Need help making sense of alignment numbers and caster!

[oscaroc]

I have a 1988 V30 crewcab dually that I recently installed a 4" lift. The problem I'm trying to correct is a very wandering steering feeling, herding chickens feel. Driver input to vehicle response is very delayed and usually needs correcting. The question I have, If you look at the caster numbers, I have 5.5 & 6.6...would this be total caster? Or is that 5.5 & 6.6 in addition to what the factory specs should be? Are the arrows supposed to be in the green or is the green area zeroed?

[SkinnyG]

The numbers you have are what the actual numbers are. You have about 6° caster. That amount of caster is perfectly fine, despite being out of spec. I'd like to see the caster within 0.5° of each other.

The camber confuses me. The arrows look fine, but the right side being a positive number seems weird. I will assume the camber is actually slightly negative on both sides. If this is so, the camber looks good.

The arrows seem to indicate a slight toe OUT - this would make the steerign somewhat twitchy or overly responsive. Knock it down to about the same degrees but IN instead of OUT, and that should improve huge.

My opinion.

I might be wrong.

[oscaroc]

Thank you skinnyG, that is what I thought about the numbers. I had hoped by correcting those numbers to alleviate the wondering in the steering. Looks like I will look into bracing up the steering box and see what that does to the responsiveness of the steering. Would some 3 degree shims added to the front springs gain me any tighter steering?

As far as yhe camber goes, I attribute that to the worn king pins that I currently have shims in to tighten up. Maybe after I rebuild the king pins and address any bearing wear, it could solve my steering issues. I could be wrong.

[Keith Seymore]

We used to run a lot of caster on the K and V trucks. Like 10 or 12 degrees if we could get it.

I used to fix a lot of customer complaint trucks that the dealers couldn't fix. Big caster number was one of my secret weapons.

Make sure your steering gear pre-loads are set correctly as well. There is a basic load which is adjusted by the big jam nut by the rag joint, and then there is the "overcenter" torque which affects on-center stablilty. If memory serves the preload is 10-12 in lbs and the overcenter is 20 in lbs.

There is a section in the service or unit repair manual that describes how to adjust the gear. It has to be removed from the vehicle to do it properly.

You definitely want toe "in". Toe out is a contributor to a wandering feeling.

K

[nonstop]

Just curious, what did you use for steering correction? If there is no correction, that can also play into the twitchy/wandering steering.

[oscaroc]

For steering correction, I installed a dropped pitman arm is all.

Keith; I have recently installed a brand new steering box. Would I still need to worry about preload and over center torque? The truck steering felt excellent before the lift was installed.

It sounds like installing shims to gain a more positive caster is going to be a necessity. I will definitely address the toe in, I was under the impression they set it toe a toe in condition.

Thanks for the help guys👍 Much needed advise.

[SkinnyG]

No, I'm reading it wrong. You want the caster at 8° you have around 6°. More caster. And toe in.

[Keith Seymore]

Originally Posted by oscaroc

Keith; I have recently installed a brand new steering box. Would I still need to worry about preload and over center torque? The truck steering felt excellent before the lift was installed.

You never know. Just because something is new doesn't mean it is right.

Originally Posted by oscaroc

It sounds like installing shims to gain a more positive caster is going to be a necessity.

Yes

K

[cadillac_al]

I couldn't quite figure out the chart but if it is toed out that is probably most of the problem. We even have to toe in the farm implements to make them track straight. When they are toed out they wander quite a bit.

[SkinnyG]

A bit confusing, this picture. I think I have it now.

Vehicle should pull left because of camber and caster spread. I like to have about 1/2° more caster on the right, and 1/2° more negative camber on the right to counter road crown.

[oscaroc]

I've got some shims, to correct caster and a steering box brace to be assured of structural rigidity, ordered and on thier way. I'll address the steering box torque spec's when I put the brace on and inspect the frame for cracks. I'm gonna redneck engineer the "toe in" and see if I can get those settings dialed in. What am I trying to shoot for on the toe in, in inches?

[Keith Seymore]

Originally Posted by oscaroc

What am I trying to shoot for on the toe in, in inches?

Off the top of my head I'd say 1/8" to 1/4" "in".

The chart above would indicate 1/16" to 3/16" (.06" to .18").

K

[SkinnyG]

Originally Posted by Keith Seymore

Off the top of my head I'd say 1/8" to 1/4" "in".

Yup!

[Damien]

If the king pins are worn you need to address that first. You will not be able to fix any alignment issues if there is slop in the components.

[oscaroc]

The king pins will be addressed this weekend. I figure that is ort of the problem, however, the wondering steering only happened after the lift was installed. No problems before

[v30crewcab]

you need at least 8 degrees caster, and about an 1/8 toe in. you can drive my crewcab with one finger with 35's on it.

[sweetk30]

i dont like the huge spread of vehicle info there on the top . makes me think there trying to do a ifs truck alignment spec .

have them try a 85 k30 crew cab spec .

and shims on the bottom of the leaf pack to help kick the pinion up also hurt the caster angles.

as said check king pin bushings . almost every dana 60 king pin bushing i have seen was toast . . . i have gaskets and new bushings in my tool box cause there so comon .

also check for pitting or groves on the pin its self . if so time for a full reman . and should be no play on lower or if play the bearings are shot and time for a reman .

as said check pre-load adjustment on steering box . i had a guy with a brand new dealer installed gm box come in were i use to work years ago and he had been everyplace and no one could get the play out of his steering . we road tested before and he showed me the play as i was driving after i noticed it . put her up on the rack and the pre-load was 3/4 turn out of spec . set that and reset toe as the rest was spot on . re-tested and he was SUPER happy ! ! ! amazing what a little bit of play will do on a box inside when the gap is not set correctly for the teeth inside .

[oscaroc]

Thanks for all the replies, it has been a huge help. I wrapped up the install of a steering box support, 3 degree shims to push the top king pins backwards. Toe is set to approximate 1/4 " in and lastly, I set the steering box preload to what it should be, that part wasn't far off.

Conclusion is, steering is much better. I may go in a bit more on toe, but overall I think we got it solved. It still feels a little squishy, but I can live with where it's at.