[SOLVED] Manual steering gearbox woes... (1 Viewer)

[JunkCrzr89]

For the TLDR crowd: I rebuilt a manual gearbox sourced from another 40, which may have had issues that were not divulged by the person/not noticed by me when rebuilding (e.g., possibly bent worm gear shaft or sector shaft???), and there is now a deadspot in the steering and the steering will not attempt to return back to dead center on its own (i.e., it gets stuck when turned left or right, and must be forced back to center).

Detailed:
We have a '73 FJ40 that my Dad bought new from a Toyota dealer back in the early spring of 1973; he is the original and only owner of it. Between 1998-2004, we did a complete frame-off restoration and returned everything back to (or as close to) original as possible (adding an Aqualu tub being the most notable exception). In the last few years, we've added City Racer OEM replica 16'' wheels wrapped in Yoko G003 MTs, converted the front from drum brakes to disc brakes, upgraded to a City Racer booster and FZJ80 non-ABS master cylinder and added a proportioning valve, and replaced all of the hard and soft brake lines and clutch lines. My daughters love the damn thing and my did still cruises around in it regularly on his mountain farm and around the local towns.

Original Problem:
We started having a lot of slop in the steering beginning about 5 years ago (roughly 15 years after the rebuild). Last year, I traced the slop to a combination of play in both the manual steering gearbox and center arm. Fast forward to this spring and Dad calls me complaining about the steering slop having gotten so bad that he can barely keep the 40 between the lines when driving over 20 mph. I have him video call me and sure enough there was ~6" of rotational freeplay at the steering wheel before resistance was felt. So we conclude that the box is likely fubar and now is a good time to just completely overhaul the entire steering system.

Attempted fix:
Earlier this month, I pulled out the entire steering system and replaced everything - all end links, pitman arm and joint, steering stabilizer, steering coupler, etc. - and I also rebuilt the center arm and rebuilt a spare manual steering gearbox that a friend gave us 10 years ago from a '74 FJ40. When I pulled the original '73 gearbox out, it was clear that was the source of most of the slop: There was 2.5-3" of rotational freeplay at the output/worm shaft, and the preload adjusting screw was screwed all the way in. By the time we got the original box out I had already "rebuilt" the spare '74 box following the FSM instructions the night before. This rebuild included replacing both bearings with new Toyota units, the worm shaft output seal and sector shaft output seal with new Musashi units, and a new gasket for the sector shaft cover, and setting preload per the FSM's specs. I noticed no irregularities in the sector or worm shafts, or the teeth on worm or sector shaft gears; it all looked to be in really good condition. So we swapped in this '74 box that I had rebuilt and bolted it all back up.

Results/Issues:
The steering is now substantially tighter and more responsive, and we are at the low end of the FSM-spec'd freeplay at the steering wheel, all of which is GREAT. However, it feels like there is a dead spot in this gearbox just a bit right of dead-center. Additionally, the steering will not even attempt to start returning towards center (or straightening out) on its own and instead requires forcing the steering back towards center. In other words, if you turn left or right and let go of the steering wheel, the truck is going to keep going left or right and never start straightening out. I've pulled this box back out, disassembled and reassembled it, and reinstalled it two more times and cannot figure out what is wrong. Thus, I've come to the conclusion that there is something wrong with either the worm gear shaft or sector shaft - perhaps one is slightly bent enough to cause it to get stuck and not return towards center?

Questions:
1) Can anyone think of what might be causing the above issues, and 2) Is there anyone who still rebuilds these manual boxes that I could send the original '73 box to? I'm thinking that having a professional rebuild the original box and then swapping it back in might be the best course of action at this point, since my attempt at rebuilding the '74 box has apparently led to issues; although, said issues may have been present in that '74 box 10 years ago when it was given to us and that's why we got it for free . I do not know.

 

[B y r o n]

When you did the re-assembly did you have it aligned? If not set the toe-in to 1/8" and see if it fixes your problem.

 

[Skreddy]

I agree with Byron. I’d be looking at alignment. Are the shackles longer than stock or a lift possibly needing caster shims?
If you jack the front tires off the ground, can you smoothly spin the wheel fully left and right? Could just have a worn spot on the worm gear and need to loosen it off a little.

 

[wngrog]

Sounds like a center arm that is too tight on the return to center.

You have 2” longer shackles from the pic. Get some STEEL 4* shims from @orangefj45 at Valley Hybrids with new center pins.

Also do the toe in as said above

 

[JunkCrzr89]

When you did the re-assembly did you have it aligned? If not set the toe-in to 1/8" and see if it fixes your problem.

We set the alignment (toe-in) via the dual tape measure approach and got it dead-on 1/4” toe-in the day that we finished replacing everything. Nevertheless, we took it to the local Toyota dealer 2 days ago for an alignment. The steering not returning to center issue persists.

If you jack the front tires off the ground, can you smoothly spin the wheel fully left and right?

No. That’s the problem - it’s getting stuck even with the front end off the ground.

Are the shackles longer than stock or a lift possibly needing caster shims?

You have 2” longer shackles from the pic. Get some STEEL 4* shims from @orangefj45 at Valley Hybrids with new center pins.

They’re 1.5” longer shackles that we installed 15 years ago, along with 4* shims from CCOT at that time. Never had an issue with the steering until the old box got sloppy a few years ago and we put the rebuilt box in this month.

 

[JunkCrzr89]

Sounds like a center arm that is too tight on the return to center.

That’s certainly possible; although I torqued the center bolt and lock nut/cover plate back and checked preload per the FSM. I’ll try backing it off a bit and see if that helps - we’ve not tried that yet.

 

[DSRTRDR]

it isn't clear to me whether you also rebuilt the center arm ? I previously found that contributing to steering problems

there's a manual steering box assembly standing around in my parts room from when I switched to power steering - and I also have a never-used spare center arm rebuilt kit that I won't need anymore . . .

I assume you have all new leaf spring bushings ?

 

[73FJ40]

"Results/Issues:
The steering is now substantially tighter and more responsive, and we are at the low end of the FSM-spec'd freeplay at the steering wheel, all of which is GREAT."

Could it be your free play adjustment is too tight? It's my understanding that the gears in the box tend to wear in the center position because most of their life they're more or less steering straight. If there is limited free play centered, when you turn left or right where the gears have no wear, there is no free play and the gears would tend to bind.

I think you should consider backing off the adjustment to the high end of the FSM spec and see what happens. If you still have binding, I'd go even further, just to see if the symptoms clear up.

 

[JunkCrzr89]

it isn't clear to me whether you also rebuilt the center arm ?

Yes, I rebuilt the center arm with a Fuji kit

and I also rebuilt the center arm and rebuilt a spare manual steering gearbox that a friend gave us 10 years ago from a '74 FJ40.

I think it’s possible that I screwed on the new center arm top cap and bolt too tight, as @wngrog suggested, which may be causing the steering to not return to center on its own.

I think you should consider backing off the adjustment to the high end of the FSM spec and see what happens.

Therein lies a problem that I forgot to note in my original post. The preload adjusting screw is unscrewed nearly all the way out, and there is so much resistance from the sector shaft on that screw that I could not get it to screw into the plate/cap more than 2 full turns. Also, I reinstalled the bearing cap/plate with the original 3 shims that it had when I took it apart. From my understanding, the only way to reduce the tightness of the steering at the box is to add more shims.

 

[Living in the Past]

From my understanding, the only way to reduce the tightness of the steering at the box is to add more shims.

Believe it the nut/square head bolt on the opposite side of the pitman arm that adjusted the tightness. Loosen the nut adjust the bolt then tighten the nut again. Keeping a wrench on the bolt while tightening the nut prevents it from moving. The shims were originally installed to center the sector shaft over the worm gear. For wear on the sector shaft moving shims to the opposite side changes where sector shaft rides on the worm gear. This helps reduce the free play in the box.

 

[JunkCrzr89]

Believe it the nut/square head bolt on the opposite side of the pitman arm that adjusted the tightness. Loosen the nut adjust the bolt then tighten the nut again. Keeping a wrench on the bolt while tightening the nut prevents it from moving. The shims were originally installed to center the sector shaft over the worm gear. For wear on the sector shaft moving shims to the opposite side changes where sector shaft rides on the worm gear. This helps reduce the free play in the box.

To my knowledge, that's a widespread misconception. IIRC, @Coolerman and others (as well as the directions in the FSM) have clarified that the screw on the sector shaft cover plate is only there to adjust sector shaft end play, and does not influence steering tightness/looseness. In contrast, the shims under the worm shaft cover plate are there for setting the worm shaft bearing preload and, therefore, removing shims = more bearing preload = tighter steering, whereas adding shims = less bearing preload = looser steering.

 

[Living in the Past]

To my knowledge, that's a widespread misconception. IIRC, @Coolerman and others (as well as the directions in the FSM) have clarified that the screw on the sector shaft cover plate is only there to adjust sector shaft end play, and does not influence steering tightness/looseness. In contrast, the shims under the worm shaft cover plate are there for setting the worm shaft bearing preload and, therefore, removing shims = more bearing preload = tighter steering, whereas adding shims = less bearing preload = looser steering.

I suggest to loosen the nut and tighten the square head nut as far as you can and tell if doesn't effect how hard it is to move lthe steering wheel. Agree it's for end play. Too loose and sector shaft moves in and out which results loose steering. Too tight and whats to bind the movement of the sector shaft. It's not a fit but will effect steering if not adjusted properly. Moving shims from one side to the other effects where the worm gear contacts the sector shaft which has less wear. Old school mechanic did this to my 68 FJ40 back in the eighties. Everything I had done up to that point had no effect on steering wondering and tracking in ruts. After that steering was fine. Never said remove shims only move to opposite side. Only effect that has is where the sector is centered on the worm.

 

[JunkCrzr89]

Moving shims from one side to the other effects where the worm gear contacts the sector shaft which has less wear. Old school mechanic did this to my 68 FJ40 back in the eighties. Everything I had done up to that point had no effect on steering wondering and tracking in ruts. After that steering was fine. Never said remove shims only move to opposite side. Only effect that has is where the sector is centered on the worm.

I can envision how that would work and possibly be useful on the older (pre-72?) gearboxes, given the circular design of the worm gear and sector shaft gear "rollers". Those boxes also had some adjustment for where the sector shaft gear was located on the sector shaft via a thru-bolt and nut through the rollers. I don't know how that could work on the later gearboxes like this '73, though, because the roller design was replaced with a worm gear that has a rectangular box with 4 teeth on it and the sector shaft gear has no rollers and a box with 5 teeth, such that the meshing of gears occurs across the entire plane. So moving the shims from the worm shaft cover to the sector shaft cover would not change where along the plane the teeth mesh together; the same teeth would mesh at the same locations across the plane.

Older gearbox design:

Later gearbox design:

I suggest to loosen the nut and tighten the square head nut as far as you can and tell if doesn't effect how hard it is to move lthe steering wheel. Agree it's for end play.

I already have that screw/bolt tightened in as far as it will go with the locknut loosened, which is not much - maybe 2 full threads is all i could get before the resistance was so substantial that it wouldn't screw in anymore.

The preload adjusting screw is unscrewed nearly all the way out, and there is so much resistance from the sector shaft on that screw that I could not get it to screw into the plate/cap more than 2 full turns

 

[thundermcawesum]

it isn't clear to me whether you also rebuilt the center arm ? I previously found that contributing to steering problems

there's a manual steering box assembly standing around in my parts room from when I switched to power steering - and I also have a never-used spare center arm rebuilt kit that I won't need anymore . . .

I assume you have all new leaf spring bushings ?

What would you need to get for that center arm rebuild kit?

 

[wngrog]

What would you need to get for that center arm rebuild kit?

Steering Center Arm Rebuild Kit for Land Cruiser FJ40 FJ45 FJ55

Steering center arm rebuild kit for 6/'69 and later Toyota Land Cruiser 40 Series or '68 to 7/'80 FJ55. Corresponds to OEM part # 04453-60020 / 04453-60021. Made in Japan.

www.cityracerllc.com

 

[JunkCrzr89]

What would you need to get for that center arm rebuild kit?

I used this kit from @cruiseroutfit

Center Arm Rebuild Kit - Fits 6/1969 - 1984 40/42/43/45/55 Applications (ST60021)

Toyota Land Cruiser Steering Parts

cruiserteq.com

 

[Living in the Past]

I can envision how that would work and possibly be useful on the older (pre-72?) gearboxes, given the circular design of the worm gear and sector shaft gear "rollers". Those boxes also had some adjustment for where the sector shaft gear was located on the sector shaft via a thru-bolt and nut through the rollers. I don't know how that could work on the later gearboxes like this '73, though, because the roller design was replaced with a worm gear that has a rectangular box with 4 teeth on it and the sector shaft gear has no rollers and a box with 5 teeth, such that the meshing of gears occurs across the entire plane. So moving the shims from the worm shaft cover to the sector shaft cover would not change where along the plane the teeth mesh together; the same teeth would mesh at the same locations across the plane.

Older gearbox design:
View attachment 3097840

Later gearbox design:
View attachment 3097841


I already have that screw/bolt tightened in as far as it will go with the locknut loosened, which is not much - maybe 2 full threads is all i could get before the resistance was so substantial that it wouldn't screw in anymore.

I don't know what to say except I am just living up to my user name.

Never had to deal with those later boxes. Only driven one of my three 9/72+ cruisers and that was back in the nineties. Only steering issue was a bent tie rod. But I noticed a seal went and drained the oil a awhile. Puddle appeared where it's stored in a garage. It's going to need new sesls as well as a 79 steering box I picked up back in 1983. Only has 30K miles on it and smooth as a baby's bottom turning by hand. With the Pittman arm removed is that big just changing deals.

 

[DSRTRDR]

What would you need to get for that center arm rebuild kit?

send me a "conversation" with an offer - shipping won't be more than $10

 

[JunkCrzr89]

Just to close this out:

First, thanks to all of you who chimed in with suggestions.

Second, we ended up pulling back out (for the 4th time ) the box that we “rebuilt” and sending it to Redhead for a proper expert inspection and rebuild.

Turns out my original suspicion was correct

Thus, I've come to the conclusion that there is something wrong with either the worm gear shaft or sector shaft - perhaps one is slightly bent enough to cause it to get stuck and not return towards center?

Redhead had to replace the worm shaft (extra $150 on top of the base rebuild) because it was slightly bent and out of spec. The sector shaft and worm gear were both still in good shape, but the bent worm shaft was causing the steering to bind and not return to center.

We got the box back from Redhead last week and dad has been cruising around in the 40 since. He says it steers better than the day he drove it off the lot back in ‘73!

I guess the lesson to learn here is, if in doubt, just send your box to Redhead and they’ll get it squared away in tip top shape. The cost was definitely worth it in our case!

 

[wngrog]

Excellent. Thanks for the follow up