dreaded growl/vibe on deceleration (1 Viewer)

[80sRGR8]

So... I am getting the dreaded growl and slight vibe on decleration and at a 60mph coast. Quick search reveals likely suspect is front u-joints.

It is lifted and I recently had castor correction bushings installed...

So - questions are:

1) What is the best way to diagnose u-joint vs t-case - vs various bearings in the third member.

2) If it is u-joint, how hard is it to replace and where should one acquire it... used vs NAPA vs OEM vs some super custom job that I don't know about but is probably being assembled and sold on MUD.

3) Is it DC driveshaft time and if so who/where?

All input welcome.

 

[Godwin]

Park it on level ground and chock the wheels. Crawl under it and shake the d-shafts at each u-joint. Do the same at the pinion flanges. If the u-joints or pinion bearings are bad you'll be able to see the movement.

My opinion on u-joints is to go OEM. Over the past two summers I've used NAPA and some other brand from Rockauto and that joint is going out. It will be replaced with OEM.

 

[Godwin]

Forgot to add that you want to release any tension in the driveline so that you can wiggle stuff around. Also some rotational movement of the differential and t-case flanges is normal due to the backlash of the gears. Being able to move a diff flange up and down is not normal.

 

[80sRGR8]

Parked. In neutral with parking brake on. Rear seems tight. Front might be a little looser but only slightly if any. Not sore what's normal but I can hear the gears in the tcase clunk when I turn either shaft. There is no up or down motion on either shaft. There is no front to back motion. Perhaps a slight front to back on the front but it's so small it could be my imagination. I really couldnt tell it if there is any. The front shaft semms a little noisier than the back as I turn it back and forth. If bad its maybe not bad enough to detect yet on vehicle??? Other techniques or advice appreciated. Xcuse typos using greasy fingers on phone!!!

 

[80sRGR8]

Ok I have shaken my driveshaft every way possible. I can't tell normal from non normal since I have never shaken another man's driveshaft. I am afraid the only way I could tell at this point is for someone else with a normal one to shake mine and see if it's different.

Sorry had to find the humor in the moment.

 

[bhmmapping]

You can drop the front shaft and drive with the cdl locked to isolate it. You can also get a better feel for the ujoint condition that way. They should be smooth in both axes without any binding.

 

[80sRGR8]

OK - I finally got around to messing with this some more... I dropped the front d/s locked the cdl and drove it around. Didn't hear the sound or feel it. However... I am no u joint expert but I couldn't feel any looseness. I did detect a little "tightness" or "grabbiness" just ever so slight in the front u-joint. But I couldn't get any slack like I would expect for the amount of noise... There just wasn't the slack I expected (based on my bush hog u-joint experience with an old tractor which is admittedly not comparable). I jiggled and wiggled and shook and could not produce the slightest metallic sound. But then again it doesn't do it all the time so maybe it takes a lot of torque to generate it?

Also - both the front flange and the rear flange would rotate 1/8 to 1/4 turn... maybe not that much but they both just felt "loose". I have a feeling that is normal gear slack on each but just not sure. The xfer case seemed a bit looser to me. I did tug on the flange for forward/backward motion... didn't feel any really. The front chunk may have had just a fraction but I can't imagine it would have been enough.

Anyhow - welcome opinions again... it's definitely the front. If I knocked it into neutral then it went away - so it's definitely driveline. It could be lots of weird things - but right now I am leaning to the simplest...

Did the castor correction 1000 miles ago - which would have slightly increased the driveline angle... so I think it is the u-joint on the front.

So - all you B'ham Landcruiser heads - any votes? Or alternate diagnosis techniques from here???

And I so a cool green l/c with tag BamaNo1 on my test drive - we honked at each other...

 

[Blackdog]

REPEAT

 

[xodeuce]

OK - I finally got around to messing with this some more... I dropped the front d/s locked the cdl and drove it around. Didn't hear the sound or feel it. However... I am no u joint expert but I couldn't feel any looseness. I did detect a little "tightness" or "grabbiness" just ever so slight in the front u-joint. But I couldn't get any slack like I would expect for the amount of noise... There just wasn't the slack I expected (based on my bush hog u-joint experience with an old tractor which is admittedly not comparable). I jiggled and wiggled and shook and could not produce the slightest metallic sound. But then again it doesn't do it all the time so maybe it takes a lot of torque to generate it?

Also - both the front flange and the rear flange would rotate 1/8 to 1/4 turn... maybe not that much but they both just felt "loose". I have a feeling that is normal gear slack on each but just not sure. The xfer case seemed a bit looser to me. I did tug on the flange for forward/backward motion... didn't feel any really. The front chunk may have had just a fraction but I can't imagine it would have been enough.

Anyhow - welcome opinions again... it's definitely the front. If I knocked it into neutral then it went away - so it's definitely driveline. It could be lots of weird things - but right now I am leaning to the simplest...

Did the castor correction 1000 miles ago - which would have slightly increased the driveline angle... so I think it is the u-joint on the front.

So - all you B'ham Landcruiser heads - any votes? Or alternate diagnosis techniques from here???

And I so a cool green l/c with tag BamaNo1 on my test drive - we honked at each other...

There was a similar question in the latest issue of Toyota Trails. Roger's answer pointed to pinion angle as the most likely culprit.

Here's the article referenced as well: Driveline 101

Did the problem start / get worse with the caster correction?

If it is pinion angle, then you kinda get into a balancing act with pinion angle vs. caster adjustment unless you do one of two things. A) get a CV drive shaft a.k.a. double cardan that will accomodate a more extreme pinion angle, or B) cut off and re-weld spring perches at the correct angle for both caster and pinion.

I looked at the double cardan to fix some vibes I was having with the rear DS on my Tacoma, and was about to do it. I ended up finding the correct degree angle shims though after some work under the truck with a magnetic angle finder and a tape measure. I may still get a one piece rear DS at some point... the two piece with carrier bearing isn't my cup of tea.

 

[bhmmapping]

I would guess it is the u-joint in the front like you said. It should be smooth, the grabbiness you describe could cause the noise for sure. before replacing try tapping the caps with a hammer to see if you can eliminate the tightness. Also check to make sure the front shaft is out of phase. On the front of an 80 IIRC the driveshaft is set up in a broken back configuration so the angles are not parallel. I doubt you're angles are far enough out to require a DC shaft with just the bushings installed.