Technical Steering Problems

I'm have problems with my 33 plymouth, it steers like crap, I mean it'll scare you. If you ever had a f250 truck with the china ball joints, it acts like that. Steering won't come back coming out of a curve and when you steer it back it'll over correct or steer to far, wanders on the road bad. It has a Speedway 2 in dropped axle, heim joints with cross steer. Spring and steering rods behind the axle. Drag link and steering rod, from the box, runs parallel with each other, and I have 7.5 degrees in caster. The box is a Speedway Vega box. I have everything just like my model A I had and it steered great, the only difference is I had a reversed Corvair box on it instead of the cross steer. I'm wondering if it's in this Vega box and has anyone used one of these. There is no play any where and I have a 1/8 in toe in right now.

 

I've read several times on here, most of the Speedway Vega boxes need adjusting right out of the box.
Might have a look at the adjustment to see if that may be the case.

 

Done that also and you're right, all their boxes need adjusting.

 

Have you tried putting more caster in it? It will help with the straight ahead tracking and return to center when turning.

 

Me, I would put in less caster, 7.5 seems extreme to me.

 

Do you have a panhard bar?

 

Just checking you sure on the 7.5 caster? Top of spindle leaned to back of car?
7.5 caster should be sufficient for return to center. The box shouldn't affect that but could be too tight or loose at center.

Sent from my SM-A102U using The H.A.M.B. mobile app

 

My hot rod has vega box 8* caster .
I have tie rod ends and it runs right down the road. Everything has to be tight with no slop.

 

I must have read right past that important note-Yes-at 7.5 degrees-castor should be more than sufficient.

 

If the car is setting on level ground, does the front raise and lower as you steer from lock to lock? Lots of caster will lift the front as steer left or right, to little and the frame never moves up or down. The weight pushing down is what returns the steering back to center.

 

No Panhard bar, yes the frame rises some when I steer it back and forth, not excessive. I tried it at 10 degrees, same thing, no change.

 

Loosen box up and try. I think it is tight in the wrong places, causing lack of return and over steer. Check toe; wandering is generally due to toe being out instead of in. Getting a better box is money well spent I think.

 

are the king pin bushings too tight?

 

If everything else is set correctly, it could be caused by the steering box being adjusted too tightly, or binding in the steering rotating components (king pins/ball joints/etc).
Is your 7.5* caster in relation to the ground or the frame (should be the ground)?
A panhard bar is always a good idea.
Also, what scrub radius do you have ???

 

Wander and darting are mostly a caster problem. What kind of tires are you running? Radial tires require a different caster angle and toe in setting. If you are using after market arms at the spindles they may have the wrong angles. Should have a slight angle toward the center of the axle. If wrong that will cause your problems. You need to compare with the original arms if you have them. I don't know if camber has much effect but it's worth a look. To adjust camber you have to bend the axle and may need to have it done at a frame shop or somewhere that does heavy truck alignment. A panhard bar may help some but fine tuning the alignment will probably be the cure. Trial and error. The Vega and Corvair boxes most dealers stock are no name imports and a lot of them are junk. I have a reversed Corvair box on my A-V8 that I can't adjust all the play out of. You have to actively drive the thing. 2" play at the wheel. I'm going to bite the bullet and buy a Flaming River version. A lot more money but worthwhile, I think.

 

You'll be money , time & headaches ahead if you find someone ( probably older) who understands front end alignment/ geometry . listen to him ,make one adjustment at a time. Throwing a question like this on a message board is akin to throwing a steak into a pen full of stray dogs . Its the " unscrew the gas cap & drive a new car under it" syndrome LOL

 

@Mimilan

 

What’s “scrub radius”......asking for a friend.....

 

In our application using beam axles, use a line through the length of the king pin center as steering axis.....
Changing wheel offsets and tire diameters will affect scrub radius.

 

Check the toe in on the ground. If it's toed out, that's a recipe for unwanted adventure.

 

Geometry. Geometry, Geometry.

 

Haven't checked scrub radius yet. Kingpins aren't to tight but that is what it drives like. Going to try and get more time to work on it, backed up at the garage and dealing with my Mom and health problems right now and I have very little time. Just getting ideas to see if I missed something.

 

My money is on the box too tight. Most guys don't know how to adjust a box, take it out of the car first, jam it into a large vise, and move the pitman arm by hand through it's travel. You should feel a drag right in the center of travel, a stiff spot, that is where the box should be set in a straight line when mounted in the car. The stiff spot keeps it from wandering. So....move the pitman arm through its travel while adjusting the play out of it, you should be able to move the pitman arm by hand in a vice, if you can't the box is too tight. Also, open the cover and see how much grease is in it, you want grease that is semi liquid, it will move in the box as the screw moves through its arc.

 

Would be unusual for scrub radius to be causing what you are describing, but bad scrub can cause some weird effects. The point I was making was to check everything, one thing at a time, to try and isolate the problem.
I agree with @2OLD2FAST , it is wise to have a professional have a look over it. Steering (and brakes) need to be spot on and safe.

 

I chuck my guess in the pot!
I'll try to say it,so I brake through the BS bubble of old wife-tails,that get passed around.
So reread about 6 times if needed!
Lot of guys adjust there steering box ,but do it wrong*****,mostly with it out of "box" on own center****<<not axle center or tierod center+/But the box center all by it's self.*........Take the rod off the pitman arm,then run the box all by it's self from one side to other<counting the turns? Come back too real 1/2 way.=real *center of box/then adjust box<there an only there*. After set front wheels straight ahead*,then re-adjust rod so it will fit on pitman arm with out moving box or arm off center.
What many fail too understand,is steering boxs teeth spacing are made with less space dead center of each/so there is less play going straight down the road. Steering to ether side goes to bigger spacing designed in to the gears for EZ movement; but more play.
There can be lots of other stuff wrong as well,but fixing this type crap in my speed shop over 40+ years on hot rods an racecars= Was most found screw up that came in steering wise!!!
Never adjust steer rod or tie rods to make steering wheel look straight in cockpit: Take the steering wheel off,put it back on shaft straight,when car is straight ahead........

 

Thanks, now my friend knows too.

 

Happy to help your friend out. Sometimes my friends need information too...............

 

The Speedway site say's that thei

Info
From the Speedway site.
Cross Steering Guide (GIF)

Note: Vega steering box is not adjusted at the factory and therefore, it is necessary that the steering box be adjusted upon installation per the instructions as provided on the PDF instruction sheet.

 

From The people who wrote the book on steering components

 

Yep, copied everyone's accomplishments for the last 100+ years.