Differential Q's, Need A's
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Joined: Sep 2009
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From: California
Differential Q's, Need A's
Hey Guys, the truck is coming up on 60k miles and I am going to be taking the differential cover off for the first time and I have a few questions. I searched around a little bit, but didn't find any of this information in any previous threads but I am sure one of you guys will be able to answer them pretty quickly.
1. What is the difference between the 1500 and the 2500/3500 LSD differential? I was reading through my Dodge Manual and noticed that the 1500 takes a 140 weight diff oil, and the 2500/3500's only take a 90 weight. Why is that?
2. I am planning on using fully synthetic Royal Purple in the rear. Is it okay to use a 90 weight, or should I stick to the recommended 140 weight?
3. The Manual says that in the 2500/3500 differentials that the additive is not needed. Why does the 1500 need it but the 2500's don't? Also, do I still need the additive if I am going to use Royal Purple. I have read/heard somewhere that you don't need the additive when using Royal Purple. Is this true?
I am planning on doing this fairly soon along with the tranny filters/fluids. Any and all help would be appreciated.
1. What is the difference between the 1500 and the 2500/3500 LSD differential? I was reading through my Dodge Manual and noticed that the 1500 takes a 140 weight diff oil, and the 2500/3500's only take a 90 weight. Why is that?
2. I am planning on using fully synthetic Royal Purple in the rear. Is it okay to use a 90 weight, or should I stick to the recommended 140 weight?
3. The Manual says that in the 2500/3500 differentials that the additive is not needed. Why does the 1500 need it but the 2500's don't? Also, do I still need the additive if I am going to use Royal Purple. I have read/heard somewhere that you don't need the additive when using Royal Purple. Is this true?
I am planning on doing this fairly soon along with the tranny filters/fluids. Any and all help would be appreciated.
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Joined: Jul 2007
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From: South Georgia/East Florida
1) The LSD in the 1500 is a clutch pack type and requires a friction modifier for the clutches to "grab" properly. The LSD in both the AAM 10.5" and 11.5" rears do not use clutches but instead uses a helical gear (think Detroit TruTrac) and therefore need no modifier.
2) Even AAMs own specs call for 140 weight in the 9.5" 31 spline, 12 bolt solid rear axle. Wouldn't be the first time I strayed from Chrysler specs, but I'd side with the manufacturer of the thing and stick with the recommended weight.
3)See #1 AND try the RP without adding any first, after you are done, drive the truck in some tight circles and figure 8s, if you get any bind or chirping, go get a bottle of additive, but instead of using the whole thing just add half and repeat the tight circles. It should shut up when you have the proper amount of modifier in it. Seen some with RP not need any, seen some need half bottle, never seen one need a full bottle...
2) Even AAMs own specs call for 140 weight in the 9.5" 31 spline, 12 bolt solid rear axle. Wouldn't be the first time I strayed from Chrysler specs, but I'd side with the manufacturer of the thing and stick with the recommended weight.
3)See #1 AND try the RP without adding any first, after you are done, drive the truck in some tight circles and figure 8s, if you get any bind or chirping, go get a bottle of additive, but instead of using the whole thing just add half and repeat the tight circles. It should shut up when you have the proper amount of modifier in it. Seen some with RP not need any, seen some need half bottle, never seen one need a full bottle...
