FJ80 Front differential - replace or rebuild

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jcarter

jcarter

Joined
Jan 8, 2005
Threads
71
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528
Location
Crestwood, MO
Starting the madness . . .

August of 1992 FJ80, 220k miles, grinding front diff won't go unless locked:

Our Land Cruiser has changed its function from "indestructible family vehicle" to "spare, project ridden, toy"

Current (1st major) project:
Bought OME suspension kit from man-e-fre (2" med-heavy 80DH kit). I don't see a problem with this for I've done this type of stuff on old Pontiacs.

Also bought Knuckle rebuild kit with bearings - not too worried about this.

Also bought Front differential bearing kit - - not too worried about this.

But, when I get into the differential, I'm worried about finding broke/torn up teeth or just plain worn out.

Looking in the service manual, it seems a lot of work to fix the differential.

With the vehicle grinding and not moving unless the differentials are locked, will I most likely run into a tore up front diff?

Assuming YES the front diff is tore up, should I try to rebuild it or get a new one? Do they sell new ones?

One last question, since I'm upgrading the suspension, I figure the entire front axle assembly will be close to off the car. So I intend on disconnecting the brake lines and bringing the whole thing inside to do the work (rebuilding the knuckles and front diff-bearings and gaskets). Good idea or too much work to get it off?
 
Thanks, I'll keep the 95k gears in mind. Seems like you've already gotten into this. You have any suggestions of "while you're there" fixes?

PS Patriots are going down this afternoon!
 
if you need to lock up, couldn't that also suggest that there is a problem with traction on one side? Flanges? splines? Maybe check the sides first?
 
e9999 said:
if you need to lock up, couldn't that also suggest that there is a problem with traction on one side? Flanges? splines? Maybe check the sides first?
Click to expand...

Yup, missed that on the first read. The PS usually takes the brunt of the wear on these trucks. I've replaced a few drive flanges on that side and one needed a Birf as well because the splines were so far gone.

Don't pull the axle as swapping springs is basically unbolt the shocks and push the axle down.
 
Whooaa!

Wait a minute! Nothing I hate worse as an engineer then people using words that don't make sense. . .

Are you guys saying the differential may be intact and the grinding is because the ends (knuckle - wheel side geared shaft that goes into the differential) is out of line or worn?

And YES, the think clinks like all hell when going into drive. I'm getting all excited. May be a smaller project then originally expected!
 
THe birfield stub shaft splines into the drive flage on the end of the axle. Take off the hub cap and the drive flange is held on by 6 nuts. It's the thing with a tin can on the center. That's what is probably gone as well as the stub shaft splines which will require a new birfield.

Don't get too excited, if it was my gears it would be a lot cheaper.
 
jcarter said:
With the vehicle grinding and not moving unless the differentials are locked
Click to expand...

Whoa there yourself, tiger.

If you have a stock 92, the only locking diff you have is in the transfer case.

Why don't you tell us a little more precisely what's going on. It drives fine with the center diff. locked? When it's not locked, someone outside the rig could see the front driveshaft spinning but the rig not moving? etc.

Sounds like there's a LOT more diagnosing you could do before you go tearing into stuff.

Curtis
 
jcarter said:
...

With the vehicle grinding and not moving unless the differentials are locked, will I most likely run into a tore up front diff?
...
Click to expand...

That's classic symptoms of a stripped drive plate. The '91 & '92 trucks have shorter splines on the birf and plate, making them somewhat weaker, prone to this failure. They can be upgraded to the newer style if new parts are needed.
 
My "Whoa" comment was a little strong, but not as strong as . .

You boys are a couple of GENIUSES!

I'll bet you are right! The gears that actually turn the wheels are probably stripped!

More history (didn't want to start out too long winded). It's been a primary vehicle, so paid Auto Service places. A few years back, after a muddy outing, got one side wheel bearings replaced (car smoked and jerked to one side). A year back other side (they felt play while replacing the tires). About 6 months ago, right (passenger) side leaks oil like crazy. Auto Service said "We don't do that kind of work". Then about a month ago, this problem. I figured poor workmanship on the bearings or tore up the seal while working on it. I think that's about it.

So, I'll hold off on diff kit (new bearings and gaskets). I'll go ahead and redo the knuckles with bearings.

Bad news, I'll probably need new birfields. Kevin, can you give me more information on "upgraded to the newer style if new parts are needed". Where? Longfield?
 
There are several vendors for burfs, Longfield and Toyota/C-Dan are a couple, some have bought them inexpensively on e-bay. IIRC the flanges are not too badly priced from C-Dan. The later parts are a bolt on upgrade, just order for a '93-'97 truck. But you got 220K out of the original ones, so if early parts can be sourced inexpensively they may be the way to go?
 
if it 's not moving when lockers are disengaged, theres a good chance that you may have a broken birf on one side or the other, and it requires lockers engaged in order to turn the opposite axle shaft. if it's not a birf, the it could just be a broken axle shaft all together.
I may be wrong, but thats my .02

as far as rebuilding the front diff. it's not a serious issue if you're willing to read the FSM and do as it says.

good luck and I hope you get it fixed.
 
Nothing but a new set of drive plates and an hour's work if you stop for coffee. Degree of certainty: 99.999%. Front diff is fine.

DougM
 
didn't read the whole thread before i gave you my input. sounds like there could be something simple or something more drastic going on. if you have a 91 or 92, then the diff lock that you speak of is at the t-case
if you're not getting movement of the vehilce unless that is engaged, then it could either be an output to the rear issue, or something on the front axle broken, loose, or not engaging.
( the power from the tranny is transfered to which ever axle has the least amount of resistance when the diff lock is disengaged)

ck your d/s for any unusual movement
start at the wheels, and work your way back. (start simple)
 
Jcarter,

I'd vote for the drive plate.
At Surf & Turf a very concerned new 80 series owner approached me with similar symptoms on his 80. He had been jumping on the dunes. On the very last one, he triple locked (front, center and rear) his 80 and gunned it.
He heard a noise as he landed and right after that, his rig would not move (sand) unless the front diff was locked.
Initially I thought it could be the front diff (like on Drexx case), others said it would be birfs. But it turned out to be a drive plate. Simple and cheap.
In fact, I think the drive plate worked as a fuse in this case. Preventing mayor damage from occurring.

Regards

Alvaro
 
Another vote for a trashed drive flange. Sometimes the birf splines will also be shot. The part number for the original flange on a 92 is 43421-60022. This is sometimes called the "short style" or "early style". In mid 1994 Toyota changed the design and made the birf longer in the spline area and incorporated a "taller" drive flange to improve durability. The later flange, sometimes called the "tall flange", is a 43421-60040.
You can run a later birfield, even one with an ABS ring on it, if you use the correct tall flange. A late flange will not fit on an early birf, it is not possible to install the outer snap-ring. An early flange will go into place on a later birf but it will allow too much end-play and you will destroy the joint in short order.
 
If the flange is bad take the one from the good side and place it on the bad side to evaluate the splines on the Birf. I've had it go both ways on a 91. One was just the flange and the other needed both. I did however install one of those cheap ebay birfs for someone and it looked real good as far as fit was concerned and it ran smooth when I was done. The Ebay birfs would require you to buy the newer drive flange from CDan.
 
Thanks for all the info. Been too cold to tear into it. Have a cost/quality question on Birfields:

local Toyota dealer: $650
cruiserparts.net: $250
ebay: $160

Any history on quality?
 
Finally warm enough. Tore into it this weekend.

Passenger Side (PS) birfield bad. Got the newer kind (after April of 1994).

Drivers side birfield good, flange worn. Ordered new flange (older kind before April of 1994).

While in it, figured to replace the brake rotors.

Spent about $500 ($250 birfield, 2*$50 flanges, 2*$65 rotors) at cruiserparts.net.

Will take a week to get the parts.

In the mean time. Since I'm doing it myself and saving money, I figured it needed shocks. Bought OME medium heavy 2-1/2" lift kit with caster corrective bushings and steering stablizer (OMEKIT-80DH) from Man-e-fre. I intend on doing this and cleaning up the existing parts while waiting on the new parts. So far spent:
$500 birfields/brake rotors - Cruisernet
$720 suspension kit - man-e-fre
$180 knuckle kit w/ bearings - man-e-fre
Total $1,500 (don't tell the wife!)

What I've learned:
1. The "cone washers" came out with little pounding. Used a standard hammer and didn't have to hit anything hard enough to mar it. Know your limits and don't buy a brass bar (unless particularly stubborn).
2. DO NOT DISCONNECT THE BRAKE LINE FROM THE CALIPER! Just unbolt and hang. Wish I didn't have to bleed my brakes.
3. Took off 54mm hub nut by gently tapping the side of it with a screw driver and hammer (again, know your limits). Intend on renting 54" socket from local autoparts store (free rent) to reinstall.
4. I also intend to rent a gear puller for differential oil seal.

All for now. . .
 
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