Changing Yokes... how tight?

[blazerpro79]

Hey guys, I'm about to go change out my yokes on my 12 bolt rear and np203 and I need to know how tight to torque my yoke bolts. Thanks in advance.
-mark

 

[mrk5]

I'm about to do the same thing. There is no exact answer, because technically you should set up the gears again.

If I was putting the same yoke back on, I would mark and the pinion and nut correspondingly and then count the number of turns to get it off. Then put it back on with the same number of turns and lining the marks up.

But, since the yoke is different I don't think that would be exactly accurate.

I'm paranoid about this kinda thing, so I've come up with a proceedure I'm going to try.

I'm going to mark it like outlined above and completely remove the yoke.

Then I'm going to re-install the old yoke lining up the marks and counting the turns. I'll use my deflecting beam torque wrench to figure out the torque it takes to line the marks back up.

Then I'll pull it back off again and install the new yoke to the torque setting I found above.

I'm also replacing the seal while I'm at it.

Randy's Ring & Pinion recommends putting some oil on the washer so it can turn if needed and use red locktight for the nut.

I also read something about using Permatex non-harding sealer on the splines, but I haven't been able to confirm that yet.

 

[Hogback Fabrication]

I wouldn't change the yoke on the 12 bolt if you don't know how to set up gears, I don't think you wil be happy with the result even if you try to count the turns and whatnot. The torque at the t-case should be about 150 ft. lbs.

 

[blazerpro79]

the yoke just unbolted and rebolted up... what do you guys mean about the gears? i didnt have to open the diff up or anything.

 

[muddybuddy]

i believe improper torqu effects how the pinion lines up with the gears. if not done properly, it can destroy ur gears. im not 100% sure tho

 

[mrk5]

the yoke just unbolted and rebolted up... what do you guys mean about the gears? i didnt have to open the diff up or anything.

The nut and the yoke you removed are what hold the pinion in the differential housing.

When gears are installed the nut is torqued down to crush the crush sleeve. That is what sets the pinion bearing preload. Preload is basically how tightly the bearing are pressed into the races which provides some rolling resistance.

So by removing the nut and yoke, you could potentially change the preload, and possibly even the pinion depth.

 

[Hogback Fabrication]

And having an improperly set pinion bearing preload could make the rear end seize up on your first drive down the street! You could get lucky and your rear end may last a little while (it's life is almost certainly shorter because without resetting the pinion bearing preload it is wrong).

 

[85mudblazin]

I doubt you can put enough force on it to crush the sleeve further with a simple ratchet.
When i did my 14b yoke, I just pulled the nut, pulled the yoke, new yoke on, and tightened it down till it got tight. You will be able to feel when the yoke gets up against the crush sleeve.

 

[Hogback Fabrication]

It does take a lot of force to begin crushing the crush sleeve, but once it starts it goes pretty easy. Since the rear end had already been assembled, the sleeve had been crushed. If I were to put one back together like this I would put the nut back on until I noticed the nut start to get tighter and then stop.

 

[Executioner]

Please explain how the "nut is torqued down to crush the crush sleeve. That is what sets the depth of the pinion. "
Thanks

The nut and the yoke you removed are what hold the pinion in the differential housing.

When gears are installed the nut is torqued down to crush the crush sleeve. That is what sets the depth of the pinion. Once the depth is set, the nut is torqued to provide a certain amount of bearing preload, which is basically how hard they are seated into the bearing race.

So by removing the nut and yoke, you could potentially change the preload, and possibly even the pinion depth.

 

[89GMCSuburban]

No...shims set the pinion depth. The crush sleeve sets pinion bearing pre-load. Crush sleeve has very little if any change on depth because the inside bearing on the pinion still sit in the cup whether the crush sleeve is torqued to hell, or on mildly tight.

When you did that to your 12-bolt, you should've used a new crush sleeve and pinion nut. Don't be surprised when the nut backs off, the pinion falls into the diff and locks your rear end up regardless of what speed you are going. How do I know this? Personal experience. That's why I have the 14-bolt now...

 

[mrk5]

No...shims set the pinion depth. The crush sleeve sets pinion bearing pre-load. Crush sleeve has very little if any change on depth because the inside bearing on the pinion still sit in the cup whether the crush sleeve is torqued to hell, or on mildly tight....

That's right of course.

I fixed my original post to reflect the correct information.

I know that just unbolting the yoke and then re-intalling it is not the official method, but I'm doing it that way based on the various methods I've been able to find.

I suppose this is probably a better method:

REPLACING A PINION SEAL

The pinion seal of a rear-drive car encircles the pinion shaft. If it is defective, gear lube will leak from the front of the differential.

REMOVING THE OLD SEAL
1. Park the car on a level surface and place wheel chocks in front of the front tires.

2. Lift the rear of the car and place a pair of safety jack stands under the rear axle housing. Be sure that the stands are securely in place.

3. Place a drain pan under the transmission slip yoke seal.

4. Use chalk to mark the drive shaft, the pinion flange, and the end of the pinion stem to which the pinion flange is attached. This will ensure that the drive shaft and flange can be reinstalled in the same position.

5. Use a box wrench to remove the four bolts and retaining straps (or the two U-bolts) that secure the shaft to the pinion flange. To reach all the bolts, shift the transmission into neutral and rotate the shaft with your hands.

6. In some cases, the nuts are locked in place with metal tabs. These tabs must be pried away from the nuts before a wrench can be placed over them.

7. Use a large screwdriver to pry the U-joint away from the pinion flange.

8. Tie the drive shaft to the exhaust pipe or chassis.

9. Wrap masking tape around the U-joint to hold the bearing caps in place.

10. Remove the rear wheels and brake drums to determine how much the pinion bearing is pre-loaded. You must know this to reassemble the unit.

11. Using an inch-pound torque wrench, turn the pinion shaft nut. Record how much force is needed through several complete rotations.

12. Hold the pinion flange with a large pipe wrench so that it won’t turn; then remove the pinion flange nut. On some cars the pinion flange can be held in place by screwing a couple of bolts into the companion flange and wedging a pry bar between them.

13. Clean the area around the pinion flange and seal.

14. Place a drain pan under the flange.

15. Use chalk to mark the pinion flange and pinion shaft in relation to one another.

16. Remove the pinion flange using a two-jaw gear puller.

17. Check the pinion flange for a seal groove, nicks, or other marks. If the seal surface is damaged, the pinion flange must be replaced; otherwise, the new seal will leak.

18. Use a small pry bar or a blunt chisel to remove the seal from the carrier.

19. Remove any burrs from around the carrier bore to prevent leaks around the seal.

INSTALLING THE
NEW SEAL
To install the new seal, use a driver with a diameter that matches that of the seal. Although there are special tools available for installing seals, a smooth piece of pipe backed by a piece of wood can be used in most instances.

1. Apply a small amount of rear-end lube to the pinion-flange area and splines.

2. Use the alignment marks on the pinion shaft and flange to install the flange in its original position.

3. Install a new nut on the pinion shaft and tighten it while holding the pinion flange. Occasionally rotate the pinion while tightening the nut and take frequent preload readings, turning the pinion nut and shaft with the inch-pound torque wrench. NOTE: If the torque readings vary during a complete revolution, something is binding and must be corrected.

4. Stop tightening the nut and taking readings when the recommended preload reading for your vehicle is obtained. It is important to keep in mind that you cannot reduce preload by backing off the pinion nut. If the desired preload is exceeded, a specialist will have to finish the job.

5. To reinstall the drive shaft, line up the chalk marks on the drive shaft and the pinion flange.

6. Connect the rear U-joint to the pinion flange yoke. Be sure that the bearing caps are completely seated in the pinion flange.

7. Install the U-bolts or retaining straps. Use a box wrench to tighten the retaining nuts or bolts securely.

8. Remove the safety jack stands and lower the car.

9. Add lubricant to the differential to bring it to the proper
level. If necessary, add transmission fluid.

Guess it's a good thing I have a 14bolt with the right gears.

 

[89GMCSuburban]

Didn't mean you, guy! I meant blazerpro... shoulda wrote that!! If he didn't use a new nut, he's asking for it....unless he used the chisel trick....