front diff lock overhaul (1 Viewer)

Jim_Chow · Aug 10, 2004

This message actually pertains to the 8" front diff lock on the 80 or 8" rear diff lock on the 4runners, as I believe they are identical except for the reverse cut gears.

Recently, mine has seemed to stick (has progressively gotten slower and slower to lock, and after recent rains, won't lock at all) . First thing I'll check is to make sure the diff is getting 12v and contacts are clean. If so, this would suggest the actuator motor.

Anyone know how to overhaul the actuator? What exactly do I need? Can it be done without draining the diff oil? I have read the article on sleeoffroad's site, but believe the rear diff lock on the 80 is constructed slightly differently than the toyota 8" diff lock.

RavenTai · Aug 11, 2004

https://forum.ih8mud.com/showthread.php?t=17701

The front actuator is very similar to the rear but with one important difference, the "shift lock fork shaft" stays in the diff and the FSM gives you instructions for timing it to the actuator

I have done 2 rears and one front, the rear will leak diff fluid when the actuator is pulled, the front is mounted higher so it may not, the front I did was on an already removed chunk, so I don’t know if you will need to drain the diff

Jim_Chow · Aug 11, 2004

Thanks, Raven. The diagram itself says a lot. Could you outline the steps of how to overhaul it? It appears from a scan of the diagram I found on the web shows one bolt attaches the actuator motor to the diff, and between the actuator and diff is an O-ring. The bolt then looks to bolt to or through the shift fork. Do I need to use the Toyota orange FIPG to attach the actuator, generic orange or black FIPG, or just the O-ring? Once I remove the bolt to unmount the actuator unit, I guess I unbolt the bolts that hold the cover on. Will a springs/ball bearings pop out that I need to beware of?

I was thinking of putting the front end on stands. That way, I might be able to get around from draining the diff oil.

Photoman · Aug 11, 2004

Jim,

Hope this helps you. I don't know if they are all the same or not but this is off a 97. No FIPG, just the o-ring. Two bolts to take apart - 8MM I think. Must remove snap ring to remove gear (watch how gear comes off as it's different on each end) Take off cover. Should be no surprises as long as it's not already apart inside. The cover has one locating pin so must be wiggled off with a small screwdriver - don't damage inside o-ring by taking too deep a bite with screwdriver.

Bill

RavenTai · Aug 11, 2004

Jim_Chow said:
Thanks, It appears from a scan of the diagram I found on the web shows one bolt attaches the actuator motor to the diff, and between the actuator and diff is an O-ring. The bolt then looks to bolt to or through the shift fork. Do I need to use the Toyota orange FIPG to attach the actuator, generic orange or black FIPG, or just the O-ring? QUOTE]

that sounds like the rear actuator, it has 4 bolts that hold the actuator to the diff and a "shift lock fork shat" (see diagram in other post) that passes through the lockers fork and gets a bolt to secure the two together, the flange with the 4 bolts get FIPG

You will need the FSM to remove and install the front actuator, there is some timing info in the FSM that you will need to reinstall it

It has been close to a year since I did the front but here is what I remember:

the front is fairly straight foreword remove it per the FSM (3 bolts 1 connector, one vent line) disassemble the same as the rear, (see other post) one thing to note is the position of the final gear, it has a bevel on one end, IIRC it also needs to be clocked on the shaft correctly (so that the line up marks on the face of the gear are clocked right to the shaft) , after you pull it off the shaft it can go on one of several ways, only one is correct, good place to use match marks on the end of the shaft and final gear with a sharp scribe (don’t go so deep as to weaken it but make permanent marks that will not rub off or be lost in the cleaning process) , the rest of the overhaul is identical to the rear disassemble, solvent clean, look for corrosion, lightly lube with non non-metalic (no conductive) grease, reassemble, install per FSM directions paying close attention to the mesh of the final gear to the shift fork, I think the O-ring is the only seal called for in the front, IIRC we used FIPG there also against FSM recommendations

if you disassemble the wait springs from the driven gear you are on your own

do not apply voltage directly to the actuator, without the logic of the controller it can over travel and stretch the wait springs, if you must use a 9v battery, the motor will have less torque and should stall before to much stretching occurs,

this is more knolege I wish I did not know but fortunatly not on my truck :whoops:

Jim_Chow · Aug 11, 2004

Here's the diagram I found on the web. It appears there are two long studs in the diff housing that attach to the actuator plus the middle screw that goes through to the shift fork. Since the diff lock stopped working recently, I took a look underneath and noticed the little plastic thing that holds up the breather hose had snapped off, so the hose was lying sideways along the axle housing. I suspect water entered the breather. Guess I'll have to lead it to the engine compartment next time. Wonder if I can find a small vacuum fitting, as the breather is much smaller than the 7/32" hose I have going into the axle housing.

RavenTai · Aug 12, 2004

Jim_Chow said:
, so the hose was lying sideways along the axle housing. I suspect water entered the breather.

ouch, if so you may be in for what cristo had to do

Jim_Chow · Aug 13, 2004

As a followup to the locker overhaul, I pulled it apart today to find there was quite a bit of sand/grit in there. I then pulled the actuator motor. It looked fine visually, but had that burned electronics smell. I didn't see anything visibly fried black, though. After struggling forever getting those little springs/magnets back together (took two persons, each using a toothpick to hold in one magnet), I tested it and it just got hot, but didn't turn. I concluded that the motor is dead. I did verify that I was getting the proper voltages from the harness. There was some rust on the parts, but not bad. Makes me wonder how the sand/grit got in....only thing I can point to is the breather (makes me wonder why one is even needed, but I guess the electronics do generate some heat that needs to be dissipated). Since the harness is homemade using a SPDT switch and two 12v bosch relays, there's really no protection against applying power too long to the motor. I'm guessing once the motor stuck, since the diff is unlocked, the lock limit switch is closed to ground, so the lock relay will keep sending 12v to the motor. I suppose the factory ECU would prevent that from happening. Trying to get a price on a new actuator from CDan....

Jim_Chow · Aug 14, 2004

I contacted CDan, who tells me the actuator ONLY for the locker is $522 (list is well over $700)!! Guess I'll either have to repair the motor w/ a makeshift replacement, or get the downey cable operated conversion kit shown at http://www.downeyoff-road.com/ChassisComponents/Lockers.html . Not a bad idea (MANUAL locker).

Rich · Aug 14, 2004

When an electric motor fails from overheat what usually happens is that the varnish on the wiring melts and results in a short circuit. One solution is to remove the wiring and rewrap with new wiring. There are motor shops that specialize in this work. It would probably cost way lot less than $500 bucks. I don't suppose they often do motors quite so small. Do a web search on "motor rewinding".

Rich · Aug 14, 2004

Regarding the downey cable conversion, others have reported corrosion problems due to poor materials and insufficient sealing. It seems to me that design needs a few improvements.

Jim_Chow · Aug 17, 2004

Jim_Chow said:
I contacted CDan, who tells me the actuator ONLY for the locker is $522 (list is well over $700)!! Guess I'll either have to repair the motor w/ a makeshift replacement, or get the downey cable operated conversion kit shown at http://www.downeyoff-road.com/ChassisComponents/Lockers.html . Not a bad idea (MANUAL locker).

Yeah, I was wondering what happened when a motor overheats. What shops rewind alternators/starters? I'd guess they'd be capable of doing it. First, I have to check to make sure i'm getting 12v at the brushes. If so, it has to be like what you say.

mickeyt · Mar 21, 2011

wondering if you can answer my locker? I am not technical so sorry if your not thr right thread to ask. I have 2 1997 LX450's, 1 with 188k miles and lockers and 1 with 85k miles and no lockers. How hard is it to remove from one and put in the other?

Kernal · Mar 21, 2011

mickeyt: I'm not the expert but AFAIK the axle housings are different so you would have to swap both axles from one rig to the other along with the wiring harnesses. Others with experience doing this will chime in and give you the complete answer.

Uncle Grumpy · Mar 21, 2011

Try this, locker retrofit

mickeyt · Mar 21, 2011

ok thanks kernal

front diff lock overhaul (1 Viewer)

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