10 MPH faster than my friend's 95 Mustang GT with no over- or understeer, feels like it's on rails. (70mph thru 35mph s-curves, 55mph in the rain)

BTW, I do have the Gymkhana suspension.