Hot diffs with gears?

Rottenbelly

New member
Anyone notice their diffs getting hot after regearing?
If so what did you do to help cool them.
Went from 3:21 to 5:13 and my diffs get to hot to even touch.
On my old jeep with 5:38's they got hot but not to where you couldn't even touch them. I ran 85-140 in them.
I am running 80-90 in these. I guess after break in I will try the 140 and see if it helps.
 
Anyone notice their diffs getting hot after regearing?
If so what did you do to help cool them.
Went from 3:21 to 5:13 and my diffs get to hot to even touch.
On my old jeep with 5:38's they got hot but not to where you couldn't even touch them. I ran 85-140 in them.
I am running 80-90 in these. I guess after break in I will try the 140 and see if it helps.

Are you still in the break-in period with your re-gear? It's possible that it runs hotter during the break-in process, but I don't really know. After you drain the oil and shavings, and fill back up, just continue to check and see if it gets better. Also, don't run it too hard during the break-in or you run the risk of chipping some teeth down the road.
 

WJCO

Meme King
I've never actually reached down and touched them after regearing (< phrasing). You could always get a temp laser though and shine it on both diffs to compare them.
 

cozdude

Guy with a Red 2-Door
Anyone notice their diffs getting hot after regearing?
If so what did you do to help cool them.
Went from 3:21 to 5:13 and my diffs get to hot to even touch.
On my old jeep with 5:38's they got hot but not to where you couldn't even touch them. I ran 85-140 in them.
I am running 80-90 in these. I guess after break in I will try the 140 and see if it helps.

They will get hot during the break in, it's normal. After that they will not get as hot. I suggest switching to 80-140 especially since you have 5.13's
 

DWiggles

Caught the Bug
Anyone notice their diffs getting hot after regearing?
If so what did you do to help cool them.
Went from 3:21 to 5:13 and my diffs get to hot to even touch.
On my old jeep with 5:38's they got hot but not to where you couldn't even touch them. I ran 85-140 in them.
I am running 80-90 in these. I guess after break in I will try the 140 and see if it helps.

Lots of guys run 80w90 so you should be fine. Keep in mind the JK is a lot heavier then "older jeeps" I personally run 80w140

My 5.13s "get hot" but not "problematicaly hot"
Unfortionately, I never shot the diff with a heat gun before the gear swap, so I have no baseline for comparison between the 4.10s and the now 5.13s. But intuitively, I would assume the 5.13s would run a little hotter being that more friction is present in comparison.
 

DKjeep

New member
You gotta think that pinion is down right humming with 5.13, its gonna get hot but thats some stuff down there thats built to take it. Run a good synthetic gear oil and dont worry about it.
 

JeepFan

Hooked
Stock or re-geared diffs can get extremely hot. My stock JK rear diff with 3.73s is almost too hot to touch after a long drive on the freeway. :yup:
 

Rottenbelly

New member
Thanks for the input. I am gonna keep the trips off the interstate till break in is done and then try some synthetic 80-140 in it.
Going to try to get a temp gauge and do some 80-90 versus 80-140 temp differences.
 
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