A shot of the shop showing
the front diff up on the work stands with my ‘custom’ cut 2×4 :), cut with
the diameter of the axle tube housing to better secure it on the stands
when working. Can also see rear diff partially assembled on ground.
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A shot of the table after
setting up the front diff, its a mess. Try to keep the area as clean
as possible during the rebuild. You can see the bearing puller at
the back of the table and the old pinion. In the background is the
box that the new gears came in.
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You can see the pressure
washer wand sitting on the cart and some suds in the diff, in the background
is Steve’s C#e%y, and one of my ’68 Mustangs.
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Installing the ring gear
onto the carrier, in this case the Detroit locker.
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Disassembly of the Detroit
Locker. Shows long threaded rod used to decompress inner spring after
top is removed.
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A – Long threaded rod,
with 1 1/2″ washers and nuts at either end. B – Top of Locker, C
– Locker bolts.(click to see large view) |
A – Thrust washers, remove
along with thrust blocks. |
The bearing cap that
needed a bit of TLC to fit. To hammer it you would rotate 90* from
the current position and then strike it on top to compress it. |
A – Shows the ‘custom’
shim needed to fix my over sanding, the larger shims are the shims
used to setup the carrier bearings. They are organized by thickness
to make the job go quicker. B – Dial gauge used to measure backlash.
Next to the dial indicator you can see our table with the attempts for
backlash setup. |
This has nothing to do
with setting up gears. Thought you would like a break. Here
you can see Steve applying one of his patented techniques for door repairs.
I am the one holding the 2×4 and 5 pound sIedge. I blame Steve for
the dent, even though he was in his own truck at the time and I was the
one driving mine. If I hadn’t been backing up to let him by this
would have never happen. |
Testing the pre load.
A – 5 lb weight. B – Rod with eye. |
Heading down a rocky
slope. |
Geting a little twisted
up. If you look close you can see that the right rear tire is off
the ground along with the front left. You’ll want to drive about
200 miles on flat ground before doing this. |
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Disassemble
the axle by removing the hubs, rotors, spindles and axle shafts, make sure
to keep the left and right components separate. Note that the spindles
may require excessive force to remove. The Steve Shaw patented technique
is: once the rotors have been removed and spindle nuts removed, to place
a block of wood on the spindle shaft, as close to the end as possible (but
not on the threads), and using a sledge hammer hit the block of wood, then
repeat. I had to do this with the Dana 50 (I needed the splash shields
from the Dana 50 for the Dana 60), and it took several hits (over the head)
to break the spindles loose, and destroyed two blocks of wood. However
with a King Pin type Dana 60, you can hit the piece that holds the brake
calipers in place with the hammer directly to break it loose. Since
this piece sits between the spindle and knuckle.
After removing the spindles and axles remove
the pinion yoke nut. If you are lucky it will come off with the impact
gun and you don’t have to worry about preventing the yoke from spinning.
Next remove the yoke with a puller. After remove the cover and draining
the fluid, mark the bearing caps for left and right (you can use a punch),and
note which direction the arrows on the caps face. The bearing caps
must be installed in the same side and direction as they came out.
The caps bore is matched to the bore in the axle housing. After removing
the bearing caps remove the diff carrier. You’ll probably need pry
bars, and a friend makes it a lot easier. However as I heard over
and over again from Steve, you can do it by yourself. Remove the bearings
and note the thickness of the shims on each side
Remove the pinion by hitting it with a
hammer with block of wood, if the gears are to be reused place the nut
back on the pinion before hitting it. Have someone ready to catch
the pinion as it is knocked loose. Note the thickness of the pinion
shims using a set of good vernier calipers. Remove the inner and
outer bearing races, old bearings make a good driver, and/or a socket from
the 3/4″ socket set. Next remove the old inner axle seals first noting
their position, you’ll need a really long bar with the correct size driver
to knock out the seals. We used another Steve Shaw patented technique,
he attached several 3/4″ extensions together to form the bar, then a 3/4″
drive socket of approximately the same diameter as the seals to use as
the driver, then drove the seals out by hitting the end of the extensions.
We actually didn’t remove the seals until after we cleaned the diff, but
it is better to do it before.
Next clean the diff, a good quality pressure
washer and degreaser helps out here. You must remove all grit from
the housing and inside the axle to make sure you don’t get any inside when
reassembling. You can use the plug in kind of pressure washer but
you’ll have to put the nozzle right up close to be effective. A 5
hp gas, 2300 psi, 3 gpm will do the job nicely.
Make sure to clean out the axle tubes as
well, since you don’t want to pick up any grit when installing the axle
shafts.
With the diff clean blow it dry with compressed
air. Install the new axle seals, using sealant between the axle housing
and the seal. Again you’ll need the long bar and driver, a 3/4″ socket
set helps here. When installing the front axle seals you should make
sure they are installed to a depth that makes them run on a good portion
of the axle shaft, this may or may not be the same depth as the originals.
If the shaft had a bad groove where they used to run, shifting them to
a different location might be a good idea.
Install the new ring gear on the diff carrier,
in this case it is also the Detroit locker. To tighten the bolts
have one person hold a pry bar between two bolts and the other tighten
the bolts with a torque wrench. Again this can be done by one person
as Steve tells me. I don’t believe it and think that his wife actually
helped more than he admits when he did his.
According to the Steve the new Detroit
Soft Locker is designed to smooth out the locking and unlocking of the
axles. A side effect of this is more torque is required to unlock
them which can cause understeer on extremely slippery surfaces (sheer ice).
Which makes driving in winter in 2wd (4wd is fine) with your hubs locked
risky, since on slippery roads there is not enough torque transmitted to
the locker to disengage. However a simple modification to the Detroit
is to remove the soft locker components, which reduces the amount of force
necessary to disengage the locker. This has NO affect on off road
performance and no increase in noise for typical front wheel axle applications.
If you live in the south you don’t have to worry about this modification.
A long threaded rod is inserted through
the locker, then nuts and washers are used to hold the inner spring compressed
while the top is removed. After the top is removed loosen the nut
on the rod to uncompress the spring and gain access to the thrust washers
and thrust blocks.
Note this procedure can be done prior
to installing the ring gear.
After removing washers assembly is reverse.
Make sure to use locktite on the locker bolts. Steve talked this
modification over with the Tractech engineers and they agreed with him
that this is an acceptable (required for winter drivers) modification.
However you should contact Tractech
yourself for complete instructions.
Now it is time to setup the gears.
This is a fairly involved process and takes the bulk of the time when rebuilding
an axle. I wont go into the details, only provide some notes on things
that make it easier.
The first thing to do is throw away the
crappy gear marking grease that came with the new gears. It is useless
horrible stuff. Now, swallowing all your Ford pride, go to the parts
desk at a GM dealer and buy GM Part #1052351 Compound 08800.
This is excellent gear marking compound, supposedly even used by Ford mechanics
because it is so much better than any of the others. It is a bright
yellow paste. You can clearly see your gear pattern when using the
GM compound. One tube is $7 and will last you 1000 diffs.
The carrier bearings are a force fit so
you don’t want to use your new bearings while setting up the backlash
because you’ll have to repeatedly hammer on-pull off the bearings for each
shim change. To make the job easier take the old carrier bearings
and grind the inside race enough so that they can be slipped on and off
the carrier (Detroit locker) without requiring a puller to remove.
The new pinion will have a + or – number
scribed on it. This is the amount in thousandths of an inch that
the gear is off from the nominal checking distance (the distance from the
center line of the ring gear to bottom of the pinion gear). Use this
number, along with the number on the original gear and the original shim
thickness to determine the starting point for the pinion depth shim thickness.
For example if your original pinion shims measured (in total) .026″ and
the original pinion gear had a +1 marked on it and the new pinion gear
had a +2 marked on it you would add .001″ to the original pinion shim depth
for a starting point of .027″. You’ll have to mix and match the shims
to come up with the desired thickness, and may even need to reuse some
of the old shims to get the right thickness. As a starting point
use the same pre load shim thickness as the original and
test the pre load with these shims prior to setting up backlash.
Ours tested out OK, but required tweaking after backlash was set.
Install the pinion gear using the OLD pinion nut for now, and torque to
spec.
Get note pad and a pen and setup a chart
to keep track of the attempts, this will help guide you as to what to do
next and make sure you don’t end up backtracking. I’ve include the
chart we ended up with when doing the Dana 60 (see below).
Your gears should come with instructions which will help explain the process
in more detail.
Now for some things that may not be covered
in the instructions and how to work around them. When you place the
carrier into the axle and place the bearing caps on the caps should fit
snug, not tight but definitely not loose. Loose caps will mean that
your bearings will spin. My luck when doing the rear diff one of
the caps was loose, and proving that I had more ‘luck’ both bearing caps
in the front were loose. Unfortunately one of the bearing races had
been spinning and was loose in the bearing cap. In order to maintain
the critical tolerances within the diff, the cap should hold the race just
tight. So off to the table sander…
You have two choices if your bearing caps
are loose, bring it to a professional machine shop to have the caps fixed
up or follow the Steve Shaw patented technique for fixing loose bearing
caps. WARNING use this technique at your own risk. Tools needed:
16 oz hammer, table top sander. Skills, knowing when to stop sanding.
A combination of sanding and quick sharp hits with the hammer will tighten
up the bearing caps to hold the bearings in place. Start by hitting
the cap by laying it on one edge and hitting the other so as to compress
the cap. Test fit it between each hit until it fits snug. Its
a judgment call what ‘snug’ is. You should be able to get it on with
just your hands and not need to hammer it on. Now it may fit snug
at the bottom but not at the top, no amount of hammering will fix this
and its time to sand. Sand both flat surfaces evenly at the same
time on the sander. Only do small amounts of sanding in-between test
fittings. Stop when it fits snugly.
Now your saying “Greg I tried this but
sanded too much”. Well that’s what I did when I made the mistake
of thinking that I knew what I was doing and didn’t wait for Steve to verify
my work. I had sanded too much and now the cap would hit the top
of the bearing before seating on the axle housing. Doh! Fear
of expensive machining to correct the problem run through my head.
Steve suggests a shim, but what do we make it out of? It’s 3:00 AM
and there isn’t a machine shop open for miles. Steve figured a .010″
shim on each side ( between the cap and axle housing) would correct my
over sanding. But I didn’t have anything .010″ around, but I did
have a sheet of aluminum that was .017″ thick. So I cut up one shim
and put it on one side, it worked! You really don’t want to get into
this situation. To make the hole in the shim I first drilled through
the sheet of aluminum (before cutting out the shape of the shim).
To drill through thin metal place the metal in-between two blocks of wood
(2×4) and drill through the wood then the metal.
OK, so now you have your starting point
for pinion shims, pre load shims, and have your bearing caps fitting snug.
Now its time to get the backlash. Setup the dial indicator and rock
the ring gear back and forth and note the amount the gauge changes, this
is your backlash. If you need to correct the backlash you’ll have
to remove the carrier, alter the shims and then install and test again.
Your gears should have come with instructions which will explain how much
of a shim change is required for a desired backlash change. We had
to do this about 4 times to get the backlash right, see
table. Once the backlash is within spec (for my Precision Gear
gears it was .008″ to .010″) apply the gear marking compound to about 10-12
teeth of the ring gear and do a gear pattern test. Apply resistance
to the pinion while rotating the ring gear, make sure to run both ways.
To get your forward pattern and reverse pattern, the forward pattern is
the most critical since you’ll be doing most of driving this way :).
Depending on the pattern you may need to alter the pinion depth shims,
or the carrier bearing shims, use the chart that came with the gears to
decide what changes are necessary in order to obtain a good pattern.
Make sure to record all changes. A good pattern is a necessity, or
you’ll wear out your gears in a very short time. So don’t get impatient.
Once you have proper backlash and a good
pattern its time to check the pinion pre load. Remove the carrier
once more, remove the pinion, install the new pinion seal, install the
pinion and carrier again.
Testing Pre load
With the bearing caps torqued on rotate
the axle housing so that the pinion is parallel to the ground. Pinion
pre load is measured in inch pounds, not foot pounds. So you either
need to purchase an expensive tool to measure the pre load or use another
Steve Shaw patented technique. Place a bar (about 1 foot long) through
the two ubolts that would normally hold on the u joint. Now place
a weight (5 or 2.5 pound) on the bar, with the bar perpendicular to the
pinion, move the weight out from the pinion until the bar rotates the pinion.
Note the distance from the center of the pinion to the point on the bar
where the pinion started to rotate. Now the pre load will be the
distance (length) in inches times the force (pounds) of the weight (T=LxF).
So if using a 5 pound weight and the distance was 5 inches the pre load
will be 25 inch pounds. If more pre load is required you have to
remove the carrier, remove the pinion and add more pre load shims.
We had to do this 3 times, which is why you may wish
to use the old nut the first few times when testing pre load, since ideally
you do not want to back off the new nut once it has been tightened.
Note the Ford rear end uses a crush
sleeve instead of pre load shims.
Your done! Put the cover on, put
it under the truck, add the fluid and drive.
Break In Procedure
When I did my diffs both were done at
the same time, so I had two sets of gears to break in. First I drove
in 2wd to break in the rear, for 15 min at 60-100 kph with the front hubs
UNlocked. Came home, disconnected the rear drive shaft, let the rear
diff cool (about 3 hours or so) then put it in 4wd high and did the same
15 min drive with the front hubs locked (or I wouldn’t be going very far).
It drives a bit funny on drive pavement like this so be prepared.
This is being a bit anal but ensures proper break-in. Come home reconnect
the driveshaft and let the front diff cool before driving. Check
the fluid levels in both diffs and top up as necessary. After this
you can drive ‘normal’ for 200 miles, well as Steve says how a normal person
would drive a normal car. So that means no hard acceleration, no
fish tails around corners, no off roading. During this part of the
break in, shift into 4wd high with front hubs UNlocked every now and then.
When out of 4wd high lock the hubs. This will drive the front gears
ensuring they get broken in before going off road. Change the diff
fluid after 500 miles or so. You’ll most likely see some very small
metal bits. This is probably from the locker. If you see large
bits you should completely remove the cover and investigate.
OK now your done.
Only other problem we ran into was with
a king pin. At around 1:00 AM one night Steve decided it would be
a good idea to check the condition of the king pin bushings and bearings.
While attempting to remove the lower king pin cover a bolt snapped.
I don’t have a torch, so that added another day to the job to take the
knuckle with broken bolt into a muffler shop to have them use a torch get
the bolt out. But that wasn’t the hard part. After getting
the knuckle off we found that the upper king pin it self was too rusty
to keep using. To remove the upper king pin a special hex male socket
must be used, its 7/8 but you’ll need a 3/4 drive one. The
king pin is torqued on with extreme force, 600-700 ft-lb. To get
it off I had an 8 foot pipe on the socket wrench, pushed as hard as I could,
loud snap, and it broke loose. You must install it with about the
same amount of torque. Fun
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