AZDoug

VERY slight left pull, maybe it will drift 5 feet left over 100 yards with hands off wheel.

Toe is correct, both sides and total. Steering is centered, except for the very light pressure I need to keep the car straight

Camber is within spec of +/- 1/2 degree of zero, but one wheeel is slightly negative and other wheel is slightly positive.

Is the variation in camber doing this? Don't recall which side was positive and which was negative.

Thanks,
Doug

Gman58

I am no expert but have you checked the tire pressure. After that the only thing I can think of is a tie rod problem. Maybe you could switch the front tires just for the heck of it. Good luck Greg

Plasticman

Doug,

Yes, camber will affect a pull. Use to be standard procedure to offset camber to compensate for the normal crown of a 2 lane road (but these days I prefer not having any compensation, since interstates and 4 lane roads may be crowned in the opposite direction).

Plasticman

1-2-b-67L89

Doug, is it a pull or a drift/wandering to the left? Assume the S/box is up to snuff????? Would like to believe your camber setting of +/- 1/2 degree would be
Chick

Old Blazer

What kind of road do you experience it on. Interstate, rural two lane roads or both. There are of course many factors to consider. Did it do it before your alignment? The best test is the center lane on the interstate where the pavement is the most level. I drive primarily on rural two lanes roads where my truck would drift to the center line because of the crown in the road. Had my alignment guy tweek the caster (I've forgotten the numbers) and it tracks great now with no ill effects on interstate driving either.

David Schuster

If your camber is positive on one side, negative on the other, you definately have built in a pull situation.It will pull to the positive side.
Caster differential can cause it also.
Toe in will not cause pull.
Dave

wmf62

Doug
this can be frustrating... after i had my frontend professionally aligned i had to hold the wheel about 1" towards the left to go straight (it had pulled to the right before the alignment and i thought the alignment would fix it; but it didn't). i went back to the alignment guy (supposedly the best in the county...) and he said that the problem was probably due to the tires, a condition called 'conicity'; so i googled it and found out

http://www.aa1car.com/library/tires2.htm

i put new tires on and the problem went away...

Bill

David Schuster

Doug
Conicity was a major problem when American companies first built radials (caused by the belt being tighter on one side than the other.
A quick check is to switch the front tires. It will cause the pull to go the other way. Switch the tires that cause the problem to the rear and it will go away. With new directional tire tread that becomes a problem.
Dave

AZDoug

I have unidirectional tires, different size front/rear, no switching or rotating is possible. M/T SR.

Steering box is centered and speced to ST-12

The car drifts to the left, it doesn't really pull, it just drifts, no matter what road crown, flat, right or left, though it definitely drifts a lot faster on a left side down crown.

I just have to keep a slight pressure on the wheel to keep it going straight. Not really a large issue, but it shouldn't do this.

I can try and center camber better, but if anybody knows what the camber formula is for drift left/drift right, that would help me adjust this out.

Thanks,
Doug

wmf62

Doug
honestly, before you change anything... try swapping your front tires side to side and see if that helps; it really could be a bad tire..
Bill

kellsdad

Doug,
You may find my experience as documented in this old thread helpful.
Click here

Matt Gruber

on my 61 i reduced caster for easier steering. then it had a pull to the left. so i adjusted caster unequal to eliminate the pull. it worked. A slight drift to the RIGHT is safer than drifting to the left(except in U.K.)
.
or try the fixes mentioned previously if u prefer.

MikeM

Put another 1/2 or 1 degree caster in the right front wheel.

63 340HP

Alignment is one of those things that having someone show you how to make adjustments, to learn what effects what, is light years faster than trying to read about it.

The left (drivers side) tire is likely the one with slight positive camber. The tire is slightly tilted out, and the increased pressure on the outside of the tread results in a slight drag in that direction.

The same (left drift) effect can happen if the right tire has excessive negative camber, but it usually takes quite a bit more negative camber to cause the mild drift you experience from drag on the inside of the tire tread. Excessive negative camber is usually more forgiving than positive camber, because with positive camber the tire drag's center-point radius is greater when compared to the king pin axis (with zero offset rims & rims with reduced backspacing, rims typical for early corvettes).

Check the camber of both front tires. Confirm the camber on both sides. The ideal is equal camber on both front tires. Take whatever the factory spec is for bias tires and add 1/4 to 1/2 degree negative for radials, and keep the camber on both tires equal (both 1/4 degree negative for example).

You should be able to adjust camber without altering the caster. If you run out of a equal amount of a-arm shims to adjust camber on one side, to the point you effect caster (to where you have to pull an unequal balance of shims on the same a-arm from your preferred caster setting), you have to live with the result. Get the limited adjustment side the best you can, and then move to work the other side of the vehicle to gain an equal balance of camber on both sides.

Setting caster is always first, then camber, then toe.

Once you have a balanced alignment set, then you can play for the drive you like. More positive caster for more self-centering, more negative camber for better limit cornering. less toe for quicker initial steering feedback (etc.). Each adjustment is a compromise, so there is a limit to the benefit of any single adjustment (the "factory" or "autocross" recommendations are not always best for anyone thinks their driving fits the description). Document what is balanced and make notes of what you like better, and what does not feel good.

Good Luck with the new tools!

mashinter

Doug:

To help you decide when you've got it right, an OEM spec. is:

It should take 10 seconds or more to drift one lane on a flat, wind-free highway. I start in the middle lane (of 3) on a quiet expessway.

Bill

jim lockwood

Doug, here's a data point for you from having the front end of my '60 recently aligned.....

The guidance I gave the alignment guy was:

1. Camber to be anything between 0* and -.5*, as long as L/R camber is the same.

2. As much positive caster as possible (which turned out to be 2*), L/R to be the same.

My car tracks straight with the alignment done to these criteria.

Jim

wmf62

my two cents, again....

eliminate all physical potential problems, like a bad tire, before trying to force a correction by intentionally misaligning it.
Bill

AZDoug

Thanks for the explanataion and points.

For point of info, these don't use shims, the caster and camber is controlled by one adjustment, an eccentric on a screw (the upper outer kingpin support pivot), as you change the camber by turning the eccentric, it also adjust the caster forward or backward as you screw the eccentric one way or the other. You most likely will end up with some sort of compromise.

Thanks,
Doug

Matt Gruber

Doug
Did it always pull?(since the 1970's)?
or did something change and then it now pulls?
What changed?

AZDoug

What changed was the sh!thead at the alignment shop that I took it to to align a couple weeks ago,and he couldn't figured out how to do adjust it and told me I needed to shim the front cross member to adjust the caster, but their machine wasn't reading caster at the moment , so he couldn't do it anyway after I explained the caster was on the same adjust as the camber,and then he forgot to tighten the tie rods ends so the tie rods started to unscrew a week or so later.

But, at least he didn't charge me for the alignment.

Doug