Manual Hub Conversion for the 1st Gen Tacoma & 3rd Gen 4Runner

I've always adored old 4X4 trucks. When I was a kid on camping trips with my dad in his primer-patched 1977 Chevy Suburban, I loved it when the road looked bad and he'd tell me to jump out and lock in the hubs. I'd hang for dear life onto the arm rest while the transfer case whined and suspension groaned as Old Blue lumbered along, leaving a trail of rust flakes to help us find our way home.


Like lots of people, my weakness for Toyota trucks started during the neon vomit paint and non-functional chrome suspension craze of the 1980s and early 90s. I liked that style but preferred low-spec beaters, especially if I saw them covered in red dirt returning from adventures that looked as white trash as our own. So of course I’m going to like modifications that remind me of the old gods of Toyota 4X4 history. I still have impure thoughts when I see them:


I had several reasons for wanting to convert my 1st Gen Tacoma from ADD (automatic differential disconnect) to manual hubs. In order of importance:

1. I scored a complete manual hub front axle assembly super-cheap from online classifieds. The steering knuckles, wheel bearings, CV axles and upper ball joints were all in good condition and reuseable.

2. I want to avoid weird vibrations and rapid CV axle wear when I get a suspension lift.

3. If the front differential or a CV axle breaks, I can unlock the hubs and freewheel back to civilization.

4. I get 2-LO with no further modifications.

5. Some who have converted to manual hubs claim a 2-4 MPG improvement, since the CV axles don’t turn in 2WD like they do on ADD trucks. I track my fuel economy anyway, so I’m interested to see if this is true or just internet hype. EDIT: I saw no MPG improvement but this is still one of my favorite mods.


Here are the additional parts I used:

E14 External Torx socket
M12 X 1.25 Bolt with washer, 35MM long (quantity 4)
Upper Ball Joint Boot Kit: 43324-39015 (quantity 2)
Inner and Outer Aisin Hub Gaskets: 43531-60010 (quantity 2) & 43422-60060 (quantity 2)
Aisin Hub Dial O-Ring: 43532-60010 (quantity 2)
Right front axle seal: 9031147010
Left front axle seal: 9031147011

Time to make a mess:


Steering knuckles are the same either way, but the wheel bearings are different. If you want to do this the hard way you can get non-ADD wheel bearings pressed into your existing steering knuckles, then source the Aisin hubs and non-ADD CV axles separately. But it's a lot easier if you have complete assemblies:


I would have swapped these in without taking them apart, but the locking hubs were stuck so I had to rebuild them. This thread and diagram were helpful:
http://www.yotatech.com/f116/aisin-locking-hubs-tear-down-build-up-158644/

The top row is incorrect and looks like Haynes mixed up the 1995.5-2004 Tacoma and 1986-1995 "Pickup" locking hubs. But the bottom row is accurate. Only the Tacoma-specific Aisin hubs with gray dials will fit Tacomas and 3rd Gen 4Runners. The older Pickup/4Runner Aisin hubs with red dials are not compatible. I painted my hub dials red for that vintage Toyota 4X4 look.

Hang the brake caliper out of the way just like when you change pads and rotors:


A 3-jaw puller will pop the upper ball joint loose WAAAY easier than beating it with a hammer. Notice I left the castle-nut partially threaded so the steering knuckle won't flop out and hit me in the gonads. Support the lower control arm with a jack, then take out the bolts for the lower balljoint. That way you can slowly release the strut tension:


If you still have a sway bar, move the end link out of the way or you won't be able to pull out the CV axle. The CV axle pops out easy if you use 2 pry bars at the same time on opposite sides:


Then when you take the castle-nut off of the upper ball joint, you can pull the steering knuckle and CV axle out at once.


The intermediate shaft has a frame bracket with 3 bolts that take a 19MM socket. Behind that are 6 E14 external torx bolts holding the intermediate shaft/ADD actuator on the front diff. If your front diff has never been apart before, these torx bolts are going to be brutal. I would strongly recommend having a set of broken stud and bolt sockets, in case you strip one of these like I did.


Here is what the front differential looks like with the intermediate shaft/ADD actuator assembly removed.


If you have a J-shift transfer case and have to reuse your ADD intermediate shaft:

Key on the ignition, shift into 4-HI and key off. Unplug the ADD actuator from its wiring harness and disassemble it. Put a hose clamp on the shift fork to keep it permanently engaged in 4WD and reinstall everything on the front diff. The hose clamp needs to be wide enough that the shift fork can't move. If you skip this step, your passenger side CV axle will not be connected to the front diff even if the locking hub is turned in. Leave the wiring disconnected so the ADD actuator doesn't burn up from attempting to shift in and out of 4WD. The ADD wiring harness can be unplugged near the starter and removed from the chassis harness.


If you have a J-shift transfer case and a non-ADD intermediate shaft:

Use the double pry bar method again to remove this gear. It has a spline and snap ring just like a CV axle. Then the non-ADD shaft fits like it was meant to be there:

Notice that I used normal M12X1.25x36 bolts instead of the stupid torx bolts. This is also a good time to install new axle seals.

If you have a pushbutton transfer case:

Leave the ADD actuator in working condition because that's what the 4WD button operates. It's the only way to shift in and out of 2-HI and 4-HI while driving. You can't have purely mechanical 4WD like us cool J-shifters, but you can still unlock your hubs for normal daily driving and greatly reduce drivetrain vibrations and CV axle wear. Thanks to @Buck18 for sorting this out.

Now you can reassemble the CV's and front suspension. Green CV axles are for ADD and blue ones are for manual hubs. The inner CV shafts are the same but the outer shafts at the wheel end are different. The easy identifier is manual CV's are splined all the way to the end, ADD CV's are threaded at the end.

Manual:

ADD:


There's also an easy identifier for manual vs. ADD differentials if you look at the left side. But it doesn't matter too much because they're interchangeable.

Manual:

ADD:


There are some myths that are frequently recited by friends and internet forums. One is that on ADD systems only the driver's side CV axle turns while driving in 2WD because it's permanently engaged to the front diff, while the passenger side CV axle only turns in 4WD. Here is my ADD CV axle and passenger side front hub. The splined section where the CV axle goes in is part of the hub and can't turn independently:

So on ADD front ends it doesn't matter if it's in 2WD or 4WD. If the truck is moving both CV axles are turning.

The other common myth is that with manual hubs you can no longer "shift on the fly," or shift in and out of 4-HI while driving. I believe this originated with 1970s/1980s domestic trucks that could shift on the fly with auto hubs, but could not with manual hubs. That's not a problem with Toyota components. As long as the hubs are turned in, I can shift in and out of 4-HI at will while driving.

I was insistent on keeping ABS until I tried it last winter and experienced how ineffective it is on the 1st gen Tacoma. My new steering knuckles don't have this port for the ABS sensors so I removed them. That will cause the ABS warning light to stay on.


Removing the two ABS fuses in the underhood fuse box does not disable the ABS light, so it's time to get into the instrument cluster. The 3rd black knob next to the gray knob holds the ABS warning bulb. Twist it 1/4 turn counter-clockwise and it pops out. Then you can remove the bulb:


Removing the ABS modulator and reworking the brake lines is a project for another day. Also, the green 4WD icon in the instrument cluster no longer illuminates since I removed the ADD actuator and wiring harness.

I will know 4WD is engaged because I'll get out, lock in my manual hubs, shift my manual transfer case into 4WD, put my manual transmission in gear and possibly crank down my manual windows. That will be more manly than John Wayne making out with Donald Trump during a Ford Super Duty commercial on the 4th of July.

 

Nice write up,I miss the locking hubs.I bet if Toyota offered a manual hub ,with manual trans and transfer case, with crank windows they would sell a bunch. They could call it the PRO

 

And charge more too. I hate when they do that. Charge more for less. Porsche does it with the GT3.

Awesome write up however.

 

Hahahaha! Great post, solid info and cracking me up!

 

Here are the pics of the Wilwood PV and ABS module delete:

 

Fantastic write up Dave. It was a pleasure meeting you the other day too.

 

Sweet write up! Wish this was possible on the 2nd gen

 

I'd buy one right now, but most people prefer luxury barges that are gilded in fake chrome and cost more than recreational property.

 

Awesome write up, this is first up on my mod list. Trouble is finding the hubs in the first place. But I'm diggin the old school red on those!

 

Thanks, @waldotoyota. The Tacoma manual hubs with gray dials are not interchangeable with the red dial manual hubs from older pickups and 4Runners. I had to paint them to get the proper look.

 

It's such a minor detail but it really says Toyota when I see the red dials. Mine are still grey, I've been too lazy. Nice write up!

 

Beautiful writeup man!. i have a tear in my eye.

 

Excellent write up. Please post more pics of your truck . Just love staring at it.

 

"I willknow 4WD is engaged because I'll get out, lock in the manual hubs, shift my manual transfer case into 4WD, put my manual transmission in gear and possibly crank down a manual window. That will be more manly than John Wayne making out with Donald Trump during a Ford Super Duty commercial on the 4th of July."

Best part...

 

I was wrong about not being able to use a non-ADD intermediate shaft on an ADD differential. I have updated the instructions with new photos. @SSchaefer3 of Sonoran Steel helped me over on T4R.org: He has a sick-sauce 3rd gen 4Runner with manual hubs:

 

I'm flattered. Here's some poverty-spec porn just for you, @lotuscupcar.

 

Gorgeous

My favorite truck on here

 

Why thank you! But @Jiveydude and @allenfab have way cooler regular cabs than me:

https://www.tacomaworld.com/threads/dude-that-build’s-jivey.308115/

https://www.tacomaworld.com/threads/allenfabs-95-tacoma-build.349241/

 

Thank you sir.