Help... Differential advice needed!

junior3382

junior3382

New member
I upgraded my gearing to 5.13:1

Two weeks later, my Dana 44 rear blew apart! Destroyed the bearings and my new ring and pinion.... was determined it cooked! Generating way too much heat!

Since then, I learned a shit ton about diffs, and that there is a very specific break in procedure for new gears, WHICH no one explained to me.... therefore I've taken responsibility as it was my fault since I use the freeway for work, and may have put way to much strain on my new gears too early....

That leads me to now.... I've been anal about following this new gear break in to the T. And due to rapidly grown paranoia, I drained the fluid to service it at 164 miles on the new gears... burnt and black.

Then when I was filling it, after cleaning it... I noticed a difference and now I'm confused again!

Pictured is my rear diff with Rancho rock gear diff covers.... the fill hole for these covers is much higher then the factory placement for my Dana 44. And according to the information I have in ALLDATA, Chrysler lists a capacity spec of 2.25 quarts of Synthetic 75W140 gear oil with a LSD additive. And maybe I'm thinking old school here, but when I filled it up, it tool almost 4 full quarts to get to the fill hole!

So, how much fluid goes in here???
Can too much fluid also cause the rear to "cook"?

I hope I'm not the only one who has experienced this. :-(



So, had rear rebuilt.... again.
 

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CJW

CJW

New member
If the service manual say 2.25 quarts then that's what you should use. Just because the fill hole is higher in your aftermarket diff cover doesn't mean you fill it that high.
 
jknikos

jknikos

Member
Yes you should stick with what the manual says. Overfilling could lead to some serious trouble. :naw:
 
ScoobyCarolanNC

ScoobyCarolanNC

Active Member
I've learned a lot in my 2 months of owning too. Use synthetic. Make use to use the correct amount of limited slip additive if you have a LSD, and don't over fill it even if it can take more. The oil heats up and expands. Too much and it will cause a slack feeling in your drivetrain, blow out of the breather tube, or worse....

I bought mine used & the previous owner never changed the diff oil. I tried a non-synth Lucas Oil that expanded so much that it blew out all over my front end & caused my drivetrain to feel loose despite using the correct amount. I went back to Mopar synthetic (friggin expensive) after 500 miles & no more issues. I found 2 small chunks on the magnet. Nothing too bad, but if I hadn't switched back it probably would have self destructed in a couple more months.
 
olram30

olram30

Not That Kind of Engineer
This looks like the weep hole, it should be a Allen bolt, remove it, if fluid comes out, it's over filled. If nothing, then it's underfilled. Looks the same as dynatrac diff cover.
 

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jnabird333

jnabird333

-
The factory differential fill level remains the same, however how much fluid it takes to get there will very. If you change your carrier (added a locker for example) and even a gear change will alter the amount of oil needed to properly fill the axle.

olram30's post is spot on and that is the level you seek. I just recently added an ARB locker which is smaller than the factory locker and I now need just under 3qts to get oil to that level.
 
jnabird333

jnabird333

-
Oh, and some other information for you.... I made a mistake installing my locker when I did my gear change that resulted in cooking my pinion. After I corrected and re-installed everything I have been monitoring my rear temps through the break in period. I noticed my oil temps started to come down after about 150 miles. but the first few 20 mile trips @ ~50MPH would easily get the diff to ~180 degrees with no indication of temp stabilization. By the time I got the 500 miles in my diff stayed less than ~175 at any speed or time duration. I just changed the oil and the diff temps came down another 15 degrees.

It is important to make MANY heat cycles in the first few hundred miles. I never went more than about 40 miles at a time in the first 300. After researching a ton, the goal is to keep the differential under 200 degrees during break in. According to my local Jeep stealership; operating temps to 225 post break in is considered "normal".
 
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mrmet1983

mrmet1983

New member
Ok first off do not listen to anyone saying to use the amount of fluid that jeep calls for that only applies to stock diff covers aftermarket diff covers are usually larger and in some cases hold more fluid due to the size of the cover. You want ur fluid to be right at the bottom of the axle tubes I use a zip tie I bend it BF use it as a dip stick to make sure my fluid is just at the bottom of the tubes there is no specific amount of fluid to use once u take off the stock diff covers. Please make sure u use a zip tie or something to make sure u have the proper fluid level or u will destroy another rear. As far as break in procedure once ur all set u want to drive it very easy for 15 min no faster then 50 mph and no hard accelerations. Then let it sit for at least an hour then I like to go for another a nice cruise around 50-60 for about 30-45 min then I let it cool again for an hour. After that I change the fluid again and usually call it a day that's just how I was taught and has worked every single time for me with not one issue.
 
wayoflife

wayoflife

Administrator
Staff member
mrmet1983 said:
Ok first off do not listen to anyone saying to use the amount of fluid that jeep calls for that only applies to stock diff covers aftermarket diff covers are usually larger and in some cases hold more fluid due to the size of the cover.
Click to expand...

:cheesy: You're kidding me, right? Exactly how much larger and how much more fluid do you believe aftermarket covers of any make hold?

You want ur fluid to be right at the bottom of the axle tubes I use a zip tie I bend it BF use it as a dip stick to make sure my fluid is just at the bottom of the tubes there is no specific amount of fluid to use once u take off the stock diff covers. Please make sure u use a zip tie or something to make sure u have the proper fluid level or u will destroy another rear. As far as break in procedure once ur all set u want to drive it very easy for 15 min no faster then 50 mph and no hard accelerations. Then let it sit for at least an hour then I like to go for another a nice cruise around 50-60 for about 30-45 min then I let it cool again for an hour. After that I change the fluid again and usually call it a day that's just how I was taught and has worked every single time for me with not one issue.
Click to expand...

You are absolutely right that the proper amount of fluid will be enough so that it reaches the bottom of the axle tubes but you're kidding yourself if think that'll be much more than the amount of what the factory calls for. When in doubt, a zip tie dip stick is a great way to determine the level of your fluid but if you have a weep hole like what the OP has, it'll be what you are wanting to fill to. Don't believe me? Just look at where it's located - at the base of the axle tube. :yup:
 
wayoflife

wayoflife

Administrator
Staff member
ScoobyCarolanNC said:
I've learned a lot in my 2 months of owning too. Use synthetic. Make use to use the correct amount of limited slip additive if you have a LSD, and don't over fill it even if it can take more. The oil heats up and expands. Too much and it will cause a slack feeling in your drivetrain, blow out of the breather tube, or worse...
Click to expand...

First off, synthetic gear oil comes with friction modifier in it. Second, there is nothing wrong with dino and if you have an ARB locker, I would recommend it as I have found synth to damage the o-ring and cause air leaks. Third, it's not just the heat that will get the oil to come out of the breather tube, the ring gear will effectively pump it out.
 
ScoobyCarolanNC

ScoobyCarolanNC

Active Member
I was just reiterating everything I've read so far, but totally defer to WoL as he definitely knows more than I do. When I bought the MOPAR synth oil at the dealer they asked me if I needed the additive. We pulled my VIN and they told me I didn't have a LSD so I didn't need it. Based on that I assumed it wasn't in there.
 
junior3382

junior3382

New member
olram30 said:
This looks like the weep hole, it should be a Allen bolt, remove it, if fluid comes out, it's over filled. If nothing, then it's underfilled. Looks the same as dynatrac diff cover.
Click to expand...

This was pointed out to me on another site. Have no idea how I did not see that....

Going to re- service the diff today and make sure it's right.... I'm all but past the break in period so am hoping this time it stays together. Lmao
 
CJW

CJW

New member
wayoflife said:
Third, it's not just the heat that will get the oil to come out of the breather tube, the ring gear will effectively pump it out.
Click to expand...

So true. I had over filled my front diff and it pumped out the breather. Went back and corrected the oil level and all is good.......except if I hit 80-85 on the freeway. Then it starts pumping out again. Anything slower and nothing comes out.
 
junior3382

junior3382

New member
I was too late to lower the level. Seems damage had already begun. Blew out yet another axle seal. So let's see, I think this is bearing and seal number 3! :-(

But it's fixed again and fluid level is down to spec... going to put a few more miles on it before checking it all out again. :-(
 

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ERAUGrad04

ERAUGrad04

Caught the Bug
junior3382 said:
I was too late to lower the level. Seems damage had already begun. Blew out yet another axle seal. So let's see, I think this is bearing and seal number 3! :-(

But it's fixed again and fluid level is down to spec... going to put a few more miles on it before checking it all out again. :-(
Click to expand...

Is there any warranty being provided? If I am reading the thread correctly, you have changes the seals and bearings 3 times? What about the gears? :grayno:
 
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