Hysteer help please (1 Viewer)

[greenbeasty]

I have done a good bit of Cruiser mechanicing, and built a couple , but never done hysteer before. Here is brought a burnt offering to throw before the knowledgeable cadre here.
I’ve run into a snag that I can’t figure out.
Truck is SOA, with Trail Gear hysteer steering arms. The top of the arms are about 1/2 inch lower than the top of the springs, and I just can’t wrap my head around it.
I’ve read thru FAQ, and several of the threads concerning hysteer.
Trail Gear told me I need 1980 plus knuckles, or mini truck knuckles.
I understand about the bolt pattern, I have the later model, the Trail Gear guy seemed to be saying there is a “ deck height” difference in the knuckles, as in where the shims are. I’ve never heard of that, and I measured several laying around, they are all 6 1/2 inches top to bottom.
I feel as if I’ve missed something simple, throw some opinions my way please.
Thanks in advance for the help.
Frank

 

[AlaskanWheeler]

Your spring perches are pretty significant, they are also taking away the clearance you are looking to gain. You'll gain some clearance back, once you've added upper shims to center the knuckle and axle relationship.

 

[greenbeasty]

I also have the springs reversed end for end, I may put them back stock to see if I gain.

 

[peesalot]

Did you turn it full lock and see if tie rod rubs spring ? I would lose the little bottom spring outa the packs and that will gain more clearance, if it doesnt touch lock to lock run it.

 

[pjohnson]

Are the arms new? They may be an older version that was designed for mini trucks with different spring pack thickness. Ask them for measurements of the height offset to compare.

Their statement about knuckle deck height differences is bs. He doesn't know what he's talking about.

Also, I don't remember if this would make a difference, but did you do a cut and turn on the knuckles to set caster angle?

 

[cruisermatt]

Your caster is probably a hot mess in the negative

 

[greenbeasty]

@peesalot Can't really turn it, the tie rod is sitting on the springs.
@pjohnson You may be on to something, they were free, unknown origin.
@cruisermatt I think you are probably right, I'm gonna check that tomorrow, and flip the springs end to end. Do you have shims?

Thanks for the pointers guys, I'll keep you posted.

 

[Mopdog]

If the arms aren’t cast they could be bent.

 

[cruisermatt]

You also don’t have U-bolts installed.

 

[peesalot]

It is close but not touching, you mean that if turned at all there is contact ? Replace that last little leaf with 2 or 4 * shims, that may screw your pinion angle. FWIW a cut n turn is usually necessary with a soa to achieve proper caster and acceptable pinion angle. I dont think I've seen a soa that wasnt even with flat springs. In the pic it does not look like yours has been cut n turned IMO.

 

[greenbeasty]

Mine has not been cut and turned. I read in FAQ I believe that an SM 420 clocks the TC enough that driveshaft angle is not a problem.
We will see, that may very well not work out in my favor. If so, I’ll take it all apart and cut.

 

[Firemedic831]

That is a odd u bolt flip kit you have . If you add a shim it will make it even worse since it will lower the axle . I think you are going to have to cut and turn to rotate the knuckles back . i would first try putting the springs in correct. then put the u bolts on and tighten them down and see what that gets you .

 

[greenbeasty]

Thanks, I will.

 

[pjohnson]

Cut and turn is to correct the caster. Doing so, it ruins the pinion angle.

 

[Firemedic831]

Cut and turn is to correct the caster. Doing so, it ruins the pinion angle.

That makes no sence . pinon will stay as is unless he cuts the spring perches off . But to cut the Knuckle balls and rotate it will not do anything to the pinion

 

[pjohnson]

That makes no sence . pinon will stay as is unless he cuts the spring perches off . But to cut the Knuckle balls and rotate it will not do anything to the pinion

I suppose it's how you look at it. It's all interrelated. You cut the housing, set the knuckles to the desired caster, rotate the housing to properly set the pinion angle and then set your spring perches. That's the way I think of it, but you could think of it as setting the pinion angle first, then rotating the knuckles to set the caster, then set the perches.
You are correct, the spring perches have to be reset.

 

[EWheeler]

I suppose it's how you look at it. It's all interrelated. You cut the housing, set the knuckles to the desired caster, rotate the housing to properly set the pinion angle and then set your spring perches. That's the way I think of it, but you could think of it as setting the pinion angle first, then rotating the knuckles to set the caster, then set the perches.
You are correct, the spring perches have to be reset.

1. Decide on type of front drive shaft.
2. Set pinion angle with spring perches according to decision made in step 1.
3. Cut & turn knuckle balls to set caster.

To the OP, all setups vary. I have 4x4 labs steering arms one of my 40's and I had to have Luke put some more height into the arms for the drag link to clear the leafs on my spring over swap. If you're trying to keep it low, its a balance of having the height to clear the leafs and not being so tall that you're hitting the frame on articulation. I agree that your spring perches are a bit taller than likely necessary. I used similar ruff-stuff perches and made them lower by removing material. The diff housing makes this a bit of a challenge on the passenger side with the stock housings.

Can you give us a full-on side shot of the front suspension? It looks like your leafs are tilting pretty good to the rear of the truck due to the shackle reversal. You'll want to try to get the leafs as flat as possible or you will never get the caster correct due to tie-rod interference. I fought with this pretty hard and ended up re building my rear shackle mounting points to go through the frame after originally mounting them to the bottom of the frame....

 

[greenbeasty]

Side view. The pumpkin perch is as low as it can go without removing material off one side or both, and drivers side actually needs to come up 1/2 once to match it.
Here is side view, I probably can remove a leaf.

 

[peesalot]

So take that little last leaf outa the pass side and run it.

 

[greenbeasty]

Ok, I reversed the springs back to OEM order, long side to the front, taking out the bottom leaf. I had 3 1/2 inches of curve with the engine weight on before, now I still have 3. I think that will be fine, although I may find later I need longer bump stops….we will see.
The tie rod barely touches the springs now, so I will do as @EWheeler suggest and lower the perches. I can loose about 3/4 of an inch there.
I’ll report back once I have it back together, then we’ll see about caster. The pinion flange is currently barely pointing up.
Thank for the help!!
Pic is after I returned the springs to factory direction.