Steering box self-centers, a little to the right.

[67Charger]

I'm working on my '71 Challenger (yeah, I know), getting it back into daily driver status. It has a Gen 3 5.7 swap and uses the Gen 3 pump, and yes, I know it makes way more pressure than the old style. I have the toe set to 1/16" in, all the positive caster the stock geometry allows (barely any), and slight negative camber. When the steering wheel is straight, the car goes straight, but if you let it go free (with hands still on it for safety) while driving at highway speeds, it wants to pull to the right about 10° on the steering wheel, but no more. I have to apply force to get it to turn sharper, and it will return to the 10° off-center of the wheel and keep turning right. It's like the box has its own center, but the steering angles (tires straight ahead) and steering wheel spline angle missed.

Can the steering coupler be rotated one tooth? I know the steering box has a missing spline, but does the coupler fit more than one way? I know I would have to reset the toe to the new position.

As I understand it, the valve on top of the box only adjusts whether the pump wants to make the steering wheel pull right or left constantly, so balancing it would cause a neutral -no pull- unless there was steering input. I don't think this would remedy the pull unless that is just where the increasing steering geometry resistance equals the force of the off-center valve.

 

[Darter6]

the valve on top of the box

Try with the front wheels off the ground on stands.With the engine running around 1200 rpm see if it goes right on it's own.If so then adjust the valve slightly.
If not a pull can be anything from road crown to brake pull and even radial tire pull.Radial tire pull is one has less resistance than the other.
Road crown can be adjusted by adding more positive caster to the left front wheel to compensate .

 

[bobsgtx]

Move the front tires from left to right. Easy and cheap. I've had the same problem on large trucks and sometime radial tires will do that. If nothing changes you know it's not the tires and move on from there.

 

[R413]

Jack the front off the ground. Start the car and watch the steering wheel.

1) Does wheel slightly turn on startup? Then adjust the valve on top.

2) does the wheel stay still, no adjustment needed.

 

[MoparLeo]

Have the thrust angle checked. Excess thrust angle will make the steering wheel crooked even if the alignment on the front end is perfect.
Also you need more caster. There are aftermarket upper control arms and offset bushing to allow more caster adjustment.
Interpreting Angles: The Important Relationship Between Caster, Camber and Toe

 

[67Charger]

Jacked up the front... Zero pull while running. I can set the wheel anywhere and it will stay put.

 

[Geoff 2]

Post #5.
What thrust angle?
And why does he need more caster when we do not know what the current caster is?

Some cars are limited by design as to how much more caster they can take. Caster moves the wheel backwards. Depending on the wheel opening, wheel diam & wheel offset with wide wheels, tyre could hit the back of the fender opening on turns.

 

[67Charger]

Moog Problem Solver offset UCA bushings arrive Wednesday. + Caster is definitely on the menu. I have the Longacre camber/caster gauge. Once I have the adjustability in it, I can try for a real number instead of the current "front adjusted all the way out and rear all the way in as much as possible without screwing up the camber" on the UCAs.

What's the best way to check thrust angle at home?

 

[khryslerkid]

Almost sounds like tie rod adjustment needed to center the steering wheel?

 

[67Charger]

Almost sounds like tie rod adjustment needed to center the steering wheel?

steering wheel straight = straight line down the road. let the wheel go, turns 10 degrees right.

can I rotate the coupler on the box 1 spline and re-enter the tierods to match?

 

[RemCharger]

The input shaft should be centered, which in turn should center the steering wheel.
Then the tierods adjusted to match center.
Thrust angle- a long straight board against the rear tire should give you some indication.

 

[khryslerkid]

Most couplers are "keyed" without a key. One spline is flat so it only goes one way. In a normal situation, the tie rod adjustment is used to center the steering wheel. The one tie rod is lengthened and the opposite side is shortened to move the steering the needed direction.

@RemCharger has a good idea to use a straight edge off the back wheel to check the front one for being straight with the steering wheel. A good eye and a string line can work also.

I'm not saying this is your problem but it could be checked before going farther and spending money.

 

[khryslerkid]

Toe in needs to be checked with the vehicle on the ground with full weight on the wheels. Make sure the suspension is settled by rolling the vehicle back a couple of feet then forward.

 

[67Charger]

Yeah, I thought the couplet had a blind spline like the input shaft, so only 1 orientation. and I do only check the toe after backing up about 10', then driving forward with light brake pressure to a stop, and leave the steering wheel dead center, not offset to the locked position.

I'll to the bar down the tire thing tonight... maybe a laser that parallels the front and rear sidewalls of the rear tires. I'll figure something out.

 

[MoparLeo]

In this illustration the rear wheels want to track to the left, this pushes the front toward the right.
To compensate with the steering wheel you would steer slightly left. So the steering wheel would be slightly crooked, pointing to the left, but you are going straight.
The steering wheel can never be centered until the front and rear wheels are both pointed in the same direction.
Click on this link for more info:
Alignment Specs: Thrust Angle and Setback

 

[67Charger]

Alignment Specs: Thrust Angle and Setback

View attachment 1355852

that does seem to be the most likely candidate. And that's an excellent sketch of the situation. We'll see how the measurements look tonight

 

[67Charger]

Thrust angle FTW. Looks like about 0.75° to the left of center. I'll add about 1/8" shim in front of the right side spring hanger and see where that puts me.