Lock Right Diff Locker Install, Front Diff
Article: Pete. R.   Photos: Pete. R.

 My Surf has open diffs at both ends and I've been caught short on several occasions. Thankfully nothing that required "rescue". But they were easy obstacles that a 4WD should have easily negotiated. I needed to do something and as with all the things I do research is where the learning begins.My research had me asking lots of questions about lots of diff lockers and which end of the truck gives the biggest bang for buck. Of course value for money was also important to me as I don't do "hard core" stuff I couldn't see the value in spending $3000+ for both diffs to be done.
I ended up purchasing a Lock Right full time locker from RockyRoadOutfitters off e-bay in the USA for $400 Australian and that included delivery. It was delivered in 8 days. As all* front diffs in Surfs and 4Runners with ADD are the same (7.5" 27 spline) the correct Lock Right part number is 1611.
* Correct me if I'm wrong.

This write up is how I installed the locker into my front diff.
What you need: 1. Basic tools including metric socket set, ring open spanner set and a cold chisel.
2. Specialist tools needed are an E14 Torqux socket, a large torque wrench (71 ft lbs+), set of pin punches and soft faced hammer.
3. Of great help will be access to an oven.

This modification took me 8 hours and an above average amount of technical ability is probably required (if you stuff it it will get very expensive).
 Note:- I have already installed Free Wheeling Hubs on my truck.


Step 1:- Remove the front bash plate.

Step 2:- Mark the electrical and pneumatic lines going to the front diff, I used some masking tape. There are two electrical (one front and one back of diff) and two pneumatic (one drivers side of bellows and one passenger side of bellows). Disconnect the diff breather line if you've already done that mod.


Step 3:- Disconnect the two front axles (CV's) from the diff and the input shaft to the diff. I marked all of these parts so that on reassembly they went back exactly as they came off.

Step 4:- Undo the two aft diff mounts and finally the front diff mount. I placed a jack under the diff to take the weight and gently lower the diff.

Step 5:- Installation of the front diff is the reverse. Refer maintenance manual for correct torques for all nuts and bolts (I use a Gregory's Hilux one).

Note:- I drained the diff after I removed it from the truck.


Step 1:- Remove the four bolts holding on the ADD selector assy and remove the selector assy. You can see from the picture that there are two locating pins (one top and one bottom) and the unit has some sealant on it. Both make it hard to remove.

Step 2:- Undo the eight bolts holding on the front cover of the diff and remove. This two has sealant holding it on, the soft faced hammer helped get it off.

Note:- I put the cover back on with two bolts to prevent dirt getting into the housing and the bearings within whilst I disassembled the rest of the diff.

Step 3:- Using the E14 Torqux socket undo and remove the intermediate axle to the ADD. This has an O ring as the oil seal and the shaft has a bearing face so be very careful with this. The ADD sleeve that moves to lock the left axle when 4WD is selected can fall off at this stage. Be careful to note the way this sleeve comes off. If you can DON'T let it come off and if it does put it straight back on the right way.

If it has fallen off and your not sure if you've got it back on correctly check the photo above for reference.

Step 4:- Remove the final ADD housing. This has sealant on it also.

Step 5:- Remove the front cover again and get ready to be brutal. Place the cold chisel between the pinion and the axle that is intruding past the planetary gears. Now give it a good wack (or two). Repeat for the other axle.

Step 6:- remove the two axles from the diff housing. You may need to use a couple of large screw drivers to help leaver them out.


Step 7:- Mark the right and left bearing cups of the spider and ring gear assy, undo the two retaining bolts on each bearing cup and remove the bearing cups. I left the bolts in their holes again to make sure everything goes back exactly as it came out.

Step 8:- There is a large shim at the end of each of the two bearings. The one at the ADD end can be taped out of the housing using one of the pin punches. It's in tight so will require some force. Be very, very careful, don't damage the bearing. Mark the shim so as you know what side it came out from. The shims are not the same thickness on each side so they MUST go back in the same side they cam out.

Step 9:- Remove the spider and ring gear assy from the diff housing and mark the second shim so as it goes back into the correct location.

Step 10:- Undo the locking tabs on each of the bolt heads holding the ring gear to the assy.

Step 11:- Undo and remove the bolts retaining the ring gear to the assy. On my assy the is a large 'J', I used this as a reference point and marked up an old cardboard box with the same mark. I then removed each bolt set and located it on the cardboard in the location in relation to the mark. This will again ensure the bolts go back exactly where they came out.

Note:- These bolts are torqued up  and are very tight to undo.

Step 12:- I then marked the ring gear and the assy so that when I reassembled the pair they went back exactly the same.

Step 13:- I mounted the assy in the vice with a lot of rags. You must prevent damage to the bearings and the assy as a whole. With a soft faced hammer start belting the ring gear off the assy. I kept working my way around the ring gear ensuring that the blows NEVER hit the assy. It took a little while but it eventually came off.


Step 14:- Using a pin punch knock out the pin holding the pinion in place and remove the pinion (it'll just fall out).

Step 15:- Rotate one of the larger spider gears and the smaller ones will come out of the assy. When the larger spider gears come out you will see a thrust washer behind each one. Remove and mark the thrust washer so as it can go back into the assy in the same location it was removed from. The two smaller spider gears also have cupped thrust washers which are discarded along with the four spider gears.


Step 16:- Place a thrust washer onto each of the outer Lock Right gears and apply some thick grease to the teeth of the Lock Right outer gear.

Step 17:- Locate each of the outer Lock Right gears into their correct location (for the trust washer) into the assy.

Step 18:- Grease the teeth of the inner Lock Right gears and put a little grease into the holes where the locating pins will go in each of the inner gears.

Step 19:- Install two of the pins that came with the Lock Right into the deep holes of each of the inner gears. The pins should be fully recessed into each inner gear.

Step 20:- Install one of the inner gears into the ring gear end of the assy, then install the other. ensure the two inner halves form the hole that the Pinion will go through.

Step 21:- Eight springs came with the Lock Right, four skinny and four fatter. Put a skinny one inside a fat one and hold them together with a little grease.

Step 22:- Use a jewellers screwdriver or similar to push the recessed pins down and install the spring set into each hole where the pin was. The spring set will follow the pin down and locate in place up into the body of the inner gear. The picture should help explain.

Step 23:- Install the pinion into the assy and punch the locking pinion locking pin back into place. The locker in now installed into the assy.

Step 24:- Place the ring gear into an oven and heat to not more than 100 deg C. (if the ring gear gets to 110 deg C it will be damaged). I let mine get to about 60 deg C. This heating process will allow the ring gear to expand making it easier getting it back onto the assy. I could push it on with my hands. Remember the marks I put on before, I made sure they lined up again.

Step 25:- I then put the bolts back in and torqued them up IAW the Gregory's manual.

Step 26:- The assy went back into the diff housing and the shims were again located in there correct position. As the first shim to come out needed some gentle persuasion so the last to go back in will also need some help (soft faced hammer) being careful of the bearings.

Step 27:- The bearing caps were again installed according to their correct location from disassembly and torqued.

Step 28:- Install the axles back into the diff, they will need to be tapped back in with the soft faced hammer.

Step 29:- At this point I cleaned all the excess sealant off the faces of all the mating parts ensuring none got into the housing and any bearings.

Step 30:- The rest goes back together as it came apart. I used Locktite 515 Master Gasket as the sealant when I reassembled every thing. Ensure you locate the ADD sleeve correctly on the shaft and when you put the ADD actuator assy back on ensure that the tong arms are correctly engaging the sleeve.

Step 31:- Now that you've finished rebuilding the diff the really hard part starts, installing it back in the car. Details for installing the diff are back up near the top of this page.

Note:- Richmond Gear recommends a thicker gear oil than normal which helps keep to a minimum the noise the locker can make when going around corners.