Part Time 4wd kit for 1991/92 Land Cruiser 80 series

by: Ethan Blasius

Kit included the following

Tools needed

Other Misc. stuff needed

Project costs

$435 US$ - 2wd conversion kit from ARB Northern in Victoria Australia

$95 US$ - FedEx shipping (three day delivery time)

$75 US$- fluids, rags, silicon, and other misc. stuff

$50 US$- Front output shaft machining

The following are the step by step fitting instructions provided along with the kit

What’s marked in bold are page references for the 1991 repair manual

  1. With the key on engage the canter diff. Lock (this makes reassembling the unit easier)
  2. Drain the Transfer case oil (Repair manual page MA-9)
  3. Remove transfer case
  4. Remove rear output housing (9 bolts) (Repair manual page TF-6)
  5. Remove front output housing (6 bolts) (Repair manual page TF-6)
  6. Remove rear upper bearing case cover (5 bolts) (Repair manual page TF-7)
  7. Remove outer circlip on bearing (Repair manual page TF-7)
  8. Separate front case and rear case (8 bolts) NOTE: Try to keep the gear set in front main housing (Repair manual page TF-7)
  9. Remove center diff. carried bolts (12 bolts) (Repair manual page TF-25)
  10. Remove tapered roller center diff. Carrier
  11. Remove gear set, cross pin and all shims
  12. Remove circlip from front output shaft
  13. Gently press or tap the shaft out of the bearing in the front housing
  14. Replace shaft with modified one from the kit (Don’t forget circlip) NOTE:
  15. Install front output housing
  16. Place one center diff. side gear shim on the small splined hub provided and install inside center diff. on the front output shaft
  17. Install circlip provided
  18. Install large splined hub to center diff. NOTE: The splined hub will only fit in one position. Install bolts by hand, if they are hard to get in, turn the hub 180 degrees.
  19. Torque bolts to 65ftlbs (Repair manual page TF-26)
  20. Loosen bolts
  21. Re-torque to 72 ft lbs.
  22. Re-assemble the transfer case and re-install in you truck. (Don’t forget the oil pump drive)
  23. Re-fill transfer case with gear oil (use 75/90 gear lube. NO ADDITIVES!!!) (2.2 quarts)
  24. Install freewheeling hubs. NOTE: If the truck was built after 8/92 it may require the axle spacers supplied
  25. Fit "H4WD" sticker to center diff. lock button. You will have to trim it to size.

THAT’S IT!!!

Pictures


Figure 1: Transfer case with front and read output housings removed.  Sitting to the left is the actuator motor for locking into 4wd.  You can see the clutch fork and sleeve still attached to the TC at the bottom.
Figure 2:Completely reassembled TC.  The front output shaft is on the right side.

Figure 3: looking at the TC from the rear output shaft side. you can see the new large splined hub before the center diff carrier bearing was pressed on.

Figure 4: Large splined hub installed with carrier bearing pressed on.  To the left you can see the 4wd actuator motor has been reinstalled.  Not pictured on the other side is the front output shaft and housing fully installed.

Figure 5: Freewheel hubs

Figure 6: All the parts being removed from the transfer cases center diff.

OK, now lets get down to my experience with this project.

After conversing with Rob Kay at ARB Northern a few times over e-mail I made the purchase with a credit card. The kit arrived a few days later in a medium sized FedEx box. Everything was accounted for and a few extra goodies were thrown in. (Thanks Rob!) The first day I received the kit I installed the freewheel hubs and the center diff. lock sticker. By installing the hubs before I had completed the kit it made it necessary for me to drive the truck with the center diff. locked all the time until I got the kit fully installed.

Installing the freewheel hubs

The installation procedure for installing the hubs was very strait forward and I won’t get into it in any great detail. Basically what your going to do is remove a front tire, remove the grease cap, remove the snap ring, remove the 6 flange bolts, replace flange with one in kit, reinstall the 6 flange bolts and snapring, install freewheel hub with the 6 machine screws provided. Reinstall tire and now do the same for the other side.

Installation of the 2wd kit required me to increase the number of tools I had, the list above will give you a good idea of what you going to need.

Remove the Transfercase

I started the conversion by first placing engaging the center Diff lock on the TC. I drained the TC of fluid, marked and removed both front and rear drive shafts, and removed the exhaust system from behind the cats all the way back. Loosen the 8 bolt connecting the transmission cross bracing to the frame. Place your jack under the center of the cross bracing and proceed to remove the bolts. Using your 2 car jack stands place them at either end of the cross bracing about 4 inches lower. You will now be able to lower your transmission and transfer case a good 4+ inches. Before beginning to remove the TC, remove all electrical wiring for the Hi/Lo indicator and Diff lock. You will also need to remove the speedo cable located on the rear output housing, some hoses and the Hi/Lo shift linkage. Remove the TC by placing your jack under the transfercase and removing 6 bolts (a couple are hard to get to!). With the jack supporting the TC slide it about 4 inches towards the rear of the vehicle to clear the transmission output shaft. Now just lower the TC to the ground and begin tearing it apart.

Transfercase tear down

The tear down procedures is pretty well documented in the direction above and in the user manual so I won’t go into any detail. The 12 center diff carrier bolts can be very hard to remove without proper tool; I’d recommend a very long handled wrench. Once you have removed the center diff carrier you will see the parts you will be removing from the TC (Figure 6) you can see all the parts you will be removing on Figure 6. Your now going to need to disassemble the front output housing to get the front output shaft free to get it machined.

Machining

This was the most time consuming part of the kit; I had to go to many different machine shops to find someone who could even cut this hardened output shaft. My advice to you is first finding someone in your area that can do this job. The machinist is going to either need a toolpost grinder or high speed lathe, my machinist used a toolpost grinder. I also talked to a toolmaker that could have done the job, but he directed me to someone who could complete the job cheaper. One other note, the plans that were included in the kit were not entirely accurate when comparing dimensions to the actual shaft. According to Rob Kay there are very slight variations in sizes for the output shaft. I also ran into a problem with my carrier bearing. The bearing inside diameter was a couple thousandths larger then the outside diameter of the new center diff carrier provided with the kit. The bearing could move on and off by hand. You can see a picture of the new carrier on (Figure 6) and you can also see a picture of the new carrier in place on the center diff before the bearing has been pressed on. (Figure 3) This problem was fixed by machining very small grooves on the mating surface of the center diff carrier and using a thread lock like product. According to Rob Kay this is also the same procedure they had used to fix this problem. He also said getting a new bearing would also work. You can see a picture of the bearing installed on the new center diff carrier and bolted to the center diff. (Figure 4)

Once you have all your parts back, reassemble the front output housing with your machined front output shaft and follow the directions for reassembling the TC. This is fairly strait forward and well documented in the above direction and your used manual so I won’t go into any detail. You can see a picture of my TC reassembled and ready to reinstall in the truck (Figure 2) and don’t forget the oil!

So reinstalling the TC is just as easy as removing, using a jack raise the TC into position and bolt it to the transmission TC adapter. Reattach the hoses, wires shift linkage and speedo cable. Reinstall your exhaust and bolt your transmissions cross bracing to the frame. Install your front and rear drive shafts and you should be ready to go! Make sure you give everything the once over before you drive off!

My driving impressions

Well for starters the first thing I noticed was how much more the truck torqued when accelerating from a dead stop. It’s very apparent the power is going to the rear wheels, the nose of the truck now raises much more then before. (I LIKE IT!). Acceleration has improved noticeably when starting from a dead stop. Handling characteristics have changed, turning seems to be much easier at slower speed and it’s easier to throw the weight of the vehicle around now that the front end seems to feel lighter. My gas mileage has also improved, before the kit I was getting a consistent 10 mpg everywhere. I’m now getting 11.5 mpg city driving and have gotten a 12 mpg on a long highway trip I took a month after installing the kit. I’m heavy on the gas, so you may even be able to get better results. So I’ve improved my average range for one tank of gas from 200 to 230/240 and have a 15% to 20% improvement in fuel economy, Not bad!

I would like to close by saying that this is the idiots guide to the 2wd kit install. I’m not a mechanic and have written this article based only on my experience. If you need technical information I recommend you contact Rob Kay at ARB Northern. If however you would like a little more detail on the installation process I would be happy to answer your questions.

ENJOY!!!!

Ethan Blasius

eblasius@yahoo.com