Drive Shaft Question

[brianrride]

4" is a lot of lift. When you had the rear prop-shaft off did you happen to measure the pinion angle? If you still have stock upper & lower links (not adjustable) I'll bet its off which will cause your ujoints to complain.

After realizing I may have lifted the front too high after reindexing my torsion bars, I lowered it about an inch. That SOLVED my acceleration vibration but I still have the constant vibes above 50mph. HMMM

EDIT: Thanks and I agree with pinion angle 100%...however, this was all happening long before the lift. The lift just caused vibrations under acceleration, which have been resolved.

 

[spressomon]

Contact Onur aka @beno for a good price on all OEM parts.

 

[spressomon]

FWIW I fabbed adjustable rear upper control arms and experimented with pinion angle. Although I could reduce the drive line vibe by adjusting the pinion angle it isn't 100% effective. But worth a try if new OEM shafts & u-joints don't get you there.

I also suspect, since I can remove the front drive shaft and have perfectly smooth driveline, the diff drop puts the drive shaft at the wrong inclination relative to t-case & diff sides to induce vibes. Just a theory (u-joints, although don't like steep angles...they don't like near zero/shallow angles either). I'm not certain there is any one dragon to slay when you have drive line vibes on 80/100's though...

After all, the Toyota engineers more or less threw their hands in the air when they opted to mount the iron & rubber damper to the passenger side frame rail...

 

[abuck99]

That's another factor regarding diff drop I hadn't considered. Choosing the lesser of 2 evils: extending CV life or attaining propshaft alignment for smoother operation. But I'm just not sure I understand how zero angle would be a bad thing?

My understanding was, as long as the pinion angles are matched between the flanges ( and yokes correctly phased and shaft is balanced) the system would "theoretically" be in balance- no vibes.

 

[brianrride]

FWIW I fabbed adjustable rear upper control arms and experimented with pinion angle. Although I could reduce the drive line vibe by adjusting the pinion angle it isn't 100% effective. But worth a try if new OEM shafts & u-joints don't get you there.

I also suspect, since I can remove the front drive shaft and have perfectly smooth driveline, the diff drop puts the drive shaft at the wrong inclination relative to t-case & diff sides to induce vibes. Just a theory (u-joints, although don't like steep angles...they don't like near zero/shallow angles either). I'm not certain there is any one dragon to slay when you have drive line vibes on 80/100's though...

After all, the Toyota engineers more or less threw their hands in the air when they opted to mount the iron & rubber damper to the passenger side frame rail...

Thanks...great info.

I will report back after I mess with it some more.

 

[spressomon]

Good reading: Tom Wood's Custom Drive Shafts - Driveline 101

Driveline 101

And an excerpt from: Pinion & U-Joint Angles
"Pinion angles can make the difference between a smooth ride, or a noisy and vibrating ride. Correct pinion angles are also very important to the life of your u-joints. Yes a driveline will work with 0* degree pinion angle, but the u-joints need a slight angle for proper lubrication. Without the correct angles, the needle bearings in the u-joint caps do not rotate. Those needle bearings need to rotate in order for the u-joint to operate reliably and smoothly. These u-joint angles should always be at least 1-degree to avoid wearing out the yoke bearings."

 

[spressomon]

One more...and a good one:

 

[abuck99]

Good reading: Tom Wood's Custom Drive Shafts - Driveline 101

Driveline 101

And an excerpt from: Pinion & U-Joint Angles
"Pinion angles can make the difference between a smooth ride, or a noisy and vibrating ride. Correct pinion angles are also very important to the life of your u-joints. Yes a driveline will work with 0* degree pinion angle, but the u-joints need a slight angle for proper lubrication. Without the correct angles, the needle bearings in the u-joint caps do not rotate. Those needle bearings need to rotate in order for the u-joint to operate reliably and smoothly. These u-joint angles should always be at least 1-degree to avoid wearing out the yoke bearings."

Thanks for the link- interesting reading. Geometry wasn't my strong suit in HS, but I catch the gist of the tutorial. The net result is that he confirms the output and pinion flanges still need to be parallel- or within 1 degree or 1/16" of each other for optimal balance or cancellation.

I can also see how one could easily drop down the rabbit hole chasing driveline vibes because of the number of interrelated components, and any 1 change /failure can adversely affect the other components: pinion-yoke-spider-propshaft-spider-yoke-pinion. Compounding that would be the shop you take the driveline to, and how much attention to detail they have and what care they take rebuilding the components. Buying the full assembly maybe be cheaper in the long run?

 

[reznunt]

Are you lifted? I started thinking my driveshaft was having problems because of a vibration I had under throttle. When I let off it would go away. Back on the throttle it would vibrate.

Turned out to be rear upper links. The bushings were worn and allowed the axle to rotate under load and it was binding the u joint up.

Thanks for this... replaced front and rear U joints but can't get rid of my vibrations under load at above 60 mph. Gonna try replacing these bushings next!

 

[reznunt]

After realizing I may have lifted the front too high after reindexing my torsion bars, I lowered it about an inch. That SOLVED my acceleration vibration but I still have the constant vibes above 50mph. HMMM

Thanks for this too... gonna lower my front 1/8" at a time to try and lose the vibrations. I think I lifted my front a little too high too. Come to think of it, the vibrations may have started after I was playing with the height trying to cheat the 60mm droop recommendation. At 60mm droop, no vibrations under load. 1/4" higher and I think I introduced the load vibrations.

 

[brianrride]

Good reading: Tom Wood's Custom Drive Shafts - Driveline 101

Driveline 101

And an excerpt from: Pinion & U-Joint Angles
"Pinion angles can make the difference between a smooth ride, or a noisy and vibrating ride. Correct pinion angles are also very important to the life of your u-joints. Yes a driveline will work with 0* degree pinion angle, but the u-joints need a slight angle for proper lubrication. Without the correct angles, the needle bearings in the u-joint caps do not rotate. Those needle bearings need to rotate in order for the u-joint to operate reliably and smoothly. These u-joint angles should always be at least 1-degree to avoid wearing out the yoke bearings."

Big thanks @spressomon... those are some great reads and full of information that I didn't know. Big help and I appreciate you.