Heavy vibration in drivetrain - driveshafts?

[LINUS]

Hey guys - I've got a vibration that has me stumped - if you think you have a good guess or have had my situation, please offer your thoughts.

HISTORY:
I just finished major service work of both axles as follows:

FRONT: New axle shell (bent & twisted old one - prior owner accident/possibly my fault too)
Full axle service including bearings & seals, birfields, spindles, 3rd member swapped with NIB locker unit that got a 4.88 regear

REAR: New bearings & seals, swapped 3rd member with a 54K unit that got all new bearings & 4.88 gears

Regear was done by Carl @ JT's, so I highly doubt the 3rd members are the culprit.

MODIFICATIONS:

OME 850/860 kit from Slee - NO caster bushings used yet on front. Springs/shocks are 5+ years old, I did however add their adjustable panhard rod kit during this round of work & servicing(DIY kit).
New Goodyear tires, fresh front end alignment because of old axle shell being bent.


WHAT MY PROBLEM SYMPTOMS ARE:

When on throttle, shimmy/vibration starts at 30MPH, increases intensity through 40-45MPH range, tapers off by 60MPH and is very mild/gone at any point in that range when you lift off the throttle & coast. It seems like has a direct relation in severity to load.

The best I can describe the vibration is that it's quite similar to driving over a steady line of "turtles" on streets at about 30MPH - it's about that severe (rattles things in cabin, can see hood sheetmetal vibrating, has that low frequency "rumble" that you "feel" in your eardrums), and about that pace.

When I did all the service work, I did it all at once. During the work I never completely took off the drivelines - I only unbolted the 3rd member end, ziptied it up, and reconnected - I did push through all my old grease at each end of both (10-12 pumps), and added 3 pumps to zerk for splines. I went easy on the spline grease as I seem to remember somebody saying less is more at that spot. New grease is Valvoline full synthetic.

If I had a caster kit, I'd blame my front driveline - but it was fine/smooth prior to work, and like I said all I did was regrease it.

I've checked my DL bolts for tightness (and all other bolts I touched), made sure bearings didn't have play, checked lugnuts just to be sure too. Tires aren't the problem either, as I drove to the tire shop on my old ones & problem was present on them too. I also put hands on the drivelines at each end & tried to shake them to see play - nothing.

It seems to me that the problem was caused either by something I did, did wrong, or overlooked as it was fine prior to this.

Sorry so long, just wanted to really describe the situation. Any of you guys have any good thoughts for me?

 

[mmuthart]

Did the two pieces of your front shaft come apart? Are they still out of phase?

 

[nello]

Probably nothing to do with your problem, but a vibration I recently cured was by replacing the flexplate. This vibration occured from idle throughout, and in park or underload. Smooth as silk now.

 

[LINUS]

Did the two pieces of your front shaft come apart? Are they still out of phase?

No, I never pulled out either driveshaft in any way - I unbolted both driveshafts from each 3rd member drive plate, and zip-tied them up into the tunnel area. The only thing I did was to regrease all 4 universals, pushing out all old grease until I saw new grease, and gave the zerk for the splines 3 pumps.

I'm still not totally clear on phase of driveshafts, but since they never came apart it's impossible for them to be out of phase as I understand the term.

Phase gets screwed up by not putting the 2 halfs back together with splines matched to each other as they originally were made/balanced - that is what I was taught as the meaning - - correct?

 

[LINUS]

Probably nothing to do with your problem, but a vibration I recently cured was by replacing the flexplate. This vibration occured from idle throughout, and in park or underload. Smooth as silk now.

What events led to the need to replace the flexplate?

Is the flexplate the drive yoke as termed in the FSM?

I ask since my front axle has seen 2 major impacts, to the point the housing was bent enough that I had to reseal the 3rd member gasket flange with FIPG / silicone to hold diff fluid with my old housing and 3rd member.

My housing, 3rd member, the RS birfield driveshaft from the 3rd member, both birfields, spindles, and bearings are all new true Toyota parts - the only non Toyota parts are the Nitro gears & Marlin shaft seals.

I suppose it's possible that my front drive yoke on the 3rd member end could have seen shock with as much as the rest of the front drive components as I've damaged & replaced.

 

[4LLC]

Did you do a tire rotate ? I had uneven wear on the tires and when i rotated them i would get a vibration that would mimic a driveline vibration .I chased it for a month until i rotated the tires back and the vibration went away . Just a thought .

 

[LINUS]

Did you do a tire rotate ? I had uneven wear on the tires and when i rotated them i would get a vibration that would mimic a driveline vibration .I chased it for a month until i rotated the tires back and the vibration went away . Just a thought .

Tires are ruled out as it occured with old 33's & new set of 35's. Same severity & at nearly same MPH range.

 

[LINUS]

Is it possible that just the increased speed of my driveshafts on the regear is causing this?

Anyone?

 

[Michael Hanson]

Sure you tightened the front bearings correctly? Mike

 

[LINUS]

Sure you tightened the front bearings correctly? Mike

Preload was right where it was supposed to be, nothing settled enough to change it - I even pulled the cover plates on the stubs to make totally sure I bent the lock washer ears the right way - 1 ear pushed back, 1 ear pulled forward.

I took it out & did a 40 mile round trip on the freeway (everything smooth at that speed) - either I'm getting used to the vibrations, or it smoothed out very very minimally.

I'm stumped.

 

[Michael Hanson]

U-joints? MIke

 

[LINUS]

U-joints? MIke

That's what I'm pretty much left with - it's going back on the lift & I'm focusing on them - aside from doing the prybar movement test, I need to do a little FSM reading to see if there's really a quanitative measurement to see what's good vs. bad.

Like I said prior - regreased them flushing out all the old grease - there was a decent amount of old stuff there & they sure aren't starved for grease now.

I think it will be Monday it goes back up in the air, so if anyone has ANYTHING at all to add, please do so - I'm grasping at straws here.

 

[Michael Hanson]

Could be they are binding slightly at times. MIke

 

[blarsen]

U-joints for sure. (my guess anyway) get some OEM Toyota u-joints, I had 2 sets from other dealers that didn't fit and was a huge pain in the butt..

 

[GrindCruiser]

U-joints

Hy mate
with your description you got the same point I had on my 80,the exact behavior at the xact speed,I checked as this happened to me too and solved it by replacing the U-joints (I discovered later that two of them was totally worn out by lack of grease).
These are my two cents,good luck.
Emi.

 

[PHIL O]

did you lubricate and balance the driveshaft?
could it be a transmission issue too? i had this vibration before. the mechanic suspected a driveshaft problem. but all was good on the drivetrain. we narrowed it down to transmission. found that the bushings and bearings have worn off making transmission rotate eccentrically. rebuilt the transmission but the problem persisted. so we replaced the entire transmission assembly. no more vibrations. is the vibration triggered by sudden thuds while coasting?

 

[jonheld]

Driveline vibrations will be more of a buzz as opposed to tire balance issues which be more of a thunk-thunk-thunk.

Remove each driveshaft and work each uni joint by hand. There should be no "notch" to the movement on each axis, and the movement should be fluid, not loose.

If you choose to replace univesal joints, go with OEM from Toyota and have a shop with a press do it. Pay attention to the direction that the grease nipple is pointing on the original uni before replacement so you'll install the new spider in the same orientation.

 

[Romer]

If you havea CDL, pull the front drive shaft and drive with the CDL engaged. If your feeling the vinbration in your seat vs the steering wheel, it could be the rear shaft.

Its not very expensive to get both shafts rebuilt with Toyota U joints and have them balanced. When I first did my lift I had to have both shafts rebuilt, the increased angle on the old joints wasn't compatible

Are your new set of tires balanced?

 

[LINUS]

Hey all -

Thanks for all the suggestions - really a lot of good stuff to work with once I'm up in the air on the lift.

Sounds like my most likely bad actor is the u-joints/driveline - I've got the CDL, so I plan to inspect & probably pull the FT driveline, give it a drive & see what the resulting drive quality on-road is.

I will report back & no matter how long it takes to resolve this, I'll post what my fix was so this thread has a useful solution on the backside. Hopefully it will be a dead thread once the driveline gets pulled & driven without, but whatever the deal I'll keep updating / bugging y'all for help here 'till I iron it out.

Thanks for all your input & advice so far, guys - this one really has me on the ropes.

 

[LINUS]

So I'd never believe it if I wasn't there for the whole thing.....it's the front driveshaft.

The odd thing is that my driveshaft was a perfectly smooth running piece when it was spinning the 4.10 r&p, but the minute it was spinning that little amount faster turning the 4.88 - it turned into a the biggest POS giving me those vibrations I described - I'm not kidding, the sheetmetal of the hood visibly shook!

Thank God, since if it wasn't a driveshaft I had no clue where I was going to start looking next.

So for future searches - this was another bad driveshaft. The wild thing was as I said how it was a great shaft one day & worthless after the R&P changeout.

I'm planning on Christo's 4" lift, so I'll be calling him in the morning & just getting a DC front shaft ahead of schedule - I wasn't going to add more lift 'till I got this handled.