question on changing out a 12 bolt rear end yoke

[mplogic]

Got my new driveshafts from High Angle (which look like high quality stuff by the way, thx Jesse) for my bro's 77 Jimmy. We got a 1350 rear as we are planning on eventually putting a 14 bolt back there instead of putting any money into the 12 bolt. So for the time being I ordered a 1350 yoke to go on the 12 bolt rear end, but I didn't really think it through. Am I correct in thinking that the rear pinion nut is what loads the pinion gear against the bearing in that rear end? If that's the case, then the right way to change out the yoke would be to pull the center section and basically re-set up the rear end using the new yoke, right? Just buzzing the pinion nut off and on with an impact wrench and the new yoke would most likely leave it either too tight or too loose and I could wipe out bearings or change the way the teeth mesh which would also be very bad.

Does this make sense or am I missing something? Would I be better off just using a conversion joint until we decide to do the 14 bolt swap? I haven't atempted setting up a rear end yet and don't have the right tools and we really don't want to put any money into this 12 bolt.

Thanks for the input.

 

[pauly383]

Well , you are supposed to reset the gears since you could overcrush the sleeve putting it back on .

I personally have thousand of miles on mine without problems , and all that we did was change yokes from the auto axle ( 1310 ) to the 4 speed axles ( 1350 )

 

[cegusman]

Can't help you with your question, but if you do swap them make sure to use a new pinion nut and some loctite.

 

[darkshadow]

i would stick with getting a conversion joint, if you pull the nut off you will need a new crush sleave, and to relock tite up the threads, its just too big of a hassel.

get the joint.

 

[Leadfoot]

How many miles on the axle?
The reason I ask is that the preload changes with time (wear). Tightening it slightly shouldn't cause any problems (this is not coming from me, but rather a guy that rebuilds trannys, t-cases, and rearends for a living).


I recently went from a stock half ton driveshaft on my 78 12 bolt to a 1350 shaft with a new yoke from High Angle. I only had less than 3000 miles on a new ring and pinion with Eaton posi and new bearings. I went slow during eh install of the new yoke and took it easy when I "checked it out" and when I saw there as no noise or vibration I started driving "normal" and it has been holding up to lots of abuse (plowing and towing).

Ideally you would want to reset preload, but you can "ballpark" it. To take the axles out and drop the carrier to put on a new yoke, although ideal, seems a little excessive.

What I did (and have done in the past), is use a NEW nut and locktite. I swap the yoke and NEW seal. I slowly tighten the nut on the yoke. You should feel it seat. When it's seated, I put a little muscle into it, to turn it slightly (no more than 1/8th turn). I then check to make sure there is no in and out play on the yoke. If there isn't, I let it go and keep an eye on it. Once you have the yoke back in, make sure to top off your diff lube. Take it easy when first driving to listen for any noise or feel any vibration. When you have put a few miles on it and everything seems ok, just crawl underneath and check for endplay again and it doesn't hurt to check your fluid level one more time.

 

[Hogback Fabrication]

The right way to do it is to redo the crush sleeve. What I would suggest is to do the conversion joint and return the yoke, you won't break a 1310 joint with a 12 bolt behind it. If you want to replace the yoke, rent/borrow a torque wrench that reads inch pounds and take the nut and yoke off. Put the new yoke on and put the NEW pinion nut on until you can feel no more play in the yoke (This is the crucial step, if you overtighten it here you will have to start from scratch and although the crush sleeve takes a ton of torque to crush, the pinion nut is a locknut so it may be somewhat hard to distinguish by feel of the wrench. Make sure you are feeling for in and out play and not just how hard the nut is to turn). Once there is no more play in the yoke, put the inch-pound wrench on it and measure rotating resistance (I think used bearings should be in the 15 inch pound range). If it needs to be tightened more, go VERY slow. The value changes very quickly. Not really too hard if you are careful and go slow.

 

[mplogic]

Thanks for the info guys, some good suggestions there. One more question tho, isn't a pinion nut supposed to get really torqued down, like 200ft lbs or something? Or is that just with a new crush collar? Or am I way off here...

 

[Hogback Fabrication]

If the axle does not have a crush sleeve then there is a torque spec which is probably in the 200 ft. lb. range. If it does have a crush sleeve (like the 12 bolt), the spec is for bearing resistance which is measured in inch pounds (BTW, crushing a crush sleeve takes more like 400-500 ft. lbs.!).

 

[Leadfoot]

Thanks for the info guys, some good suggestions there. One more question tho, isn't a pinion nut supposed to get really torqued down, like 200ft lbs or something? Or is that just with a new crush collar? Or am I way off here...

Yes and No.

As stated yours is based on a bearing preload (rotational resistance). In order to START crushing the sleeve it requires 200+++++ ft/lbs. Once it starts crushing it doesn't take as much and it can be easy to "overcrush" if you are not carefull.

For a rearend that has already been setup and I swap yoke, I bring the nut down tight (easy to feel is you go slow), then I snug it and make sure there is locktight and/or I dimple the nut (depending on application). As long as the nut does not back off, preload will not change (except for bearing wear).

As stated, there are several options:

A. Tear the whole thing apart and risk disturbing something else and/or getting contaminents in the bearings (although this is the "by the book way").

B. Use common sense (work smarter not harder) and replace the yoke without having to tear the whole thing apart.

C. Screw it up any way you do it. I have seen new ring and pinions, bearings, etc screwed up by people who tried doing their own ring and pinion setups. They "followed the book" and still found a way to do something wrong.

One thing to consider too is how old the pinion bearings are. The older the bearing the less tolerant it is. Bearings can also start wearing in a pattern and if you disturb that pattern, you can do more harm than good. If they are original bearings, you might think about replacing them anyways (at which time you could set it up "by the book). Pinion bearings, crush sleeve, and seal, should be able to be gotten at a reasonable price. Check with Tim's Offroad (vendor on this site....and see what he can do for you).

Whatever you decide, I hope it all works out for you .

 

[mplogic]

Yea, the rear end has quite a bit of mileage on it and we've already decided we're going to swap in a 14bolt before we spend any money on this one (bearings, etc.).

We decided to go with the conversion joint and not risk "disturbing" the old rear end as it's working right now and I don't want to open up pandora's box. But I appreciate all the info, good to know if I should have to swap a yoke in the future.

We ended up getting a conversion joint at 4 wheeler supply on Washington for $37 incl tax. We asked their service manager guy if they could press it in for us. His answer was "sure bring in the driveshaft and we'll pound that right in for ya." I asked if they had a press they could use instead and he said "no, we just hammer those in". I declined and took it to a mechanic friend who had the right tools. I can understand using a hammer on a universal (or other bearing) maybe as a last resort trail fix, but I'd think a shop would know better. Hopefully the actual mechanics there know better than to hammer on bearings but I don't think I'll have them doing any work on my trucks any time soon.