Getting rear diff rebuilt, but told entire driveline should be rebuilt too

[fordbluefamily]

It has been theorized that the aluminum cases spread under load and change angles of things. My tbirds with IRS never had this issue. The diff was the one part of them that DIDNT wear out. I have heard of people modifying 4th gen diffs to work in a third gen but its definitely not a plug and play thing.

 

[blue_goose]

My bad, I stand corrected. I have heard that the seal where the driveshaft goes into the rear diff is a bad design. It was redesigned a few times for the later model years but apparently that didn't make it any better. I can see the seal leaking on mine, has since I got it.

 

[fireball 440]

In my experience 90% of pinion and rear axle seal failures are caused by the vent line being plugged with dirt. The location of the vent on the Explorer is pretty protected though. Just about every bad seal on a F-150 rear end I did had a plugged vent.

 

[dubbio]

great, looking to fwd to this on my 02 with 185k...

 

[MikeCA]

Here's an update.

I've had the rear-end rebuilt and the truck now flies with literally no vibration at 65+ (the speed at which it would begin) other than what I would attribute to the tires (over-size BFG AT KO's) and perhaps slight pitting on one or two wheels. It's smooth as butter by comparison to what was there before**.

**Since the job was done on only a couple of occassions I have felt a sudden and sharp vibration from what I would attribute to be the rear-end that lasts at most 2 seconds:
- occurs when starting the engine, then
- moving forward always with turned wheels from the start
- slow speed
- flat surface
- shudder dissipates within 1-2 seconds, quite possibly as wheels are straightened out, can't remember
- no other vibration is felt while driving at all speeds, no other vibration while turning at slow speeds from four-way stops, etc.
- occurs randomly so I've had difficulty replicating this to gauge where it might be originating from, but it definitely feels like it's coming from the butt-end

Any idea if this is something to do with the rebuild just getting worn in or has something been botched? As I've mentioned before, the rebuild is working really well with no problems other than this shudder that's come up 3-4 times since the job was completed just before Xmas.

Thanks in advance.

 

[MikeCA]

Mods, we can close this thread. I'll pose my last question in a new thread as it seems to be a separate issue.