Power Steering Problems Again (long post)

[68RAT]

Okay I got a re-occurring problem. First some history and facts: I installed a new (old system new parts) Power Steering system in the 68 last year. I had some problems then and adjusted the power steering control valve until it was balanced in the middle quite well. It seemed to operate okay but not as easy as I thought it would. I decided to live with it, as it was an improvement on the old non power steering.

I also got an alignment last year and my settings were as follows:
FRONT:
Caster Left: 2.4* Right: 2.4*

Camber Left: -0.1* Right: 0.1*

Toe: Left: 1/16" Right: 1/16" Total: 3/32"

REAR:
Camber Left: 0.1* Right: 0.1*

Toe: Left: 0.0" Right: 0.0" Total: 0.0"

Thrust Angle: 0.0*

The previous owner(s) installed on the front suspension new bushings, ball joints, tie-rods, idler arm, spindles, bearings, larger diameter sway bar, springs. (550lb). The rear suspension has a new VB&P fibreglass mono spring and added a sway bar.

I'm running 255/60/15 BF Goodrich T/A Radials with 26 lbs of air. I was noticing some wondering so adjusted the power steering control valve again and it is centred again. It was off a centre again…. Should it need centring again?

The re-occurring problem:

I find on some corners (usually hard ones when I'm pushing it a little) the power steering will pulse with effort to a real easy turn then back to what it was before. This of course causes the car to turn sharper for a 1/4 second as the steering wheel will turn sharper because I am really cranking it in the corner. Besides scaring the $hit out of me it is dangerous. This is very more pronounced if there was a bump/crack or deep groove in the road. It will also jump from side to side when there are ruts in the road made by the HEAVY loaded trucks.

TODAY the wife and I were coming home from a car show and I pulled out to pass a slower car on a straight away and during the pass I crossed a cement bridge with a large 'crack' in the pavement where the cement and pavement met each other. When the front tires hit this crack the car's steering literally bounced the car sideways to the right about a foot or more. I was already past the car I was passing so I was nowhere near that car but it sure scared the $hit out of me. (and worse the Wife TOO!!!)

The Wife refuses to ride with me now until I get this FIXED. Do I need another alignment? Do I need to replace my control valve as I have read that sometimes that even a new one may not operate properly right out of the box. Would new narrower tires on the front help? More/less air pressure?

I'm reaching for straws here guys. I need help. I just remembered that my steering is a little loose as I have a little play in the steering wheel. It's not much. I can move the wheel from 12 o'clock both ways about a ½ hour each way. I've driven vehicles with WAY worse than that and NOT had any kind of similar problems.

Sorry this is a little long but I am trying to give all the information I can to try to get to the bottom of this problem. I LOVE to and want to do LOTS more driving but this is starting to get scary. We want to go on a 2000 mile road trip this September but if this isn't fixed we won't be taking the vette.

Thanx for any all suggestions.

68RAT

 

[Corvettes White]

Long shot, and I have not heard of it happening on older sharks, but given that you are in Canada (rust); check for a crack in the frame where the hardware bolts on. Fatigue may have opened up something and you only notice it under hard loading.

George

 

[mrvette]

I remember reading that you want toe in for the rear, and it's because when deflected, the tires go to a tow out position, and that's scary.....


also the previous comment on condition of the frame....

and obviously all the suspension components....

One thing I note is you on 15" tires, interesting, as I was under the impression stock size tires didn't give much reaction like that.....but when going to a larger dia rim, like 17+ and wider as usual....it is very common to get your complaint/reaction like that.....
I had the same reaction with my car and 17x9.5" wheels/275/50/17 tires....

it folllowed truck ruts like mad...dodged all over the road at speed....

cured it by installing a rack setup...winter 01-02....

:drink::drink:

 

[BBShark]

I think you have two problems. The cogging that you feel in the steering wheel is probably pump "catch up". That is were the pump has to supply a flow rate (in response to a quick steering input) that it is unable to supply.

The rutted road darting could be helped with more caster and is sometimes made worse by lowering the front too much. Another contributing factor to darting is a sway bar that is too big. The Chevy Power book recommends a 15/16 bar and that's for a race car.

 

[big2bird]

I would do two things right off:
Rear toe should be 1/8" each side
Rebuild that box, or have Gary do it.(Takes a $150.00 special torque wrench to set up correctly). It will make a large impact on how it handles.

 

[big2bird]

Another contributing factor to darting is a sway bar that is too big. The Chevy Power book recommends a 15/16 bar and that's for a race car.

I dunno Larry. I run a 1 1/8" front bar. The only darting I ever encountered was zero toe. It was quite darty. 1/16" toe both sides, and it steers quite true.

 

[mrvette]

Another contributing factor to darting is a sway bar that is too big. The Chevy Power book recommends a 15/16 bar and that's for a race car.

I dunno Larry. I run a 1 1/8" front bar. The only darting I ever encountered was zero toe. It was quite darty. 1/16" toe both sides, and it steers quite true.

what tires do you have?? 17/15??

:stirpot:

 

[big2bird]

Another contributing factor to darting is a sway bar that is too big. The Chevy Power book recommends a 15/16 bar and that's for a race car.

I dunno Larry. I run a 1 1/8" front bar. The only darting I ever encountered was zero toe. It was quite darty. 1/16" toe both sides, and it steers quite true.

what tires do you have?? 17/15??

:stirpot:

P255/60R/15 all 4 corners

 

[MYBAD79]

I run a 1 1/8" sway bar too and have no issues with it...

Make sure that all mounting points on the frame are solid...

Additional caster should add more stability but eventually the 255-60 tires will hit the rear corner of the fender... ask me how I know....

I run my tires at 30-32 psi, no excessive wear at center so I guess it's not too much pressure.... 26psi seems very low....

 

[BBShark]

Another contributing factor to darting is a sway bar that is too big. The Chevy Power book recommends a 15/16 bar and that's for a race car.

I dunno Larry. I run a 1 1/8" front bar. The only darting I ever encountered was zero toe. It was quite darty. 1/16" toe both sides, and it steers quite true.

A large sway bar can make rutted road darting issues worse but is not the cause of the problem. Some tires are worse than others for this. It's called tire lead or spalling when you get the inside edge of a tire loaded and the outside edge of the opposite tire loaded (the condition you find on rutted roads).

 

[mrvette]

As some of you know, over the 15 years I have owned this car, it's been a hobby toy...as such the suspension was totally redone on all 4 corners, and back then the 40 series tires in C4 sizes were pretty much all I could find...so I ran them for some years....then the Nitto 50 series and others came out...
at first I had 1 1/8 front bar, 460 vbp springs, and KYB shocks...
rear was 360 vbp plastic spring (huge improvement over that steel junk, just in ride alone) even with the KYB shocks and a huge sway bar like 3/4? in there...

but after the move here to Florida, and all the PC rumble strips on the feeder road in/out of here, the potholes, and the rutting, I got tired of beating myself to death, maybe I just got older too...:gurney: so the front bar is like 7/8 now and stock 9/16 in rear, and switching to Bilsteins really smoothed out the car, and even with all the comments about rear bars and small front bars, I find the car does pretty good, but the rears are 275/50/17 and the fronts are 255/50/17 the switch to 50 made the ride a hell of a lot better, and they don't look so much like rubber bands on there....fills the wheel wells better....

the rut following jerky handling on truck ruts was pretty bad, but the switch to the rack cured that shit.....night and day, and I know full well that the steering box was tight as new....I got my own damn ideas as to why about that steering don't go with modern rubber, unimportant for now...:drink::drink: