You tell me... how bad am I screwed?

[nckwltn]

So I was planning on swapping out the seal from behind the flange where the rear drive shaft connects into the differential. I have a diff in my garage with the 4.27 gears, so I tested on that and the flange slid right off with a couple of taps of a hammer to the back of the flange.

So i did the same to the rear that I have installed, which has the 4.636 gears. Only it didn't tap off very easily. I tap it with a little more force and it does finally come off....


Now I've got this


the shaft on the other diff seems to be rock solid....

how bad am I screwed? To boot, it seems that I have the wrong seal too... so I woudln't have been abel to do the job anyway.

 

[nckwltn]

if I put the flange on and turn it by hand... the thing I'm holding will move in and out about 3/4ths of an inch. I can see there is a bearing which in the FSM is labeled as "Drive pinion front bearing inner race" moves around as well. You can see it move with the drive pinion at about 13 seconds into the video....

Do I basically need to pull the rear and setup everything from scratch? I assume that as I turn the pinion, the reason it moves in and out is because it is moving against the ring gear.

Or by some stroke of luck can I just put the flange back on, put it to torque and drive the rest of my days without a care in the world?

 

[jeep-N-montero]

Do you have the right tools to set the pre-load on the pinion nut/bearing, or did you even follow the steps when removing the nut to know what to torque it to?

 

[nckwltn]

Do you have the right tools to set the pre-load on the pinion nut/bearing, or did you even follow the steps when removing the nut to know what to torque it to?

I'm going to have to answer negative on both of these... It looks like I need a inch lb torque wrench, which I can source no problem... but can the pre-load be properly set with the ring gear installed? I can pull the axle shafts out easy enough so the ring gear turns freely.

basically, my bearing pre-load is screwed up, correct?

 

[nckwltn]

Although, it is probably my inner bearing that is incorrect now. When I hit the back of the flange, all of the force would have been against that bearing, and not the one that I can see in my video.

But isn't the back of the inner bearing pushing up against the gearing from the pinion?

 

[JamesW]

Does it make a heck of a racket while you're coasting? I.E. Slowing down without applying power? Mine was doing that,and all I did was keep tightening the pinion nut with a torque wrench until it went away,the bearings had worn a bit,and needed a bit more pressure applied to them,it was nearly undrivable the way it was,bit of a nip up and it hasn't acted up and over a month. Think I finally tightened it to 187nM though,which is a lot

 

[Toasty]

You're probably fine, the only adjustment is with shims on the pinion head so even if you drop the pinion into the diff it will go back into it's rightful place upon final torque. I've changed many pinion flanges out and have dropped the pinion into the diff a couple times without any issues after reassembly.
Torque the pinion to spec then check the rotating resistance with the inch pound torque wrench (beam type) if it checks out you're golden. if not you probably had a bearing issue you were not aware of before hand so when you released the load on the bearings they ******** the bed.

 

[Toasty]

Pinion final torque is 159 ftlbs and the rotational resistance is; (with new or used bearing and gear oil in the bearings) 5.6-6.5 in.lbs with oil seal

As per 1999 FSM 9.5" locking rear

 

[nckwltn]

Does it make a heck of a racket while you're coasting?

I only had about 70 miles on this pick-a-parts diff... but it didn't make any noises that I was able to notice.... had a good mix of highway and surface streets miles.

Torque the pinion to spec then check the rotating resistance with the inch pound torque wrench (beam type) if it checks out you're golden. if not you probably had a bearing issue you were not aware of before hand so when you released the load on the bearings they ******** the bed.

Can I do this with the ring gear still attached? or am I going to have to pull the diff? (I'm assuming that I have to pull the axle shafts clear)

 

[nckwltn]

I guess my big concern is that I've moved the inner bearing closer to the pinion gear by tapping the back of the flange. Or is the inner bearing snug against the back of the pinion gear head, such that the bearing can't physically get any closer anyway?

 

[stioc]

There's a crush collar in there that gets crushed as you tighten the nut but I seriously doubt you crushed it further by tapping the flange out- it takes 100+ft-lbs to get crushed.

No need to remove anything, just tighten the nut to spec after you replace the seal and it should be fine. Personally I hate diffs; lash and preload are black magic so it's one thing I'm happy to pay an expert for (John at All4Wheel in Corona in my case).

 

[nckwltn]

well... worst comes to worst... I watch the pick a parts locations for the next few weeks and pick me another rear diff I'm sure that is cheaper then paying someone to make this one work properly.


although, if I had the time (and tools), I'd be down with trying to adjust everything... I need to a friend that does this kind of stuff.... and a friend with a lift... and a friend with a large workshop... preferably all the same friend! :wings:


Picked up the right seal from Oreilly today.... FYI they are open until 11pm at my location!

 

[Toasty]

There's a crush collar in there that gets crushed as you tighten the nut but I seriously doubt you crushed it further by tapping the flange out- it takes 100+ft-lbs to get crushed.

No need to remove anything, just tighten the nut to spec after you replace the seal and it should be fine. Personally I hate diffs; lash and preload are black magic so it's one thing I'm happy to pay an expert for (John at All4Wheel in Corona in my case).

There is no crush sleeve on any Montero axle ever though, the depth is set by shims.


nckwltn, the bearings are still in their correct places most likely. The bearing can just slide out of the outer race (tapered roller bearings), the parts that are pressed in place are not easily moved. But yes tighten the pinion nut after you replace the seal then check the resistance and you'll be fine. You will need to make a spanner wrench to hold the pinion flange while you torque to spec, basically a bar with two studs that fit your flange to hold it in place. I have done it against the parking break in a pinch but it's better to have something holding the flange.

 

[nckwltn]

You will need to make a spanner wrench to hold the pinion flange while you torque to spec, basically a bar with two studs that fit your flange to hold it in place. I have done it against the parking break in a pinch but it's better to have something holding the flange.

I plan on stopping by homedepot and picking up some flat metal bar (perhaps one with a 90 degree bend) and building a bar. I saw someone post a picture of one in the past that they also used on their crank shaft pulley... it should do the trick for this as well.

Hopefully it does work out, I'll post an update!

 

[nckwltn]

So I've got the flange back on, it doesn't move too much more than the flange on my old diff. (see video)

The flange on the old diff slides on and off VERY easily and smoothly, the flange on this 4.636 diff had to be cranked on by tightening the nut. I made a tool I saw someone else make a while back. Cost me $11 and change from home depot. Most of you guys probably have this stuff laying around your shop/garage. I cut the last 8 inches or so off of a 3 foot bar, drilled some holes and wammie bam, I have the tool I need for crank shaft and pinion flange tightening... and probably others as well.

I did hit 150lbs torque on the nut (according to my cheep torque wrench)




Let me know if anyone sees anything here that would give me reason for concern. I can spin both wheels freely and smoothly I can also turn the flange by hand, probably requiring more torque than the 4 inch lbs, but I still have the wheels on. I'd like to avoid pulling the axles out a few inches, but I don't know if I'll be able to avoid it to really test the preload. Although, I have no proper tools by which to measure, short of putting a 5lb weight an inch out from the center of the bolt and checking to see what gravity does.




Question: if the preload is bad, what kind of failure time are we talking about... are we talking about failure in 250 miles, 2500 miles, or 25000 miles? Obviously it depends on how bad it is.... my point is that I don't want to be in the middle of death valley in the fall, coming down lippincott pass and have my rear bearings die... so is there some kind of warning that I should be listening for?

Also, if I were to just bolt up the drive shaft and drive it as is... is that really any different knowing that I don't have the proper tools to fix it anyway? Can I just drive it until I hear the warning signs, then drive out to the pick-a-parts place and grab another rear for 100 bucks?

Thanks for any feedback