How to spot a bad pinion bearing? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > How to spot a bad pinion bearing?

Bill Baird Motorsports DIY parts - NalinMFG.comFS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitFS: Wranger BRIGHT License Plate LED! Just $3! Great value

Reply
Unread 01-21-2014, 05:42 PM   #1
FastSUV
Registered User
1998 ZJ 
 
Join Date: Sep 2012
Location: , oklahoma
Posts: 636
How to spot a bad pinion bearing?

Is there a good way to know if your rear pinion bearing is worn or needs to be replaced soon? No leaks, but I am wanting to re-do all of my rear bearings again eventually (did them before) but I never messed with the pinion bearing because I do not ave the expertise to re-set the R&P. My hope is to find a way to know if the pinion bearing is fine and be able to replace my carrier bearings again because those and the worn axles and outers are noisy.

__________________
ZJ - 5.9 Limited
WJ - 4.0 Laredo
WJ - 4.7 Laredo
WJ - 4.7 H.O. Freedom
FastSUV is offline   Reply With Quote
Unread 01-21-2014, 05:49 PM   #2
riot1987
Registered User
1997 ZJ 
 
Join Date: Jun 2012
Location: In your attic, with the squirrels and wrapping paper
Posts: 3,524
Are you hearing any excessive howling noises coming from the rear end?
__________________
http://www.jeepforum.com/forum/f22/riots-97-grand-1436100/

Build thread^^
riot1987 is offline   Reply With Quote
Unread 01-21-2014, 11:07 PM   #3
igids1
Registered User
1997 ZJ 
 
Join Date: Oct 2013
Location: brockton, ma
Posts: 31
Lift the rear wheels off the ground. Disconnect the driveshaft. See if you are able to lift/wobble the yoke UP AND DOWN. If you can, it needs to be replaced. If you are only changing the bearings, you will probably be fine not having to set the ring and pinion. Save and reuse the factory shims. Lets be honest, if you are reusing the ring and pinion, you are probably not going to make a better measurement than the factory did.

You can also raise the rear wheels off the ground, have someone place vehicle in drive and accelerate. See if the driveshaft is rotating in a circular motion, or more of a football shaped motion.

Now, bear in mind, many people feel you need to have a PHD in rear differentials to rebuild them. I read 1,000 posts, and was almost scared away from trying to rebuild mine. I rebuilt mine, without any special tools or measurements (other than a high torgue impact gun), 3 months ago. It rides like brand new still. I would recommend buying/borrowing a needle torque wrench, so that you can properly measure/set the pinion pre load. Other than that, its really a straightforward repair, like any other.

Sure, without calibrations to the 1/1000 of an inch, you might not get 200,000 out of the rebuild, but is the jeep going to be around that long anyways? Even if it is, you can rebuild it for 85 bucks yourself, so even if you have to do it a couple of times, it doesn't matter.
igids1 is offline   Reply With Quote
Unread 01-22-2014, 04:39 PM   #4
FastSUV
Registered User
1998 ZJ 
 
Join Date: Sep 2012
Location: , oklahoma
Posts: 636
I replaced the limited slip clutches in the past and have replaced the outer bearings and carrier bearings myself in the past. I had the ring gear and carrier out of course to do this. It roared real bad before i replaced the bad outer bearings...now it is noisy still but not as bad.

Are you suggesting that I can re-do the whole thing again AND remove the pinion without knowing how to set backlash? It would be very nice to have all fresh bearings in the rear-end and be able to do it all myself and stick in a few new heavy-duty axles. But then again that is why I am asking because if there is a way for me to know for sure the pinion bearing "seems" fine then I probably would not bother with it.
__________________
ZJ - 5.9 Limited
WJ - 4.0 Laredo
WJ - 4.7 Laredo
WJ - 4.7 H.O. Freedom
FastSUV is offline   Reply With Quote
Unread 01-22-2014, 06:03 PM   #5
KJK
Registered User
1998 ZJ 
 
Join Date: Jan 2007
Location: Dallas, Texas
Posts: 855
Quote:
Originally Posted by FastSUV View Post
But then again that is why I am asking because if there is a way for me to know for sure the pinion bearing "seems" fine then I probably would not bother with it.
If your carrier bearings were bad then the pinion bearings are almost assuredly worn also. The pinion spins more than 3 times faster than the carrier and sees pretty large loads.
The pinion bearings can seem fine and be spalled and pitted enough to really howl. It can feel tight and smooth and you won't necessarily feel it turning it by hand. If there is any sideways play at all then that thing is done.
If you re-use the same gear set and same carrier and same axle housing then you will be fine reusing the original shims in their respective places. The shims are for variations in the manufacturing tolerances of these parts. Bearing tolerances are so much tighter that the new bearings will be (for all practical purposes)exactly the same as the old bearings.
The only thing you'll have to pay special attention to is the pinion bearing preload. Get the FSM and a good inch-pound torque wrench and you'll be all set.
I rebuilt my entire front axle using this method a few years ago and it's still great.
__________________
5.9 ZJ SCT tuned PCM/ KJK CAI/ Thorley headers with 3" Magnaflow cat and muffler/ Modded kegger/ TransGo shift kit/ Vanco brake kit/ Braided steel brake lines/ Mopar cupholder insert!
KJK is offline   Reply With Quote
Unread 01-23-2014, 08:00 AM   #6
zjosh93
Registered User
1993 ZJ 
 
Join Date: Aug 2010
Location: Austin
Posts: 1,086
I set up my own gears on a Ford 8.8 and then later swapped the carrier from open to Traction Loc. If you are just replacing bearings you should be able to reuse all the existing shims and everything should be fine. I'd just check the backlash on the gears when you are done to make sure it's still in spec. All you need to set the pinion is a torque wrench, needle-type inch-pound torque wrench, a big breaker bar, a new crush sleeve, and a way to hold the yoke still. Some of that you can rent and the rest is pretty cheap.
zjosh93 is offline   Reply With Quote
Unread 01-23-2014, 09:14 AM   #7
speedbucket
Registered User
1993 ZJ 
 
Join Date: Jan 2011
Location: chesapeake, VA
Posts: 3,552
So yah....what about the clamshell, press, brass punch, dial inchpound torque wrench, etc....if you don't have access to all these you will spend more money in tools than the repair would cost to someone that does have them. I know several guys that install gears for 2-300$ ....you start buying specialty tools and you'll hit 200$ quickly, heck ...my buddy's clamshell setup was 400$
__________________
http://www.jeepforum.com/forum/f22/speedbuckets-zj-build-1361322/
V8 zj at 6" . Double tri rear and true 3 link front. Stretched to 108"
speedbucket is offline   Reply With Quote
Unread 01-23-2014, 10:00 AM   #8
zjosh93
Registered User
1993 ZJ 
 
Join Date: Aug 2010
Location: Austin
Posts: 1,086
You can use a cheap beam style inch-pound torque wrench to set the rotating torque on the pinion bearings. They run under $50. You can rent the big torque wrench and breaker bar at most auto parts stores for free. You don't need the case spreader if you are just pulling the carrier and putting it back in. Even if you did there's a write up around here to make one out of hardware store parts for cheap. Brass drifts are only $5 at my local parts store but you can get a piece of aluminum for a couple bucks at the hardware store that works just as well. A dial indicator set runs about $30 at harbor freight and you can find a 20% coupon to bring that down to $25. Shops around here charge $5 to change a bearing so $15 for new bearings installed. So even if you have none of the special tools you should be able to get all the ones you need for under $100. He's not setting up new gears, just replacing bearings.
zjosh93 is offline   Reply With Quote
Unread 01-23-2014, 12:28 PM   #9
FastSUV
Registered User
1998 ZJ 
 
Join Date: Sep 2012
Location: , oklahoma
Posts: 636
Quote:
Originally Posted by zjosh93 View Post
You can use a cheap beam style inch-pound torque wrench to set the rotating torque on the pinion bearings. They run under $50. You can rent the big torque wrench and breaker bar at most auto parts stores for free. You don't need the case spreader if you are just pulling the carrier and putting it back in. Even if you did there's a write up around here to make one out of hardware store parts for cheap. Brass drifts are only $5 at my local parts store but you can get a piece of aluminum for a couple bucks at the hardware store that works just as well. A dial indicator set runs about $30 at harbor freight and you can find a 20% coupon to bring that down to $25. Shops around here charge $5 to change a bearing so $15 for new bearings installed. So even if you have none of the special tools you should be able to get all the ones you need for under $100. He's not setting up new gears, just replacing bearings.
I have a shop press and an in/lb and ft/lb torque wrench...but mine are click wrenches and not the beam kind...does that matter?

The last time I had the carrier out, I did not need a case spreader, although the guy helping me mixed up the bearing caps so I have no idea if the correct shims/caps went back where they came from! It still works though.
__________________
ZJ - 5.9 Limited
WJ - 4.0 Laredo
WJ - 4.7 Laredo
WJ - 4.7 H.O. Freedom
FastSUV is offline   Reply With Quote
Unread 01-23-2014, 12:39 PM   #10
zjosh93
Registered User
1993 ZJ 
 
Join Date: Aug 2010
Location: Austin
Posts: 1,086
You need a torque wrench that reads the torque dynamically so the click type wrenches won't really work. You are measuring the force it takes to rotate the pinion caused by drag on the bearings and slowly tighten the pinion nut until it's within spec. The spec is around 40 in/lbs IMS. You need a new pinion nut BTW. There are some good write-ups here if you search. Ratmonkey had a good explanation somewhere too.
zjosh93 is offline   Reply With Quote
Unread 01-23-2014, 05:10 PM   #11
FastSUV
Registered User
1998 ZJ 
 
Join Date: Sep 2012
Location: , oklahoma
Posts: 636
Quote:
Originally Posted by zjosh93 View Post
You need a torque wrench that reads the torque dynamically so the click type wrenches won't really work. You are measuring the force it takes to rotate the pinion caused by drag on the bearings and slowly tighten the pinion nut until it's within spec. The spec is around 40 in/lbs IMS. You need a new pinion nut BTW. There are some good write-ups here if you search. Ratmonkey had a good explanation somewhere too.
awesome, thanks - RIP
__________________
ZJ - 5.9 Limited
WJ - 4.0 Laredo
WJ - 4.7 Laredo
WJ - 4.7 H.O. Freedom
FastSUV is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.