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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.
Looking at this picture, it appears the teeth are pitting from lack of lubrication which is caused by the back lash not set up properly. If the back lash is to tight the gear teeth will not lubricate properly and that will start to erode the tooth surface. Just from the picture I would be concerned if that's only after 200-300 miles but confirm yourself if the surface is pitting or is it just the way the picture is making it look.
Last edited by Dirt Hammer; 06-22-2020 at 06:00 AM.
Reason: new info
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.
After several test drives I noticed the whirling sound only occurs when the A/C is on and doesn't associate with whether the jeep is warmed up. Seems to be unrelated to the re-gear at this point and I probably noticed it now because I'm a new owner and haven't been running the A/C until recently.
Originally Posted by BoraBora
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.
I bought the master overhaul kit w/ Timken bearings.
Originally Posted by Dirt Hammer
Looking at this picture, it appears the teeth are pitting from lack of lubrication which is caused by the back lash not set up properly. If the back lash is to tight the gear teeth will not lubricate properly and that will start to erode the tooth surface. Just from the picture I would be concerned if that's only after 200-300 miles but confirm yourself if the surface is pitting or is it just the way the picture is making it look.
Interesting, the shop is opening it up on Wednesday to fix the sensor issue and I'll take a close look and try to get some closeup photos at this point (close to 1K miles).
Looking at this picture, it appears the teeth are pitting from lack of lubrication which is caused by the back lash not set up properly. If the back lash is to tight the gear teeth will not lubricate properly and that will start to erode the tooth surface. Just from the picture I would be concerned if that's only after 200-300 miles but confirm yourself if the surface is pitting or is it just the way the picture is making it look.
They just opened it up at 900 miles and the tech said the gears seem to be wearing "funny" and was planning to run it by some of his references for advice. He mentioned he had a similar issue w/ Motive gears before. I did research before selecting gears and found Motive commonly recommended. I was willing to pay for good gears just couldn't find an obvious consensus on the forums. Photos below. rear drive side - 900 miles rear coast side - 900 miles
Originally Posted by resharp001
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.
The sensor plunger was bent. They replaced it and the locker works and reports correctly now. They didn't pull axles just loosened carrier and moved axle tubes to get some play. I thought I read that not removing axles could risk damage to the seals? I suppose I just need to watch for leaks?
The red arrows are pointing at what I believe is called the "Fillet" part of the gear tooth. You have what looks like a lot of contact in that area and looks to be damaging.
The green arrow is pointing at the gear tooth "tip" it also shows signs of contact.
Looks like the pinion gear tips are making contact with the ring gears fillet. Some of the fillet looks eroded away form the picture.
In my non professional opinion the gear tip and fillet should never make contact with each other when gear lash is properly set up. But I'm no axle professional.
My opinion doesn't mean much, but the shop did a shoddy regear and is trying to blame the brand of gears. I don't believe it is the G2 gears that cause weird wear, it's improper shimming. This sounds like a general shop rather than a shop that deals with jeeps regularly. That isn't to say that they can't do a good job, but you're typically better off with someone that regears jeep axles regularly IMO. There's just so many red flags, and yet another one is the fix to get the locker plunger in there. If they simply removed the bearing caps and pulled the carrier out enough to jam that in without having removed axle shafts.....that seems like a jacked up short cut to save themselves some time in an effort to fix their F-up. Was that the front or rear axle the plunger was jacked on? If it was the front, for sure keep an eye out for leaky seal, which will piss you off more since carrier will have to come out yet again. tbh....they're likely gonna have to regear that again. Make sure they replace the seals at that time while everything is out.
The red arrows are pointing at what I believe is called the "Fillet" part of the gear tooth. You have what looks like a lot of contact in that area and looks to be damaging.
The green arrow is pointing at the gear tooth "tip" it also shows signs of contact.
Looks like the pinion gear tips are making contact with the ring gears fillet. Some of the fillet looks eroded away form the picture.
In my non professional opinion the gear tip and fillet should never make contact with each other when gear lash is properly set up. But I'm no axle professional.
Thanks for highlighting this, seems like a pretty big problem now that I'm looking more closely. The pinion does appear to be too close to the ring and wearing the root. The wear on the ring tip probably indicates there is corresponding wear on the pinion fillet. I would imagine this is likely to increase friction (perhaps explaining the excessive rear diff temps I observed), increase stress on the bearings, and reduce the strength of the gears by eroding the fillets. I have enough oil to refill the front so I think I should image that more closely and then talk to the shop about replacement plans.
Originally Posted by resharp001
My opinion doesn't mean much, but the shop did a shoddy regear and is trying to blame the brand of gears. I don't believe it is the G2 gears that cause weird wear, it's improper shimming. This sounds like a general shop rather than a shop that deals with jeeps regularly. That isn't to say that they can't do a good job, but you're typically better off with someone that regears jeep axles regularly IMO. There's just so many red flags, and yet another one is the fix to get the locker plunger in there. If they simply removed the bearing caps and pulled the carrier out enough to jam that in without having removed axle shafts.....that seems like a jacked up short cut to save themselves some time in an effort to fix their F-up. Was that the front or rear axle the plunger was jacked on? If it was the front, for sure keep an eye out for leaky seal, which will piss you off more since carrier will have to come out yet again. tbh....they're likely gonna have to regear that again. Make sure they replace the seals at that time while everything is out.
The rear axle plunger was bent. Based on what Dirt Hammer pointed out it seems the rear at a minimum needs new gears. The front also did not have a great wear pattern but I think I need some better photos to evaluate.
If I were to properly address the situation now (shortly following a re-gear with a new master overhaul kit), would the scope of work be replacement of the ring/pinion front and rear, and replacement of the seals front and rear? Were you recommending replacing the seals on the rear axles because they didn't pull them when they replaced the locker sensor, or that it's just good practice to replace the seals when you pull axles? Do I need a new overhaul kit or any of the specific bearings or parts replaced, or can they all be reused?
Sorry, I was thinking that was the front and since the front seals are inside the tubes by the carrier bearings that would have been a bigger concern and they are a hassle to get to in order to swap a $16 part. The rear seals being out at the end probably a bit more forgiving with what they did to replace the sensor plunger, but still....pretty cheap and dirty way for them to do it. I can't speak for others, and I'm no pro, but if they replace the rear gears, I'd be using all new bearings....an entire fresh start.....especially considering how hot you said that rear diff was getting.
Here's an update to hopefully help someone in the future. I inspected the front a few weeks ago (photos below). The pattern is not as well centered as the rear. The surface hardness seemed better in the front in general but still showed some signs of streaking and material removal. Drain plug has fine powder no large shavings. Oil was changed earlier at 300 miles so this is the second oil change in front.
I contacted Northridge 4x4 and Motive about the abnormal wear and naively requested a refund and labor credit.
Response from Motive support: "In my professional opinion, that is a totally normal wear pattern for a ring and pinion. The Drive side on the front is a little closer to the heel than I would like and you can see it in the way it walked off a bit, but it is what it is at that point"
Response from Northridge 4x4 support:
"I showed the images to two of our gear installers before letting them know what the Motive Gear reps comments were and they both agreed the patterns are acceptable, although not as good as we would like to see on a vehicle we are sending out the door. There is no gear quality issue here and therefore no issue for Northridge or Motive to resolve. The pattern isn't perfect, which is on the installer, but it's not terrible either. A manufacturing issue with one set of Motive gears would be extremely rare and the odds of a one customer receiving two sets of gears with the same perceived issue would be unheard of."
Doesn't look like I'm getting any financial relief from Northridge or Motive, and it was a little surprising to hear them say this is a "totally normal wear pattern". I haven't seen many gear wear photos after break in so I only have my stock gears (which look a lot better) for comparison. Not sure if these gears are going to last long enough (say 50K miles) or if I'm going to see a failure sooner.
Plan at this point is to see if the shop that did the install will work with me and maybe just replace the rear. The shop's stance is that it wasn't a setup issue and it was the gear brand, but after talking around more it sounds like this is generally what happens when the customer supplies the gears and something goes wrong.
06-22-2020, 05:58 AM
