There isnt much info out there for us WJ guys who want to re-build/re-seal our steering boxes. Even less if you want to add a hyrdaulic assist setup.
Being a mechanic I couldnt justify spending 500+ dollars to send my gear box out and have it rebuilt and tapped, then returned with 2 pre-made/non-serviceable universal fit hoses, and a ram. Thats not even a complete kit, as its missing one major component. An oil cooler! So, I deceided to do it myself.
From the begining I was shooting to build a complete, quality, hydraulic assist setup. Including, a re-sealed and tapped box, quality ram, field servicable hoses and fittings, an oil cooler, and a "upgraded" pump, at as little cost as possible without sacrificing quality.
I figured while I was at it I figured I would do a write up for anyone who is interested in tapping their own box for hydro assist. This writeup will also work for anyone interested in re-sealing their gear box. (just skip the drill and tap steps)
List of tools required:
Pitman arm puller
- These are decently expensive to buy, if you dont already own one, you can rent one from your local parts store and it will work well enough for you to get the job done
Snap ring pliers
- having a set would be nice, but a minimum a medium pair would work
Small & medium flat head screw drivers
- I used these to pop some of the seals out of place
Side cuts/wire snips
- Aid in removing seals
3/4 inch socket
- used to remove input shaft seal
1 1/16 inch socket
- for installing input shaft seal and bearing
TWO 1/4NPT taps
- One gets cut to make a "bottoming tap" Only needed if your tapping the box
Quality 7/16 drill bit
- I say quality because we are drilling through cast. only needed if your tapping the box
3/16 or close drill bit
- Used to make a pilot hole. Only needed if your tapping the box
- used for gently tapping out/in the pitman shaft
Parts required for re-seal
Steering Gear seal kit
Autozone part# 8774 List price of 39.98. I could only find a seal kit, I could not find a complete re-build kit that offered all the bearings as well. I assume that your could get them all from the dealer, but im sure that wouldnt be cheap. I decided just to re-seal this box because I couldnt find any play in the bearings. Had there been, I may have looked more into finding bearings.
Advanced auto also offers and identical kit, just a different brand (probably made by the same company). I chose autozone because I get a significant discount from them.
Parts required for hydro assist
All of my parts for the assist portion were sourced from Summit Racing. They are somewhat local to me, so all standard shipping is next day delivery for me.
1/4 npt to -6AN adapters X2
Fragola part# 581606 $1.95 each
-6 AN fitting caps
Aeroquip part# FBM3602 $6.95 a pair. I purchased 4 (2 sets) of these just in case I blow a line on the trail and it cant be fixed. I can simply cap off the fittings on the gearbox and ram and drive off the trail as a normal rig would.
Please keep in mind that these instructions are going in order that they need to be done. BUT, some of the pictures were taken during assembly. It was a lot easier to get the proper pictures once everything was cleaned up.
Remove your power steering lines and your pitman arm from the gear box. The pimtan arm puller will put pressure agaist the pitman shaft, and the pitman arm and seperate the two. Once the pitman shaft is completely off, place it back on loosely by hand. We are going to use the pitman arm to center the gear box. Use the pitman arm to turn the pitman shaft all the way left, then all the way right. Find the center point and leave the box in that position. The pitman shaft must be centered or it wont come out.
Remove the 7 15mm bolts that hold the input shaft housing and the pitman shaft to the gear box housing (only the 3 input hosing bolts have been removed in this pic)
After that, you can gently tap the input housing off the gear box. As well as tap the pitman shaft out of the housing. REMEMBER, the pimtan shaft must be centered in order for it to clear the housing.
Remove the snap ring from the piston/worm gear assembly. CAUTION, after snap ring is removed DO NOT turn the flat on the worm gear. If you turn it to much the balls with fall out internally which will require disassembly
Sadly, I turned it to much and all the ball fell out. So if that happens to you, just keep reading and I will show you how to fix it.
Remove piston/worm gear assembly, see step 5a
I could only get the piston assembly out to a point before it locked up. The end seal was catching on the housing, so I cut outer purple teflon seal off and slid it out. After that the piston assembly came right out.
We now have a bare housing and are ready to start the drill and tap portion. If you are only using this thread in order to re-seal your box skip ahead to step 1 in the assembly portion of this writeup
The is the vein we are going to drill and tap for one of the ports. You can see in the next few pics that this vein runs from the front of the box to the back along the top.
You can see in this pic the two raised portions along the top of the box, I deceided to drill and tap the one closest to the input side of the box. Technically you could drill and tap any portion along that vein that runs along the top. I chose the hump because there is more material for better thread engagement.
Here you can see where we are going to place the fitting and how once drilled and tapped it will go into the vein
Center punch, then start drilling your pilot hole. You can see that I was slightly off center, but not enough to worry about. You going to want to be in the center of the block, but lined up with the vein.
After getting a pilot hole started, I switched over the the 7/16 drill bit. At this point I kept the bit as greased up as possible. The greas will keep most of the chips from falling into the vein.
Pic of the drilled hole once finished.
Tap the hole using your 1/4 npt tap. Keep the tap well lubricated, and work slowly. Back completely out of the hole every so often to clean the tap, at this point its do or die, you dont want to mess it up because you got lazy. If you do, you will be buying another box. You want to tap down as far as you possibly can. The more thread engaged, the better the seal and strenght of the fitting. This is where the bottoming tap will come in.
Step 4) Making a bottoming tap
Looking at the tap, can see the the bottom portion is used to help center the tap in the hole. That is great when tapping an open hole, or one thats plenty long enough for the whole tap to go in without issue, but in our case we need every thread we can get. So we make a bottoming tap by removing those first few threads. This will allow the tap to continue to cut all the way down untill it reaches the bottom of the hole its cutting into.
Mark the threads your going to cut off. I used a piece of stripping tape to mark 3 or so threads to be cut off. You dont want to take a lot of material off the end (remember its NPT so its tapered) or it will become too big to fit in the hole you tapped with your first tap.
Cut the threads off. I used a cut off wheel, but a hack saw or similar would work im sure. The key is too keep the tool cool. You dont want the tap to get too hot and loose its heat treating and strength. It took me about 4 cuts to make it all the way through. I would cut a little bit, put it under cold water, cut a little bit, cold water, etc...
clean the edges up with a file or grinder etc.
Finish tapping the hole on the top of the box. Remember to keep the tap well lubricated, keep it clean, and work slowly. Sadly I forgot to take a picture of this part, but its not really much different than step 3. After that test fit the -6an/ 1/4npt adapter. You should get a minimum of 3 threads engagement.
Step 9) locating adpater location
From the pitman shaft bolt hole flat, your going to measure 1 5/16th down. Almost directly across from the casting rib shown on the left in the pic. Marc the position with a marker
From the flat along the side of the box, measure over 3/8 in. Where this measurement and your measurement from step 9 cross will be where your going to drill.
I placed rags inside the box to help keep the shavings out of the bearings. After that just drill and tap this location just like you did in the previous steps. This time there is plenty of room for the tap to go in, so there will be no need for the bottoming tap.
Test your fittings. Test each fitting to make sure it goes properly and you get good thread engagement. Tap more if needed. After you have insured they fit well, remove the fittings. They are going to be the last thing we install after the box is back together.
CLEAN THE HOUSING. After I finished tapping the last hole I cleaned everything thoroughly using a parts wash. Brake clean would work just fine though. After that I took the wire wheel to the housing because I plan on painting it once its finished. After your done with that, clean it again. You want to make sure there is no metal shavings/dirt in the housing.
After your done cleaning, lubricate the inside of the housing using powersteering fluid. The more lubbed up, the easier it will be to installl everything. You cant have too much power steering fluid on all the parts.
This ends the drill and tap portion of this write up. Now we go back to box assembly
Flipping the box upside down in the vise (pitman shaft portion up) we are going to install the 2 seals, spacers and snap ring. The get re-installed as follows- Seal/plastic spacer (seal part in), Metal washer (buts up agains plastic spacer), Snap ring, Than outer dust seal. Basically the same was as shown in the pic (from left to right) except i messed up and switched the position of the snap ring and the dust seal. Prior to installation I gave everything a nice coat of grease.
Install pitman shaft seal/plastic spacer. Seal portion goes down
Install metal spacer
Install snap ring
Install lower dust seal
Install the new teflon seal on the piston assembly. The seals are installed as pictured from left to right. I put the large white seal on first. After that I thought it would be easier to put the green teflon seals on starting with the top seal, then slowly work my way down. My thinking was that once I got the seal into its groove, I wouldnt have to fight to keep the next seal from falling into that groove making install easier. I WAS WRONG. It was a PITA! So, start with the bottom (considering the large seal the bottom) and work your way up. (also notice the rubber o-ring on the far right end. that is part of the 2 piece rubber/teflon seal. see next step)