[Bill H]

Is my 67 GTO with power steering supposed to have self centering steering? If it's supposed to my doesn't work?? Would this be caused by a worn gear box,or front end alignment? mine is the original box. No other steering problems have been encountered.

[Bill H]

Is my 67 GTO with power steering supposed to have self centering steering? If it's supposed to my doesn't work?? Would this be caused by a worn gear box,or front end alignment? mine is the original box. No other steering problems have been encountered.

[PMDRACER]

You need to have the alignment checked. Self-centering is more of a function of caster than anything else. If you are somewhere between +1 and -1 degree caster, the car will have a hard time self-centering.

I'm also assuming all the front end parts are in good shape, and not binding at all.

TIGER EFI - Electronic Fuel Injection for the Traditional Pontiac Engine. bill@tigerefi.com

The point to life isn't necessarilly the decimal.

[Bill H]

Thanks PMD, I'll get the front end checked out. I replace all the control arm bushings and ball joints quite a while ago, put all the shims back in the location I got them from but never got the alignment checked, what a dumb ass .
Thanks again

[78 GHOST]

I have the same exact problem with my '70, all components are in excellent shape. Mid and high speed characteristics are great, just will not self-center at low speeds AT ALL.

Can you provide me with as many exact specs as possible, so I can request that they be set up to a specific number?

Thanks in advance for your help.

____________________________________
Much love out to my Peeps

[Steve Barcak]

I like the benefits of adding caster. I've tinkered with adding caster for years on many Pontiacs. It helps tracking and stability. Lots of shims on the back stud will be needed, header clearance may be a problem if you have them. The '68s and newer have more room for this. My other car, a '61 was so bad and too hard to add caster so I experimented and built a pair of offset upper control arms. So far I have about 25,000 miles on them including a lot of heavy towing. Big improvement. Steve www.pontiacheaven.org

[78 GHOST]

OK, I'm not sure but I seem to recall the number -1 degrees being discussed when we were talking about the specs on the caster.

I'm using 235/70/14 BFGs so ordinarily they do OK, better than bias ply tires.

Steve, you are certainly a pioneer with these cars. Man, that is an innovative solution to early cars suspension problems. Very cool.

____________________________________
Much love out to my Peeps

[trigger]

anyhwere from 2-4* positive caster will help greatly with centering the sttering, especially at lower speeds. Any more than 5* (if you can manage to get that much adjustment) will cause the car to behave erratically under braking, especially if the car is toed out at all. Our Firebirds have always been happiest with between 2-3* caster.

Are you running an underdrive crank pulley? My power sttering pump had a really hard time at idle when underdriven.

1981 Trans Am, 462ci/4sp
1995 Formula
1963 Bonnie (for sale)

[78 GHOST]

Trigger, the car is bone stock except tires.

I do not have a problem with tracking straight. If I understand correctly, more positive Caster will aid in tracking straight, and hinder quick steering response. Moving towards negative Caster will aid steering response and hinder tracking straight.

Won't a high positive Caster value aid in self-centering? It seems like the wheels would naturally "like" to find center.

I'm trying not to go too far either way as the car handles great other than the lack of self-centering at low speeds. When at speeds below 25MPH I must manually return the wheel to center, if left alone the car will continue turning at any given radius. The front wheels have zero tendancy to return unassisted to center.

____________________________________
Much love out to my Peeps

[george kujanski]

If I recall correctly from my alignment days, Steering axis inclination also plays a part in centering. If you look from the side of a car as the wheel is turned, the end of the spindle moves thru an arc in the vertical plane, the highest point of the arc being when the wheels are straight ahead, the spindle being lower at the ends of travel. This is where the wheels will naturally tend to return to. Too much caster will tend to move the spindle down in the curve, possibly reducing stability.

George

[trigger]

Steering response (how quickly the car "turns in") is more a function of toe and camber than caster. Every adjustment has a trade-off in comfort, performance, stability, tire wear, etc... Too much positive caster angle can cause a "dead spot" on center. Extreme caster settings (either positive or negative) will cause the car to misbehave under sudden weight transfer in the longitudinal axis (quick braking or acceleration).

If increasing the caster angle solves the centering issue, but also kills the responsiveness, much of that can be regained with optimized camber and toe settings. The entire alignment is a set of compromises... there is no "perfect" setting that will work for everyone.

A fun, semi-inexpensive way to experiment with the effects of alignment settings is with a 1/10th scale r/c car (which also gives one the excuse to play with nitromethane on a tight budget). It's amazing how much the handling of a car can be altered without ever touching the shocks, springs, or sway bars.

1981 Trans Am, 462ci/4sp
1995 Formula
1963 Bonnie (for sale)

[Steve Barcak]

I do a lot of towing and I use my '61 Pontiac wagon. In stock form, even rebuilt, they are scary even by 70's standards. Trailer brakes on both axles help but, still not enough. After setting the car up with 4 wheel discs, it stops very well but, still handles poorly. i'm not trying to make it corner like a T/A but, I am more comfortable with some stability at freeway speeds and when pulling over 5,000 lbs which is common. i put on a rear sway bar off of a GTO and it helped, a T/A st box helped too but, the caster increase was a substantial improvement in stability. I don't remember exactly, but, I think it is about 10 degrees positive. I was told that a lot of fancy foreign cars on the other side of the Atlantic use a lot of caster. I only know it works because I tried it myself and I use it.
Though the car is worlds better than stock, I am now wanting more and plan to frame clip it with a front frame from a '78 Grand Safari wagon with 12" rotors. It should make the car even more enjoyable to drive for the next 100,000 in the next few years.