Rear Diff Rebuild Parts

[donalds]

A quick Google reveals Ford Racing gear sets…not sure if they’re the same as OEM?

I used them 373 gears
Ran into your problem exactly

 

[CDW6212R]

I'm sure Ford still makes all of the popular gears, that parts guy is an idiot. I have a set of 3.08's on order, from Levittown Ford, two months now. The gears were about $150, and the installation kit(the full kit) was about $135, total just over $300. I need to contact them and see if they have come in, or what's up.

I wouldn't choose 3.55 gears for the SOHC 4.0 if I had a choice, I'm guessing you have a 4WD. Changing the front gears is easier to just find a good 3.73 front assembly from a V8.
Hold out for FMS gears if you can, they will install better, an last longer.

 

[C420sailor]

Yeah I have the SOHC 4x4, so 3.55s are stock, 45 axle code. 3.73s would be nice, but I this thing is my highway road warrior, and the mileage hit wouldn’t be worth it

 

[Fix4Dirt]

jmo, but i like 373 for an all aroubd gear, its still ok on hughway mileage while getting decent passing power/around town, imo 355 is a bit less for me aroubd town, and i dont notice a mileage difference (that i can really calculate with certainty (maybe like .5 mpg))

 

[CDW6212R]

Yeah I have the SOHC 4x4, so 3.55s are stock, 45 axle code. 3.73s would be nice, but I this thing is my highway road warrior, and the mileage hit wouldn’t be worth it

The 3.73 ratio is the all around best for fuel mileage. I took my 93 Limited to MN when the Firestone scare hit, they were on the truck then. We got 20mpg going up there, 1120 miles, and 18.5 coming back. We were loaded coming back, my aunt came with her belongings, to GA. The 3.27 truck I had(91 XLT) never got 19mpg, it was always just under that. The 3.73's with the OHV 4.0 did very well on the highway at 70mph.

A 4.10 SOHC wouldn't do great on long trips, but the 3.73 is a great compromise. The 3.55's will do best at high speeds on flat roads, when you are on hilly highways, the gain is lost with the 3.27 or 3.55 gears. Unless you knew it would see lots of long trips on flat highways, I'd want 3.73 gears.

 

[C420sailor]

It does. I regularly do 400mi shots between VA and NY. As a matter of fact, I’ve put roughly 90,000mi on her going between those two states

I am a speed limit kinda guy, and I see 21mpg or so, depending on the wind. That’s with a lightbar on the roof, which is likely coming off soon.

 

[CDW6212R]

I wouldn't change the gears for the trouble it takes to do each diff. But if a nice 3.73 front turned up, I'd think about the rear to match it. The SOHC is a better and more efficient engine, I bet it would get similar mileage on that VA to NY trip.

 

[410Fortune]

Ford ring and pinions are very good
Yukon and precision gears also very good

 

[C420sailor]

Got ‘em! CL5Z-4209-A

$250 shipped from a Ford dealer.

Any recommendations for a good diff cover? Not looking for anything crazy, but the ability to drain and fill without pulling the cover and having to fill from the front (PITA) would be nice.

 

[Fix4Dirt]

the arb one? looked at that sucker before, strongger than the rest of the diff its got dupstick filk and drain bolts, would wsnt one but too much $$$... noteure which other ones are available, havent really looked too hard...

 

[C420sailor]

Lol yea, I don’t get all these billet ones with huge fins and ****. Maybe if you tow heavy?

 

[Fix4Dirt]

maybe? imo the diff-erence (heh) aint too big, considering the price difference... but the ARB one dont got the fins... ARB Differential Cover for Ford 8.8 Axle Assemblies

looks good ot me, even got the dipstick!

 

[CDW6212R]

maybe? imo the diff-erence (heh) aint too big, considering the price difference... but the ARB one dont got the fins... ARB Differential Cover for Ford 8.8 Axle Assemblies

looks good ot me, even got the dipstick!

That looks like a very good choice for an 8.8 cover. That one has a dipstick to set and check the level with. Almost all covers have a fill hole, but no way to tell when it's full. You have to use the stock fill hole to check the level with, except for this kind of rare cover.

 

[Fix4Dirt]

That looks like a very good choice for an 8.8 cover. That one has a dipstick to set and check the level with. Almost all covers have a fill hole, but no way to tell when it's full. You have to use the stock fill hole to check the level with, except for this kind of rare cover.

yeah, i may get one myself, not to sure! maybe when i install a no slip out back maybe!

 

[CDW6212R]

I bought two covers long ago for two projects. I got an FMS cover for my Explorer, I like that look the best, but I also got a cheap brand plain one for one car. Most of the aftermarket covers have a similar shape inside as stock, they need that curvature built into them which matches the shape of the ring gear. A fully open/large cover with no curve there doesn't channel the gear oil properly back to the front, to the pinion bearings etc. So avoid any cover that is very large inside without the matching shape of the ring gear.

Banks may make one some day which has big cooling fins on the outside, they haven't seen the 8.8 as popular enough yet.

 

[C420sailor]

Ford gears came in. Came with bearings, seals, bolts too. Neat!

Getting this done in the next couple weeks. I was initially going to pull the diff, but I’m thinking I may just do it in the truck. Any thoughts?

 

[donalds]

Ford gears came in. Came with bearings, seals, bolts too. Neat!

Getting this done in the next couple weeks. I was initially going to pull the diff, but I’m thinking I may just do it in the truck. Any thoughts?

I did mine in the truck
Just put it high enough to have room to crank on the pinion nut

 

[CDW6212R]

Ditto, having enough leverage to tighten the pinion nut is the big key step. Beyond setting the pinion depth with the crush washer, the rest is a minor difficulty.

 

[C420sailor]

Finally got it done. Took two days. Original gears at 330k looked brand new, but the bearings were on their way out.

Notes:

1) The HF bearing puller/separator set works well, but you’re gonna need a torch. An Oxy-acetylene. Maybe MAPP will work. Cut the roller cage off. Put some tension on the bearing with the puller, then heat the inner race cherry red. You’ll hear a pop. Start cranking and the race will slide right off. Works on the pinion and carrier. Cut a ball off a hitch and take a grinder to it for the carrier bearings. You’ll see what I mean.

2) Putting the bearings on. Throw the carrier and pinion in the freezer, heat the bearings in the oven at 300°F. Pinion bearing will pop right on, but the carrier will need some persuasion. I used a 2x4, then used the old races for final seating.

3) For the ring, throw the carrier back in the freezer, heat the ring to 350. Pop it on, align it, and throw a couple old bolts in just to hold it tight and lined up while everything cools down. Then pull the bolts, and install the new ones with red loctite.

4) I used Ford gears, same ratio, the original carrier…so not much changed. I used my stock shims and everything came out PERFECT. Backlash was about 0.012”, gear pattern looked great. Carrier bearing preload was good—nice and tight but not binding. It was tight enough to be a bit of a ***** to turn by hand, but not tight enough for tools. Wear heavy gloves when you install the carrier—the ring gear teeth are sharp, and I cut myself.

5) Pinion preload. This sucks. I couldn’t get enough torque on a breaker bar to crush the sleeve. Couldn’t get the truck high enough to add a cheater. I did make a flange holder out of some scrap angle iron I had…but I ended up having to torque it with an impact. I know, I know. My air wouldn’t cut it, so I used the Milwaukee M18 FUEL. Strong *****. The key is go SLOW. It will take a LONG time. The tighter the nut gets, the less it takes to increase the preload. It went from 10 in-lbs to 20 in-lbs in literally 1/16 of a turn, tops. It’s very easy to overtorque.

Edit: In hindsight, invest in a torque multiplier. You can find PROTO 3.33:1 multipliers on eBay used for $250. Apparently you can ‘brinnell’ your bearing using an impact…and that’s bad. I got lucky, it seems…but I bought a multiplier for next time.

6) You need a way to measure that preload in inch pounds. Think ahead in terms of beam torque wrench, and socket adapters to make this happen.

Job is a pain in the ass, but rewarding. This rear is SILENT now.

 

[donalds]

After I did mine I changed the oil at 6k just to clean out the break in sludge

And the magnet will have metal on it clean it

Sounds like a job done well