Topic: Vibration - Driveshaft Yokes and Balancing Question

[Plainview]

I replaced both U-joints in the rear driveshaft.  When I did this, I took the flange-side yokes off both ends of the driveshaft and tossed them in a bucket of solvent to clean them up.  I didn't mark anything with regard to orientation or which end of the driveshaft they came off of because even though the two castings are a little different, the critical dimensions are the same (bolt hole sizes & spacing, distance from flange to U-joint centerline, etc.) and I didn't think it would matter.

*Then,* just because I was curious about something I read the Chilton's manual procedure for replacing U-joints and it notes that you should mark the orientation of the yokes to the driveshaft so they go back together the same way.

When I put everything back together I had no idea which yoke came off which end of the driveshaft or how they were originally oriented.  I'm having a hard time wrapping my brain around why it should matter, but there must be some reason why the manual says to make sure they go back in the same position.

And, of course, I'm now noticing a pretty heavy vibration but only in 2nd gear and only under partial throttle.  Given how much has changed (different transmission and differential, also) it's hard to say exactly what could be causing this.

I just wanted to ask to see if anyone has experienced noticeable driveline vibration after reassembling the yokes in different positions from the way they were originally...?

[:)bestgen4runner]

Question?
Is it really only in second gear or is it at a speed that is consistant with second gear?
Drive shaft vibrations tend to get worse the faster you go.
But, a drive shaft out of balance could produce a lighter vibration at a specific drive shaft speed.

Did you pull the slip yoke apart. Clocked wrong?
Is it a standard cab single transfer case?

[Plainview [OP]]

I only notice the vibration in 2nd gear when the engine is between 2000-2600 RPM and light throttle. This corresponds to right about 25-30 mph.  Don't really notice it when coasting and it seems to smooth out under heavy throttle.  At part throttle, light load, such as when you're maintaining speed up a slight incline it's pretty noticeable as a "shudder" that shakes the dash and steering wheel.  Problem is, at that speed it's most noticeable I'm going a little too slow for 3rd gear, the engine lugs if I upshift.

I checked the slip yoke and the two ends are aligned.  Would it matter if it was 180 degrees out?

Yes, standard cab and single t-case.  Just a stock W56-C as far as I can tell though someone has been into it at some point as there is red sealer on the mid-plate and the front driveshaft flange on the t-case is drilled for three different bolt patterns, which I'm pretty sure isn't stock.

Going to drive it to work tomorrow so we'll see how it does on the freeway.

[:)bestgen4runner]

I have an extra drive shaft for that configuration.
You are welcome to try it as a test part.
That way you can eliminate the drive shaft from your list of possibilities.
Do you have a build thread?
My opinion is that it is not drive shaft or diff.
Sounds like engine run ability to me.
Keep the info coming. The More info the better I can help.

[OOPS]

Do you have the u-joints phased right? The only thing I can think of if you swapped flanges is you threw the balance off. Best thing to do is take it and have it balanced.

[redneckcustoms13]

Pinion angle issue possibly? Is she stock or has the rear hight been adjusted?

[Plainview [OP]]

I have an extra drive shaft for that configuration.
You are welcome to try it as a test part.
That way you can eliminate the drive shaft from your list of possibilities.
Do you have a build thread?
My opinion is that it is not drive shaft or diff.
Sounds like engine run ability to me.
Keep the info coming. The More info the better I can help.

More info after driving to work today -

Freeway driving:  It's smoother than it used to be!  Without the t-case output flange wobbling around and with new, tight u-joints and a low-mile diff in place it feels almost like a new truck on the freeway.  I'm getting a very light cyclic vibration at freeway speeds but I'll bet that's the wheels/tires, and these tires sing pretty good at speed, too.

Low speed vibration - seems like maybe it's vehicle speed dependent.  On my route to work I was able to get onto a long straight stretch of road with a very slight uphill grade and no traffic, perfect for really feeling this out.  I do feel the vibration when coasting, just not nearly as strong.  It can also be felt in 3rd gear though again, not as strong because the engine is only turning maybe 1600 RPM and not making much power compared to 2000-2400 RPM in 2nd which is where you feel it the most.  Once the speed goes above about 30 MPH (hard to tell because my speedo is off so bad due to the 32" tires) it smooths out.

I've added a link to my build thread in my signature but I haven't updated that thread with all this recent work.  I'll get around to that soon.

Do you have the u-joints phased right? The only thing I can think of if you swapped flanges is you threw the balance off. Best thing to do is take it and have it balanced.

The u-joints are aligned at either end of the driveshaft, if that's what you mean.  To steal 79coyotefrg's description:  If I had a dowel sticking straight up out of my work bench that was the same size as the U-joint caps and put that dowel through the holes in one end of the driveshaft I'd be able to put another dowel through the holes at the other end and it would be perpendicular to the bench also.

I might take bestgen up on his offer to try his driveshaft first.  That should confirm or rule out balance as the issue.

Pinion angle issue possibly? Is she stock or has the rear hight been adjusted?

Hmmm... possibly.  It's possible that with all the other work I've done it's now smoother everywhere else and I'm just really noticing this vibration for the first time since installing the new suspension because it stands out now.

Suspension is OME springs and 5" shackles which give about 3" lift.  I covered what I did in the build thread.

Thanks for all the input!  Overall the truck is definitely smoother than it used to be, but this one vibration right at ~25-30 MPH is pretty strong and I'd like to work it out if I can.

[redneckcustoms13]

Does it feel at all like it could be dw coming from through the steering? That's about the speed it normally occurs. I've had drive line vibes and the feeling from them really could only be translated by holding the shifter. You could feel the truck moving but grab the shifter and it was amplified.

[Plainview [OP]]

Does it feel at all like it could be dw coming from through the steering?

I dunno about coming through the steering but you can definitely feel it in the steering wheel and the whole dash shakes.

That's about the speed it normally occurs. I've had drive line vibes and the feeling from them really could only be translated by holding the shifter. You could feel the truck moving but grab the shifter and it was amplified.

Are you saying that ~25-30 mph is where pinion angle vibrations normally occur?

I notice the vibration in the shifter too.  Let me drive it home from work today and I'll focus on what I'm feeling in the shifter vs. everywhere else.

I think I have an angle finder at home.  I'll see if I can put that on the flanges too.

[redneckcustoms13]

No sir. Death wobble normally occurs about 25-35 mph.

[Plainview [OP]]

No sir. Death wobble normally occurs about 25-35 mph.

Okay, I'm confused.   

Can you spell it out for me?  I'm obviously a little slow.  What is this death wobble you're talking about and what causes it, if it's not pinion angle vibes...?

[:)bestgen4runner]

Your description is not death wobble.
Disregard

[Plainview [OP]]

Hey, I don't want to start a fight or rule anything out here.  I'm curious to hear Mr. redneckcustom's description of the problem.  Even if it's not what I'm experiencing, that info could come in handy either for myself or someone else.

Just to sum up the issue once again:

What I'd call a "shudder" or vibration, similar to what you feel driving on a washboarded dirt road right in the 25-30 MPH range.  It's probably not as strong a vibration as a badly washboarded road but it is strong enough to rattle the dash.  Most prominently felt in 2nd gear under light-throttle at 2000-2400 RPM.  Can still be felt in 3rd gear though not as strongly, and can still be felt a little when coasting.

Smooths out under heavy load and at higher speeds.

[redneckcustoms13]

Death wobble is simply an improper alignment of the front wheels. When the caster and camber aren't correct the front wheels will begin to "wobble" left and right fighting one another until they reach an agreement on where they need to be going.

I realize this may not be your issue but it always worth learning something to rule it out.
On another note, I have probably replaced over 300 toyota u joints in the past years. I have never marked the axle flange side of the joint. The only thing I have ever marked is the spline section as to keep it in sync so the balance isn't affected.  if it's a 2 piece shaft even more important to keep it all lined up.

[emsvitil]

Take it off and see what happens with front wheel drive........

[Plainview [OP]]

Death wobble is simply an improper alignment of the front wheels. When the caster and camber aren't correct the front wheels will begin to "wobble" left and right fighting one another until they reach an agreement on where they need to be going.

Interesting in light of the fact that caster and camber aren't adjustable on these rigs.  Well, I suppose you could change the caster by shimming the spring perches, but not adjustable via any other means.

I do have positive camber on the front.  This seems to be a common issue with these trucks and my google-fu has revealed that no one really seems to know why or what to do about it.  Just seems that some front axles tip the tires out a little at the top...  My only guess would be that this was intentional by the factory to impart understeer when pushed to the limit (most cars and trucks are designed this way as it's safer than oversteer for the average driver) but if that's the case, why doesn't every rig exhibit this?

The longer shackles should have moved the caster more negative.  On every car i've built, more negative caster is a good thing as it improves steering stability and turn-in response.
 

I realize this may not be your issue but it always worth learning something to rule it out.
On another note, I have probably replaced over 300 toyota u joints in the past years. I have never marked the axle flange side of the joint. The only thing I have ever marked is the spline section as to keep it in sync so the balance isn't affected.  if it's a 2 piece shaft even more important to keep it all lined up.

It's definitely something to consider and good info to have, thanks! 

[Plainview [OP]]

when you lift these trucks with a non cv rear driveshaft(single ujoint both ends) you almost always get some kind of vibration even if your transfer case and pinion flange angles are the same. using long shackles will start to point the pinion up which creates a phasing problem.you could shim it down but if your driveshaft angle is around 15 deg or more it is recommended to use a cv rear driveshaft and point the pinion up to the transfer case. tom woods has a good writeup on this http://www.4xshaft.com/driveline101.asp

quote from above link: "There are other factors to consider though. Beginning with what you are willing to live with. Bear in mind that with a driveline pushed to this 15 degree limit you may notice a slight (slight can be a matter of definition) vibration on smooth highway at about 45-50 M.P.H. when you flutter the gas just right. Most people can live with this. When in doubt or if you are near this upper limit, I recommend that you install a double cardan (C.V. ) type drive shaft."

I recently got a cv rear shaft and it fixed at least 3 issues I thought were unrelated.

1.a feeling like the clutch was slipping when taking off from a stop
2.noise that sounded like grinding in the transmission that was most noticeable when coasting
3.vibrations at certain speeds and road types

FYI, I have a single transfer case and a similar lift as the OP.

Interesting, thanks!  Hope I still have my angle finder laying around.  Afraid I might have left it on a jobsite...

[blackdiamond]

caster is adjustable with a cut and turn of the knuckles. it is practically a must on spring overs and would benefit most of us with a lift it's just a lot of work but there are a lot of good write ups on it. a high pinion combined with slight shimming may help caster also but shimming without a high pinion would mess up your front cv driveshaft angle
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=toyota%20axle%20cut%20and%20turn

the only other option is to use shims for caster combined with a double cv shaft (pictured)

For what it's worth, my driveline angles in the front are horrible and I have a lot of vibration starting above 25 mph if the hubs are in.  I run a CV style driveshaft, but the angles are so far off that neither style would be anywhere close for alignment.  I have zero drivability issues in 2wd and really don't need to drive faster in 4wd except for rare occasions so have not worried about it.

[OOPS]

If the spring hanger has a 1" drop your shackles should only be 4.5 inches bolt hole to bolt hole. This will set the frontend at about factory setting on the caster. The stock shackles are 3.5 inches bolt hole to bolt hole. So it makes sense if you drop the front of the spring 1", you drop the rear of the spring 1",

[blackdiamond]

If the spring hanger has a 1" drop your shackles should only be 4.5 inches bolt hole to bolt hole. This will set the frontend at about factory setting on the caster. The stock shackles are 3.5 inches bolt hole to bolt hole. So it makes sense if you drop the front of the spring 1", you drop the rear of the spring 1",

Not easy to measure exactly on a SAS?

[Plainview [OP]]

Another dumb question -

Which way should the slip-yoke on the rear driveshaft be oriented?  Should it be closer to the transmission, or closer to the differential?

[emsvitil]

Mine's closer to the tranny.......