Whining on Deceleration

[PontiacHO]

Wondering if the repair shop had to change the pinion seal and/or pinion yoke during replacement?
It takes a seasoned technician to know (by feel) the proper torque to reinstall the pinion nut (hopefully new) for sufficient bearing preload. Otherwise the preload can’t be accurate when tightening the pinion nut with the carrier/ring gear still engaged.

 

[D60]

Good excuse to buy the proper 10mm sq for the fill plug, too. 3/8" drive is technically too small.

And yeah, the 10.25 had a long history of wheel seal problems. They finally went to a revised "Scotseal" that spins within itself, which seems much better. BUT wheel seals alone aren't going to cause your problems unless the fluid level dropped dramatically-- although this could have happened at any point in the life of the diff.

Good news: unlike 14b's, the rear drums just slide off once you've removed the wheels. Might not hurt to yank the drums and look for gear oil goop in the drum, on the shoes etc.

If pinion bearings are suspect or pinion nut is loose, *I* have long maintained I'll only accept yanking the carrier, installing new bearings and setting a new crush sleeve to properly measure preload. I still don't see how anyone thinks they can account for the drag of the carrier bearings and r&p interface, but I do believe guys with LOTS of experience can judge it well enough (not me). Basically at that point it's 99% art and 1% science. Or get the pinion unimpeded and it's 99% science with an inch lb torque wrench

 

[i6pwr]

wheel seals alone aren't going to cause your problems unless the fluid level dropped dramatically

Good point, but I did want to clarify my statement earlier on the seals. If the seals go bad, sometimes it will be from a worn bearing, when the axle rides on the seal harder than normal, due to not being centered.

The worn seal would follow a worn bearing if severe enough.

 

[Dehaka]

took to mechanic shop today and took mechanic for a ride. he said to drive vehicle as is and see if noise gets worse or goes away and bring back if it gets louder. most pronounced between 20 and 30 mph. said it could be the new tires or just the transmission winding down (?) . but only happens when truck is warmed up.

 

[i6pwr]

Did you verify the fluid level in the rear differential?

 

[Dehaka]

Did you verify the fluid level in the rear differential?

i asked them to check it. they said is full.

 

[Lubener]

Wondering if the repair shop had to change the pinion seal and/or pinion yoke during replacement?
It takes a seasoned technician to know (by feel) the proper torque to reinstall the pinion nut (hopefully new) for sufficient bearing preload. Otherwise the preload can’t be accurate when tightening the pinion nut with the carrier/ring gear still engaged.

This is done with a precision torque wrench capable of reading torque specs of 8-14 inch pounds, slightly higher if a new pinion bearing was used. The brakes have to be partially disassembled so that the brake drag is not influencing the reading.To do this correctly, you do not do this by "feel".

 

[PontiacHO]

Yes, pinion bearing preload is checked/set without the differential carrier in the housing. (Salisbury axle) It’s based solely on the rotating torque of the pinion gear. Yes it’s done with an inch pound torque wrench. Axle and brake drag can’t and don’t come into play then. Most seasoned techs do not completely disassemble a rear axle to replace a pinion seal. Thus their experience and ability (by feel) to secure the pinion yoke/nut is practiced. I’ve replaced many pinion seals this way. Always used a new pinion nut. They are a one time use fastener. I’ve overhauled many rear axles. The last being a 1967 Chevelle 12 bolt with Yukon 3.73 gears and Eaton posi. The rotating pinion yoke torque was measured at 19 to 21 inch pounds. The pinion depth was set with .031 pinion shims. Backlash set with .243 (total) carrier shims.
Moving on to Ford and their removable center section (Hotchkiss)…the pinion can be removed separately without differential carrier removal. The rotating torque can be checked with inch pound torque wrench before reinstalling the pinion.