High Steer... WTF?

[ckruzer]

In all my "research" of what to do and not to do, I have never come across this thought pattern. Would like yalls input, just to make sure I havent missed anything. Thanks guys!!!

Info: 78 f250 d44. Stock knuckles (5 bolt, not 6). Moog BJs. 1 ton high steer kit from @4wheelsupply and high steer arms from him as well.

NOTE: Do not reply unless you have this exact same setup and your knuckles are also painted red.

After posting the attached picture on another forum build thread, someone had this to say:

You're making nice progress. Just keep moving forward.

Looking at those steering arms, I'd suggest you consider running the tie-rod on the knuckle (under the springs), and just do cross-over steering rather than full high steer. Running full high steer on those arms is going to impact your turning radius unless you run a much longer than stock pitman arm. Running crossover would allow you to use the shorter hole for the drag link and keep a tight turning radius.

I also don't like the idea of full high steer on a d44 without upgrading to something like the Reid knuckles.

EDIT: Found someone on Pirate who says highsteer will make BJs not last very long. That crossover would be more optimum for better road manners.

 

[ckruzer]

@Jody Treadway had this to say:

Essentially, as long as your center to center length of your pitman arm matches the same length of your steering arms (center to center) your turning radius won't be limited much, if at all. The tie rod in the stock location is always best

My reply:

Well fudge. What is the point in going high steer if i leave the tie rod under the springs? I like the idea of the tie rod out of the rocks. No “smart” way to leave it high? Lets say I do put in stock location. Then would be best to use the furtherest hole for the drag link to have more “leverage” or would that cause the issue of needing the longer pitman arm? If thats the case what if I leave the tie rod on the high steer but on the furtherest holes and do the drag link on the holes closer to the BJs.. reducing the pitman arm to steering arm ratio? Hopefully that made sense. lol

 

[Fabrik8]

What is cross over? Is that some made-up term for putting something on each side of the leaf spring?

Maybe I'm not understanding something, but if the high steer arm is the same length as the stock steer arm then the steer ratio is the same.

 

[drkelly]

What is cross over? Is that some made-up term for putting something on each side of the leaf spring?

Stock Chevy and Yota solid axle trucks had a push/pull drag link from the pitman arm to a steering arm mounted on the driver side knuckle. Switching it to 'crossover' steering is when you have the drag link connect either to a high steer arm on the passenger side knuckle or connect to the tie rod itself close to the knuckle on passenger side. Either one is a huge improvement over stock when you start getting flexy suspension offroad.

 

[Fabrik8]

Stock Chevy and Yota solid axle trucks had a push/pull drag link from the pitman arm to a steering arm mounted on the driver side knuckle. Switching it to 'crossover' steering is when you have the drag link connect either to a high steer arm on the passenger side knuckle or connect to the tie rod itself close to the knuckle on passenger side. Either one is a huge improvement over stock when you start getting flexy suspension offroad.

Oh, I see now. Longer drag link, less geometry change with axle motion. The part where the drag link switches to the other knuckle is what I was missing.

So yes, you wouldn't need a different pitman arm length if the high steer arm length is the same as the stock steer arm length, unless the steer ratio is reliant on drag link arc angle instead of purely on linkage length. That would only happen if there was a large ratio of pitman length to steer arm length. Maybe I'm missing something in the view of that picture about a change in high steer arm angle (from wheel plane centerline) that would change Ackerman. I don't see what else would really change turn radius there.

It's all just pitman steering geometry, it's just arcs and lengths.

 

[paradisePWoffrd]

Oh, I see now. Longer drag link, less geometry change. The part where the drag link switches to the other knuckle is what I was missing.

What they are referring to as "crossover" is draglink going to the high steer arm on pass side, and tierod being on the stock steering arms. High steer is everything up high.

@Jody Treadway had this to say:



My reply:

Well fudge. What is the point in going high steer if i leave the tie rod under the springs? I like the idea of the tie rod out of the rocks. No “smart” way to leave it high? Lets say I do put in stock location. Then would be best to use the furtherest hole for the drag link to have more “leverage” or would that cause the issue of needing the longer pitman arm? If thats the case what if I leave the tie rod on the high steer but on the furtherest holes and do the drag link on the holes closer to the BJs.. reducing the pitman arm to steering arm ratio? Hopefully that made sense. lol

I will agree with Jody on the pitman to steering arm ratio. I would also put the tierod on the front and draglink on the inside hole.

The biggest effect from moving the tierod up is going to be ackermann change.

I cant tell from the pictures, are you steering arms straight, or do they taper outwards and align with the factory steering arm holes?

If they are straight or tapered in, your ackermann will be off, meaning the outside tire will turn more than the inside, thus hurting turning radius. If they are tapered outward the same as stock arms, the ackermann and the holes align with the stock hole, the ackermann will not change.

Given the same steering arm length, I would argue that the steering forces are minimally different or the same on the balljoint, from the stock steering arm to the highsteer arm.

The loading on the knuckle itself will be different, however. If possible, I would also try to tie the highsteer arm into the stock steering arm to share some of the loading.

 

[Fabrik8]

Given the same steering arm length, I would argue that the steering forces are minimally different or the same on the balljoint, from the stock steering arm to the highsteer arm.

I would somewhat disagree with that, or at least say that it will be different. Steer arm length is only part of the equation, because with the high steer you've changed the point of application of steer force to a different location along the steer axis (between the ball joints). With the high steer you've got a greater radial load and moment on the upper ball joint than you did before, and it should be less on the lower ball joint for the same reason. You're really just taking the same forces but moving those forces more toward one ball joint than the other.

Whether it creates a problem with ball joint failure, I don't know, as I have no personal experience. But the forces are different.

I'd imagine the people with high steer ball joint problems are probably people who are using hydro steering setups.

 

[ckruzer]

@drkelly the dside is so close, never even thought it *was* an option.

@paradisePWoffrd @Jody Treadway And just to be clear; the pitman arm c2c (regardless of curvature) needs to be the same length as the high steer arm?

Refreshing up on ackermann angles now.

Speaking of which... i attached a pic of the original steering arm on this. wtf? and... regarding ackermann angles... the oem arms look more perpindicular to the rotor than the high steer arms do. so wouldnt the high steer arms actually be better for ackermann?

 

[Jody Treadway]

In a nutshell...
Measure the distance between the center of the ball joint centerline and the center of where the tie rod mounts in the knuckle/high steer arm.
That distance needs to be darn close to the distance between center of pitman arm hole to center of pitman arm hole.
Otherwise you'll run out of steering throw.

Edit: There's even more to it than that. Like Ackerman angle, etc. But those lengths mentioned will be paramount to setting up your steering effectively.

 

[XJsavage]

1:1 ratio my friend.

Read what he said^^^

 

[paradisePWoffrd]

@drkelly the dside is so close, never even thought it *was* an option.

@paradisePWoffrd @Jody Treadway And just to be clear; the pitman arm c2c (regardless of curvature) needs to be the same length as the high steer arm?

Refreshing up on ackermann angles now.

Speaking of which... i attached a pic of the original steering arm on this. wtf? and... regarding ackermann angles... the oem arms look more perpindicular to the rotor than the high steer arms do. so wouldnt the high steer arms actually be better for ackermann?

I believe the stock steering arm looks more "straight" because of casting, vs the bolt location of the high steer.

While you have your tape out to measure ^^^, measure the distance between the balljoint centerlines, then stock tierod centerlines, and highsteer tierod centerlines. As long as the highsteer centerline distance is longer than the balljoint distance, you should be ok. From the pic, id guess stock is longest, farthest hs hole, back hs hole, bj is shortest.

 

[paradisePWoffrd]

I would somewhat disagree with that, or at least say that it will be different. Steer arm length is only part of the equation, because with the high steer you've changed the point of application of steer force to a different location along the steer axis (between the ball joints). With the high steer you've got a greater radial load and moment on the upper ball joint than you did before, and it should be less on the lower ball joint for the same reason. You're really just taking the same forces but moving those forces more toward one ball joint than the other.

Whether it creates a problem with ball joint failure, I don't know, as I have no personal experience. But the forces are different. [emoji14]

I'd imagine the people with high steer ball joint problems are probably people who are using hydro steering setups.

I would agree that if the knuckle hit the steering stops, the force on the upper bj would be higher.

Most of the loading on the bj will be coming from forces acting on the tire/hub, moreso than from the steering. Larger tires and big rocks will wear out your balljoints faster than the extra forces from highsteer.

 

[ckruzer]

As long as the highsteer centerline distance is longer than the balljoint distance, you should be ok. From the pic, id guess stock is longest, farthest hs hole, back hs hole, bj is shortest.

You meant to say, as long as the balljoint center on center length is longer than the....


???

Because if is how you said it, then even stock location is no good, and only arms that moved *into* the wheel well would be good.

correct me if i am wrong please (see attached image). This is how I understand ackermann

 

[ckruzer]

I would agree that if the knuckle hit the steering stops, the force on the upper bj would be higher.

Most of the loading on the bj will be coming from forces acting on the tire/hub, moreso than from the steering. Larger tires and big rocks will wear out your balljoints faster than the extra forces from highsteer.

That makes more sense

 

[Fabrik8]

Most of the loading on the bj will be coming from forces acting on the tire/hub, moreso than from the steering. Larger tires and big rocks will wear out your balljoints faster than the extra forces from highsteer.

Yep, completely agree there. Steering forces are pretty huge, but high steer shouldn't be killing ball joints unless the ball joints are already pretty marginal.

 

[paradisePWoffrd]

You meant to say, as long as the balljoint center on center length is longer than the....


???

Because if is how you said it, then even stock location is no good, and only arms that moved *into* the wheel well would be good.

correct me if i am wrong please (see attached image). This is how I understand ackermann

That picture has the steering arms behind the axle.

This would be the pic you want to look at.

Ideally the arms are at an angle that the imaginary lines through them (tierod center to bj centerline) intersect at the rear axle.

 

[ckruzer]

ahhhh. i understand now.

ok.

well. that chafes. it would seem the majority of high steer arm makers/vendors out there have bassackwards thinking... no way to do anything about it now, but going to look into having high steer arms made properly.

 

[Fabrik8]

well. that chafes. it would seem the majority of high steer arm makers/vendors out there have bassackwards thinking... no way to do anything about it now, but going to look into having high steer arms made properly.

No, you're fine. Look at the top-view picture you posted. Look at the upper ball joint, and look at the tie rod end. The tie rod end is outboard of the ball joint, just like the kingpin Ackermann picture above..

The Ackermann angle with the high steer may not be ideal for your track width or wheelbase, but that's the only thing that you would reasonably be able to correct. There's a few assumptions about that picture above, like neglecting that Ackermann changes with castor angle, kpi, and scrub radius (wheel offset), because all of those things change the amount of inner/outer turn radius delta with respect to steer angle. Ackermann is a 3D concept, the diagram above is just a 2D starting point at zero steer angle.

In other words, don't get too wrapped up in that blue top-view diagram. It's a very well known fact that different trucks came from the factory with the same front axle in different wheelbase versions, so obviously there's an Ackermann difference there just from the wheelbase. And again, castor/kpi/scrub.

 

[ckruzer]

53 inches vs 57 inches oem. 55 high steer.