Early fluid changes: differentials, transfer case, manual transmission

[ShadowsPapa]

The smaller teeth in this picture or something similar. I assumed they were part of the factory limited slip, but I have not personally rebuilt one, so perhaps I am mistaken. I have seen 4 instances where they were broken off in a little more than a year and two myself with less than 35k miles. I also had it happen in a Jeep Liberty years back. All my rigs had the factory limited slip, so I made the assumption.

Those are in ALL differentials, every one of them for decades.
If the teeth broke it's not a problem with limited slip unless the thing was under extreme torque stress going around a corner and the clutches didn't slip.
They just don't break.
Those gears are how one axle can go a different speed than the other in a differential. The torque is transmitted from pinion to ring gear - which is bolted to the carrier housing, then through the pin and spider gears to the larger side gears which the axles are splined to.
I've busted AXLE shafts but never taken teeth off those gears.

Here is a non-limited slip differential (AMC 15 from an Eagle) ->

Liimited slip (AMC used 4 pinions or spider gears in the limited slip instead of 2 like the standard open differential had)

Trac-Loc ->

Lots of different configurations, some with 2 spiders (carrier pinions) and some with 4, but all have the same basic configuration unless it's an after-market setup.

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[JTGuy]

My Diffs are probably overfilled by 1/2 inch. I don't think that will be an issue. I have always overfilled my diffs and never had a problem. Think of how fast the spiders are going in the front with the CAD.

 

[RavensEyeOffroad]

I'm nearing 30k miles on my Mojave.
I'll probably do my differentials soon, before it gets too cold.
How much fluid do I need to buy for both?
I think I read the gasket is reusable, is that correct, recommended if so?
Do you recall the torque specs for the bolts?
(Sorry for all the questions lol)

 

[TheRealStreetcommander]

Minor bone to pick, just so we can add the most value. I’m pretty sure the LSD pack does have splines or teeth on the inner diameter of the frictions and face-teeth or radius lugs on the outer diameter of the steels. That said, I agree I’ve never seen these teeth create debris in the oil, although they do wear. The average mechanic is no different than the average clown we work with in our own jobs. They say clown things because it comes natural.

Sometimes I’m guilty of missing the trees for the forest and have to remind myself that these new Dana 44/220’s are objectively larger, stronger, and more efficient than dare I say nearly EVERY previous rear end offered in any mid sized truck in human history. I’d probably have to give the nod to the Ford 8.8 as the pinnacle, but these 44’s are stout. Jeep gave us a great product. Not to mention tow ratings have gone through the roof.

As noted above, 85, 90, or 140, probably doesn’t matter as much as frequency of change. I try and spill and fill mine every 30-40k. At that interval, good quality conventionals are probably appropriate as well.

 

[Maximus Gladius]

I'm nearing 30k miles on my Mojave.
I'll probably do my differentials soon, before it gets too cold.
How much fluid do I need to buy for both?
I think I read the gasket is reusable, is that correct, recommended if so?
Do you recall the torque specs for the bolts?
(Sorry for all the questions lol)

I can say for sure the gasket is reusable. As far as quantity, it holds about 1.5q each. Is it exactly 3 you need?? Probably get 4 and you’re good. If the fluid specs are different for both, you’d get 2 for the back and 2 for the front. That’s what I had to do for my 21 JTR. The back on mine is Limited Slip and the front isn’t. Your dealership parts department would confirm fluid type and bolt torque specs.

Also, some info about the bolts say to replace with new ones. I didn’t on mine and the diff cover is still there, no leaks

 

[Maximus Gladius]

Oh ya, almost forgot…
While you’re in there with the rear diff cover off, don’t forget to clean off the locker sensor magnet and inspect the sensor for oil intrusion. There’s one Torx screw holding it in place over the magnet. It’s easy to see oil in the sensor through the light coloured housing. If there’s oil in it, you’ll want to do a warranty claim and have the dealership take care of it.

 

[bd100]

Well in the end I got an entire new back axle on the truck at 20,000 miles. No more noise. I'll wait for break in then change the fluid to 75w140, and change again around 5-10,000 miles later to see how the new axle is doing, then maybe every 20,000 from then on.

The first sign of trouble around 10,000 miles or so was faint hissing noise heard at the parking brake handle. The parking brake cable is mounted on the top of the differential, and noise travels up the cable into the cabin. Got pretty bad until the repair, and now gone.

Also heard grinding and whirring noises, but that started around 15,000 miles, or later. Started getting worse quickly as it approached 20,000 miles.

The repair note said metal in the fluid and scored bearings and gears, without specifying which ones. And I had just changed that fluid not too long ago, so this was a noticeable amount of new metal in a very short amount of time.

So this was a gradual failure. The truck did its heaviest towing a year ago climbing Rocky Mountain passes with some camping cargo plus a 2000lb trailer in tow. Full power for minutes at a time. But it didn't really fail until a year later, which had some casual flatland towing trips, and the most recent was several months ago.

The parts were on back order, but the repair got done in about three weeks.

Edit:
The original axle had a drain plug, the new one does not. I may put on an ARB differential cover to get a drain plug, but it really isn't too hard to use the hand held suction gun either. Which way I go may depend on whether the new fill plug has a magnet, which would be great if so because then I can watch the magnet for filings w/o spending on the ARB cover, and I already have a rear diff guard I could slap onto the stock cover.

 

[Free2roam]

So I just purchased from the stealership 4 qts. of I believe it was 75-85/GL5 and two limited slip additives for close to 340$ I heard that the gear oil is in short supply and they are currently looking for a new vendor. Also UAW is possibly going on strike soon.

 

[Hootbro]

So I just purchased from the stealership 4 qts. of I believe it was 75-85/GL5 and two limited slip additives for close to 340$ I heard that the gear oil is in short supply and they are currently looking for a new vendor. Also UAW is possibly going on strike soon.

That's nuts! Over $70 a quart.

You paranoid about warranty denial?

 

[RavensEyeOffroad]

I just did some looking and found
https://www.amazon.com/Ravenol-J1C1144-001-SAE-75W-85-Gear/dp/B071JVBHLM/
Which is listed a compatible. I'll probably go that route, unless you guys give me a better suggestion. No way I'm paying that for the mopar stuff they rebranded and slapped a label on.

 

[Hootbro]

I just did some looking and found
https://www.amazon.com/Ravenol-J1C1144-001-SAE-75W-85-Gear/dp/B071JVBHLM/
Which is listed a compatible. I'll probably go that route, unless you guys give me a better suggestion. No way I'm paying that for the mopar stuff they rebranded and slapped a label on.

Ravenol is good stuff. When I had a Tacoma and Tundra, was the only brand I could find for their single 75W monograde oil for the transfer case outside the OEM Toyota bottled stuff.

If you are receptive to using 75W-90, it really opens up a lot more quality options at a way cheaper price point. Most dealerships that offer packaged price services will throw in 75W-90 in place of 75W-85 without blinking.

 

[RavensEyeOffroad]

Ravenol is good stuff. When I had a Tacoma and Tundra, was the only brand I could find for their single 75W grade oil for the transfer case outside the OEM Toyota bottled stuff.

If you are receptive to using 75W-90, it really opens up a lot more quality options at a way cheaper price point. Most dealerships that offer packaged price services will throw in 75W-90 in place of 75W-85 without blinking.

ill check on the 75w-90 i dont drive much most of my miles are highway on long adventures. I run 35's but am considering going back to 33's. (only person on the planet im sure)

 

[bd100]

... and the new axle w/o a drain plug DOES have a magnet on the fill plug. Minor particles after 40 miles or so of break-in.

 

[Free2roam]

Today. Not much on the mag plug some flakes but not much in the cover itself either. Looking pretty normal after 40k miles

 

[Maximus Gladius]

Today. Not much on the mag plug some flakes but not much in the cover itself either. Looking pretty normal after 40k miles

Keep in mind that the locker sensor magnet will have the same amount on it too. If you notice it takes a while for the lockers to engage or disengage, it’s because of that.

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