Saginaw Steering Not Centering

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RWBeringer4x4

Mechanically Challenged
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Ok - I know there was just a thread on this recently, but there hasn't been a definitive answer. Now experiencing the same issue and I thought I would revisit this with a couple of very specific questions.

I just replaced the Steering shaft and power steering box on my FJ40 (saginaw conversion). Picture of the finished product below. At the same time, I replaced the drag link ends and tie rod ends with new 555 ends from Kurt. The truck was then re-aligned by an alignment shop.

Also of note: I have stock height springs/shackles, along with 31 inch tires. No lift.

The new steering feels great, the truck tracks straight (no drift) but it isn't re-centering out of turns.

From what I've read, there are 2 potential issues:

1. Caster: Reading some other forums, it seems like caster is what returns the wheels to center. As far as I know, the truck was returned to stock caster specification (I'll have to ask). Because I have a "non-stock" steering setup - could caster shims be necessary?

2. Box Adjustment: This was a rebuilt, 4-turn, 76' J20 box I picked up from AutoZone. To my knowledge, nobody moved the screw from wherever the rebuilder left it. Should I mess with the adjustment screw, and see if it helps?
Finished Steering Box.jpg
Hose Routing.jpg
 
I would add about 2 degrees positive caster, lower the driveshaft end of the diff, with shims to see if that helps. The Saginaw system may not respond to the minimal amount of stock caster, which IIRC is about zero to 1 degree positive. John
 
I would add about 2 degrees positive caster, lower the driveshaft end of the diff, with shims to see if that helps. The Saginaw system may not respond to the minimal amount of stock caster, which IIRC is about zero to 1 degree positive. John

Right, everything I have read says stock is 1 degree positive caster. Just been reading conflicting reports of whether or not more is necessary with power steering. Some seem to blame caster. Others blame "bad box rebuilds" etc.
 
I would add about 2 degrees positive caster, lower the driveshaft end of the diff, with shims to see if that helps. The Saginaw system may not respond to the minimal amount of stock caster, which IIRC is about zero to 1 degree positive. John

I concur. Take it to at least 2º (maybe 3º) positive caster. I am assuming the shop got the toe-in right.

That said, just two months ago I replaced a leaking box with an O'Reilly "rebuilt" that had enough slop to produce the dreaded death wobble :eek:. Put on another box and presto! No problems.
 
I concur. Take it to at least 2º (maybe 3º) positive caster. I am assuming the shop got the toe-in right.

That said, just two months ago I replaced a leaking box with an O'Reilly "rebuilt" that had enough slop to produce the dreaded death wobble :eek:. Put on another box and presto! No problems.

Thanks, Dick!

Reading this post, I just realized that I still owe you a busted transfercase. I'm sorry! Totally slipped my mind...

I talked to my mechanic, sounds like the alignment was set to stock - 1 degree positive caster angle...

I'm not getting any death wobble (only taken it to about 50mph so far) and the tires aren't tracking ruts in the pavement or anything - steering just isn't resetting. There's also about 1-1.5 inches of "dead" space from center in either direction before the wheels respond. I'm not sure if that's normal...Either way, BOTH of these things were true with the previous power steering box (not resetting and some dead-space) so my guess is caster is the culprit...

Has anyone run their stock settings, with success, when running a saginaw setup - or is more caster pretty much essential?

At this point, should I even mess with the gear-lash settings in the box, or should I assume caster and look for shims, etc. first?
 
You could test the theory out by temporarily installing a shorter set of rear tires , probably about 2" difference to the front . That will increase the angle on the front king pins and show if castor is the issue .
Sarge

Never thought about doing this...Very cool trick I'll have to remember.
 
You could test the theory out by temporarily installing a shorter set of rear tires , probably about 2" difference to the front . That will increase the angle on the front king pins and show if castor is the issue .
Sarge

What about just letting 2 inches worth of air out of my existing tires?:hillbilly:
 
I realize the OP is really looking for caster advice, but if someone is considering purchasing a rebuilt steering box I HIGHLY recommend these guys: http://www.redheadsteeringgears.com/

Unlike the typical "re-seal and re-paint" rebuilds that you'll get pretty much everywhere, the Red Head boxes are re-machined and improved. Definitely worth the money (I've bought three)...
 
I realize the OP is really looking for caster advice, but if someone is considering purchasing a rebuilt steering box I HIGHLY recommend these guys: http://www.redheadsteeringgears.com/

Unlike the typical "re-seal and re-paint" rebuilds that you'll get pretty much everywhere, the Red Head boxes are re-machined and improved. Definitely worth the money (I've bought three)...

Good to know, if it winds up being the box, I'll consider it. If you don't mind me asking, what is their pricing like? PM me! Thanks.
 
2-3 I run 6 with 35's and love it.

By the way very very nice job on installing the lines and boxing everything in. Don't see many people take the time to do the finish work.
 
2-3 I run 6 with 35's and love it.

By the way very very nice job on installing the lines and boxing everything in. Don't see many people take the time to do the finish work.

Thanks Trollhole -

I've been discussing this on my "Clustertruck" thread as well - I also have a nasty, bent shackle that may or may not be contributing. (see below) I'm going to overhaul my entire front suspension (pins, bushings, shackles, u-bolts) and see what happens. I'll probably pick up some 4* shims as well, as I have some (free-to-me) extended shackles laying around. I think they're about 1.5" over stock.

Honestly, I can't take credit for the welding, as my local shop did this for me. I've gone to him for fabrication work before and I've always been extremely impressed with his work. He really went above-and-beyond on my frame. I'm really impressed with how it turned out! Good to know someone who takes pride in his work!
Bent Shackle.jpg
 
I wouldn't trust an alignment shop that would do an alignment with a shackle that looks like that.

So should I buy a hardware store angle finder and figure out what kind of caster I'm currently working with? Or is it irrelevant because it will be changing when I fix the shackle?

I checked today, seems like the shackle absorbed the impact - spring hangers look straight...
 
A simple angle finder will show to a certain extent where you are at with castor but it really takes an honest guage to do that which requires attaching it to the front hub and rotating the steering through it's axis - this zero sets the guage and then you can take an exact reading . I have an old Snap-On kit that was given to me by a guy that quit turning wrenches and it's come in quite handy . Simplest way is to install some shims and go from there , you can guage scrub by turning the wheels through a wet patch of pavent and looking at the tire tread for indication if it's running too far on the inside of the tread .

That shackle isn't helping a bit and could be binding that one spring to not allow the axle to rest on it's correct castor angle . Also, look very closely at the springs both fore and aft of the spring perches and make sure they aren't bent , usually pretty obvious .
Sarge
 
A simple angle finder will show to a certain extent where you are at with castor but it really takes an honest guage to do that which requires attaching it to the front hub and rotating the steering through it's axis - this zero sets the guage and then you can take an exact reading . I have an old Snap-On kit that was given to me by a guy that quit turning wrenches and it's come in quite handy . Simplest way is to install some shims and go from there , you can guage scrub by turning the wheels through a wet patch of pavent and looking at the tire tread for indication if it's running too far on the inside of the tread .

That shackle isn't helping a bit and could be binding that one spring to not allow the axle to rest on it's correct castor angle . Also, look very closely at the springs both fore and aft of the spring perches and make sure they aren't bent , usually pretty obvious .
Sarge

Thanks sarge,

The other three springs seem pretty straight, obviously. The one in question - obviously this one is being pulled inward by the shackle, so it has to be bending, at least slightly. Not sure how to tell whether or not it is permanent without unbolting the shackle. What's the recourse there - can bent springs be "unbent" effectively, or am I looking at new springs? I'd probably be looking at replacing all 4 if that was the case, as I have no idea who made the ones currently installed...

The plan is, ultimately, to go to a 2-2.5 inch lift to clear 33's anyway, so this wouldn't be the end of the world. That said, it would turn an otherwise inexpensive suspension overhaul into a much more pricey proposition!
 
Like I said , drop the rear by a couple of inches and that should gain around 1.5* on the front axle and see if tries to return to center better . Low speed will show if it's working . A small angle finder will help too but it's tough to get a decent reading off the knuckle arms especially if it's an earlier small pattern set .
Sarge
 

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