Rearend

[sporty1200xlc]

Im changing fliud in my rearend. I was also going to change the pinion seal. The guy at autozone said there are two sizes. So which size do I need. 72 1/2 ton 2wd. Cover has 12 bolts. Ring gear is 43 pinion gear is 14. Ratio of 3.07. Thanks for any help.

[cdowns]

i'd get both seals and save the reciept and take back the one that dont fit

[Longhorn Man]

being the nature of your question, yoy may want to pay a pro to do the pinion seal. If you don't do it right, you'll be replacing everything in the diff.

[fastwillie 696969]

Originally Posted by Longhorn Man

being the nature of your question, yoy may want to pay a pro to do the pinion seal. If you don't do it right, you'll be replacing everything in the diff.

i agree and dont count the threads on the pinion and try to match the lineup marks ,you need to set the back lash also i would change the crush sleeve as well
The four essential differential adjustments are pinion depth, pinion bearing preload, backlash and carrier bearing preload.

Crush Sleeve Design: If you are unsure about getting the correct pinion depth, it may be easier to install the pinion without a crush sleeve until the correct pinion depth has been established. Always use a new crush sleeve for final assembly. Slide the crush sleeve on the pinion shaft (unless you are using the trial and error method) and install the pinion through the rear of the housing. The yoke usually must be tapped on while applying pressure on the pinion gear head to hold it in place. Use an impact wrench or huge breaker bar to apply the torque necessary to crush the sleeve. Proceed very slowly so that you don't overload the bearings. The pinion preload will be zero until the bearings contact the races but will then increase very quickly. Use an inch-pound torque wrench to check the preload. If the pinion bearing preload exceeds the specified allowable range, install another new crush sleeve and start over.

Preload Shim Design: Clean the shims completely so that there are no particles that may cause a false preload reading or cause the shim stack to change thickness over time as the vehicle is driven. Slide the shim pack over the pinion shaft to the shelf. Use the original shims on the first assembly or add 0.003" to the original preload shims to make up for the bearings settling into the housing. Tighten the pinion nut to approximately 250 foot pounds. Go slowly so as not to damage the bearing if the preload shim stack is not thick enough. Use an inch-pound torque wrench to check the preload. If the preload is too loose then remove shims so that the bearings will be tighter against the races and increase the preload. If the preload is too tight then remove the pinion gear and add shims so that the bearings will not be as tight against the races.

All Designs: After reaching the correct preload, moderately tap both ends of the pinion to seat the bearings, races and yoke. Be careful not to hit the pinion so hard that it damages the bearings. After "seating" the pinion, check the pinion bearing preload again.

Install Carrier and Adjust Carrier Preload and Backlash

Carrier bearing preload is not specifically measured, but a good tight fit is important in all differential designs. Inadequate carrier bearing preload allows the carrier to move when under load and this can cause the backlash to open up. Check the backlash by mounting a dial indicator to the housing with the plunger set perpendicular to the ring gear teeth. Hold the pinion yoke and rotate the ring gear back and forth. See the specifications section. The backlash will generally change about 0.007" for each 0.010" that the carrier is moved. To decrease the backlash, move the carrier closer to the pinion centerline. To increase the backlash, move the carrier away from the pinion centerline.

Screw Adjuster Design: Oil the adjuster threads on both the housing and on the adjusters themselves. While holding the races on the bearings, place the carrier in the housing. Install the carrier caps according to the marks made during disassembly so that the threads are seated evenly on the adjusters. Third member differential designs require a 10 to 12 inch spanner wrench to tighten the adjusters. Chrysler differential designs require an extension bar and special spanner to access the adjusters through the axle tubes. Tighten both the left and right adjusters evenly by hand until they are fairly tight. If the backlash is too wide, tighten the left adjuster until the backlash is correct. If the backlash is too tight, tighten the right adjuster until the backlash is correct. If necessary, open one adjuster and tighten the other. Both adjusters must be fully hand tightened when acceptable backlash is obtained. The final adjustment should tighten the left adjuster since the ring gear is forced away from the pinion gear while under load.

Shim Design: Some differentials use shims between the carrier bearing races and the housing and some use shims between the carrier bearing and the carrier case. Carrier bearing preload is established by the tightness of the shims. The carrier should be shimmed tight enough that it must be tapped in with a plastic dead blow hammer. While holding the races on the bearings (and outside shims on the races) start the carrier into the housing and tap it in with the hammer. Install the carrier caps according to the marks made during disassembly. Check the backlash. If the backlash is too wide, move or add shims to the left side. If the backlash is too tight, move or add shims to the right side. (If the carrier is snug, move and replace the same thickness; if the carrier is too tight or too loose, remove or add shims accordingly.)

[Longhorn Man]

see... it's not just a nut and bolt job.

[LONGHAIR]

Originally Posted by fastwillie 696969

i agree and dont count the threads on the pinion and try to match the lineup marks ,you need to set the back lash also i would change the crush sleeve as well
The four essential differential adjustments are pinion depth, pinion bearing preload, backlash and carrier bearing preload.

Although I always recommend that rearend work be performed by a professional.....this is not necessarily one of those cases.

While the above "Copy & Paste" is accurate, most of it is irrelevant....

The only one of those adjustments that can possibly change with a pinion seal install is the pinion bearing preload.....and it takes a lot more torque than you would think to crush the sleeve.
None of the rest of those details matter at all in this case. If they are already wrong, there is nothing that you can do about it now anyway.

Pop the yoke off, swap the seal, and put it all back together. Torque the nut to about 75 ft-lbs with red Lock-Tite and run it. That is plenty of torque to keep the nut tight and not nearly enough to crush the sleeve any more.

The whole in-lb "rotation" thing is based on a completely stripped housing, no carrier, axles, or seal.....and that is for new bearings. Used are going to be looser anyway....and it is not advisable to "mess with" trying to tighten them up.

The real issue here is that you may already be "too late". If the pinion seal is leaking, the bearings may already be shot....which kills the seal in the first place.

[special-K]

I'd do what CDowns recommended or remove the seal first and take it into the parts store. A good parts house will be able to match it up.
If you have some degree of mechanical skills,a proper manual,and the ability to read and follow instructions you can do differential work.

[sporty1200xlc]

Thanks for all the help guys.

[Jeffs70]

really helpful tips and info here.