New JK owner looking for some advice following a re-gear. Note: I did the oil change/inspection at 300 miles per Motive gear break-in recommendations for pulling a trailer. Some comments/questions:

• Quite a few shavings after first oil change @ 300 miles
  • Is this reasonable at 300 miles?
    
  • Should I expect the next oil change to have very little shavings?
    
  • Any indication that the gears should be adjusted or replaced by the shop?
    
• Wear patterns showed streaks on face
  • Are these streaks a sign of a problem at 300 miles?
    
  • How many miles before the gear wear patterns are stable?
    
  • Should the wear patterns eventually smooth and polish to look more like the stock gears they pulled out?
    
• Rear diff gets hot, can only touch for ~1sec without burning
  
• Rear e-locker light just keeps flashing
  • Used to work fine
    
  • Seems rear locker is at least partially engaging but light just keeps flashing
    
  • Was planning to ask the shop to troubleshoot/fix this since it used to work
    
• New whirling/howling sound
  • Seems to occur after evertyhing is hot from extended freeway driving
    
  • Sound only occurs when shifting after depressing clutch (so when load is removed)
    
  • Could this be related to re-gear, or perhaps just a bad timed issue with the trani, etc.?
    

Details on Jeep:

• Bought 2012 JKU Rubi @ 43k, re-gear to 5.13 at 45k
  
• Re-gear at local aftermarket truck shop, I supplied master overhaul kits, Ten Factory (Motive) gears, and AEV diff covers
  
• 37" tires, 4" EVO long arm lift, manual trani
  

Timeline of re-gear:

• Shop did 2 heat cycles, 10 mi each
  
• I did 3 heat cycles 10 mi each
  
• I did more 20-30 mi cycles, mix of 45 mph 4hi and 60mph 2hi to get to 300 mi total
  
• Pulled front dipstick, some shavings
  
• Pulled rear dipsitck, more shavings than front
  
• Pulled front drain, about a raisin sized amount of shavings on magnet, visible glitter in oil
  
• Pulled rear drain, about an almond sized amount of shavings on magnet, oil was dark
  
• Inspected front ring wear pattern, appears offset toward heel, some visible streaking on faces
  
• Inspected rear ring wear pattern, appears more centered, some visible streaking on faces
  
• Replaced w/ Mopar 80w-90 1.5 qts front, Mopar 75W-140 Syn 2.5 qts rear
  
• Hooked up 2000 lb trailer and drove 200 miles lightly, cool down every 30-50 miles
  
• Drove 50 miles light offroad
  
• Drove trailer 200 miles home
  
• Re-inspected front/rear dipsticks (450 miles after oil change)
  • Front had a few fine shavings oil looked clean
    
  • Rear had more fine shavings than front and black residue on stick for first few pulls, then oil looked clean after

All photos below are from the first 300 mi oil change.



front dipstick

rear dipstick

front drain plug

Front diff cover slurry at drain plug

front coast and drive side

front coast side

front drive side

rear coast side

rear drive and coast side

rear drive side

 

Hard to tell from the pictures, but to me it looks like the pinion is in to close to the ring gear, centered well, but just tight

Can you feel any backlash in the pinion?
There should be a small amount

 

Those shavings aren't unusual at all during the break in.

Your rear contact pattern actually looks good.

The contact on your front is much more towards the outside of the ring gear (heel side), indicating your backlash is a little high.

Your pinion depth looks fine to me though. Front and rear.

I'm no expert though. Just doing lots of research in anticipation of doing my own gears this summer.

 

First, thanks for the quick reply this forum is awesome--hoping to add value for other folks going forward as I gain experience.

Re: the pinion being close to the ring gear are you referring to the back gears? For the front, the gear tech said he ran out of adjustment range (or something to that effect) and could not get the pattern centered heel to toe.

Re: backlash, I'll do some research on this today.

 

Randy's Ring and Pinion has a big FAQ on their website that goes over a lot of install questions/issues. Here is one of the blurbs you may find interesting.

 

Whirling/howling is not normal. The snapshot nthinuf posted there is nice and handy. That diff shouldn't be so hot you can't touch it. That seems like a red flag to me. I'd bet that when they put the carrier assembly back in the diff, they bent the plunger which sends the indication the locker is engaged or not and that is why the light keeps flashing. @TheDirtman can give you the best opinion on the wear. Not that this comes in to play necessarily, but having potential issues is why it is almost always better to let the shop doing the install take care of supplying the gears and master install kit. That way if an issue does arise, there is no question in getting it covered. When you supply parts and someone does the labor, the window is open to start pointing fingers and it's harder to remedy the situation.

 

It could just be my small phone and aging eyes looking at a digital picture, but the rear is the one I was looking at, the pattern is centered well, but just has a funny look to me like the pinion may be too close to the ring gear causing a burnished look instead of just engaging.
hard to tell without actually seeing the real thing and feeling the back lash. That is the travel back and forth of the pinion without the ring gear moving

 

Ok, many of the posts I saw were claiming a good install should have basically no shavings so I wasn't sure. Should the wear patterns be stable after say 1K miles such that future oil changes should have minimal shavings?
I will measure the backlash next time I have it apart.

This is great, thanks. I will try to reproduce the sound again and listen more carefully to try and document it better.

This is best photo I can find for the rear drive pattern. It sill shows some signs of streaking like the other wear surfaces but not quite as bad.

rear ring drive side 2 - 300 miles


Agreed that the new sound isn't normal. They said it could be because the gear ratio changed but it seems more likely that it's related to the re-gear given the timing.
Regarding the heat, it seems these thick AEV covers would allow the diff to heat up more but I'm not sure what to expect.
I talked to the shop about the plan for parts and it seemed easiest for me to just pick and bring the parts (all brand new from Northridge 4x4) but there wasn't a mention about this voiding any warranty for the work. Good lesson for next time.

 

Yeah, I had small shavings like that after the first 500 mile gear fluid change. None since.

Your rear looks really acceptable, and I'd run it. What bearings did you use? I had a whirring and howling sound, and it was my rear pinion bearings. Replaced with Timken bearings and they've been solid since.

My rear locker also stopped engaging recently. Check for 12 volts at the wiring harness before the diff.

 

Keep in mind as well that locker is a big magnet. If you have that many metal shavings there is a chance you have a lot stuck in the locker. Maybe clean the heck out of that with brake cleaner.