HD Rear U-joints

[blzrgb]

I've got to replace the rear driveshaft u-joints in my 1008 and was looking for an upgrade for the u-joint. Also will be swapping from a strap to a u-bolt design yokes. If anyone has a part number or can steer me in the right direction for a stronger u-joint..... Thanks.

 

[raiburn]

Ebay has something like that, it also has a beefed up bearing support, or something.

 

[OLDCHEV4X4]

I use the Spicer forged u joints when I want strength. Afordable and have never broken one yet. Something else lets go before the u joint.

 

[4bogginchevys]

just wanted to mention that sometimes it's good to have a predictable weak link, u-joint serves this purpose well. The 1350 u-joints that the rear shaft uses are twice as strong as half ton stuff to begin with, I cant imagine it being a common problem to break them unless there is another problem like drive line angularity, shaft to long, worn out locker. If you are set on heavy duty u-joints for the truck you can try the duralast gold from auto zone, the name was changed from BRUTE FORCE about a year ago but thier the same thing. They use synthetic grease and will last a long time, I've never broken 1 and I used them on my 1/2 ton with 36's and wheeled the heck out of it. Good luck

 

[gaunt1969]

DITTO ^

Ujoints are cheep compaired to pinions, ring gears, trans main shafts. And a whole **** of a lot more easy to replace.

 

[Croatan_Kid]

Stock 1-ton stuff is 1350 series, you can upgrade to 1410s for a lot more strength. That's what I did since I had to have a rear driveshaft made during my whole motor/drivetrain swap.

1350 and 1410 have the same diameter caps, but you go from 3 & 5/8s to almost 4 & 1/4 inches across.


1410s are some big ol jokers! Here's a picture for reference in sizes:

http://www.pirate4x4.com/tech/billavista/PR-1410_Yoke/images/DCP_9300.JPG



But, if you don't want to upgrade like that, just use Spicer Life Series u-joints. Great stuff and will last a long time, harder to find though. Probably easiest to find them on the internet. I can't imagine you'd ever break a u-joint with a stock 6.2 though.

 

[CDN-CUCV]

Good point made about a 'predictable weak link'. Easier to fix in the field than a twisted yoke or worse.

I've always used the Spicer units myself, having moderate success until I realized I had driveshaft length issues (yeah, I've left myself wide open with that comment...) Turned out my slip yoke was worn and the driveshaft was 1.5" too short. Once I had it lengthened, I installed new Spicer u joints and haven't looked back.

About the Duralast/ BRUTE FORCE ones, Are they the solid/non greasable type? I know alot of the race truck guys around here use them. I was warned once about using them if I'm putting alot of miles on my truck since they don't take a greasin'.

 

[4bogginchevys]

Good point made about a 'predictable weak link'. Easier to fix in the field than a twisted yoke or worse.

I've always used the Spicer units myself, having moderate success until I realized I had driveshaft length issues (yeah, I've left myself wide open with that comment...) Turned out my slip yoke was worn and the driveshaft was 1.5" too short. Once I had it lengthened, I installed new Spicer u joints and haven't looked back.

About the Duralast/ BRUTE FORCE ones, Are they the solid/non greasable type? I know alot of the race truck guys around here use them. I was warned once about using them if I'm putting alot of miles on my truck since they don't take a greasin'.

correct, they are non greasable, when I ran them I bought a tube of synthetic grease to make sure they were greased well before installation, then I would use the rest of the tube to re-do wheel bearings/other u-joints . I never had any trouble with them getting worn or failing prematurely with highway use, infact I always thought alot of road time would just help them "settle in". I put close to 12,000 a year on that truck, probably 1500 miles of it was knee deep in mud!

 

[blzrgb]

You guys are prbly right. To upgrade the joints can put the weak link towards a more expencive part. But, I do want a greasable joint. Also, is there much truth to installing a "greasable" u-joint the wrong way. In other words install it so the hole for the zerk fitting is not spreading when under a torque load.

 

[skark_burmer]

I think another fantastic weak link on the 14b axle is the straps that hold the u joint in. You can get a u bolt arrangement for cheap, and they'll hold your join in a lot more securely.
As for beefier u joints: CTM
I run them in all my Dana 60's and they are impressive.

 

[Croatan_Kid]

CTM joints are great, but aren't they like 250-300 bucks....a piece?!


I'm glad someone mentioned greasable vs. non-greasable. I use non-greasable for just that reason, in theory (and it makes sense) they're stronger. Another reason for just using non-greasable is you usually can't get to the grease zerk once the u-joints are installed anyway They're pretty easy to replace and fairly cheap compared to other things and they don't wear out that often, so it's not a huge deal that you can't grease them.

Yes, you should always install greasable u-joints so that the grease channel will be under compression (being pushed on) during normal forward driving.



The first thing that pops into my head when I think weak link with these trucks is either the hubs or the u-joint at the diff on the front driveshaft. For some odd reason, they decided to make those joints 1310s. I just don't know which would fail first, but either way it'd be an easy enough fix.

 

[skark_burmer]

They sure are, but you get free stickers with every purchase!

 

[jdemaris]

I've got to replace the rear driveshaft u-joints in my 1008 and was looking for an upgrade for the u-joint. Also will be swapping from a strap to a u-bolt design yokes. If anyone has a part number or can steer me in the right direction for a stronger u-joint..... Thanks.

Have you had a high failure rate of the rear joint, or just want to upgrade? I ask because many of these rigs have chronic rear joint faiure. Not breakage, just the two bearing caps burning up (the two that get strapped to the pinion flange). The K5 design already has the built-in problem of a short wheel base and transfer-case that sits a lot higher then the rear axle. Add to this a pinion flange that has become out-of-round, and your rear joint at only those two spots will be burning out every 5K-10K miles.

Lots of ways to fix, but no sense posting them all unless this is your problem. Blazers have a tendency to have driveshafts come completely unhook at high speeds when a rear joint goes - and will sometimes cause the alumiinum transfer-case to blow to pieces.

If you want is a simple upgrade to a larger joint, there are many pinion flanges made to fit that 10 bolt rear axle that take larger joints. Just about any specialty driveline place will have them. The original joint is a Mechanics 3 type. You can buy a pinion flange that accepts the Spicer 1350 joint . . . and if you want - use the driveshaft as-is. You do that by using a coversion U-joint that is Mechanics 3 on one end, and Spicer 1350 on the other.

 

[Crackerjax]

On my wifes K5 she is running OX u joints in the drive shafts and in the front knuckles..... they seem to work well. on my XJ I am running OX u joints in the Knuckles and Tom Woods CV drive shafts.... if you want something stronger upgrade to CV with OX or CTM u joints but be prepaired to brake something else in the driveline if you run it hard.. the dang straps in the K5 u joint at the pinion are crap they dont put equal pressure on the bearing cap and they fail...u bolts are better.

 

[4bogginchevys]

when I was making the switch from a 1/2 ton truck to a 3/4 ton with axle swaps I ended up using those conversion joints for a while...JUNK, they would always burn up within 5000 miles or so, I found a 3/4 ton van and took the slip yoke from it, it slid right on the rear drive shaft and solved that problem easily.....conversion joints are complete and total junk!

 

[jdemaris]

.. the dang straps in the K5 u joint at the pinion are crap they dont put equal pressure on the bearing cap and they fail...u bolts are better.

The strap design isn't the problem. There are many vehicles with that strap design that have zero failure problems. My 87 diesel Suburban is one. Also, it doesn't suffer from the short wheelbase the K5 Blazer has. When all is right, those straps certainly do put even pressure on the caps. Problem is, that once a pinion gets damaged and a little "tweaked" and out-of-round, then there IS an even pressure problem. If a pinion is out-of-round, either a strap or U-bolt will put uneven pressure on the cap.

 

[jdemaris]

when I was making the switch from a 1/2 ton truck to a 3/4 ton with axle swaps I ended up using those conversion joints for a while...JUNK, they would always burn up within 5000 miles or so, I found a 3/4 ton van and took the slip yoke from it, it slid right on the rear drive shaft and solved that problem easily.....conversion joints are complete and total junk!

If they are truly "junk" as you claim, please provide some details. If parts fail, there is always a specific reason. Weak or inproperly hardened metal, bad seals that loose lube, bad fastening system, inadequate size for the load, etc.

If your joints failed - OK. What failed? Did they break? Did they dry out and burn up? If you're going to blame the joint itself, and not other possible driveline problems, please elaborate.