Driveline Vibrations---Possible Driveshaft Issues?

[Keeper]

Good luck BB! Hopefully you’ll get another. Soon.

no no no and no

 

[alignman88]

The new zinc weights are going to be bigger in size/volume for a given mass, right? So "big weights" aren't really as big as they look, if you're used to lead.

Yes that’s correct. You’d be surprised how much even lead weights vary. One year we had everyone that drove to HQ bring buckets of used wheel weights to a national meeting, and they were each weighed on certified postage scales and recorded. It wasn’t huge but definitely made for a funky line on that fancy graph. That’s how stacking of tolerances can add up, especially as control arms and other items become lighter/more susceptible to disturbances.

Some of the higher end balancers have provisions to select the composite strip weights like 3M that come in a roll like tape, due to exactly what you pointed out.

Maybe it’s like picking fly poop out of your pepper, but little things can add up.

 

[alignman88]

Hey everyone, sorry I have been out of pocket. It's been a busy few days.

I hate to inform you, but my neighbor made me a fantastic offer and I accepted. It doesn't cover all of the work, but it was more than I paid originally. With all I have going on work, family, and other side gigs, I just needed my life back.

I am very very grateful for all of the help. The search begins for a replacement. You guys have seriously been great and I really do appreciate the time you took to help.

Now let the roasting begin!

Priorities man, your time is worth something. But hopefully we all walk away with just a little more knowledge from it. That alone makes it all worth the time right????

“Every time you go to school you have to pay some tuition”. This was cheap I’d say.

 

[BBslider001]

Priorities man, your time is worth something. But hopefully we all walk away with just a little more knowledge from it. That alone makes it all worth the time right????

“Every time you go to school you have to pay some tuition”. This was cheap I’d say.

I agree! I love increasing my knowledge and got to meet a few new dudes who love these trucks.

Yup, I suck. I know ......I'm a quitter LOL.....nah, at some point you gotta weigh priorities and such. Single dude with lots of time? Sure. Married guy with lots of commitments and other extracurricular activities going on? Makes it tough. MY neighbor is super stoked and I'll get to see it regularly. I really don't miss it. I'll let you guys know when he figures it out.

 

[chevius]

I hesitated before posting here. Coulda started new thread i wonder. Sorry if screw-up!

ZERKS - Compression side of D/S:
sewlow in post #26 i found a point down the post a ways - So here I've quoted the point, from his old man talkin' to him again - about "compression side of the D/S's rotation" ZERK position.

Install the grease zerks on the compression side of the D/S's rotation.
That way, the weak spot in the universal created by the drilling of the hole for the zerk is being squeezed against as opposed to being pulled apart.
The zerk prevents the hole from collapsing under torque.

I was gonna just see which way the driveshaft spins and guess that the compression side is with the zerk towards the front of the truck. Actually i have no idea.

Figured: I'd actually like to know the finer points as there's gotta be near 3 ways to get it wrong.

Can anyone comment on one of the many super interesting bits? On, HOW the compression side of the D/S's rotation can be deduced on my two piece Drive/Shaft? (full quote of sewlow's comment is above)

About 2 brief drives ago (C2500/ext/Nv4500 noted in sig.) the rear wheels seemed to grab/slip/grab going up the slight hill in the gravel driveway here. No biggie i thought.

Then at the end of that day and all the next short drive day the multiple moderate jerks/hesitations might have felt like the engine was missing, though for SURE engine's not causing the problem.

Happens always at low/start end of each gear's acceleration, even when gently accelerating. And, may settle out and mostly stop in the middle/top of any gear. NV4500 5-speed.

Gonna check the ujoints soon (REAL SOON) and create new post i've decided. My new post on the issue(s) will be wondering about what I should replace at the output gear of my NV4500 IF NOT CRAZY HARD, -- tail-shaft bushing, and mount, and any other. Done some studying already.



whatever happens fine as always.
Hey, it'll soon be Spring and time for contrasting last year's maintenance with some NON-SLACK maintenance!

SUPER TO BE HERE -!!!!!!!!!!!

 

[alignman88]

I was gonna just see which way the driveshaft spins and guess that the compression side is with the zerk towards the front of the truck. Actually i have no idea.

Figured: I'd actually like to know the finer points as there's gotta be near 3 ways to get it wrong.

Can anyone comment on one of the many super interesting bits? On, HOW the compression side of the D/S's rotation can be deduced on my two piece Drive/Shaft? (full quote of sewlow's comment is above)

About 2 brief drives ago (C2500/ext/Nv4500 noted in sig.) the rear wheels seemed to grab/slip/grab going up the slight hill in the gravel driveway here. No biggie i thought.

Then at the end of that day and all the next short drive day the multiple moderate jerks/hesitations might have felt like the engine was missing, though for SURE engine's not causing the problem.

Happens always at low/start end of each gear's acceleration, even when gently accelerating. And, may settle out and mostly stop in the middle/top of any gear. NV4500 5-speed.

Gonna check the ujoints soon (REAL SOON) and create new post i've decided. My new post on the issue(s) will be wondering about what I should replace at the output gear of my NV4500 IF NOT CRAZY HARD, -- tail-shaft bushing, and mount, and any other. Done some studying already.



whatever happens fine as always.
Hey, it'll soon be Spring and time for contrasting last year's maintenance with some NON-SLACK maintenance!

SUPER TO BE HERE -!!!!!!!!!!!

I stand by my original suggestion of finding a shop near you that has an EVA meter (Electronic Vibration Analyzer) or similar tool to determine order and frequency of the disturbance once you’ve done a very thorough visual and hands on inspection and nothing is found. It could be many things such as clutches sticking or failing in a position-trac differential, broken gears on differential, torque converter failing. Too many to throw money at.

First order vibration will only be from out of balance condition:

• A component rotating the same speed as the driveshaft that is out-of-round.
• A component rotating the same speed as the driveshaft that is out-of-balance.
• Drive axle problems.
• Driveshaft balance issues can generally be felt at vehicle speeds over 30mi./h

Second order vibration:

• Incorrect Vehicle Trim Height
• Powertrain Mounting Problems
• Failed or Failing U-Joints
• Improperly phased or twisted driveshafts
• Improper driveshaft angles. Driveshaft angle problems can be felt at very low speeds, and higher speeds
• Drive Axle Problems

Third order although rare from driveshaft:

• Failed, failing or binding Constant Velocity (CV) Joints.
• Remove the driveshaft and rotate the CV-joint through its full range of motion while feeling for any rough spots or looseness.

 

[Schurkey]

I was gonna just see which way the driveshaft spins and guess that the compression side is with the zerk towards the front of the truck. Actually i have no idea.

Figured: I'd actually like to know the finer points as there's gotta be near 3 ways to get it wrong.

2 ways wrong, 2 ways right. Zerk facing front or rear means nothing, except you'll have no room to access it if you get that wrong. The issue is which side of the driveshaft ears you put it on.

Power flows from front (engine) to rear (axle). (Or from transfer case to front axle, but let's leave that alone for now.)

Typical U-Joint has four caps. Two caps pressed into the forward part, two caps on the rearward part. For the rear U-joint the forward part is the driveshaft tube ears, the rearward part is the differential yoke. The trans tailshaft (or transfer case tailshaft) yoke is ahead of the driveshaft tube. The driveshaft tube is ahead of the differential yoke. Figure out which direction the shaft rotates when the vehicle is moving forward.

The space between the U-Joint cap connected to the forward part and the cap connected to the rearward part, advanced in rotation is under compression (being pushed.) The space trailing in rotation is under tension (being pulled.) Four caps--two locations under compression, two under tension.

The stronger U-joints don't have a grease zerk, so you never have to feel guilty about not greasing them once they're assembled. Damn good reason to buy non-greasable U-Joints, and then you can forget all this nonsense.

 

[chevius]

Dang... couple of awesome replies.

And the zerk info above rare as rare gets i'd say. Same as the first order, second order, third order vibration points. waaay cool!

YES on the get non-greaseable.
YET: went to Rock and the non-greaseable unknown (to me) brand FVP is near same price as entry-level moog.

1994 CHEVROLET C2500 PICKUP 5.7L V8 Universal Joint | RockAuto

RockAuto ships auto parts and body parts from over 300 manufacturers to customers' doors worldwide, all at warehouse prices. Easy to use parts catalog.

www.rockauto.com

so yep on forgetting the grease-gun stuff -- though moog vs FVP ?


I'm probably just doing what i normally do.
getting obsessed before doing the work and then not giving a hoot when the going gets tough.
something like that. hahaha


THANK YOU
Spring's coming and I'm gonna find all kinds of truck stuff to do. errr... I'll be baaaack. (with another thread and/or major searches)

real soon i bet!-)

UPDATE: re-read "properly" both posts, and, i didn't know any of it... every bit helpful. new area(s) for me.
I'm motivated!! (gotta be a joke about me in there -- I've been more, 'think and read' than, 'get out and do' - that's gotta smooth out!)

 

[highwaystar]

Just to pile on this vibration thread: 1) I never rotate the tires/wheels, why do it? To save a few miles on tire life? Once the tires "bed-in", I'm leaving as is. I've heard rotating can cause minor vibrations till they "bed-in" again, eh. 2) As mentioned previously, torque specs are imperative on wheels!

 

[alignman88]

Just to pile on this vibration thread: 1) I never rotate the tires/wheels, why do it? To save a few miles on tire life? Once the tires "bed-in", I'm leaving as is. I've heard rotating can cause minor vibrations till they "bed-in" again, eh. 2) As mentioned previously, torque specs are imperative on wheels!

Tires don’t “bed in”. Any radial tire casing can be ran in any direction of rotation with zero effect on casing integrity. The vibrations that may be felt after a rotation could be any number of things but most likely either a higher radial force variation (stiff spot in sidewall that doesn’t compress same as others) tire placed in a position that transfers the disturbance more, or same for an imbalanced tire.

Tire rotation is done to even out the heal/toe wear typically found on open shoulder or aggressive tread patterns on free rolling non powered axles, and to extend mileage over leaving a pair on a driven axle. Tires on my daily 1500 GMC 4x4 are $1,500 replacement cost for the set, and with 55,000 miles and at least another 25,000 east left on them I’d never achieved that without rotation.