Mini- Truck Steering Box Rebuild

77mustard40

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Good evening all. A little over five years ago I ditched the OEM manual steering box for a mini-truck box in my 77. At the time it was one of those mods that leaves you wondering why you didn’t do it sooner. My truck is no show princess but more of a fairly clean rig that gets driven regularly and gets wheeled hard a couple times a year. When I committed to the mini box set up I started collecting parts which took several months, once I had a good used steering box in hand I sent it over to San Angelo for West Texas to rebuild it. Unfortunately it was just a few month after the install that it developed a slow dripping leak. Just enough to put a couple drops under the truck a week. Over time a couple turned to a few until a couple of weeks ago when it started to puke pretty bad. My first thought was to pull it and send it to RedHead Gears but when I got the quote I decided to see how bad I could mess it up on my own. Sometimes I need to just pour myself into an a project I haven’t attempted just for the hell of it. I ordered a Gates rebuild kit off Rock Auto that set me back $30 and committed myself to at least trying to do this. There’s a first time for everything.

This weekend I started tearing down my steering and it was a terrible weekend here for garage time, high temps both days was north of 107F at my house. I debated pulling it without removing the fender but decided to open her up and clean up what I could while it was apart. Removing the fender and steering box was pretty straight forward. Tearing the box down was a little bit of a challenge. The adjustment screw had been adjusted down to where it was flush with the lock nut (I never adjusted the box) and I struggled breading it free. Ended up backing off the nut and screw as a unit a few turned and then dropped the whole box into the vise, torched the crap out of the nut and screw and finally got them to break free. It looked like a combo of painting the box after it was assembled along with Loctite on the treads. Once I got that separated the box came apart without too much difficulty. I’m praying I caught all the ball bearings that came out!

The heat shut me down since this is happening in the garage, so I will pick it up once the heat breaks later in the week.

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Believe the mini truck box because of it's location in the truck did not have a heat shield. In the 40 series steering boxes have a heat shield starting 9/75. That was shortly after the 2F started. If you don't have one I would suggest making something. Headers heat the engine bay more than stock exhaust. Not sure it would help with the seals but know it wouldn't hurt.
 

77mustard40

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Believe the mini truck box because of it's location in the truck did not have a heat shield. In the 40 series steering boxes have a heat shield starting 9/75. That was shortly after the 2F started. If you don't have one I would suggest making something. Headers heat the engine bay more than stock exhaust. Not sure it would help with the seals but know it wouldn't hurt.
Appreciate the input. I installed a Champion radiator to my truck a few weeks ago and it has an integrated cooler on the bottom of the radiator so I was planning to re-route my low pressure side to use that capacity for the PS system but had not thought of a heat shield. Definitely something to consider.
 

pjohnson

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Definitely something to consider.
My drivers floorboard always got pretty hot. So much so that I could feel it through my shoes. How hot does your floorboard get?
I had a saginaw box so it didn't affect my ps, but it sure made it hot in the cabin.
 

77mustard40

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My drivers floorboard always got pretty hot. So much so that I could feel it through my shoes. How hot does your floorboard get?
I had a saginaw box so it didn't affect my ps, but it sure made it hot in the cabin.
I know it might sound crazy but I don’t have a heat problem in the cabin.
 

pjohnson

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The heat shield from the FJ40 manual steering box is easily modified to fit the minitruck PS box. But, of course, you have to still have an FJ40 heat shield in the first place... ;)
 

iptman

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@SuperDuperCruizer did a really good write up on the rebuild process.

Found it....

 

77mustard40

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Finally got a few minutes this afternoon to get a few things done. After reading the thread referenced in post #9 I decided I better count the ball bearings, wouldn’t you know I have 43 and it sounds like I should have 44. I’m pretty darn sure I didn’t lose one while disassembling so I need to figure out if I should find one or reassemble with 43, thoughts?

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77mustard40

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Got some of the seals and Teflon rings replaced. Used some hot water to soften the Teflon and also used some light grease to assist. The Gates kit I bought doesn’t have every Teflon ring so I’m going to hit the deck for the Toyota kit.

I also noticed I have a slight wear ridge on one of the shafts. What’s the best way to clean that up? Emory cloth, if so what grain? Seems like I need something really fine.

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77mustard40

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After another month of 100+ temps it finally cooled off here and I got my lazy butt out in the garage. I used some 1,500 grit and a plastic shipping strap to polish up the cross shaft. Not perfect but it’s cleaned up and the wear ridge is minimal.

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77mustard40

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Noticed a gouge in the worm shaft, probably from its last rebuild, so I removed the old Teflon and rubber rings and filed out the burr before replacing those rings. BTW these rings don’t come in the Gates kit but are in the Toyota kit

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77mustard40

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Assembled the worm shaft into the power piston. After reading the thread referenced in post #9 I decided to take a different tack with the ball bearings. I inserted the worm shaft into the power piston about an inch and a half and started loading the ball bearings so that as I rotated the worn shaft further in, the balls would rotate into place. I watched for them show up looking down the second hole. Once I had that section of the shaft full of bearings, I filled the cross tube with ball bearings and added a little moly grease to each one to hold them in place. Next I mated the opposing half of the cross tube to the one with the bearings and worked it into place. Set the cross tube with the set screws and that part is done.

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77mustard40

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The last o-ring to replace was the small one the sits in a recess in the cap where the ATF passes into the housing, nice and quick switch. Then I ran into trouble assembling the power piston into the housing. The new o-ring / Teflon on the outside of the power piston makes for a really tight fit. I didn’t want to f up that ring and need to buy another kit just to replace that one ring if I fubarred the darn thing. I put a hose clamp around that Teflon ring to compress it and will try again in the morning.
 

77mustard40

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Getting it back in the housing without cutting the Teflon ring was the hardest part for me.
Any tricks to the trade? It’s a tight mother, I can’t get it to start down the cylinder.
 
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The heat shield from the FJ40 manual steering box is easily modified to fit the minitruck PS box. But, of course, you have to still have an FJ40 heat shield in the first place... ;)
@SteveH Did you do this? Do you have any pics? I have a mini truck box and headers. Not an issue yet, but I can see its potential to be one. I have the heat shield off my old steering box that I can modify or fab up a new one.
 

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