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rebuilding / replacing front & rear diff

10K views 40 replies 5 participants last post by  Ram1878 
#1 ·
What year front & rear differentials will work on a 01 4x4?
The rear diff is whining pretty bad, the anti-spin isn't working well anymore, and with almost 180k miles, its probably time for a rebuild. I am going to re-gear to 4.11 or 4.56 while I am doing the rebuild so I'll need to do the front (dana 40?) as well.
What year donor trucks can I pull from to get direct bolt-on housings?
I can't have the truck down, so I'll need to source salvage yard axles, rebuild them in the garage, then swap out the brakes & housings when done.

thanks in advance.
 
#2 ·
Front is Dana 44. Any axle will swap from 94-02 including 2500 Dana 60 axles.
 
#4 ·
was it 98 when the abs went to the frt axle?
also sway bar end links come in many styles. so there a few things that could complicate the swap out!
I THINK, if you buy the sway bar with the axle, that would make things easier and put in your original drive shafts and appropriate wheal hub bearings -with/with out the sensor to finish off the axle any housing could be made to work. the 2000s and up used larger control arm bolts too so, if you had an older type housing- you will need to drill for your appropriate caster through bolts.
 
#5 ·
Thanks for the heads up on possible fitment issues.
If I do find the proverbial needle in the haystack that just needs a refresh I may save some coin on gears.
I would definitely like to upgrade to a dana 60 front axle as I'll be going with 35-37s later on.
 
#6 · (Edited)
I decided to rebuild the front & rear axles and install 4.56s in place of the 3.55s.
All-in parts will be just over $500.
Since I will be swapping out the rear axle and since the factory bearings have almost 200k miles it's probably time for a refresh.
The rear donor axle is a 9.25 from a 98 1500 with 70k miles on the odo.
The bearings and races looked to be in good condition but will be getting replaced anyway since it's part of the master install kit.
I'll be re-using the spider gears & pin.
The factory 9.25 carrier will be reloaded with dana clutches for the limited slip function. and motive gear 4.56 R&P with timken bearings.

The parts for the rear diff arrived last night - R&P, master install and clutches.

So far I have torn the donor housing down to the bare case, and installed outer wheel bearings and the inner pinion race.
I am hoping to have the new bearings pressed onto the pinion yoke & carrier by the weekend and have the new axle setup and ready for install by Monday.
Pics to follow.
 

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#11 ·
Hmm. I just replaced my drum brakes and they look all different than yours. At least the ebrake assy and springs. But man, that is crusty.
 
#12 · (Edited)
Hmm. I just replaced my drum brakes and they look all different than yours. At least the ebrake assy and springs. But man, that is crusty.
That's what I get for buying an Ohio plated truck...I have removed pounds of rust off this thing with my grinder - replaced all 4 doors, tailgate, and hood.

I am starting to get the upper hand on the underside - a wire wheel, lots of rust reformer, and paint/undercoating.

I'll clean up the backing plates and replace all the hardware. I'll be checking my work against a diagram for the brakes, been a while since I did drums.

edit: on the upside I just got a killer deal at advanced auto parts. 2 rear wheel cylinders, 2 axle seals, full drum hardware kit, new brake shoes, brake fluid, rtv, 80x-90 gear oil and the friction modifier for $80.42 OTD.
Cheaper than rockauto due to shipping costs.
 
#15 ·
total hell

I forgot I need a larger carrier for the front D44...:banghead:

Now everything for the front is on hold until next week, and I had to drop another $80 for a D44 open carrier. :banghead:

That brings the running total for the front diff to $340 + fluids.

Rear diff total is up to $413, but that's with new brakes and hardware on both sides.
Diff parts only so far ~$675. I take back what I said about "just over $500" lol
shit adds up quick.
 
#20 ·
Some random pics of the diff build.

I have the carrier sitting in the deep freeze and will stick the ring gear in the oven for a few minutes when I attempt installation after work this afternoon.

I made sure to mark the carrier bearing caps as they are line bored with the housing, installing in an incorrect orientation can lead to problems.

The new pinion bearing races went into the housing with the help of a 5lb sledge. For the inner (larger) pinion race I used the old bearing and a drift punch, for the smaller outer bearing race I used a 2" socket.

The old bearings installed on the pinion have been machined to slip on and off to allow for pinion depth adjustment without the need for a press. Once I get the correct amount of shims installed I'll have the new pinion bearings pressed on and install the new crush sleeve, pinion yoke seal, and lock nut. The other housing had a different pinion yoke (pictured), mine uses a flat plate plate type. I will use the one pictured for setup as it's easier to turn.
 

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#21 ·
progress pics.
Got the new front carrier and gear in yesterday...it appears you can't install the ring gear until after you install the center pin...not sure how that works but then again I've never worked on a D44.
Power washed the rear axle housing and put a few coats of a Rust reformer protective coating. according to rustoleum it stops the existing rust and coats the material to prevent future rust. Either way the rear housing looks like new with a fresh coat of paint.
The freezing the carrier and warming the ring gear has worked great for both the rear & front assemblies.
 

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#22 ·
problem: the pinion appears to be binding when I torque it down to ~200 ft lbs using the old bearings and crush sleeve.
After checking to ensure there was no spacers or anything missing, I am hoping the new bearings and crush sleeve will provide the room needed to ensure clearance.
The parts I have on the pinion are: the shim between the pinion gear and the inner (larger) bearing, the inner bearing, the crush sleeve, the outer bearing, seal, yoke, washer and pinion nut.
Am I missing something?
 
#24 ·
get a bigger compressor

So hit a delay when trying to finalize the install of the rear pinion...the crush sleeve wouldn't crush.

We tried using my buddy's impact at his shop and it didn't crush the sleeve.

So Bertha (my large impact) is rated at 650 lbs torque, and my 2 stage compressor is rated at 125 psi @ 9cfm. This got it close, but still had some play and the bearings spun freely (as the crush sleeve had not crushed).
After breaking several screwdrivers and bending grade 8 bolts trying to secure the yoke, my buddy suggested he borrow Bertha and take the diff to his shop. His compressor is also a stage 2, but puts out 190 psi at 9 cfm.
This got it done.

Pre-load wound up being ~24 in lbs, which should loosen as the bearings wear in.

Next up is carrier installation, side load adjustments, then loading the friction disks...
 
#26 ·
fail

after managing to get the clutch disks compressed enough to get the spider gears back into the housing I hit a brick wall.
No matter how much I compressed the disks I did not have enough clearance to "slip" the shims behind the spider gears. I tried compressing both sides, one side, no sides, still no dice.
Today I am taking it to the trans shop I use in the hopes of working a deal with the builder to finish the install in his spare time one day this week.
Working 12s 7 days a week doesn't leave much time to work on the truck and it needs to be done soon.

The truck must be running no later than the 18th and I've still got to assemble the rear, re-install the axle under the truck, then plumb the brakes and rebuilding the rear brake assemblies...oh and then there is the matter of the front axle that is still under the truck...:banghead:

I'll be busier than a one legged man at an ass kicking contest to get this truck ready for tow duty on time.
 
#27 ·
The procedure to make the center pin clear the larger gear set.
Some opt to notch the pin, but I was advised against this by my local shop as it can weaken the pin and cause it to walk inside the carrier.

https://youtu.be/DJwmwDndGZU
 
#28 ·
rear axle going back under truck

Finally got the rear carrier assembly back together, gear pattern set, and installed in the housing.
backlash is best guess around .08-.010, everything got locktite blue going back together.
New axle seals and axles are installed, which necessitated me borrowing a cherry picker to get it down off my work bench (it's a little heavy).

Once it's physically under the truck I'll install the e-brake cables, new brakes & hardware and bolt it up to the u-bolts.
Hoping to have the rear done by Sunday, work permitting.
 

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#31 ·
I had a detroit in my first truck and it was too harsh for daily driving IMO.
They are also a bit pricey, this was a budget friendly rebuild.
The original clutches lasted 180k miles, so I'm hoping these will last atleast 100k miles with the larger tires.
 
#32 ·
test drive with 4.56s

the truck moves again :)

After topping off the fluids and adding the friction modifier I went for a drive.
Did a few figure 8s per the instructions on the clutch packs, to get the fluid worked into the friction disks.

the 4.56s allow the use of O/D at speeds as low as 40 mph with no bogging.
The truck accelerates with much less pedal from a stop.
While the rpms are slightly higher from 65 mph up, the city rpms are the same since O/D can be used.
The engine having less load (less gas pedal) should equate to better city mpg. The transmission is also running about 10-15* cooler so far, which combined with the added mechanical advantage of the 4.56s, should give me longer trans life.

I have to put 500 miles on the gears, doing 10-20 mile heat cycles, before I can tow or accelerate aggressively. I am expecting towing will be much easier as well.

Now on to the front axle...
 

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#33 ·
just went for a drive out to a field site and averaged 10.8 mpg with the 4.56s vs 9mpg with the 3.55s

70 mph = 2200 RPMs
 
#34 ·
my Detroit trutrac is not harsh
 
#35 · (Edited)
I installed a Detroit locker back in 1998 and it was a no non-sense gear type locker. Worked great off road but had some drive-ability issues on the street, like chirping the tires or 'popping' when trying to turn and accelerate at the same time.


If money was not an issue I'd install front & rear e-lockers.
 
#36 ·
geez, I really like my cork screw locker! and to me it isn't a problem. actually i'm thinking bout installing one in the D44..
 
#37 ·
I'm sure technology has improved since the late 90s :grin
 
#38 ·
more good news...I had to order a replacement pass side inner axle shaft, the CAD shift fork, pass side unibearing/wheel hub, brakes, and CAD collar. Was able to overnight all the parts through summit except the collar. Dodge should have it here on Wednesday morning.
 
#39 ·
progress pics. Replaced missing bushing between inner & outer axle shaft, which ruined the inner shaft.
Also replaced the pads that go on the shift fork. Carrier, ring & pinion, diff bearings, unibearings, rotors, brake pads, cad system...just about everything on the front axle other than the calipers and spider gears is new, so hopefully it lasts another 180k miles :grin
Truck should be back on the road by thursday.
 

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#40 ·
update: had the truck back on the road a little while now and all I can say is wow -it drives so much better with the 4.56 gears.
I no longer need to turn O/D off every time I start the truck, O/D engages and locks from 40 mph up.
The truck accelerates and tows in O/D, the city mileage is up to 11 (from 9) and highway is about the same at 15.
The revs are at 2200 rpm traveling at 70 mph in O/D with 34" tires.
Trans temps are way down, pulling a 4000 trailer in 90* ambient the trans temp gage stayed between 160-170 in traffic, down to 150s when moving. This is with a deep pan, two 16" e-fans pulling air through the cooler and the A/C on.

The best change is the trans no longer gear hunts when driving in traffic, just about any gear it's in has enough leverage to accelerate without downshifting.

Crawl speed in 4 lo is also much better, I can take my foot off the brake and creep without the need to give it any throttle.

If anyone is on the fence I would say definitely do it, makes the truck much more fun to drive (specially with larger tires).
 
#41 ·
I'm on the fence because its costs $3000!

Unless you want to come and do mine for a sixpack. . .
 
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