1994 Jeep Grand Cherokee ZJ, 3.73 open diffs
March 5th, 2005
Last week I registered for the 39th annual Easter Jeep Safari (a week late, but better late than never).
Years have been slipping by and I found myself never going out to wheel. Anyway, I still don't know
what trails I'll get (it's a lottery system plus I registered late) but I'm hoping they'll be challenging.
I signed up for minimum of 3-1/2 and max of 4-1/2+ rated trails.
Which brings me to my ole Grand Cherokee with 187,000 miles. A few years back I installed
a budget boost 2"
lift and 31" tires. I called a few auto shops last week to see how much they'd charge me to install a
locker. I didn't call a 4x4 shop, just your typical neighborhood shops. No one would do it! Hmmmmm. It
couldn't be that hard. I didn't want to spend a bunch of money (which is why I didn't call a 4x4 shop to
begin with). I called Randy's Ring and Pinion to see
what they recommended. Some day I'd like to build the ZJ up for serious off-roading, but for now I wanted
something cheap to put in an axle I wasn't planning on keeping long term. Lock-Right was the quick answer,
it's dependable, it's price was right (around $240 bucks), and it's easy to install. I ordered it. Then
I got online and had trouble finding how-to's on this particular installation. I ran across
a seemingly good article, but it ended with a worthless locker spinning and grinding in the rear diff.. yikes!
I wasn't following their install notes!
So here we are. I received my locker, read through the instructions and although they could have been a little clearer I
figured I could handle it. I also thought this might be good for the website, so I took plenty of pictures along
the way for you. It took me a little over 2 hours, a lot of this was stopping to clean my hands to take
pictures. This installation was particular to my axle and is my own experience only.
other words don't hold me responsible for your installation, when in doubt refer to the actual installation
manual/notes that came with your locker. I hope you find my personal notes useful.
Here is the actual LOCK-RIGHT™ Performance Locker Installation Manual
in PDF format (install instructions I followed).
Click on any image for a larger view.
Here's the contents of the kit. I was a surprised at how small the locker actually was.
Then I had to remember it's only for Dana 35 (not the stoutest of rears to begin with). The kit
consisted of the following parts: Side Gears
(2), Stop Pins
(4), Bias Springs
(2), and a Pinion Shaft
. In addition to these parts you'll need to save
the Thrust Washers
from your existing open diff. I'll
refer to these parts by the above names, hopefully making in clear which is which. If you
look at the exploded view it shows all the parts in the order they will be installed in. I
scanned this image from the install manual and modified it to reflect this particular installation.
Here is what you'll need for this little project:
· 1/4" combination wrench
(12 point only)
· 13mm socket
· Small screwdriver
· Oil pan to catch diff fluid
· Jack stands, jack, wheel lug wrench
· Gear lube (I used 75-90 weight)
· Putty knife or gasket scraper
· RTV (or buy a diff gasket if you'd like)
· Lok-Tight for the pinion shaft bolt
· Medium weight grease
to hold things together
· Brake cleaner to clean any parts before install
First thing, put your vehicle on jack stands. I placed the jack stands on the frame to
allow the axle to hang freely. Next take off the wheels and brake drums. Trust me on
this I was hoping to skip this step, but your axles will not slide far enough inwards otherwise.
Remove all but one cover bolts using your 13mm socket. Loosen the last bolt but leave
in place to keep the oil from splashing out. Pry the cover loose.
After most of the lube drains remove the last bolt and remove cover. I noticed
some metal shavings at the bottom. I didn't figure it was too bad considering the high miles.
Remove the 1/4" pinion shaft bolt using your 12 point combination wrench. I turned my driveshaft with a
big pipe wrench until I got the alignment you see here (put transmission in neutral). This allowed me to remove the pinion
shaft bolt without disturbing the bearing cap.
Rotate the driveshaft until the carrier opening starts to show. The pinion shaft should fall out, if not give it a push from the back
with your finger. Remove this and put it aside.
Here the pinion shaft is removed. Notice the spider gears will come right out. Go ahead and
remove these at this time. One came out the front of the carrier, the other came out the back.
Also be sure to remove the spider gear washers, they will likely be stuck to the top and bottom
of the carrier in the rounded concave indentions (they may be stuck to the spider gears).
With your wheels and brake drums removed push each axle inward. The C-Clips will fall out, remove them.
Pull the axles back out a couple of inches on each side. The side gears can now be removed.
The side gears may seem tight, just wriggle back and forth until the "suction" lets them go.
Double check that the Thrust Washers are attached to the side gears. If they aren't, then
remove them from the carrier. If you don't have Thrust Washers you'll need to buy some, these
are important for your warranty. They'll be there unless someone intentionally left them out.
Prepare locker Side Gears with Washers and Thrust Washers.
Put some grease on the flat side of Washer and "paste" it into the grove of the Side Gear.
Take the Thrust Washer from the original side gear, grease it up, and put it on the back
of the new locker Side Gear. Repeat for both Side Gears. Place one of the Side Gears
into the left side of the carrier (side with ring gear) and push the axle shaft through it.
You'll see the C-Clip groove. So far so good!
Now that the axle shaft is pushed through, put some grease on a C-Clip and stick it in
the axle c-clip slot. Grab the left axle and pull it out (away from center). This pulls
the C-Clip against the Side Gear assembly (Thrust Washer, Side Gear, Washer). Grease up
the Spacer and place the open end over the C-Clip. It also fits over the Washer (remember we
"glued" the flat side of the Washer to the Side Gear?). Make sure the Spacer overlaps
the Washer correctly, they fit perfect together.
Here's a close up of a Stop Pin, Bias Spring (large), Bias Spring (small). Now is a good time
to prepare the Drivers for install. Take a Stop Pin, grease it up, and slide it into the
Driver window slot (seen as an oval shape from the side). Do this for all four Stop Pins,
two in each Driver. Prepare the Bias Springs for assembly as well. Take a larger Bias Spring
and slide a smaller Bias Spring into the center. Use grease to "glue" the two together.
Set them aside for now.
Grease the teeth on a Driver assembly and slide it over the Spacer of the left Side Gear
and rotate until the gears mesh together.
Prepare the right Side Gear by "gluing" the old Thrust Washer onto back (you should have already done this). Don't worry about
the Washer yet, leave it off for now (or take if off if you followed my early step). Put the right Side Gear assembly into right side of
carrier. Push the right axle into right Side Gear until the axle end is flush with the gear
side of Side Gear. You'll see an opening between the left Driver and right Side Gear. It's just
wide enough for the remaining Driver assembly.
Prepare the remaining Driver for install. This one is set up a little different from the first side.
The fit is tight. Grease up the remaining Spacer and Washer and insert into the Driver. The open end
of Spacer should face the direction of the Driver teeth. Then "glue" the Washer against the open end
of Spacer so flat side of Washer is flush with Driver teeth.
Take this assembled Driver and slide it into the opening between existing Driver and right Side Gear.
Orient it in such a way that the Driver teeth with mesh with the Side Gear teeth. Try to keep the "c-clip window"
in the Driver facing towards you. This slot will be used to insert the remaining C-Clip (next step). You may have
to roll the Driver back or forth to find the narrowest (flat spot) of Driver before it will slip in. Once it's in
place, mesh the gear teeth of the right Driver with the teeth of the right Side Gear.
With the right Driver "c-clip window" facing towards you, push the right axle towards the
center completely through left Side Gear and Spacer.
Here is where it get's a little tight.
I tried to take enough pictures here to show the different stages of getting that last
C-Clip in place. In the first picture you'll see the "c-clip slot" and behind it will be
the Spacer. Take your small screwdriver, or awl, or coat-hanger (if that's all you got),
and gently start to pry the Spacer apart from the Washer (second photo). Eventually, you'll
see the axle c-clip slot come into view (kinda hard to see in third photo). Don't worry if
right Driver slips towards the left as you do this, it's okay. Grease up the last C-Clip
and slide it through the Driver "c-clip window" and onto the axle c-clip slot (fourth photo).
The last photo is there so you can kind of see what it looks like with the C-Clip installed
correctly. In reality you should have the C-Clip opening rotated so it's pointing downward (to
keep it from falling off).
Pull both axles outward so the C-Clips are up against the Side Gear assemblies. Rotate
the locker until you see the pinion shaft opening. Push the spacers back towards each
respective axle. This makes room for the pinion shaft.
We're almost done and it's time to install those Bias Springs. First, take your small
screwdriver and push a Stop Pin from the Driver pin window into the opposite Driver. Second
take a greased up pair
of Bias Springs (smaller inside larger) and push it into the Driver pin window. Rotate
the locker and repeat these steps for all four Stop Pins and Bias Spring sets.
The first photo here shows the old and new Pinion Shafts. The new one doesn't have the
notched areas. Line up the new locker pinion shaft hole with the carrier pinion shaft hole.
Grease the new Pinion Shaft and slide it up through the carrier and locker. It would be
a good idea to put a little lok-tight on the threads of the pinion shaft retaining bolt.
Using your 1/4" combination wrench tighten the bolt.
That's it, you're done with the installation. Not very hard was it?
Clean up the rear diff and cover. Install a new gasket and/or put a bead of your favorite RTV.
Tighten all the cover bolts using the 13mm socket. Take your time to cross back and forth
while you tighten the cover bolts. You don't want a warped cover, after all you've been through.
I filled my diff with 75-90 weight gear lube, I think you can go up to 140 weight (I've never
used it that thick). Put your brake drums and wheels on and tighten lug nuts.
The install instructions suggest rotating the wheels around and around while listening for the sound of locking
and unlocking. I spun them a few times after I filled with lube oil and dropped it for a
of the whole project was good. I enjoyed getting my hands dirty and
documenting it for you all. I didn't have any help, it's easily a one-man job. Very few
tools are needed. If you're somewhat mechanically inclined and the idea of changing your
own diff fluid doesn't bother you, you can handle this project. Since my Dana 35 is the
c-clip version all of this can be done without removing the carrier. If you don't know, this
is a good thing. You don't have to worry about upsetting the gear backlash measurements.
That's a time saver in itself. Richmond did a great job designing an easy-to-install locker.
The price wasn't the cheapest, but Lock-Right is getting a good reputation, I'll let you
know if I explode it on the trails of Moab!
I slowly backed out of the garage in anticipation of those loud pops and bangs. It didn't
happen. I rolled my windows down as I backed on to the street and finally I hear a faint
ratchet sound. Good they're working. No noise when I started moving forward. Slight noises
going around sharp corners slow (without power). I found a little dirt and did a donut or
two, yep both rear tires definitely were spinning together. Wondering how it would respond
to throttle on pavement I tromped on the pedal while taking a corner. I never heard my
ZJ make such a noise! I felt like I was in my old 70 Chevelle SS with a big block. Those
tires were squealing and I saw a little smoke. That inside tire was definitely locked up
and spinning as fast as my outer tire. To be honest it sounded pretty cool. With full time
four wheel drive it used to take a pretty heavy foot to get even the smallest tire chirps.
I drove around for about 10-15 miles and took it to the local quick-lube stop place for an
oil change. I had them check the diff fluid in case it needed to be topped off. It was good.
I've driven a few times since, it drives just as before. Unless you knew it was there it would
be hard telling. So far I give it an A+
Tomorrow I'll install my eBay bought CB Radio ($20 bucks, can't beat that for cheap!).