CORed

On my truck (see sig), my rear pinion seal on my D80 is leaking. Not terrible, but it's leaking. I have done some searches and it seems that getting alignment / measurements correct during re-install is of utmost importance and I've never done one before and am thinking I'm not qualified nor do I have the right tools.

Can anyone confirm the skill / specialized tools required for this job and how long it should take? I'm no ASE and only have done many brakes, u-joints, fuel pumps, electrical, alternators, and oil changes on various vehicles over the years.

Also, what should a ballpark cost be to have a shop do it?

Thanks!

patdaly

The only thing you really need special is an inch/Lb torque wrench.

I check the rotational torque before pulling the yoke ( obviously wheels off the ground ), buzz off the nut, pull the yoke, change the seal, reinstall and pull nut moderately tight, check rotational drag, and then adjust nut tightness till I get it close to where it was. Refill diff, and you are good to go.

I have seen ASE techs just use their impacts and never check rotational torque and have good luck also, but it always seemed Hillbilly to me.

BigIron70

Recommend replacing nut with the seal, (locking type nut used) Dana 80 do not use crush sleeve for bearing preload. Dana 80's use shims to control the pinion bearing preload. New nut is recommended since nut is a locking type and must be torqued to spec which is 440 ft lbs. Don't know of many people that can tighten nut that tight laying on their back. Even with truck on a lift using 3/4 drive torque wrench takes everything I have to reach 440 ft lbs
If you reuse old nut then I recommend blue locktite and mark the nut and top of pinion shaft so nut is tighten back to the same mark, which should be close to 440 ft lbs. I've also seen techs use impact gun also but you run the chance of damaging bearings. Good Luck


INSTALLATION
Clean the seal contact surface in the housing bore.
Examine the splines on the pinion shaft for burrs or wear. Remove any burrs and clean the shaft.
Inspect pinion yoke for cracks, worn splines and worn seal contact surface. Replace yoke if necessary.
Apply a light coating of gear lubricant on the lip of pinion seal.
Install new pinion shaft seal with an appropriate Installer.
Position pinion yoke on the end of the shaft with the reference marks aligned.
Install the yoke with Installer D-191 and Yoke Holder 6719A (Pinion Yoke Installation).
Install the pinion yoke washer and nut.
Hold pinion yoke with Yoke Holder 6719A and tighten shaft nut to 597 N·m (440 ft. lbs.) (Tightening Pinion Shaft Nut). Rotate pinion shaft several revolutions to ensure the bearing rollers are seated.
Rotate pinion shaft using an inch pound torque wrench. Rotating resistance torque should be equal to the reading recorded, plus a small amount for the drag the new seal will have (Check Pinion Rotation Torque).
NOTE: The bearing rotating torque should be constant during a complete revolution of the pinion. If the rotating torque varies, this indicates a binding condition.

Install propeller shaft with the installation reference marks aligned.
Install the brake calipers.
Add gear lubricant to the differential housing, if necessary.
Install wheel and tire assemblies and lower the vehicle.

high bid

I followed instructions as "somewhat" noted above, purchased parts from RockAuto and it took me about 30min.

Dane

I was gonna reply "it's not that hard" I mark the nut and housing before removing and put it back where it was using some locktite to keep it there.

CORed

Well - after reading everyone's input and the detailed installation instructions, I decided for the price, to have the dealer do it. I had them also install a new pinion nut as was recommended above. That nut was $30. I didn't have a torque wrench or a ft/lb gauge that went that high either.

The total cost was $280. The existing seal was cracking all the way around and leaking - but not severely - down the diff. I only have 106K on the truck, but most of what I use it for the past couple years is towing a 5th wheel and tandem ATVs. I just wanted it done right and have piece of mind. I plan on changing the diff fluid this weekend.

While they had it on the lift, the mechanic showed me that the slip yoke on the rear of the NP241DLD is leaking where some sort of "welch" plug is on the very back end of the yoke - right where the U-joint is. It's not bad, but I plan to use metal epoxy there when I replace the u-joints on the drive shaft.

Thanks again for all the replies and details.