Driveline Vibration
 

1990 Suburban, 3/4 ton, 4x4, 2 in lift, 3.73 gears

I've got a driveline vibration that starts at 57 mph and partially smooths out at 64 mph and faster. The vibration does not vary with load nor does it change when taking it out of gear. The vibration used to not start until reaching 62 mph but that speed that it starts keeps decreasing.

Here is a photo of what I've got. The driveline is only 35 inches on this vehicle because of the long overdrive manual transmission combined with a Gear Vendors overdrive. I measured some angles as indicated on the photo.

https://preview.ibb.co/k1Oihy/Driveline.jpg

Re: Driveline Vibration
 

Take a look at the attached:

http://67-72chevytrucks.com/vboard/s...d.php?t=522180

This will demonstrate the proper technique for driveline measurement.

If you can follow the thought process on the flow chart you can fix anything.

K

Re: Driveline Vibration
 

Update:

I think I may have found the source of the problem. Check this video out. Looks like there is some slack coming from the yoke. How can this be fixed? How about a big c-clamp?

https://youtu.be/3t1pIPfFv8s

Re: Driveline Vibration
 

It needs a new U-joint before it grenades and ruins the yokes.

Re: Driveline Vibration
 

I can put in a new U-joint but I believe the yoke ears ears had been spread apart during the last U-joint installation. I need a way to bend those yoke ears back together and take out that slack.

Re: Driveline Vibration
 

Hmmm, I just assumed the u-joint was worn out. I didn't realize the caps are spread apart. That 8 seconds goes by fast so I'll take your word for it. I have often seen the ears bent in from being hammered on. I would hate to recommend hammering on it. If it was mine I would just compress it in the press and hope they end up even. I don't know the history of your driveline mods and if those yokes are original or swapped in.

Re: Driveline Vibration
 

Spend a few bucks now and replace it or spend a lot of bucks later and replace it...along with the other stuff it takes out when it grenades.

Re: Driveline Vibration
 

^^^what he said....^^^....new parts are much cheaper than grenaded parts....if you did try to squeeze it back whats to say you could ever get it back to perfect...

Re: Driveline Vibration
 

After you get your yokes repaired, the slip joint re-built & the shaft balanced, check your driveline angularity. The trans/ engine centerline & pinion centerline are supposed to be in the same plane. After you get this adjusted, measure the drive shaft @ trans yoke angle & the pinion angle. Add them together & divide by 2. If you can keep this measurement under 3 degrees then You're GTG. If not, then you may need to rotate pinion up to meet drive shaft true angle & go with a CV type drive shaft like we did on our K5 Blazer. No more vibration!

Re: Driveline Vibration
 

I had the same thing on my 83 C20 granny 4 speed with a gear vendor. The previous owner who had the gear vendor installed never had the driveshaft rebalanced after modification. I still had a little vibration after I had the driveshaft balanced, but that was due to out of balance tires.

Re: Driveline Vibration
 

I removed the driveline and got a better video of the issue. Is this yoke toast or can it be repaired?

https://youtu.be/rMLDhlAOeqk

Re: Driveline Vibration
 

Only way to find out is remove that u-joint and see how easily the cap of a new u-joint fits. Should be snug going in.

Re: Driveline Vibration
 

that looks like the ujoint may be worn.......does it have play twisting it cw and ccw like it would in the truck under load...the side to side play is obvious. ...a new slip yoke wouldn't hurt.....but try a new joint like geezer suggested.....your gonna need one a ujoint anyway...

Re: Driveline Vibration
 

I put in a new u-joint and one of the caps fits kind of loose in the yoke. I'm not sure where to source a new yoke for this. I could not find a part number on it.

https://preview.ibb.co/mbSPQJ/IMG_20180615_155007.jpg

Re: Driveline Vibration
 

These guys will have what you need.

http://www.dennysdriveshaft.com/c461...iveshafts.html

Re: Driveline Vibration
 

I think I would be buying a new driveshaft with all new components that you won't have to worry about for many years.

Re: Driveline Vibration
 

Well, with over half a million miles on the truck, something else is going to break. I'm just going to buy a new yoke and call it good.