CK5
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'89 R3500 Crew Cab 2wd to 4wd conversion & beyond

Started out with 2wd TBI350 with SM465 to current 4wd with 454, 700r4, NP241
My Burb has rubber on the rear of the rear spring, they are the bigger sized ones on the 63's and at the time nobody had them or made them or something.
 
interesting

I set my axle up on a rolling stand so I could do some prep work with it. I had to change my high steer set up to work with this truck.

20130222_122750.jpg


I'm using my old tie rod to check clearances and angles.

I have been toying around with my steering setup doing a lot of reading about different choices, basically parallel versus Ackermann.

Parallel would have the tie rod holes space the same distance apart as the king pins. If you draw a line through the king pin and tie rod hole on each side those 2 lines would be parallel.

parallel-steering.jpg


I have figured out this is how many aftermarket high steer arms are set up, at least the 3 different brands I've laid hands on.

With parallel steering, both tires will turn at the same angle. So if your maximum steering angle is 40 degrees, when you turn the steering to full lock both wheels will be at a 40 degree angle.

Ackerman steering puts the tie rod holes outside of the king pins (if the tie rod is in front of the axle). This will cause the inside wheel to turn at a sharper angle than the outside tire.

ackermann-steeringinaction.jpg


This helps with steering on flat pavement because naturally your tires want to follow different arcs. With parallel steering one of the tires will end up slipping in order to make the same turn.

You can determine tie rod location by graphing it. You need to know the king pin separation and wheelbase. I measured the king pin separation at 52.25" on my axle. The wheelbase I'm shooting for is 150". You make a "V" with the bottom being the centerline of your rear axle and then each side of the V intercepts a king pin. Here's what mine looks like:

ackermann-steering.jpg


So the tie rod holes need to fall somewhere along those V lines.

The first problem I ran into is that I don't have enough room on my steering arms to accommodate the separation I need between the tie rod holes. I can't bring the tie rod close enough to the king pin to get a manageable hole separation because the tie rod will hit the u-bolts. This is at 5" out from the king pin.

20130222_123115.jpg


I plan to use regular tie rod ends instead of heims this time around. So I think if I cut the excess thread off the u-bolts, the tie rod will just clear. The problem is at 5" away from the king pins my tie rod holes need to be just under 54.3" apart to land on my Ackerman lines and I only have about 56" from outside edge to outside edge on the steering arms. I might be able to get the holes in there, but there wouldn't be enough material left to hold much stress.

Then to put the nail in the coffin of Ackerman steering, I discovered another issue to prevent success. If you reference back to post 117 I was adjusting my steering stops for maximum steering angle that my axle shaft would allow. As I noted there, the Reid knuckles only have steering stops on the front side of the knuckle. Problem is in order for Ackerman to work, the steering needs to be hitting the BACK side steering stop on the inside wheel/knuckle because that is the wheel hitting the sharpest angle. Without that backside stop, the steering keeps moving until the outside knuckle hits the stop. Which pushes the inside tire way past the binding point.

I know there is a big ol' can of worms that can open up with a discussion on Ackerman versus parallel steering in the off road world. I can concede the argument that Ackermann doesn't apply when the suspension is fully articulated navigation large rocks. However I was hoping to get this Ackerman set up for better street manners.

Some may be wondering about the factory tie rod locations. Well as we all know they only sell one set of knuckles for all of the GM trucks running 106" to 164" wheelbases; this is often the argument against the importance of Ackerman steering. I measured what the separation should be for the proper toe-in at the factory tie rod hole locations and came up with a number that would fit a 117" wheelbase, or about that of a short bed pickup. And regardless that still won't help because I have the issue with the steering stops.

So I guess I'm going to set up for parallel steering. Which is a good setup for trail running at least. I think the additional tire wear will be less of an issue since this isn't a daily driver vehicle.

The good news is was afraid the ORD springs would be too tall for high steer, but that isn't going to be a problem. 38377k5 told me it can be a clearance issue with their (ORD) high steer arms, but it seems as tho these OTT arms are taller.
 
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What if you ran the offset tie rod end from Ruff Stuff? That would push the whole tie rod a little further forward.

As for the knuckles, couldn't you just switch them side to side, basically running them backwards so the stops are on the back side?
 
The knuckles can't swap side for side. The first thing that comes to mind would be the brake caliper mounting because the Knuckle is "notched" out to clear the caliper. Aside from that, I'd wonder if the upper and lower king pins would line up. :thinking:

I had thought about the offset tie rods but I think they might push the tie rod into the the draglink. I'll have to take a look at that though.
 
I haven't done it personally but I'm pretty sure you can swap the knuckles side to side, as mentioned you have to flip the caliper mounting bracket as well.
 
Interesting. I guess the only other nit picky problem with swapping the knuckles around is that I'd lose the 5th mounting hole for the steering arms.

Using the offset TRE's wouldn't help enough. I can only gain 1/2" and then the offset on the arms gets in the way of the nut on the bottom side.

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I have had this discussion a couple of times with different people.

I honestly thing that its not nearly as important on our trucks as some would make it out to be.

On something like a car that is running much much better tires than we are that have much much less sidewall than we have and that uses a rack and pinion with much less play than our recirculating ball steering has, it would be much more important.

I have had 2 different set of high steer arms. ORDs and Parts Mike arms. I like the ORD arms much better overall but the steering difference was nill. The arms and hole locations and lengths are different.

I never calculated how far off the ackermen angle either of them were but I am sure both were quite a bit off.

I do not think ackerman is nearly as important in a normal driving down the road truck. In something that you may do some high speed maneuvering in I think it would become much more important.

Even more so in a driving down the road truck with really tall sidewalls.
 
There is even a lot of debate I found in regards to Ackerman in go-fast cars. In that case they were talking about the difference in loading on the tires deccelerating into and accelerating out of corners. It seems that the Ackerman is perhaps most important only for stuff like parking lot maneuvers.
 
There is even a lot of debate I found in regards to Ackerman in go-fast cars. In that case they were talking about the difference in loading on the tires deccelerating into and accelerating out of corners. It seems that the Ackerman is perhaps most important only for stuff like parking lot maneuvers.


Which is why I think its not nearly as important as a lot of folks do.

So many more things are so much more important.
 
Came up with an idea that will solve several problems.

The OTT arms I picked up used were intended for high steer, full-hydro steering. The existing holes are 7" out from the center of the king pin. Most of the arms I've checked are 6.5" and I think this coincides with the pitman arm I have which is also 6.5".

My original plan had been to set the arms up for typical high steer with the draglink in front on the passenger side and the tie rod running across closer to the king pin (regardless of whether I could attain proper Ackerman steering). I was also planning to move the axle forward 1" when I install the spring hangers. So I was afraid that with the 7" hole location, I was going to have trouble with the draglink hitting the tie rod.

It occurred to me today that if I mounted the tie rod in the existing 7" holes, it would solve several problems. No problem with the draglink and tie rod hitting. The ram I have now is 8" stroke and is the perfect length for the tie rod travel at the 7" holes. On a minor note, I would only need to drill 1 new hole for the draglink (as opposed for 2 holes for the tie rod).

The only downside I see is a loss of mechanical advantage with the draglink closer to the king pin. However I'm thinking this is offset with hydraulic assist. I was wondering if this would put more stress on the steering box, however.

Would there be anything else wrong with putting the tie rod in from and the draglink nearer the king pin?
 
This sounds all awesome and all but I'm completely lost on what Ackerman steering is...

Sounds like something I want to learn for my swap but I don't need to complicate it more.... :haha:
 
Yeah, definitely something that can get your head spinning.
 
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