Ok guys, some anecdotal information and some questions here - it's a long story, so I'll lay out my questions first and then go into the cherokeeforum novel.

Q1 -- I see a listing in my parts manual (my 95 C8.25) for the rear yoke with 2 different part numbers - 53007787 and 52068839. The parts manual says only that one is 2.75" (7787) and one is 3" (8839) but no other distinguishing information. Quadratec identifies the 3" as 27 splines.

Looking at the pictures, the 53007787 "looks" like the yoke that is currently on there.

Are these interchangeable? They're about the same price so I'm leaning towards ordering the 53007787 as it seems the proper part for my 95. I do have the distinction that this is a 5-spd XJ, so there are some minor/subtle differences and the big difference in this regard - the 3.05 gear ratio.

Q2 - Replacing the pinion yoke on the C8.25 -- I've read that folks have had success with swapping out JUST the pinion yoke and seal and while certainly not exactly the "proper" replacement steps, saves one the trouble of dealing with all the fine-tuning nuances of differential work. What do folks think about this?? I'm considering replacing the yoke for a number of reasons, but definitely do NOT want to try my hand at the complex aspects of differential work and backlash and all that.

So the long story:

I had some issues with vibe several months back and eventually discovered that the rear driveshaft that I had installed was messed up somehow. I had a second driveshaft that was not wonky and by installing that, the vibe went away. Granted, it's a 26 year old Jeep with a ton of miles on it, so there's always a small amount of vibrations that are well within the "tolerable" range.

So a couple weeks ago, I was driving home from work and I hear a pop, and dragging sound. I pull over to inspect and find that rear driveshaft is hanging off. I don't know exactly why this happened, I suspect maybe one of the u-joint caps started seizing and either caused or coincidentally had one of the strap bolts work out.. regardless, I end up with a sheared off u-joint bolt.
Over the course of a couple days, I am on a side street near my work, trying to drill out this sheared off bolt. Unlike a previous event like this where the sheared off bolt just came right out with the drill, this time I was not so lucky. A broken drill bit later and I have drilled it deep enough to tap 1/4-20 threads to get -something- on there to get my Jeep home. (Oh yeah, so AAA left me waiting 1.5 hours waiting on a tow truck that never came - that was the first night, so I was reluctant to deal with towing)

So I get the yoke drilled out enough and tapped enough that I'm comfortable with driving it for some distance, but again, the vibe is back. This vibe was characterized by being imperceptible at lower speeds, but once crossing about 55-ish MPH, would become pretty bad, to the point that I wouldn't be OK driving it like that.

This situation was bad enough that I seriously entertained ideas of giving up on my XJ. It was a difficult time, I was wrong, I'm sorry.

So after replacing the u-joints, having my trusted tire shop inspect the Jeep, I'm still uncertain what the heck is going on. The driveshaft was in remarkably good condition - it seemed unaffected by a short span dragging on the pavement (I think even that it was the u-joint that was contacting the pavement for the 150ft or so..)

I figure - OK, I reused the u-joint straps like they say not to, this thing is 26 years old with over 350k miles on the tranny/xfer case and axle, maybe I've got play in the xfer case output shaft... I'll pull it apart again and check the xfer case and axle pinion for play and put some new joint straps on.

Long and short, there was zero play in the pinion, it it rock solid and no detectable play in the output shaft. It was hard to tell with the xfer case, all attempts to wiggle with the driveshaft connected at the slip yoke side moved the whole xfer case on the mount.. I couldn't get any play by hand on the shaft or by trying to wiggle against a steadied xfer case with the shaft, so if there is any play, it is too small to detect by crude and amateur techniques.

However, as I was taking the shaft off for what seemed like the 8th time in a week, I stumbled upon on the issue. The u-joint, when set in the pinion yoke was NOT tight. I could move it side to side when the straps were loose. It occurred to me that what was likely happening was that at low speeds, the joint was not moving too much side to side in the yoke, but once I reached the higher speeds, the force of the shaft spinning would push it hard enough to move in the yoke and hence --- vibe.

I inspected more closely and realized the little tab on the side that keeps the caps on, on the side where I had to drill out the bolt hole, was chipped a bit.. not enough to notice without looking very closely at it, but enough to give a tiny bit of room for the joint to move in the yoke.


I ended up putting a snap ring on the pinion yoke side to take up the slack as there was just enough room to get it in the chipped part to fill that space. TBH, I'm a bit surprised that actually worked for more than a brief test drive...

I took the Jeep on the highway and lo and behold -- vibe is gone.

So really, between the buggered up drill-out, AND the chipped retainer tab, it's pretty damn clear that I need to replace this yoke and sooner rather than later.

I'm hoping I can just buy the new yoke and a new seal, pull those parts off of the axle, slap the new parts on there, bolt everything back up and call it done. However, considering the precise replacement steps, backlash, torque measurements, etc. it's definitely something I'm hoping I can get some advice from this forum on before I go and make my current problem any worse than it already is.

 

I may be misunderstanding this point, but zero play in the pinion is really bad. There should be .006 play in the pinion-ring interface if you were holding pinion steady, and a whole bunch more if you add in spider slop (or do you have a locker or the like in the diff?).

 

Sorry Dave -- I mean zero play in the pinion bearing (pushing on the yoke).. up/down, side/side, in/out.... there's slop in the turning, per usual within the actual differential itself. Sorry for the lack of clarity on that.

 

OK that makes more sense!

I believe you can get away with just slamming in the new yoke. The key is if the crush sleeve will have any crush left or if additional crush is even necessary. The bearings should have worn more that the crush sleeve and since you have no perceptible play in the pinion bearings you should be fine. The manual says to torque a new pinion nut to 200 ft. lb. and check to see if there's a little resistance when spinning the yoke (I use a fish scale to measure pinion preload) (this part is a little dodgy because you have the rest of the drive train providing resistance, so you only have spider slop to work with).

If there's no perceptible resistance you can torque the nut up to 350 ft. lb. till you do.

If you torque to 200 ft. lbs. and the pinion doesn't turn you need a new crush sleeve or solid spacer kit.

Plan B:

Pull the carrier, punch out the pinion, slam in a new crush sleeve and be done with it.

 

Awesome - that's what I was hoping to hear. Thanks Dave!!!

 

Dave - getting ready to do this - I have a new yoke, seal, nut and u-joint and strap kit just in case.

So stupid question (I hope), I can remove the old nut, yoke and seal, and put it back on with the wheels on the ground, right? In other words, it's the wheels on the ground that provide the inherent resistance for separating the nut to remove and for tightening the nut up to the prescribed 200 ft/lbs when putting the new yoke on - correct?

Is there anything weird or anything like that I need to look out for?

I'm assuming once the nut loosens up, it comes right off (and is regular threaded, right), the old yoke pulls off from there and the seal will pop off with a little bit of leverage via a seal puller and the new parts go in reverse order. Yes - no?

 

There's a shop tool that fits in the holes left by the little U-bolts. However, impact should do the trick if it's got enough HP. Torque wrench/breaker bar may not work cause the brakes usually can't hold the pinion in place.

Plan B would be to go down to HFT and get that Mongo pipe wrench to hold the yoke if the nut is a PIA.

 

Oh hey check this out! Never knew they made these!!!!!!!

 

Bleepin' Jeep got into the act:

 

Nice!

I should only need this stuff if I pull the carrier though, right?

Shouldn't the axles, wheels and weight of the Jeep sitting on the wheels keep the pinion from spinning once I hit the end of the spider slop? (Being I'm hoping to just replace the yoke and not have to deal with crush sleeves, pinion measurements and all that stuff.)

 

If you use the impact, maybe to probably.

If you use a breaker bar, absolutely not.

 

Because of the leverage the pinion puts on the ring (like it takes 3.54 revolutions to turn the ring once)(or whatever you have in there) a tremendous amount of torque is able to be applied to the ring, so 200+ lbs. of torque is gonna turn the tires even if the XJ is parked in front of a tree. And depending on what shortcut you try, potentially snap teeth off.

 

Oh my --- sounds like fun!

So there really is no option then - it's got to be the impact or specialty tool... and being that I can (probably) replace my busted electric impact via a trip to the local retailer or drive down the street to get to my parents' where my air compressor and air impact are...... or wait a few days for a specialty tool... it looks like we have a winner! Impact it is.

This makes sense with the number of folks who claim they've done this sort of thing successfully by the highly scientific "number of brrrps" method.

 

If you don't have an impact available, then put a large pipe wrench or medium sized one and a cheater pipe on the yoke and let the handle hit the ground. Then get that breaker bar going and you will have it

 

I got one of these (and back when they had the 20% coupon)(sign up for the app occasionally they throw the coupon out there)(there'll be Labor Day bargains) but still it's cheap and if if it breaks bring it back and scream "Manufacturer's Defect!"

https://www.harborfreight.com/24-in-...nch-61361.html

Then there's this Bad Boy:

https://www.harborfreight.com/36-inc...ench-1132.html

for only 24 bucks, and it will DEFINITELY do the trick.

You probably PBed the nut already?