Jeep Enthusiast Forums banner

Rear End - to Ignore, Rebuild, Swap, or Buy New?

867 Views 8 Replies 4 Participants Last post by  Xmind
Short version:
If your rear pinion seal is leaking, change the diff fluid when you replace the seal
Looking for opinions on if I actually need to change the rear end and if so, what do people suggest?

Long version:
The ring and pinion has always been loud since I got the Jeep with around 87k miles in 2012. Recently (since April 2019 when I started driving it again after it sitting for nearly 20 months) the rear end was also making a bit more noise than before....almost like a bearing might be going....on top of the rear end whine. Lifted the rear and wheels seemed okay for play to indicate it isn't a bearing issue. Opened the diff and oh boy, very milky. Wasn't over the drain plug level though. This was quite surprising considering I changed the diff fluid about 40k miles ago. Not sure if water got in due to a leaky pinion seal I had earlier (but still post diff fluid change) or if it sitting for so long some how got a lot of moisture in the diff housing.

Changed the fluid and added the friction modifier. Definitely helped with the noise, but still a bit louder than it used to be.

With the noise and the issue with it running with water for some period of time I was doing some research and it appears I have 4 options:

1. Ignore it? - The rear end has been making noise since I got it and hasn't had a noticeable step in noise increase besides this recent issue. The gears look pretty good, but some slight play. Is there really an problem with just to keep driving it as is with the noise? I could understand if there was considerable slop or vibration, but it doesn't seem excessive.

2. Rebuild the rear end - New ring and pinion, axle bearings, and possibly diff and you are looking at $500-900 in parts and $600-$1000 to have some one rebuild it (not sure if this is something I'd be willing to tackle....I mean for $1000 I'd give it a shot)

3. Swap in a Junk Yard Axle - seems you can get junk yard replacements for ~$350 to $600. However most of them have >100k miles on them and I don't want to spend the time to swap an axle just for the same problems to occur again. On the flip side, if I can swap the front and rear to get the 3.07 ratio, then I'd be interested.

4. Buy New Axle - For money, what am I missing about buying a new axle assembly such as this for ~$1300 shipped?: https://www.moparpartscorp.com/oem-parts/mopar-axle-assembly-5191214aa It may not have the electronic limited slip, but not sure I'd miss it if it is new and saves me $1000?
1 - 9 of 9 Posts

· Registered
Joined
·
198 Posts
Discussion Starter · #3 ·
Yes, I did pop the diff cover and replace the fluid. I haven't driven very many miles yet, but I doubt expect the pinion whine to get better than it has been after I changed it 40k miles ago. Unless your saying if it is just pinion whine now that I cam safely defer any further action as long as I can bear the extra road noise?

Sent from my SM-G935U using Tapatalk
 

· Registered
Joined
·
167 Posts
Yes, I did pop the diff cover and replace the fluid. I haven't driven very many miles yet, but I doubt expect the pinion whine to get better than it has been after I changed it 40k miles ago. Unless your saying if it is just pinion whine now that I cam safely defer any further action as long as I can bear the extra road noise?

Sent from my SM-G935U using Tapatalk
Did the R&P gears look good? If so, possibly get a second opinion from someone local. I would at most buy a master rebuild kit and get the bearings changed out if the R&P look good.
 

· Registered
Joined
·
198 Posts
Discussion Starter · #6 ·
Did the R&P gears look good? If so, possibly get a second opinion from someone local. I would at most buy a master rebuild kit and get the bearings changed out if the R&P look good.
Yeah the ring and pinion gears looked good. Still clean sharp-ish edges and no major metal debris found inside the housing. There was a bit of sludge at the bottom that I blasted out with brake/ carb cleaner though.

Sent from my SM-G935U using Tapatalk
 

· Registered
Joined
·
198 Posts
Discussion Starter · #7 ·
I would go new or used after a proper diagnosis. I don't consider them to be serviceable due to cost.
That seems to be the conclusion I'm coming to.... kinda surprised that is the case, but I guess it isn't a 5 minute job to rebuild these and I heard some people having a hard time getting the axle shafts out to replace the bearings...... which is a high probability considering this vehicle spent 5 years in Newfoundland and now 7 in Michigan.

Sent from my SM-G935U using Tapatalk
 

· Registered
Joined
·
198 Posts
Discussion Starter · #8 ·
Well ~1200 miles since the oil change (MI to WI and back last week) and everything sounds like it used to prior to the "grinding" kind of noise. I.e. loud ring and pinion, but no longer the gritty or bad wheel-bearing kind of sound. I also got the best fuel economy to date (at highway speeds). Got 25.5 mpg on the way out to WI and just over 27 mpg on the way back. Average probably around 70 mph between the 4 states on the way out and probably 60 mph with the last fuel up due to all the WI local driving.

I still need to find a good drive train guy to take a look at the diff in case this noise is just a backlash adjustment issue. Anyone have some recommendations in the metro-Detroit area?
 

· Registered
Joined
·
198 Posts
Discussion Starter · #9 ·
well....sh*t....

Just got around to changing the front differential fluid a little over a week ago.....except only about a 1/2 quart (if that) actually drained out.....more like a 1/4-1/3 of a quart actually!

Seems the right seal had been leaking for a long time. I.e. there definitely wasn't any fresh oil on the right seal/drive shaft to indicate a slow leak. I did refill hoping it was a slow leak to buy me some time to get parts to fix, but within 2 days my nearly 2 quarts of oil was sitting on my garage floor under the right axle.

I'm now positive there hasn't been any oil in this thing since at least April when I got back and I wager that the oil hasn't been in the front diff for years before that. That is a damn resilient front diff and glad I didn't rent the camper trailer for a vacation a month ago as I originally planned as I can't imagine that front diff would have been happy with an actual load on it.

So seems I'll have to plan on dropping the diff to see how bad it is (or isn't) inside and either buy a rebuilt one or if everything is "okay" and just replace the seals (and mounts and bearings as long as I'm in there).

<sigh>

So ironic that other than a leaky injector seal and a bad camshaft position sensor, nearly all my problems stem from what Jeep is known for: their drivetrains. I'm half tempted to replace the entire drive train in this thing as I'm not sure I have confidence in any one of the pieces.....
1. The rear drive shaft was replaced in 2011 (by previous owner)
2. Rear pinion seal replaced 4 years ago
3. Occasional slippage of transmission/transfer case in cold weather
4. Water in the rear diff
5. Leaking front diff axle seal
6. Loud ring & pinion since I bought the thing in 2012
7. Slight vibration in the pedal at certain speeds that seem to come from the drive line vibrations.

.....I don't think I'll be buying a lotto ticket anytime soon as I think I'm using all my luck to not have a full catastrophic failure here yet!
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top