FJ40 Steering Mods - Pucker up!

[RuckitUp]

So I picked up a project '77 40 with a 350sbc. Saginaw ps upgrade it appears with a tilt steering column installed.
The sphincter was tight when I was driving it past 75kph as the steering would walk on me or wander. Hard to control and IMO unsafe. So I'm looking to do some troubleshooting, starting with the least expensive first. Thought I would throw it out to the masses to see if you have any harsh observations of what was done previously and some suggestions.
My first thoughts, which may be seen by pics:
- steering linkage ok, but worth replacing tie-rods.
- replace steering damper, but not a fan of how its set up rn
- there is a 2.5-3" lift from what I can tell, so is angle from track bar and drag link too much?
- too big of tires, 17 inchers but really wide. looking to replace with OE rims and 33x10.5r15s like my 60
- ps box leaking, rebuilds kinda suck
- can't see what the rag joint looks like yet
- another joint closer to firewall with what appears to be a torn rubber joint. crappy sitch here is it real tight to exhaust pipes.
- yes i know my birfs need attention

Any other observations would be awesome.

 

[RuckitUp]

more photos

 

[pb4ugo]

Your knuckles needs to be serviced evidenced by the badly leaking knuckles, The front crossmember has been hacked to fit the steering box. This is a high flex area in the frame. You can see the crossmember is starting to crack. This needs to be address b4 it causes some serious frame damage. Have someone shake the wheel back and forth and look for movement or slop at the tre's and be sure the box is secure to the frame. Your steering geometry may be out of spec. What is the current caster angle? Negative caster or not enuff caster will cause the symptoms you describe. It also looks like your box is leaking. You may have a lot of bump steer because of the angle of your drag link in relation to the tie rod. I would install a U joint instead of the cupped joint in the steering shaft and run a double D steering shaft if it doesn't have one already. The whole setup is a little sketchy.

 

[pb4ugo]

It looks like the steering shaft is rubbing the frame too.

 

[fjc-man]

Are you using a wheel spacer on the L/F but not on the R/F?

 

[Grayscale]

Is the lift partly accomplished with longer shackles? You'll notice that the wedges between the axle housing's spring perches and the top leafs are almost in slightly different positions on the passenger and driver-sides? My guess is that the spring pins are not threaded thru the holes in the castor-adjustment wedges, as there looks like a gap in the aft-side of the perch, where they should be closer to flush. You might need a longer spring pins so that the springs are in the right place on the axle housing's spring perches?

 

[cruisermatt]

Start with the bald, cracking, 20 YEAR OLD, tires

 

[franklin40]

crossmember for sure needs to be reinforced where the steering shaft goes through. check bushings in the springs (they look like newer springs so they’re probably ok but worth checking) make sure shackles are snug but not too tight that they don’t move. check castor angle. and make sure you’ve got enough. with power steering you could probably go (edited to correct) pos 3-5 degrees. what that does is cause the knuckles to be at the lowest point in their arc when centered. the weight of the vehicle will keep it there and it’ll want to track straight. if there’s too much castor then the wheels will wander and the more your axle is rotated forward eventually the arc center will be at the highest point the the steering arc and it will want to settle to a fully turned position making it impossible to track straight. longer shackles and lift springs can chance that. mine wandered like crazy before i addressed those things.

after than have someone move the steering wheel while parked and see if you can find any play in your linkages and address as you find issues.

 

[franklin40]

and just because we need more pics of the rest of the rig!

im in the process of a mini truck power steering conversion on my 72. my manual steering box is very loose and i want to run 33s so im hoping itll be my last step to a 40 that tracks straight!!

 

[pb4ugo]

crossmember for sure needs to be reinforced where the steering shaft goes through. check bushings in the springs (they look like newer springs so they’re probably ok but worth checking) make sure shackles are snug but not too tight that they don’t move. check castor angle. and make sure you’ve got enough. with power steering you could probably go neg 3-5 degrees. what that does is cause the knuckles to be at the lowest point in their arc when centered. the weight of the vehicle will keep it there and it’ll want to track straight. if there’s too much castor then the wheels will wander and the more your axle is rotated forward eventually the arc center will be at the highest point the the steering arc and it will want to settle to a fully turned position making it impossible to track straight. longer shackles and lift springs can chance that. mine wandered like crazy before i addressed those things.

after than have someone move the steering wheel while parked and see if you can find any play in your linkages and address as you find issues.

Negative Caster=BAD, wanders and is darty, white knuckle driving. Positive Caster=GOOD. Tracks straight, steering wheel returns.

 

[pb4ugo]

 

[franklin40]

Negative Caster=BAD, wanders and is darty, white knuckle driving. Positive Caster=GOOD. Tracks straight, steering wheel returns.

yes that is correct i had my pos/neg backwards. sorry! axis of steering rotation should be angled backwards.

 

[RuckitUp]

That's awesome guys. Great info.
I have some concerns with placement of the steering box, notwithstanding the frame repair, as it is level. I have come to believe that having a stub shaft and u-joint, shaft then another cup joint or u-joint is a big no-no. To top it all off there is no support of the shaft near the u-joint.
That box should be set on an angle, no?

 

[B y r o n]

So it appears that you have a set of OME Dakar springs and caster adjustment shims. From a cost perspective, have the alignment checked. They can give you the numbers and are setup to correct things if the alignment numbers are bad. They will also inspect the tie rod end joints for excessive wear which can also cause it to handle poorly.

You can also inspect the connections yourself with a friend. Have them turn the steering wheel left and right and look for slack in the tie rod ends. You can also check your toe in and ensure it is between 1/8" & 1/4" at most.

You already know the gearbox is leaking and needs to be resealed or replaced. If it is worn than it can also exhibit slop and cause wondering on the road.

Steering dampeners were employed to delay wondering. A good steering setup does not need a dampener which only adds resistance in steering effort, power steering hides this resistance.