Changing u-joints

[green55]

One of the next things on the list is swapping out both u-joints on the rear drive shaft. This 4" add-a-leaf kit just tears them up. Can't wait to go down to a 2" suspension lift....

Anyways, I've never done this before, but looks simple enough from the videos that I've watched. Seems like borrowing a ball joint press from a parts store makes life even easier.

My questions
1. I have an 89 Jimmy. I've read a good number of threads on here about u-joints. Seems like general consensus is Spicers are the best. Is this the correct one for both u-joints on my truck's rear drive shaft? Would y'all recommend a different one? I'm going to go non-greasable because from what everyone on here says they're stronger. And, knowing myself, I probably won't be greasing them anyways.
2. Sounds like there is a chance I'll lose some transfer case fluid when I pull the yoke out of the transfer case. How do I figure out what transfer case I have so I know what fluid to top it off with? And any pointers on avoiding losing fluid so I don't have to worry about having the correct fluid?
3. Anything else a newbie might need to know?

 

[sweetk30]

208 and 241 tcase is ATF fluid same as your trans . Tiny bit will be lost when shaft is pulled .

Spicer is good stuff .

I do NOT press u-joints it can bend yoke ears . I just use a 4lb mimi sludge hammer and a vise . Then a socket to tap new caps in to line up clip groves .

Make sure clip groves or flat faces for clips are clean and flat for good fit and seat .

Make your slip yoke to drive shaft and line them back up . I have seen and fixed vibs after when 180* off after u-joints swapped .

Slow and steady you will get it .

Since they have been done before there should be no molded in plastic caps . But if so you need to heat them up with a torch to ozzz out and release . But be carefull of HOT POPPING plastic . Then let the whole thing cool down before working on it .

 

[green55]

I'd definitely have a 208 or 241 tcase then? No need to check to make sure?

 

[green55]

Did a little more digging to makes sure I order the correct u-joints. The Spicer site linked to danaaftermarket.com to find the right ones.

Seems like both u-joints for the rear driveshaft are either one of the 1350 ujoints (options 1, 2, 3) or the 795 ujoint.

The main difference I notice is the location of the snap rings. Right now, I have the C shaped rings on the inside of the u-joint. The 1350 have the snap rings on the outside and 795 has it on the inside. Does this matter? Are there other differences? What would y'all recommend?

 

[sweetk30]

1350 is 3/4 or 1ton for our trucks unless aftermarket bigger stuff like drive shaft / slip yoke / rear axle yoke .

 

[green55]

1350 is 3/4 or 1ton for our trucks unless aftermarket bigger stuff like drive shaft / slip yoke / rear axle yoke .

Oh ok. So I need the 5-795X then? Everything on mine is still stock as far as I know. Thanks!

 

[sweetk30]

i have not played with 1/2 ton in a long time . so i dont recall the part # off the top of my head sorry .

 

[Gentleman Jimmy]

Your t case should be a np241c in 89. One year only t case. There should be a tag riveted on the rear passenger side if I remember correctly. You should measure your caps to verify what you have before you order anything. I’ve had a couple that had crossover joints in the rear even with the 10 bolt (1310 to 1350).
You can do a quick search for u joint identification to compare your measurements. Driveshaftspecialists.com used to have a good reference page.

 

[green55]

Guess I’ll be measuring. Crazy how difficult this is. Thanks for the help y’all!

 

[diesel4me]

Guess I’ll be measuring. Crazy how difficult this is. Thanks for the help y’all!

Be glad it's not a Ford...they use a hodge-podge of different U-joint sizes on the same vehicle often..
I don't miss being an auto parts counterman when a guy would come in,and I'd sell him all the u-joints for a 80's F-250-350 4x4 and have him come back in a few hours later pissed,with every box opened,greasy,and some needles missing from the cups!...
Then the boss would say "we cant take these back"....
Things got pretty heated a few times!..

GM can have a lot of choices on some trucks too,and listings are not always correct--I always told customers to either bring the old u-joint in to match up or measure carefully to avoid these headaches..

 

[green55]

That sounds horrible haha the good news is I only have to figure it out once, then I'll always know what I need!

 

[diesel4me]

The fact so many different years of GM 4x4 parts will interchange adds to the chances of getting the "wrong parts"too...you never know who may have swapped what into a used truck,especially drive train parts...its not bad enough the factory uses whatever they had on hand at the assembly line !..a 14 bolt rear gets swapped into a 1/2 ton,etc,things get complicated fast..

I had to keep a "parts list" for several of my 4x4 trucks ,so many things had been swapped or replaced (by me,or former owners),I had to figure out which parts were correct and keep a list of them in the glove box,so I knew what to buy without guessing "next time"...

Back in the day we had size charts in the back of the catalog to help figure out what U-joints had the right dimensions...today you'd probably need the "application" (year & model of whatever vehicle uses the correct part you need) to get them looked up at an Autozone,etc....

There isn't many guys locally at parts stores that will go thru the labor of looking up parts by dimensions now--maybe at NAPA where a few guys my age still work--and you'll pay extra for their time and experience..the other stores will either keep opening boxes,look up other vehicles,or simply say "we don't have that part"after a few attempts..

It used to be we had to make every effort to sell a part,even if it meant a half hour of research --today the store managers tell employees to "keep things moving--don't waste time on customers who have "modified" vehicles ..cant say I blame them,the returns were always a big hassle..customer eends up mad at me because I wasn't allowed to give a refund..

 

[6.2Blazer]

The factory automatic trans K5's of that era should have the S44 joints. The 1350 joints were used in the rare 4-speed equipped K5's in the late-80's/early 90's. But as mentioned above you are dealing with a truck that is 30+ years old so something else could have been swapped in.

I usually use a bench vice and combination of tapping the joints in. I'll put it in the vice and get the caps started, apply some pressure and then some light taps to take off some pressure, then some more pressure on the vice. I constantly slide the joint cross back and forth to make sure it is not binding or any needles have fallen down. When the caps are fully seated I'll give the yoke a few good whacks with the hammer to seat everything. Generally when you just press them in it squeezes the yoke ears together and it will be difficult getting the snap rings in.

 

[diesel4me]

I probably replaced a few hundred u-joints in my younger days,one parts store had a machine shop and I often was elected to do them when the "machinist" was busy doing valve jobs or engine boring,etc..
I also got to do a lot of busted exhaust manifold stud removals too..

Everyone has their own method of doing things--I used to use a vise,not the press to R & R u-joints...

I found pressing them often bent the "ears" on the yoke inward and made it difficult to get internal snap rings in,usually I had to use a chisel & hammer to beat the ear back out until the snap ring groove was fully exposed again..this resulted in a few ears cracking,ruining the shaft..
Most of the time we never used the press unless we had a stubborn one that had the injected nylon stuff GM used ,with some heat to melt it free..

I would open the jaws on the vise wide enough for the u-joint "cross" would bear against the jaws,and use a 3-5 lb hammer on the base of the yoke,usually a few good whacks pushed the cups up out of the ears and didn't create any problems when it was time to put the internal snap rings in...
I used thick grease to hold the needle bearings in the cups,the stuff they ship them with is too thin much of the time..

It is best to make note of the position the oem u-joint was in,and install the new one the same way..sometimes just having the grease fitting pointing the wrong way could throw off the balance--also make sure when the splined couplings are mated ,the u-joint caps are "phased" 90 degrees apart,or it'll vibrate --some dually trucks with 2 peice drive shafts had to have the u-joints phased a certain number of splines "off" or they'll shake themselves apart...

 

[green55]

Time for my stupid question(s) of the day:

Finally got around to doing this. Got the old u-joints out, new ones in. Did lose a little bit of fluid from the transfer case as expected. It was red, which I think solidifies that it's ATF, right? I was going to refill with this...look correct?

Also, in the photo below of my transfer case, the top bolt is the fill and the bottom bolt is the drain, right? And to refill, do I need one of these so I can easily pump fluid in? It seemed like it hardly lost any so not sure its even necessary to top it off.

 

[sweetk30]

208 / 241 just use std dex3 ATF .

upper is fill hole and lower is drain hole .

those are not to hard to fill with nipple cap on bottle but up to you if you want a pump .

and did you wack the ears on the yokes after new u-joints installed ? if NOT do it . but flex the joint first . then wack them . reflex and you will be amazed the difference . if you dont do this it cuts the life of the joint down . old time tech showed me this trick years ago .

 

[diesel4me]

^ Agreed,if you leave it "binding" the journals will quickly get spiral grooving from the needle bearings and start growling after some miles..

 

[Clark75K5]

If the top hole is a drain you needed to let some out anyway, or you're in big trouble cuz your rig is upside down.