Front/Rear Diff Service - DIY

[Dave D]

Im seeing a lot of talk about 75w140 but im wondering if that would be a good idea if you live up north where I am and see -30 temps in the winter.

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[JT1]

Im seeing a lot of talk about 75w140 but im wondering if that would be a good idea if you live up north where I am and see -30 temps in the winter.

the W number is still 75 so no difference in cold flowing ability.

 

[Sigz]

Okay -

So can I reuse the diff cover bolts or not?

Some folks do? Some don’t?

Some say to clean the threads and apply new thread locker but don’t torque to 30#?

Little confused…

 

[DylanM]

Okay -

So can I reuse the diff cover bolts or not?

Some folks do? Some don’t?

Some say to clean the threads and apply new thread locker but don’t torque to 30#?

Little confused…

If you're really confused, inexperienced, or unsure of what to do then stick with the official instructions as outlined in post #6. On the other hand, if you're comfortable with deviating from those instructions and going with what has proven to still work just fine, then clean, inspect, and reuse the bolts (and gasket). Thread locker on the bolt threads isn't a bad idea and can't hurt, but IMO not really necessary if you're using the 26ftlb torque spec.

 

[g2020]

Okay -

So can I reuse the diff cover bolts or not?

Some folks do? Some don’t?

Some say to clean the threads and apply new thread locker but don’t torque to 30#?

Little confused…

Welcome to the world of automotive contradictions. You won't be wrong if you choose one or split the difference.

• According to the torque values spreadsheet, Jeep states that the torque for the rear differential cover bolts is 30 ft-lbs (also see first attachment below).
  • The torque for the front differential cover bolts is 15 ft-lbs + 20°.
• Spicer (the axle manufacturer) states that the torque for the [rear] differential cover bolts is 26 ft-lbs. The initial torque, or what I call "torque round 1", and the bolt tightening sequence are shown in the same post.
• According to the torque values spreadsheet, Jeep states that the rear differential cover bolts should not be reused (also see first attachment below).
  • In the same spreadsheet, there is nothing said about reusing the front differential cover bolts.
• It appears that my selling dealer reused the bolts (no bolts listed, under group D, on invoice below). An independent shop also reused the bolts at a later date (invoice not shown).
  • Also see description of MOPAR part number 68218656AA (gear & axle lubricant, confirmed) below
• The independent shop did not use Threadlocker or any other sealant, but you can certainly use it if you like. Some do, some don't.

Torques from Torque Values Spreadsheet on This Forum

Invoice from My Selling Dealer
Front & Rear Differentials (Group D), Transfer Case (Group C), and Wheel Alignment (Group B)

MOPAR Part Number 68218656AA Synthetic Gear & Axle Lubricant SAE 75W-90
Source: MOPAR 2017 Vehicle Lubricant & Chemical Catalog

 

[Pliny]

Little confused…

Disclaimer: I do not have a background in chemistry, materials science or mechanical engineering.

Here is a link to the retail versions of Loctite threadlockers made by the Henkel Corporation:

Loctite Threadlocker Properties Chart

I have used blue, red and even a green loctite once. The columns for torque (break/prevail), temperature range and cure speed are all relevant. Permatex brand orange threadlocker falls in between the Loctite blue and red, where it is stronger than blue but doesn't need to be heated to remove the fastener.

Now on a production line in a factory, it is likely that people aren't going to be using little squeeze bottles to apply threadlocker.

Which is why there is a whole other set of Loctite pre-applied products with different properties:

https://dm.henkel-dam.com/is/content/henkel/LOCTITE_preapplied_threadlockerspdf

And there are companies that pre-apply the coating, for example:

https://thecoatinghouse.com/coated-fasteners/

"LOCTITE® DRI Thread lockers are a dry-to-the-touch pre-applied film for threaded fasteners. It remains inert on the fastener until assembly of the threads releases a quick curing resin. The resin fills all the voids in the threads and cures to securely lock and seal the assembly. Our Pre-applied thread lockers come in different strengths, colors, and temperature ranges."

I bolded that text to highlight that these pre-applied threadlockers are also going to act as thread sealants. I'll note that in that preapplied product pdf, the first two groups of products are thread sealing products, not threadlocking products. Where some of the thread sealers are good for up to 5 assembly / disassembly cycles.

Which, if your location in your profile is accurate and you intend to drive your JT during winter when they use salt on the roads, you may care about the thread sealing properties to keep those little bolts from rusting into the axle housing, because some of the threaded holes in the housing are open on the back side.

When you are applying torque to a fastener, some percentage of that applied torque goes to overcoming the friction of the threads, the rest is used to stretch the bolt creating the desired clamping force on the assembly. If you look up recommended torque values for fasteners, you can find tables that give different values depending on the finish on the fasteners, e.g. raw steel vs. zinc plated, or dry vs. lubricated fasteners. Why? Because different finishes will result in different amounts of friction on the threads.

So does the pre-applied thread locker on the original equipment or Mopar / Spicer replacement bolts increase or decrease the friction exerted by the threads? Thereby impacting what value the bolts need to be torqued to to achieve the desired clamping force?

I don't know. My guess (refer to the disclaimer in the first sentence) is that the two pass torque procedure in the instructions that came with the replacement bolts is that the first pass releases the quick curing resin, and then in the second pass that resin is acting as a lubricant necessitating that second torque value.

 

[Wheelin98TJ]

Okay -

So can I reuse the diff cover bolts or not?

Some folks do? Some don’t?

Some say to clean the threads and apply new thread locker but don’t torque to 30#?

Little confused…

You don’t need new bolts, thread locker, or even a torque wrench. Old bolts tightened to snug works perfectly fine.

 

[Maximus Gladius]

It’s easy to over think something that’s “simple” to us wrenchers. One can get lost in all the options of what to do, the multiple ways each one of us does something, or this job specifically. In fact, when we do maintenance jobs like this dozens/hundreds of times, the job is nothing and are brains are thinking about other things while we do the job.

As @Wheelin98TJ said, “snug” is good enough. He’s right but snug may mean 110 inch lbs/9-10 ft lbs (like I do) and snug will be 300 inch lbs (approximately 25 ft lbs) like others do. My bolts don’t fall out, and when i change those fluids annually, the bolts are still in place.

The gaskets we have are double rubber ribbed/steel material. It doesn’t take bolt snapping torque to create a seal. “Feeling” the right snug point will take practice so for a newbie, I’d recommend an inch lb torque bar.

If you settle on crazy low torque (like me), give yourself permission to bend down every now and again to see if oil is gushing out all over or check and see if bolts have unwound themselves and scattered around or missing. I’ve not found any of that yet.

One more point this random guy has to say is crawl underneath and look at the transmission pan bolts. That pan uses the same type/style gasket as the diffs. Look at the spread distance of those bolts and compare to the spread distance of the diffs bolts and ask yourself why is the torque value of the transmission bolts at 98 inch pounds/9-10 ft lbs and they are more spread apart AND hold the weight of 5.5 quarts + the pan weight and all the oil and bolts stay in place and the diff bolts need 25-30 lbs to hold the cover on and keep the 1 or 2 quarts of oil in place?

We can then look at the difference in the two bolt types and say tranny bolts are longer/thinner and diff bolts are shorter/wider. I would bet if you could take the ends of the threads and pull them in a straight line, they’d be the same length.

 

[JTGuy]

I have never used a torque wrench on diff cover bolts and never broke one. Never had a cover fall off. I do torque lug nuts and some suspension bolts.

 

[GunnyB]

Hey gang,

After getting the courage to not just replace the main battery of my 22 JT Sport S - but also diving deeper under the main to get to othe aux and replace, it is about time to change the front/rear diff service as my JT is hitting 34k miles.

The dealer who I have free oil changes for life quoted me aroudn $900 to do front/rear/trans service - but after watching a few online Youtube videos - it looks pretty straight forward, and something I can do on my garage floor.

My only concerns and questons are;

1. Since my 22 JT does NOT have a drain plug - I assume I would need to remove the fill hole plug first, and then loosen the top two diff cover bolts, and remove the rest for the oil to drain out?

2. The dif cover should have a gasket - I would assume this is reusable?
2a. Should I invest in a different cover if I plan on DIYing this down the line?

3. The diff cover - can it be cleaned out with parts cleaner? How about the actual differential/teeth area?

4. What is the gold standard/recommended oil to use for a vehicle that doesn't rock crawl, and does some minor light trailer hauling for the front/rear?

5. Should I use YELLOW teflon tape around the fill plug?

6. Does anyone have the torque specs for the bolts?


I've read folks can do this easily at home, and spend about $100 vs $900 from the stealership. I just want to verify everything before I jump in.

Thanks!

-Brent

I have a '20 Sport S. It DOES have drain plugs F & R. Just changed-out gear oil (Valv 75W-90 full-syn) in both, took approx 30-45 min incl clean-up. E-Z - P-Z. Can't imagine a dealer asking $900 to do it, even if they did have to R&R punkin' covers!

 

[Sigz]

I have a '20 Sport S. It DOES have drain plugs F & R. Just changed-out gear oil (Valv 75W-90 full-syn) in both, took approx 30-45 min incl clean-up. E-Z - P-Z. Can't imagine a dealer asking $900 to do it, even if they did have to R&R punkin' covers!

Nice.

And yes as stated before 21’s and up do not have the plugs.

 

[Maximus Gladius]

I have a '20 Sport S. It DOES have drain plugs F & R. Just changed-out gear oil (Valv 75W-90 full-syn) in both, took approx 30-45 min incl clean-up. E-Z - P-Z. Can't imagine a dealer asking $900 to do it, even if they did have to R&R punkin' covers!

The quote also included the transmission and that would have taken the $900+ by itself. The quote was way off by a lot.

 

[Sigz]

The quote also included the transmission and that would have taken the $900+ by itself. The quote was way off by a lot.

I called and asked the dealer to itemize the work:

And front/rear diff would be $150 each.

 

[Hootbro]

I called and asked the dealer to itemize the work:

And front/rear diff would be $150 each.

If that includes the fluid, not a bad price for a overhead shop labor.

OEM service data says to replace the bolts each time the cover is off with new hardware. I can say from experience that the old bolts can be used but the torque specs need to be backed off about 5 FT-LBS or there is a 50/50 chance of snapping them, especially if you go the full 30 Ft-LBS for the rear.

While not in the owners manual, service data give advice to use 75W-140 if equipped with a tow package. They do not define if that means the Max Tow option or any of the other lesser tow packages. DANA Advantek aftermarket axles use and recommend 75W-140 for them.

 

[WILDHOBO]

Hey gang,

After getting the courage to not just replace the main battery of my 22 JT Sport S - but also diving deeper under the main to get to othe aux and replace, it is about time to change the front/rear diff service as my JT is hitting 34k miles.

The dealer who I have free oil changes for life quoted me aroudn $900 to do front/rear/trans service - but after watching a few online Youtube videos - it looks pretty straight forward, and something I can do on my garage floor.

My only concerns and questons are;

1. Since my 22 JT does NOT have a drain plug - I assume I would need to remove the fill hole plug first, and then loosen the top two diff cover bolts, and remove the rest for the oil to drain out?

2. The dif cover should have a gasket - I would assume this is reusable?
2a. Should I invest in a different cover if I plan on DIYing this down the line?

3. The diff cover - can it be cleaned out with parts cleaner? How about the actual differential/teeth area?

4. What is the gold standard/recommended oil to use for a vehicle that doesn't rock crawl, and does some minor light trailer hauling for the front/rear?

5. Should I use YELLOW teflon tape around the fill plug?

6. Does anyone have the torque specs for the bolts?


I've read folks can do this easily at home, and spend about $100 vs $900 from the stealership. I just want to verify everything before I jump in.

Thanks!

-Brent

You can definitely do both. For the transfer case, get a hand pump at least, to put fluid back in. Otherwise it’s very easy.

For the diffs without bottom drains, don’t bother removing the fill plug initially. Just put a bucket under the diff, loosen all the bolts, but don’t remove, and gently by hand crack the bottom edge. Let it drain. Then remove the cover and be careful with the gasket, but they’re absolutely reusable. I wouldn’t replace the cover. For cleaning the cover, just wipe it with throw away lint free paper towels. No need for parts cleaner, and you don’t want it missing with the diff fluid anyway. Check for any chunks of metal. If there isn’t anything more than VERY smooth metal sand on the magnetic fill plug, you’re good. No cleaning inside the housing. Just leave it unless there is metal. That’s a different story if there is. You almost certainly won’t have any issues. Put the clean cover back on with finger tight bolts only. Then carefully tighten with hand tools only in a star pattern. No torque wrench is necessary. Just common sense method. If it leaks, tighten slightly more. I’ve never had either of mine leak after a bunch of intervals with the original gaskets. Refil through the fill hole until it drips out. Close and wipe off. Enjoy.

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