Rockwells make your sac swell!

[Skidkid]

Could you explain or define ackerman?

Steering arm geometry for turning in corners at speed. Say you're on the interstate and you take an exit to another highway. This exit you take is on a cloverleaf loop. While you are on this exit loop your cars outside turning tire is at a less of a turning radius then your cars inside tire. So to prevent your tires from scrubbing around the turn Ackerman angle is used. Some guys name that fingered it out.

With what we do with these rigs Ackerman angle is not of any real concern.

 

[Skidkid]

thats what my buddy thought the first time I guess it all depends on the way you wheel and tire size blah blah alot of different factors

Was your buddy running bolts on his high steer arms or studs with tapered nuts countersinking into the high steer arms?

 

[patooyee]

Crap, I need to retract my past few posts. I just got to the shop and realized that the ram I am using leaves .75" of shaft showing at full travel. My steering gain measurements included that which means I'm really only using an additional 3/8" or so of ram travel which could easily be accounted for by the switch in steering arms. So I guess I'll report back on if having correct Ackerman makes a big difference later today along with get pics up of the new steering setup.

As for explanation of Ackerman, I don't have time to type up a whole rehash of threads that I read about it in. But this is where I learned the most and here are some pics I modified to try to help explain it in terms of rockwells better.

http://www.tgwforums.com/post/2.5-ton-top-loaders-5237611?&trail=20

 

[Skidkid]

Crap, I need to retract my past few posts. I just got to the shop and realized that the ram I am using leaves .75" of shaft showing at full travel. My steering gain measurements included that which means I'm really only using an additional 3/8" or so of ram travel which could easily be accounted for by the switch in steering arms. So I guess I'll report back on if having correct Ackerman makes a big difference later today along with get pics up of the new steering setup.

As for explanation of Ackerman, I don't have time to type up a whole rehash of threads that I read about it in. But this is where I learned the most and here are some pics I modified to try to help explain it in terms of rockwells better.

http://www.tgwforums.com/post/2.5-ton-top-loaders-5237611?&trail=20

Why would almost all pickup trucks on the market use incorrect Ackerman angle ?!?

 

[NTIDWELL]

Was your buddy running bolts on his high steer arms or studs with tapered nuts countersinking into the high steer arms?

niether as you can see in pics posted above studs with lock nuts the fifth bolt takes a lot of pressure off of the knuckle bolts there for making a stronger product will the four studs hold up yes in most cases but in the sport it's all about making **** stronger/better so why not spend the extra time and do it right.

 

[Skidkid]

niether as you can see in pics posted above studs with lock nuts the fifth bolt takes a lot of pressure off of the knuckle bolts there for making a stronger product will the four studs hold up yes in most cases but in the sport it's all about making **** stronger/better so why not spend the extra time and do it right.

IMO studs with countersunk holes and tapered nuts is the correct way. Or use the tapered locking shims rockwell used OEM. Locknuts or bolts ain't gonna hold up.

 

[Neal3000]

http://www.tgwforums.com/post/2.5-ton-top-loaders-5237611?&trail=20

so to be correct in a forward facing steering arm setup the steering links need to attach to the arms on the outside or outbound of the kingpin or balljoint rather than inline or on the inside?

 

[TBItoy]

so to be correct in a forward facing steering arm setup the steering links need to attach to the arms on the outside or outbound of the kingpin or balljoint rather than inline or on the inside?

exactly.

Supposedly, the angle is supposed to intersect at the center of the rear axle too.

 

[Skidkid]

exactly.

Supposedly, the angle is supposed to intersect at the center of the rear axle too.

I'm thinking if they are out front like on a D44 D60 and other diffs, it has a lot to do with the orientation of the drag link joint boss location on the knuckles as well.

 

[fordcontraption01]

So if this is the way a Rockwell is supposed to have the steering set up does it not have as good a turning radious if the steering is on the front?

 

[ridered3]

So if this is the way a Rockwell is supposed to have the steering set up does it not have as good a turning radious if the steering is on the front?

Sounds like Patooyee gained + or - 6 degrees of steering by switching from in front of the axle steering to behind the axle steering so yes it sounds that way.

 

[patooyee]

Sounds like Patooyee gained + or - 6 degrees of steering by switching from in front of the axle steering to behind the axle steering so yes it sounds that way.

I ****ed up my measurements. I only gained a minute amount in actual degrees of steering and it was probably a result of using the stock vs home made arms.

So if this is the way a Rockwell is supposed to have the steering set up does it not have as good a turning radious if the steering is on the front?

With stock steering arms in the front of a front axle it will not turn as good as if they were behind the front axle. Instead of the inside tire turning sharper in a turn like it should it will turn not as sharp as the outside tire resulting in the two tires fighting each other in the turn and the outside tire tending to plow a straighter path forward and less of a nice smooth arc turning.

 

[patooyee]

so to be correct in a forward facing steering arm setup the steering links need to attach to the arms on the outside or outbound of the kingpin or balljoint rather than inline or on the inside?

Correct.

I'm thinking if they are out front like on a D44 D60 and other diffs, it has a lot to do with the orientation of the drag link joint boss location on the knuckles as well.

Not really sure I understood what you just said, but if you look at a stock Dana steering arm the tie rod hole is outside the kingpin center line.

 

[Neal3000]

Supposedly, the angle is supposed to intersect at the center of the rear axle too.

that's out for me.....the wheelbase for a '97 F350 (what my front axle is out of) is 168"

 

[patooyee]

that's out for me.....the wheelbase for a '97 F350 (what my front axle is out of) is 168"

Yeah, a deuce is pretty long, too.

But apparently Ford wasn't that worried about it because they used the same knuckles in every wheelbase for several generations.

You can't really do much about the Ackerman angle that is build into your knuckles. I think the main thing is just not to arrange them in a fashion that results in reverse Ackerman if you can help it.

 

[toreadorranger]

niether as you can see in pics posted above studs with lock nuts the fifth bolt takes a lot of pressure off of the knuckle bolts there for making a stronger product will the four studs hold up yes in most cases but in the sport it's all about making **** stronger/better so why not spend the extra time and do it right.

Id be willing to bet that is the issue. The cone washers would probably have solved his issue.

 

[Skidkid]

Not really sure I understood what you just said, but if you look at a stock Dana steering arm the tie rod hole is outside the kingpin center line.

Basically the diagram you posted up is stating front located steering arms is incorrect Ackerman angle and they should be located behind the axle. I'm wondering why it is used OEM on most all light duty trucks?!?

The orientation of the cast in tie rod bosses to the kingpins or ball joints may play a factor in it but I don't see it helping that much. They would have to be pretty far out from kingpin or ball joint line to rear axle

But like I said, pretty moot with the purpose build most of these rigs are for. Not like anyone is driving 40 mph round a paved cloverleaf with their buggy. .

 

[NTIDWELL]

Id be willing to bet that is the issue. The cone washers would probably have solved his issue.

educate me here studs was pulling threads out of knuckle/shearing studs off happened both ways made up knuckles like in pic no problems and beat the **** out of it for 2 yrs no more problems How do you get studs from pulling out of knuckle by installing cone/tapered nuts vrs flat surface to flat surface. I could see this being the issue if the studs kept working loose but that was not his issue

 

[toreadorranger]

Pulled this from billavista's article on (Billavista.com)

The way I understand it, your still subjecting the hardware to a shear force which eventually shears studs. With the cone washers you minimize this effect. Thus preventing or extending their life in this situation. Which is why I bet with the proper cone washer setup and the double shear tie rod bolt, there shouldn't be a problem.

The steering arm obviously experiences continued cyclical loads that place the mounting devices (bolts or studs) in shear load. ( I realize the strength of the joint is primarily achieved by the friction between the mating surfaces - none-the-less the fasteners still experience these loads - as evidenced by them loosening) SAE bolts are not designed to be loaded in shear, not to mention are not manufactured to close enough specs to allow a tight enough fit so that play will not develop and they will not begin to oval out the hole. Not to mention, drilling holes is not the proper way to achieve an exact dimension hole - it should be rough drilled and then reamed to final size. So if bolts are used, holes should be reamed, and proper shear bolts (like AN - can't quote a number off the top of my head) should be used. This is expensive and rare and more difficult, so GM came up with the ingenious solution of using a stud with a split cone washer, so that as the nut tightens, the cone cinches down and provides the required zero clearance fit while still allowing use of SAE grade/spec hardware.

You can use bolts, but you have to use the right kind, or do something else to compensate (like using interference fit locating dowels).

 

[patooyee]

Basically the diagram you posted up is stating front located steering arms is incorrect Ackerman angle and they should be located behind the axle. I'm wondering why it is used OEM on most all light duty trucks?!?

Its not front / rear that matters. Its tie rod mount inboard vs. outboard of kingpin.

Rockwell knuckles have the tie rod inboard of the kingpin. That means for rockwell knuckles, on a front axle, the arms have to point backwards to get correct Ackerman.

Dana knuckles have the tie rod hole outboard of the kingpin so that correct Ackerman is obtained with the arms pointing forwards. If you swapped sides with Dana knuckles so that the arms pointed backwards you would get incorrect Ackerman.

I tried to find a good pic of a d60 knuckle and can't. The best one I can find that demonstrates all this is a CAD model pic:

Notice how the tie rod hole is obviously outboard of the kingpin?

Now see hoe the rockwell tie rod hole is obviously inboard of the kingpin:

If you looked at a birds eye view of the knuckles and draw a vertical line from kingpin to rear axle and then another line from kingpin through tie rod hole, the angle between these two lines is your Ackerman angle. Ideally when you do this on both sides the lines intersect in the center of your rear axle. But if you draw this same diagram with rockwell knuckles pointing forwards that is not what happens. Instead the lines intersect somewhere in front of the vehicle giving you crap steering.

And this isn't just for race cars. I immediately noticed the difference just pulling out of the shop today at .5 mph. The rig turns noticeably sharper.