Left Turn Steering Vagueness - OME Dakar

[Semper Gumby]

Installed the Ultimate 40 Series OME Dakar kit in 2018 from Cruiser Outfitters (huge assist by @cruiseroutfit ) on the 1978 FJ40.

When parked, the FJ40 doesn't show much sag. But when you sit in the driver seat, it feels like it tips that way. Concerning is left-hand banking and turns have the steering wheel swimming and feeling vague. Right turns are less of concern.

Running BFG 31x10.5 R15s (air pressure - check) and a Saginaw power steering conversion (seems fine)

For the OME, the shackles are aligned (front & rear). The front springs are "o" driver side and "-" passenger side. I don't recall the rear springs being identified as such.


I'm 6'3" and 230lbs, so yeah, there's some weight on that side. But I've gained maybe 10-15lbs since the install but this feels like more than that.

Sounds similar to what this guy experienced: Unpredictable cornering - https://forum.ih8mud.com/threads/unpredictable-cornering.1287590/

I went through Cruiser Outfitters leaf spring tech page (Cruiser Outfitters - https://www.cruiseroutfitters.com/tech_OME_leaf_tech.html) but my issue seems a little more specific than what's covered there. At one point I thought about flipping the spare carrier to the other side to balance things out. Otherwise I need the wife riding on the outside step like the J22 & J24 boat racers.

Is 6-7 years about right for the driver side spring to sag from regular use, or should I be checking bushings and other components first?

 

[peesalot]

My 40 always developes a left turn vagueness when the pass side front shackle is loose, FWIW. As far as the sag, maybe add a medium leaf on the driver front pack ? hold the big guy up....

 

[mattressking]

Sagging springs won't directly cause vagueness. Like any car, start at the wheels and move towards the steering wheel. First make sure each tierod is tight and doesn't have play. Then check the tension/play on the center-link (these need grease and rebuilding overtime). Then adjust the drag link per FSM (something like full-tight, then back off 3/4 turn or something like that). Once that is all tight and verified and the toe measurement is set, then look at steering gearbox. Make sure its tight and adjusted correctly with fluid and preload is correct, this will require removing the gearbox.

If all that checks out and its still vague, check the wheel bearing pre-load AND the knuckle (trunion) bearings for correct preload.

Lastly, make sure tires are filled to ~32psi and match, lugs are tight, steering rag joint is in healthy shape and leaf spring/shackle bushings are all healthy and tight.

FYSA; The steering damper doesn't fix anything, it's there as a comfort aid just so you're aware.

 

[Semper Gumby]

Sagging springs won't directly cause vagueness. Like any car, start at the wheels and move towards the steering wheel. First make sure each tierod is tight and doesn't have play.

You're right. I need to do the work instead of looking for an easy answer.

Got lazy and thought the forum might save me some time.

Tie rods and drag link - weren't replaced in 2018 because they were tight. Six years in SWFL, they're probably done. I'll check for play.

Saginaw power steering - Previous owner did it years before I bought the rig. The conversion looks like an old Downey Saginaw kit. The drag link et al ... are probably created by the lowest price manufacturer ... so likely time to replace. I dig into the proper alignment as I took it for granted all these years.

Steering box - the vagueness only happens in left turns. Right turns feel solid. Kicking the issue with my next door neighbor who drift races - he challenged to me to think over-pressure in the Saginaw causing over-assist. This Borgeson article covers it: Diagnosing Saginaw Power Steering Woes With Borgeson Universal - https://www.chevyhardcore.com/news/diagnosing-saginaw-power-steering-woes-with-borgeson-universal/

Wheel bearings and knuckle bearings - will check preload.

Basics - tires at 32psi, lugs tight. Will check rag joint and spring/shackle bushings.

Steering damper - understood its comfort only. I'll check the OME unit to rule it out.

 

[Semper Gumby]

My 40 always developes a left turn vagueness when the pass side front shackle is loose, FWIW. As far as the sag, maybe add a medium leaf on the driver front pack ? hold the big guy up....

My wife says I might be a little too big to hold up

 

[Gotta40]

got any pics of your drag link? mine has adjustable ends on the drag link, and they were loose. wasn't super sloppy, but the steering wheel was centered different from time to time. had to readjust them.

 

[B y r o n]

Sag cannot be avoided when adding weight to only one side of the vehicle. You might have alignment checked, without you in the seat and with you in the seat, to see if you're changing the alignment.

 

[Semper Gumby]

Quick update and credit to everyone who told me to start at the wheels and work inward. I finally crawled under the 40 properly and… yeah, this one’s on me.

When I installed the OME in 2018 along with the PS adapter plate, I knew it would change the Saginaw geometry. I even planned to let the springs settle and re-check the drag link/pitman angles. That never happened. I drove it “because it felt fine,” and then 6–7 years and ~12,000 miles of settling and wear quietly pushed everything past its limit.

Here’s what I found:

1. Drag link is 2.5–3” above the tie rod
2. Pitman arm TRE is sitting at a terrible angle
3. Steering shaft is now rubbing the exhaust manifold and engine mount (fresh marks)
4. Original TREs and original pitman arm still in place
5. Geometry that “worked enough” in 2018 is now actively unsafe

As the springs softened and the front end loosened up, the bad drag link angle went from “wrong but driveable” to “vague steering and binding on left turns.”

"Cocoa" parked until this is fixed: proper dropped pitman arm (2.5–3”), fresh TREs, and box/shaft alignment so the shaft clears the manifold.

Photos attached below for anyone curious. Appreciate the nudges as this forced me to look at what I should’ve checked years ago.

 

[cruisermatt]

Nothing in your pictures would have really changed from springs settling. The steering box is mounted to the chassis and shouldn’t move, so the steering column rubbing the chassis/header is most likely from improper installation to begin with.

lowering the drag link angle would be nice but what you have there isn’t that bad angle-wise.
However you will need a drop arm when you rotate the box up to fix your column rubbing issue

 

[Semper Gumby]

Nothing in your pictures would have really changed from springs settling. The steering box is mounted to the chassis and shouldn’t move, so the steering column rubbing the chassis/header is most likely from improper installation to begin with.

lowering the drag link angle would be nice but what you have there isn’t that bad angle-wise.
However you will need a drop arm when you rotate the box up to fix your column rubbing issue

Reading through 2017 emails with Kurt at Cruiser Outfitters to retrace my steps.

Bought a non-running FJ40 2015. Rebuilt the engine, fixed the electrical, then dealt with a serious driver side lean. That's what led to the OME upgrade and connect with Kurt and team.

Previous owner's Saginaw conversion worked with OEM suspension but was marginal.

2018 OME install - front driver shackle interfered with leaf removal. Cut it off and modified to fit.

Added Cruiser Outfitter's box plate. Kurt said it might not work with my 3-bolt box. He strongly recommended a 4-bolt box.

Never found the 4-bolt box and forgot to source the appropriate pitman arm. Put the FJ40 back together anyway; drove it nearly every weekend and to work occasionally.

New plate shifted the box. Shaft started rubbing. Geometry went off. Six (6) years later, here we are. I am damn lucky the shortcut didn't make me test my rollover skills.

 

[65swb45]

Judging from the placement of your lower column coupler, it’s reasonable to assume that you have an AA spud shaft from there to the box. Those spud shafts are old-school, and add an extra link in a chain where Saginaw is supposed to eliminate links.

A direct connection to the steering box would change the angle of the steering shaft, elevating it, and possibly clearing the header. Obviously you would need a new intermediate shaft. Those are readily available from Summit Racing.

As far as the pitman arm goes, the drop arms have a shorter reach, so while they resolve bump steer, they decrease steering radius. I agree 100% with @cruisermatt that the angle is not that bad, and the reach looks pretty good too. You might want to consider just bending the arm you have down a bit.

 

[peesalot]

it may be the pic but that drag link end looks broken ?

 

[Semper Gumby]

Judging from the placement of your lower column coupler, it’s reasonable to assume that you have an AA spud shaft from there to the box. Those spud shafts are old-school, and add an extra link in a chain where Saginaw is supposed to eliminate links.

A direct connection to the steering box would change the angle of the steering shaft, elevating it, and possibly clearing the header. Obviously you would need a new intermediate shaft. Those are readily available from Summit Racing.

As far as the pitman arm goes, the drop arms have a shorter reach, so while they resolve bump steer, they decrease steering radius. I agree 100% with @cruisermatt that the angle is not that bad, and the reach looks pretty good too. You might want to consider just bending the arm you have down a bit.

Thanks for that explanation finally snapped the picture into focus for me (along with everyone else who responded)

I’ve been around FJ40s a long time. Picked up my first one during my first Iraq tour back in ’03, and I’ve had three (3) over the years. This one has been with me the longest. After I retired in ’06, I kept up with it for a while, but life widened in a lot of directions. I picked up my old CJ7 again, added an M35A2, and somewhere in all of that the FJ40 slipped from the center of the rotation to the back corner of the shop.

Now, in my 60s, I’m starting to feel the same drift in myself. Crawling under the truck this week drove home a simple truth: when you stop paying attention, small problems turn into structural ones. The steering wear, the angles, the binding and none of that showed up overnight. The truck wasn’t vague; I just wasn’t listening.

Your breakdown on the AA spud shaft and the compounded angle makes total sense now. That alone explains the interference and the slop. I’ll move toward a direct box connection and a proper intermediate shaft, measure everything clean, and correct the pitman arm the right way instead of chasing symptoms.

Whatever direction I go with the FJ40 long-term, ignoring it isn’t an option.

Appreciate you all snapping me out of my drift both for understanding what the FJ40 needs and for reminding me why I enjoyed these rigs in the first place.

 

[Semper Gumby]

it may be the pic but that drag link end looks broken ?

it may be the pic but that drag link end looks broken ?

Good eye

The photo definitely makes it look that way, but it’s not broken. Just a bad angle and some compression from the camera. I’ve checked it since and it’s intact.

 

[peesalot]

OK, if not broken the boot is gone and it may be able to be greased & booted but may also be toast ?
When you remove the spud shaft the connection to box becomes difficult to access, I have found that leaving box loose from frame, pushing inward, attach steering rod, reattach box, I think you have to pull hoses. The frame cut for your box is rough, there is a plate made all bent and ready to weld, dont recall the manuf, maybe Georg ? The frame cut needs a little curve shape cut out of top to allow the hose bosses to go inward far enough to make that steering rod connection accessible on the engine side. Take a look at the frame plates I mentioned, you'll see the pattern.