Child Labor: Installing the Transfer Case Skid Plate

Cleaning in the garage, wife asks what this pile of metal is doing in the corner.

Well hon, its like this… uh… yeah… they go on the truck? Yeah, sure, I’ll get them out of here. No problem?

I have the bolts, I guess its as good as time as any to put the sucker on. Hey, and an opportunity for my little one to make some money helping dad with the truck.

This skid plate bolts to the frame right below the transfer case. It protects the transfer case from debris. I’ve already painted it with POR15, only thing left is to install it.

The first step is to paint the entire top side of the skid plate with Fluidfilm, since I won’t be seeing that surface again for a while. Little one does a fine job.

Second, we chase the threads in the frame with a tap. This because the previous owner had coated the frame with epoxy. Without doing this it was impossible to screw the bolts into the frame.

Skid Plate held in place with car jack, little one tightens the bolts.

Third, we hold up the skid plate with a car jack and screw in the bolts. Little one is good at this.

Finally we go over everything again with fluidfilm.

The smile of someone earning cash-money.

Skid plate in forground

 

Rebuilding the Aisin Locking Hub

Lets review:

• Engine drives the transmission.
• Transmission drives the transfer case
• Transfer case sends power to the rear diff, and to the front diff when 4wd is engaged.
• Front diff drives the hubs…
• driven hubs, when locked, cause wheels to spin

Odd feature of this vehicle, you must manually lock the hubs before the front wheels will be driven. I suppose this is a feature to save gas and wear on the diff.

Anyway, the other day I had car jacked up, noticed that with transfer set to 4wd and both hubs locked, that the drivers side wheel was correctly locked but the passenger side wheel would spin freely. No amount of jiggling would lock that hub. Last weekend I took the hub apart, cleaned it out.

Again the factory service manual is amazing. Each step takes about 2 minutes seconds. Wonderful well written instructions and everything so simple!

Probably the most difficult part for me was removing and installing the circular clip that holds the axle in place against the hub. Removing was difficult because of all the grease, installing was difficult because of all the grease. I think main issue is that my pliers suck.

After taking it apart and cleaning it, fiddling with it at the kitchen table I was confident in how it worked and that it shouldn’t have trouble engaging. I didn’t see why it wouldn’t work. Hmm, mystery.

I reinstall onto truck and before cinching everything down I try spinning the wheel with the hub locked. Hmm… it still spins freely. Shit. I visually verify that the hub is in fact locked. How can it be spinning? I reach in with cover removed and am able to freely spin the axle. With my fingers? The axle is spinning freely? How is that possible? The universal joint in the “birfield” can’t be broken, the bearings are all tight… it must be that something is wrong in the differential?

Dang. Oh well. I reinstall with torque wrench according to specs. Yeah, still doesn’t lock. Shoot.

Later that night, round about 9:30pm I have an epiphany. I didn’t lock the other hub!

Explanation:

Transmission is in first gear, transfer set to 4wd. Engine isn’t moving so transmission won’t move, so transfer won’t move. But the diff is open. If one hub is locked and the other free then the force of spinning the locked wheel takes path of least resistance and spins the unlocked hub! I go out with headlamp, jack up car again and sure enough the hub is locked once I lock them both. Sheesh. Stupidity. Now I know I verified that the driver’s side locked previously, but maybe I unlocked it before moving to the passenger side. I’ll never know.

Well I guess the good news is that I’m not afraid of hubs now and know how to rebuild them after my dwell time at the kitchen table.

Anyway, here are photos of the rebuild:

Jack up car:

Elevate car with jack, use jackstand!

Locking cover about to be removed.

Bolts out of cover.

Cover removed. Lots of grease in there.

Remove the hubcap surround.

Picture of the greasy cover. The grease spelled like burned gear oil.

Next step was strange. Instructions said to hit bolt studs with brass rod and hammer. This will loosen the “cone nuts”. I looked and couldn’t tell what they were talking about. The cone nuts go between the studs and the hub and are pressed into place with the hub cover. Sure enough I pounded on the studs and the cones came loose!

I didn’t have a brass rod so used a steel socket extension.

Two studs, one with and one without the cone nut.

Pound on the stud and the cone nut pops out like magic.

Now I forgot to take a picture of the next step. Using some circlip pliers you remove a circlip from the axle. This allows the hub to come free.

This was probably the most difficult part, probably because I bought the cheapest circlip pliers there are ($6 for 4 pliers!)

Hub removed from wheel.

Another view of hub and splines.

The cover cleaned of grease.

All the parts disassembled and cleaned.

Closeup of the cleaned cover (with clutch and spring).

To reinstall was a little difficult. The axle wants to slide in. Thread a bolt in, had wife pull axle out while I slid the circlip back on. Took about 6 tries.

Lots of grease on reinstall. Sure enough it locked up great, no issues.

For good measure I took apart the driver’s side as well. Again the grease was stinky so good to clean it. Amazing that inside the parts look like new.

Back on terra firma, now with genuine 4wd.

Big ol honkin toyota hood in the rain.

Junk and Jewelry

Found a new knob for the transfer case shifter. It’s nice to have the pattern on it. This was $15 from cruiserparts:

New transfer shift knob, now with shift pattern!

It’s surprising how easy it is to find parts for this thing. Took me months to find the shift knob for my 930. Judging from the different size this may not be correct though, but what do I care? I want to see the shift pattern on the knob, and at least this pattern is correct.

If you’re wondering what a transfer case is…

Transfer Case and Locking Hubs

This vehicle is 4 wheel drive. Or, its got a transmission that can be configured to drive all four wheels. Normally the vehicle only drives the two rear wheels. This is done for efficiency. When 4wd is needed there are two things that must be done.

1: the hubs must be locked. The front hubs on this vehicle can be locked and unlocked. Locked means the wheel turns with the axle. Unlocked means the wheel turns independently of the axle. This unlocked state is the low friction state, the wheels just spin on their bearings. When the hubs are locked the wheels move with the front axle and differential, which is less efficient.

2: the transfer case must be set to one of the two 4WD modes. These modes cause power to be directed to the front differential and then to the axles. The transfer case is a second transmission. Its just like the main transmission except it has fewer gears. The main transmission has 5 forward gears, neutral, and a reverse gear. The transfer has 2WD, 4WD, Neutral, and 4 WD Low. This transfer case connects the main transmission and the wheels, so each of its settings can be applied to each of the main transmissions gears. If we consider the main transmission to have 6 unique gears (not counting neutral), and the transfer case has 3 unique gears, then the car has 18 settings. The difference between 2WD and 4WD is that the front wheels are given power, the difference between 4WD and 4WD low is that in low mode the transfer lowers the ratio of each gear. If first gear normally gets you to 7mph, in 4WD Low you’ll get to 3.5mph before needing to shift. These low gears are useful offroad as you have nearly infinite torque and the ability to compression brake down very steep hills.

In situations where you might be changing between 2WD and 4WD, it is ok to leave the hubs locked and the transfer case in H2. This means the transfer only drives the rear wheels, the front is left to move as it will. When the front wheels are locked the front axles are turning with the wheels, the axles turn the differential, and the differential spins the pinon shaft between the differential and the transfer case. When transfer is changed from H2 to H4 the transfer now locks the front pinion to the engine and 4wd is engaged. I guess back in the day this was luxury! You can change from 2WD to 4WD without going out in the elements and dealing with a freezing muddy hub.

Yes!? Luxury!

De-Rusting that Junky Old Spare Tire Carrier:

In other news, I’ve been working to de-rust the spare tire-carrier that was included with the car. It was pretty rusty and I don’t have access to a media blaster. Instead I’m using phosphoric acid to convert the rust to calcium phosphate which is pretty easy to scrub off. Man I wish I had access to a media blaster.

By the time I’m done it might be warm enough to give it a coat of epoxy paint. Check out this piece of junk, isn’t it something that this has value?

The spare tire carrier. It was pretty rusty, now all that white stuff is calcium phosphate, converted rust.

The bolts to hold this to the frame are $1.25 each, so this isn’t a big deal to install. Only issue I don’t see to have the tool that’s used to lower the tire. It’ll be nice to get that tire out of the back of the truck.