Nova Joe

I've a '67 coupe, big block that originally had manual steering/brakes. I've completed a restoration and installed power steering and added radial (Michelin) tires. Straight line, car is ok. Any corrections and it seem a bit twitchy. Biggest problem is when negotiating a curve at speed, 50 mph or so, the cars tends to tuck into the turn. Oversteering? Very disconcerting. My 8 year old Tacoma seems to handle curves better!

I've had the car aligned but suspect it's still an alignment issue and wondering if anyone has changed alignment parameters to address radials. I put radials on the car when it still had manual steering but that was back in 1969-70. A long time ago but recall being impressed with the improvement in handling.

Avispa

Not surprised your truck handles better than your 67. You're dealing with a chassis that was designed in 1962. A 1" front stabilizer and F 41 front springs will help a lot. If you want to try alignment, 1/2 degree neg camber and 3-4 degrees pos caster will help some.

Nova Joe

I've got the F41 springs, stabilizer bars front and rear. Front at '0' camber, rear a shade less than 1/2 degree neg camber with full fuel. Car corners flat and a bit of right foot in the turn helps stabilize things. I don't recall it being this 'twitchy' before the power steering and relocation of tie rods. I haven't checked toe-in having trusted the alignment being correct but will check in post haste.

Nova Joe

Thanks for your suggestions.

65 Pro Vette

I have a 66 big block with manual steering and I have absolutely no drivability problem at all. It handles very well at almost any speed. Are you sure your shocks are in good shape. A lot of alignment shops are not very good. It took me a couple of tries to find A good one in my area.

Nova Joe

Body off restoration completed 2013. Shocks are new KYB. All suspension components, ball joints/a-arms, trailing arms, spindle bearings are all NOS with less than 12,000 miles on them. As I said, I don't recall the problem prior to installing power steering which I did late last year.

To be clear, entering a curve at speed on our country roads, car begins the turn and then just a bit more steering input results in a lot of turn. I believe this is referred to as oversteer. The PS install calls for tie rod ends relocated to the steering arm hole closest to the spindle.

I suspect an alignment problem but before trying another shop, wondering if anyone else experienced this with a PS install.

Thanks for your input.

tbarb

Did you work on the steering box during the P/S install. If the box was apart is it centered andand adjusted properly. Where did you get the P/S from.

davekp78

Are you using an OEM type PS control valve? My '65 SB felt twitchy to me with a rebuilt control valve. After some research, I learned the valves originally came with two different springs. I had the weaker (30 lbs) spring. When I finally got an early 55lb spring and rebuilt the valve, things were much better. I believe all the currently available valves and rebuild kits have the weaker spring. The 55 lb springs are now pretty much unavailable, except by cannibalizing an old valve.

Nova Joe

First, thanks to all for the responses.

The gearbox was rebuilt by Bair's Corvettes of Linesville PA, a very reputable company. The PS kit came from Zip Corvette and was claimed to be all new parts except the pump was rebuilt.

The 'twitchy' I can pretty much deal with particularly since the heavier spring may be unavailable. The bigger issue is the tendency to oversteer.

As an aside, the PS kit left a lot to be desired in terms of fitment and integrity. I don't know what the OEM installation looked like but this one is horrid. Brackets didn't line up well-required homemade spacers-and provided bolts were incorrect in some cases. Hard to get to filler cap as it is directly under a bracket. Leaks-at the pump and at the cylinder.

I don't know if these kits all come from the same vendor but this one certainly is lacking. Not at all pleased except my wife (and I) finds it more pleasant around town with easier steering.

tbarb

The factory power steering is a very nice upgrade for your car, makes the driving experience much better.

It's sad you pay big $$$ for something and get nothing but problems with it.

Disconnect the belt and try the corner just to see if the over steer is really the power steering. The car will be hard to steer because pushing fluid around plus the quick steer tie rod holes but you may be able to isolate the problem some.

Did you replace the factory springs front or back and do you have the original sway bars.

Jackfit

Smaller belt will help aline pump fill, caster (lack of) is part of problem. Stock a arms only allow 0 ish , hard to get more without offsetting bushing shsfts

DansYellow66

Kind of unusual for a BB car to be accused of actually over steering. The SB guys think of them all as pigs that push the front end in heavy understeer. I assume this tightening of the steering is not associated with powering through the corner under heavy throttle? I'm not enough of a suspension guy to understand all of the dynamics but most of the radial tire alignment specs I've been seeing for older cars, seem to recommend about 1/2 to 1 deg neg camber as well as cranking in all the caster you can achieve.

63Corvette

I would have your alignment shop check your rear suspension for evidence of toe-OUT at the rear.

Pilot Dan

If the car goes down the road straight, the alignment is probably pretty good. Suggestions for improvement like adding caster will help. Also, 1/16 total toe in (front) works well with RADIAL tires.

One question, did you change the tie rod mounting holes in the spindle to the FRONT position which is for power steering?? If not, that will make a difference. It is a faster position. I have not tried it the other way (P/S using the manual spindle holes) but would be interested in hearing if any one has tried that as an experiment.

All of that being said, I can see where you would think there is some oversteer in this design. I feel the same way compared to all the other modern vehicles with R&P steering I drive daily. I know my alignment is optimized and my 64 goes down the road at modern highway speeds straight as an arrow, but can be a little twitchy on the turns if you are not used to it. I've learned to accept it as part of the design. Remember, this is a power assist sytem and not a true power steering set up.

SWCDuke

Toe affects transient response. Toe-in causes transient understeer and toe-out, especially at the rear can cause transient oversteer You mentioned caster and camber, but what about toe. It should be listed on the alignment report. What does it say?

For radial tires, toe per wheel should be nominally 1/16" toe-in, front and rear, which is less than the OE spec for bias ply tires, and it is ABSOLUTELY ESSENTIAL that total rear toe-in is equally divided between the right and left wheels.

It sounds to me like the rear may have toe-out, which can cause transient oversteer.

Duke

tuxnharley

Two things occur to me.

First of all, the old style PS boxes are linear in boost - i.e., full boost at all times, even for minor movements from dead center. So what you describe as only a small amount of additional steering input will produce larger results than what you may be used to in a modern car. That is because modern PS boxes are progressive, having little boost at center and increasing boost as steering input increases. The Borgeson conversion kit - which I have - uses a modern box and works very well.

Secondly, once you convert to PS and particularly if you are then in the fast ratio steering position you really should have some caster added in your alignment. I have seen as much as 3* used successfully, depending on how much your set up will physically allow.

rene-paul

Did you change the manual steering pitman arm to a power steering pitman arm?

C4toC2

I'm going to agree with 63Corvette - Check for toe out in the rear. It doesn't take much to through things off. As the weight transfers to the out side, a toed out outside wheel will gain traction and steer the rear farther to the outside of the corner.