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Rear Drive Shaft.

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Supervillainmc

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I'm having a problem with my rear driveshaft . The gap is way to wide at the rear u joint point that it had to be welded in to stay secure. It was ok for a few months but now it's starting to vibrate at certain shift points and speeds. A few months before I had to change it with the same problem. Can anybody tell me what year Blazer rear driveshafts are compatable. Up here in Nyc they want as much to rebuild this one that it would cost me for a new one. Any help will be greatly appreciated..
 
Count the number of bolts holding the cover on so we know what diff you have. Sounds like either the diff or the driveshaft aren't original. You can get conversion u-joints that are different sizes on the cross shafts for just this type of problem.
 
Is it lifted?
How much?

What are your driveline angles?

What 'gap' are you referring to at the rear ujoint?
 
1977k5 said:
Is the rear end stock or did you swap it? What year Blazer?
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pblaze725 said:
Is it lifted?
How much?

What are your driveline angles?

What 'gap' are you referring to at the rear ujoint?
Click to expand...
Truck is not lifted. Stock off road suspension. There's a space too wide where the u joint goes in. It just slides rite out now. I have the truck 11 yrs and I changed the u joints before and the gap was never that wide that's why it was welded after it was snapped in for extra protection . I had to change the u joints 3 times in less than a year. And yes rear U joint Furthest to rear differential. I have 33in tires
 
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rampage said:
Count the number of bolts holding the cover on so we know what diff you have. Sounds like either the diff or the driveshaft aren't original. You can get conversion u-joints that are different sizes on the cross shafts for just this type of problem.
Click to expand...
The glovebox says it was a 308 . It's been 392 since I have it 11 years. The previous owner swapped it. Now the stock u joint size is in. I believe Moog U joint. Are you saying i can put the next size bigger u joint to solve this issue?
 
11 years I have the truck. I bought it with 392 gears. The glovebox says it was a 308. Not lifted just 33 in tires. I changed the rear u joint before. The past 8 months or so I changed it 3 times. I never had any problems with it before this. The space where the joint snaps into the shaft got so wide it won't stay in securely after its snapped in. It actually moves from side to side up and down.It has to be welded at points for support . It only lasts a few months if that. Is there a bigger u joint I can put in to solve this issue or just get a new shaft? I can't drive the truck the way I want. Now I get vibration at variable rpm and lower speeds at shift points.Im afraid if I Wot it the drive shaft is gonna come shooting out. Thx for help guys.
 
Umm...

Well I'm still not sure what gap you welded, and you didn't exactly answer the previous questions so it's kind of hard to help but I'll keep trying.

-which rear axle do you have?
It's either 10 bolt, 12 bolt, or 14 bolt.
I figure it's a 10 bolt since it's a K5 and still stock suspension.

- driveline angles... Since you say it still has a stock suspension I think driveline angles is not the problem.
Using an angle finder measure the slope of the transmission output, the angle of the driveshaft, and the angle of the axle input to determine the driveline angle. This will help to determine if your U joint operation angle is within specs.

- welding the gap-???
What gap? Did you replace the u-joints with the wrong ones that were too small and then try to weld the cap to the axle yoke? I just don't know.

Can you post some pics to help clarify?
 
If the ears in the shaft are wallowed out and spread (which is what you are describing as near I can tell) you need the yoke replaced.

A driveline shop can *probably* cut the weld and put a new yoke in.

Someone asked you to count the bolts on the housing to know what you are working with, this chart will help http://totaldrivetrainsupply.com/image/obj1750geo1106pg47p129.png

I'm *guessing* you still have the stock axle (8.5"/10 bolt), or your u-joint problems wouldn't have just started.

You are introducing all sorts of variables when the u-joint isn't captured properly in the shaft, let alone welding on the u-joint.
 
The rear is a Gm 8.2 8.5 10 bolt . Yes the ears in the shaft are wallowed out. Exactly. How does it happen? Can it happen from letting your u joints go without changing? I wanna Thank Everybody for the help. U Guys Are Great. This is the Best K5 Site and Forum by Far!! Thx so much
 
Supervillainmc said:
Is it worthed to cut and weld in a new yolk or get another shaft?
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As long as the shaft isn't rusty enough to compromise the integrity, and it doesn't have any noticeable dents in it, probably cheaper to have a yoke put in it.

Tubing probably isn't that much, but having another shaft built is going to be the tubing, plus two yokes. This might be the "mightaswell" time to do new u-joints on both ends of the shaft too.

Best thing to do is stop into a driveline shop and either have them look at it, or explain what you need done. Then get into the "what will a complete new one cost me, out the door?". Drivelines used to be relatively cheap, now there are fewer shops than ever, and the prices are quite high IMO.

I've never heard of wallowed out yoke ears before. I've seen similar happen on the axle side because the caps weren't seated properly, but the yoke is a press fit. My guess would be from letting it run too long with a bad joint, and/or screwing the yoke ears up pressing a new joint in.
 
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I've seen a few rear end yokes have the little "tabs" that prevent the u-joint caps from sliding outward snap off before,and the yoke had to be replaced,welding blobs on the yoke & cap didn't hold well enough to be trustworthy..but I haven't seen a driveshaft that had the ears spread far enough apart not to crack (yet !)..
I would suspect the U-joint wasn't the right one--perhaps in the past someone swapped a different rear axle or drive shaft in,with different sized yokes and it should have had a conversion u-joint with two different sized caps or "spread" on the rear end yoke or drive shaft,and running it with the wrong one ruined one or the other..
 
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