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bad noise after drive shaft install

J

JaredsDad

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Casper, WY
Got the new drive shaft in. New shaft and u joints and new yoke at the rear end. Drives great except... when I take my foot of the gas I hear a winding/grinding noise. Give it some gas and it stops. I raised the rear tires off the ground and cant reproduce the noise. And since I cant be under it while its going 30 mph... I'm sure its something I did or didn't do because it didn't do it before the swap. Its a stock 87.
 
My concern would be when you replaced the rear axle yoke you over tightened the pinion nut and damaged the bearings.You only need 15 rotating inch pounds on a used pinion bearing and its easy to over tighten if your unaware of it.
 
I'm pretty sure its not to tight. Wouldn't it sound bad all the tie if I had? Not just while coasting? And I cant figure out why it wont make the sound when the back tires are in the air. I'm at a loss
 
Climb under there & take a real good look to see where it's rubbing. Last time I heard that noise the drive shaft was rubbing a cross member. I couldn't find it for a while because it only made the noise when I was bouncing or romping around.
Also I always try to think of the :doah: stuff. You remembered to grease the U joints right?
 
With the tires in the air there isn't any reverse load on the gears. That could be why it doesn't make the noise when up in the air. When the tires are on the ground and you let off the gas, the forward momentum and friction of the tires/road put reverse pressure on the back side of the ring gear.

If you did happen to get the gears out of sync then it may only be out just enough to slightly grind on the "coast" side of the ring gear. I am not a pro by any means but I am setting up my new ring and pinion at this point and what you describe "could" be the pinion grinding on the back side of the ring gear. You replaced the yolk, and it looks like the crush sleeve was not replaced, that may have moved the pinion just far enough to cause some noise. Esspecially if it was right on the verge of being out of spec in the first place.
 
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If it is a bearing the only repair would be to replace them so if you cant zero in on it just keep driving it and it will eventually be bad enough you would have to be def and blind not to figure it out.
 
Mine did the exact same thing. It was due to bad u joints and angle. I have a 700r4 and 241. What i did was use temparary shims to point my pinoin directly at the back of my t-case so that it made a perfectly stright line with my drive shaft. small if no difference it made. Then replace the rear u-joint it was shot and it made a little difference. Then i decreased the upper angle at my t- case by dropping it 1". not ideal but like a said temporary till i decide my suspension setup. This made a huge difference but still some noise so i replace the top u-joint even though it looked fine this took care of it pretty much. Now i only have a little noise above 65-70 on the freeway when i am coasting. you can barely hear it.

Are you positive the u-joints are good and is the drive shaft balanced? Did you change shafts styles or just purchase a new one exactly like your old one? any lift modification like pinion angle or height changes?

The noise comes from the gears or rear end moving faster than the driveline this is why it doesn't work when the truck is lifted.

I am not a professional and i am only talking from experience from similar problems i have done this 4 times now and that is about how i went about it but i fixed it every time (except the tiny noise on my own:mad:

hope this helps cuz i know your pain i never want to hear that noise again!
 
I had the drive shaft built. Its an exact replica of the original. Blazer sits at stock height. My old u joints were shot so they put in new ones for me. They have a great reputation in this town so Im assuming they greased them (how do I check that?). They also balanced it for me. I am 90 percent sure its not making contact anywhere but I will double check that tomorrow.

How do I check to see if the gears are in sync? I know a bit about engines but drive lines are new to me. Thanks to all that have taken the time to help so far!
 
Sounds like it's a pinion/Yoke issue. Make sure you cannot move the Yoke in any direction other than rotational first off. Anytime you remove a Yoke on an axle that uses a crush sleeve you are supposed to ALWAYS install a new crush sleeve and start over with the pinion bearing preload adjustment. Once a crush sleeve has been crushed (axle was previously set-up and being used) it will crush VERY EASY if you remove the Yoke and reinstall it and tighten the nut. How did you go about tightening the Yoke after you replaced it?
 
I did have about 3 full turns tighter than it is now. I second guessed myself and backed it off. I'll pull it out and replace the crush sleeve. Do auto parts stores carry it? I'll have to do a search for the bearing preload adjustment.
 
That would be your problem then... the crush sleeves for a 10b are in the help! Section.at most parts stores.
 
Read up on how to do it. It takes a lot of torque to compress the crush sleeve. You'll need a long pull handle or cheater pipe.
Don't confuse the torque necessary to crush the sleeve with the correct torque that it takes to turn the spindle after the sleeve is crushed.

But, you may have damaged the spindle bearings, its hard to say.
 
JaredsDad said:
I had the drive shaft built. Its an exact replica of the original. Blazer sits at stock height. My old u joints were shot so they put in new ones for me. They have a great reputation in this town so Im assuming they greased them (how do I check that?). They also balanced it for me. I am 90 percent sure its not making contact anywhere but I will double check that tomorrow.

How do I check to see if the gears are in sync? I know a bit about engines but drive lines are new to me. Thanks to all that have taken the time to help so far!
Click to expand...

There should be grease fittings on the U joints. You should be able to get a grease gun in there & squirt some grease in it.
oftentimes I've had to tap them myself. I could see where someone could forget to install them, heck I almost forgot once. -...just once
 
In reading and watching videos online I've noticed it takes a lot (breaker bar and cheater pipe) to crush the crush sleeve. Could I really have crushed it to much with just a 1/2 inch drive? I never had to muscle it or anything.
 
answered my own question about crushing the crush sleeve. Going to install a new one today. Fingers crossed
 
JaredsDad said:
In reading and watching videos online I've noticed it takes a lot (breaker bar and cheater pipe) to crush the crush sleeve. Could I really have crushed it to much with just a 1/2 inch drive? I never had to muscle it or anything.
Click to expand...

When they are brand new yes, after they start to crush they crush VERY EASY and QUICK.
 
I dont have to much knowledge in this either, but i had a rear pinion seal leaking. So upon inspection i find the pinion nut loose, i mean finger loose. So the first thing i did was to tighten the nut (ever so gently) until all the play was gone from the yoke. Counted the threads, marked the nut, yoke and end of pinion.
Removed yoke and replaced seal, re-installed yoke and nut back to the proper thread count and my marks. Hit her with a little with red lock tite and staked the nut. Maybe i got lucky with the gears but no noise and lots of miles later, it seems fine to me.
I've never over crushed a sleeve so i have no idea how much grunt this would take. Good luck........Roger
 
To expand slightly on 4X4's crush notes, no pun intended, when you start the crush, it takes a lot of torque to make the initial fold, then it is fairly easy to crush it farther.

They could make the sleeves already slightly folded, and they would work just as good and be a lot easier to use, but I think the very high pressure at the start is to ensure that the bearings and races are completely seated in a new installation.

So, after you make it give slightly with the cheater bar, then you sneak up on the correct amount gradually with a regular pull handle.
Crush slightly, check the turning torque, crush, check, until you get there. If you go too far, you have to start over with a new sleeve.
 
The bearings look ok to me. Put a new crush sleeve and seal in. Having trouble getting it to crush. Every time i get in a position to get some pull on the cheater, the socket slips a little. I need an extra pair of hands but the only person I know out here is my sister and shes recovering from surgery. Any ideas on how I can do it alone would be greatly appreceated!
 
JaredsDad said:
The bearings look ok to me. Put a new crush sleeve and seal in. Having trouble getting it to crush. Every time i get in a position to get some pull on the cheater, the socket slips a little. I need an extra pair of hands but the only person I know out here is my sister and shes recovering from surgery. Any ideas on how I can do it alone would be greatly appreceated!
Click to expand...

The socket slips? What size are you using
 
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