Rear Pinon Yoke

[7212Mopar]

I have a 489 case 3.23 sure grip 8-3/4 and a 904 original to the car. The driveshaft uses 7260 U joints. After my 904 broke I replaced with a 727. Then I measured it up and placed an order for a new driveshaft that has 1350 front transmission yoke and I asked for a 7290 rear yoke and 7290/7260 conversion u joint. The shop wrote me back saying that they cannot build that the way I asked and not recommending that I keep the 7260 rear pinon yoke at my power level (491 HP, 528 Ft Lb dynoed). My 8-3/4 is freshly put back together with new seals, fluids, bearings greased, painted and brakes mounted and bleed. I hate to have to tear it all apart again. So here is the question.

How difficult it is to change the rear pinon yoke? Do I need to pull the axles again? I read that I should get a crush sleeve eliminator kit and pinon seal. I need to torque to somewhere around 175 ft lbs on the nut and then check bearing preload. If it is not in range I need to add washer and re-torque and check again. Can this be done with 8-3/4 mounted in the car and on jack stands? I think I have space problem pulling the axle on one side of the car and the 8-3/4 might need to come out.

[Shane Kelley]

You can unbolt the yoke by removing the large pinion nut. Dr Diff sells very nice forged yokes at a very reasonable price. Your going to have to pull your yoke on see if the pinion is a fine spline of the large spline. Get a new pinion nut. It's that simple.
Pic is fine spline and that's probably what it will be.  I didn't have a pic of the course spline but you will be able to tell by looking at it. You can remove the nut and washer to see it. Leave the yoke in until you have the new one. Gear oil is going to run out. You can swap them fast enough where you won't lose hardly any oil.

[RUNCHARGER]

I had a 1350 front and back built and I bought a new 1350 yoke for the 489 case too. That was about 3 years ago.

[7212Mopar]

You can unbolt the yoke by removing the large pinion nut. Dr Diff sells very nice forged yokes at a very reasonable price. Your going to have to pull your yoke on see if the pinion is a fine spline of the large spline. Get a new pinion nut. It's that simple.
Pic is fine spline and that's probably what it will be.  I didn't have a pic of the course spline but you will be able to tell by looking at it. You can remove the nut and washer to see it. Leave the yoke in until you have the new one. Gear oil is going to run out. You can swap them fast enough where you won't lose hardly any oil.

Thank You Shane. I did some more web searches and the steps are as follows. Please let me know if I miss something. I don't want to mess up my center section.

1. Get an inch pound torque wrench and check the preload by spinning the diff with the tires off the axles and car supported on the frame.

2. Get an impact wrench to undo the nuts.

3. Get a puller to remove the yoke.

4. Remove the seal.

5. Remove the crush sleeve.

6. Insert the new crush sleeve eliminator and washers (How many to start with?)

7. Install new seal.

8. Install new pinion yoke.

9. Torque nut to 100 ft-lb and check preload.

10. Continue to torque nut to at least 170 ft-lb.

11. Check preload to specs. If too much undo nuts and add shim, torque nuts and check again.

If I am going to do all this, I will get the 1350 pinion yoke.

[7212Mopar]

BTW, can the old crush sleeve come out from the pinion yoke side? I have not done this before.

Thanks

[GoodysGotaCuda]

BTW, can the old crush sleeve come out from the pinion yoke side? I have not done this before.

Thanks

Yes, once the yoke and seal is out, you can pull out the outer pinion bearing. The crush sleeve is between the two pinion bearings.

[7212Mopar]

Thanks. More wrenching soon going down the 1350 path.

[RUNCHARGER]

There is a recommended shim pack to start with on that conversion but I can't remember what it is. Hopefully it will be in the instruction sheet or if you buy it from Dr. Diff he will let you know what to start with.

[7212Mopar]

I plan to measure the old crush sleeve and start with that and check new and old yokes. Can I reuse the original nut and washer? I forgot to order that.

[Shane Kelley]

I like to use a new nut but it's not mandatory. I recommend peening the nut with a punch or chisel. When running a crush sleeve eliminator it's less likely to loosen up as well.

[7212Mopar]

Thanks Shane. The new 1350 yoke did not come with a shield over the seal. Did you reuse the original? Looks like it just held on by the yoke.

[GoodysGotaCuda]

I plan to measure the old crush sleeve and start with that and check new and old yokes. Can I reuse the original nut and washer? I forgot to order that.

Red loctite on the nut.


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[Shane Kelley]

Thanks Shane. The new 1350 yoke did not come with a shield over the seal. Did you reuse the original? Looks like it just held on by the yoke.

Yes.  That's a stock yoke.  I'm not sure if they come off or not. I run this billet yoke that I got from Mancini on my Road Runner and it came without a dust shield. Been a couple years now with no issues. The red circled area doesn't mean anything. I must have used the picture in a different post.  The Dr Diff 7290 comes with a shield. See second pic.

[7212Mopar]

According to Cass, 489 case 29 splines require the pinion nut to be torqued to 285 ft lbs. I have two Craftsman torque wrenches, one max at 250 and one max at 260. Who makes higher rated torque wrench? I am going have to eat a lot of wheaties and spinach before trying. Where is Popeye?

[GoodysGotaCuda]

According to Cass, 489 case 29 splines require the pinion nut to be torqued to 285 ft lbs. I have two Craftsman torque wrenches, one max at 250 and one max at 260. Who makes higher rated torque wrench? I am going have to eat a lot of wheaties and spinach before trying. Where is Popeye?

I'd hit 260, give it one more grunt and send it.