Rear Differential Service

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jdn112011

Well-Known Member
Oct 18, 2015
1,191
307
83
26
Roseau, MN
Truck Year
2015
I was borderline between severe service and regular maintenance so I opted to do the fluid change on my 3.55 limited slip at about 29k and 1 year old.

Ram differentials do have drain plugs which is very helpful! Located to the passenger side behind the casting for the fill and cover. But it requires a rather odd bit. A 9/16 hex, and or a 14mm Allen wrench. The latter of which I was able to find locally at the Fleet Supply store for $4 opposed to purchasing a $30+ oversized hex socket set which I really did not need.

Anyways from there on the drain is rather simple, be sure that you are level, and pull the plastic plug first to vent the drain.


20160524_183414.jpg

I drove around a bit being as 75-140 is a bit thick and warming promotes an easier drain. But the factory fill gear oil is very foamy. As shown.

20160511_122630.jpg 20160511_122625.jpg

After replacing the drain plug. Refilling, full synthetic 75w140 gear oil. Many have limited slip additive already. I like and use Mobil 1 so I Used that. Quantities are not very clear for fill but it takes a little under 3qts. Dealer parts guy told me almost 35$ a quart for fluid and 3.5 capacity.

I did use the mopar friction modifier which I mixed into the last quart. You can fill directly from a gear oil bottle though you will not get quite the whole thing without lowering or removing the spare tire, I just transferred remaining fluids into the next container to utilize as much a possible.

Capacity again is just under 3qts

Spray it down with brake cleaner afterwords and good to go.
 
Last edited by a moderator:

jdn112011

Well-Known Member
Oct 18, 2015
1,191
307
83
26
Roseau, MN
Truck Year
2015
Edit: 9/16 = 14mm @BoostN could you correct that?
 

jdn112011

Well-Known Member
Oct 18, 2015
1,191
307
83
26
Roseau, MN
Truck Year
2015
@BoostN I think it's time to sticky this! @Capt Tim had to ask me where to find the service thread because it's a page back now!
 

BoostN

Administrator
Staff member
Administrator
Jul 27, 2013
3,250
800
113
Tennessee
www.ecodieselram.com
Truck Year
Not Listed
@BoostN I think it's time to sticky this! @Capt Tim had to ask me where to find the service thread because it's a page back now!
Great idea. If we all can generate enough content we can make a "DIY" section. What do you think?
 
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jdn112011

Well-Known Member
Oct 18, 2015
1,191
307
83
26
Roseau, MN
Truck Year
2015
Great idea. If we all can generate enough content we can make a "DIY" section. What do you think?
It sounds like you're asking me to work on this. ;)
 
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Reactions: BoostN

Capt Tim

Member
May 7, 2017
35
15
8
St Johns, FL
Truck Year
2014
I was borderline between severe service and regular maintenance so I opted to do the fluid change on my 3.55 limited slip at about 29k and 1 year old.

Ram differentials do have drain plugs which is very helpful! Located to the passenger side behind the casting for the fill and cover. But it requires a rather odd bit. A 9/16 hex, and or a 14mm Allen wrench. The latter of which I was able to find locally at the Fleet Supply store for $4 opposed to purchasing a $30+ oversized hex socket set which I really did not need.

Anyways from there on the drain is rather simple, be sure that you are level, and pull the plastic plug first to vent the drain.


View attachment 677

I drove around a bit being as 75-140 is a bit thick and warming promotes an easier drain. But the factory fill gear oil is very foamy. As shown.

View attachment 678 View attachment 679

After replacing the drain plug. Refilling, full synthetic 75w140 gear oil. Many have limited slip additive already. I like and use Mobil 1 so I Used that. Quantities are not very clear for fill but it takes a little under 3qts. Dealer parts guy told me almost 35$ a quart for fluid and 3.5 capacity.

I did use the mopar friction modifier which I mixed into the last quart. You can fill directly from a gear oil bottle though you will not get quite the whole thing without lowering or removing the spare tire, I just transferred remaining fluids into the next container to utilize as much a possible.

Capacity again is just under 3qts

Spray it down with brake cleaner afterwords and good to go.

This is an awesome post! I have three qts AMSOIL 74-140. I am not going to use the anti-friction because my ED
I was borderline between severe service and regular maintenance so I opted to do the fluid change on my 3.55 limited slip at about 29k and 1 year old.

Ram differentials do have drain plugs which is very helpful! Located to the passenger side behind the casting for the fill and cover. But it requires a rather odd bit. A 9/16 hex, and or a 14mm Allen wrench. The latter of which I was able to find locally at the Fleet Supply store for $4 opposed to purchasing a $30+ oversized hex socket set which I really did not need.

Anyways from there on the drain is rather simple, be sure that you are level, and pull the plastic plug first to vent the drain.


View attachment 677

I drove around a bit being as 75-140 is a bit thick and warming promotes an easier drain. But the factory fill gear oil is very foamy. As shown.

View attachment 678 View attachment 679

After replacing the drain plug. Refilling, full synthetic 75w140 gear oil. Many have limited slip additive already. I like and use Mobil 1 so I Used that. Quantities are not very clear for fill but it takes a little under 3qts. Dealer parts guy told me almost 35$ a quart for fluid and 3.5 capacity.

I did use the mopar friction modifier which I mixed into the last quart. You can fill directly from a gear oil bottle though you will not get quite the whole thing without lowering or removing the spare tire, I just transferred remaining fluids into the next container to utilize as much a possible.

Capacity again is just under 3qts

Spray it down with brake cleaner afterwords and good to go.

Thanks. This is great info. The dealer (service advisor). balked at the job but it so easy. I'm not going to use the anti-slip as I've got conventional rear end. Hope it is same volume though.
 

Capt Tim

Member
May 7, 2017
35
15
8
St Johns, FL
Truck Year
2014
He said the tech wasn't qualified that was changing my supplied Amsoil SS 5-40. No way I'd pay that much though. They charged me $19.95 to charge oil but the filter was $65. I read some time ago on this forum someone found our oil filter much cheaper somewhere.

I read conventional rear-end shouldn't get anti-friction additive. I'm not an expert though; I'm an operator that cares.
 

jdn112011

Well-Known Member
Oct 18, 2015
1,191
307
83
26
Roseau, MN
Truck Year
2015
Balked at the job! They could have charged $250 for about 15 min of work!

Based on some reading it looks like the friction modifier is recommended even with fluids that claim limited-slip compatibility.
Yes and I stated that in the Post. Even though I Used "limited slip friction modified fluid" I still added the mopar friction modifier.

But that being said, @Capt Tim stated that he has a standard open differential. Not limited slip.
 

Bw1605

New Member
Oct 9, 2017
3
0
1
Truck Year
2016
So I was told by 2 different people at the dealership 2 different things. One said I have a limited slip diff and the other said I don’t. I’m planning on changing the fluid his weekend but need to know for sure. Is there any easy way to find out? I’m going crazy trying to figure it out. Online build sheets don’t really tell me, that I can find. I have a 3.55 on a 16 Laramie
 

jdn112011

Well-Known Member
Oct 18, 2015
1,191
307
83
26
Roseau, MN
Truck Year
2015
So I was told by 2 different people at the dealership 2 different things. One said I have a limited slip diff and the other said I don’t. I’m planning on changing the fluid his weekend but need to know for sure. Is there any easy way to find out? I’m going crazy trying to figure it out. Online build sheets don’t really tell me, that I can find. I have a 3.55 on a 16 Laramie
Very simple mechanical answer to this, Jack up your rear end with truck in Neutral, rotate one Tire by hand, if they both rotate same direction you have lsd, if they rotate opposite it's an open or standard Differential. Or I suppose a guy could do a burnout and check that way lol (powerbrake not technically a burnout..)

Have dealership pull up your vin, or reference your build window sticker.

If you use the readily available fluid that I did, it probably contains enough modifier to be fine if it is lsd without adding the extra.
 

Capt Tim

Member
May 7, 2017
35
15
8
St Johns, FL
Truck Year
2014
Good luck on the change. I researched for sure my rear diff via RAM VIN data sheets. RAM Website was excellent resource. BTW, recently changed my conventional rear end and it required just under 3 quarts; like JDN stated in his DIY help post.
 

Bw1605

New Member
Oct 9, 2017
3
0
1
Truck Year
2016
Good luck on the change. I researched for sure my rear diff via RAM VIN data sheets. RAM Website was excellent resource. BTW, recently changed my conventional rear end and it required just under 3 quarts; like JDN stated in his DIY help post.
Can you point me in the direction of the data sheet? The ones I have found don’t really tell me much. Other then I have a 3.55 diff
 

Capt Tim

Member
May 7, 2017
35
15
8
St Johns, FL
Truck Year
2014
73C00764-D0F3-4DD1-B320-F4DE3CC9846A.png 954DCC74-2C96-4BBE-8EAF-9B60CA705F06.png 44F1622B-662E-49E4-97DE-8B347DE1B670.png D735DBBA-B267-4773-8E9C-5E37F7482AA9.png

I will try. Use the MY RAM app. Follow the picture sequence; the first list is under “other” second list is under “standard”. The “other” shows my 3.55 gearing. The “standard” list shows my Conventional Rear Differential (i.e. non-LSD). Hope this helps.
 

Bw1605

New Member
Oct 9, 2017
3
0
1
Truck Year
2016
That’s perfect. Mine actually shows conventional differential rear axle. So no Limited slip for me. Thanks
 

mel

New Member
Nov 4, 2017
2
0
1
Truck Year
2015
Thank you for the info on the rear diff. It looks like the front diff also has a drain plug just below the fill, is that correct.