vibration highway speed when no load (1 Viewer)

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2fpower

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I I have 97 FZJ80 and when I am on the highway at roughly 65 mph I get a vibration when there is no load on the drivetrain. It does not occur under acceleration or engine braking. I currently have removed the front DS and it drives smooth as glass and no noise or vibes.

have a 5' lift that has settled to be about 4" lift. I have the slee bars that rotate the front axle, and it looks about perfectly straight driveshaft going into the axle.

I have not replaced u joints, but feel no slop in them.

Where do I start?

Thanks in advance.
 
Well it sounds like you have narrowed down your issue to the front end.

Do you have the correct caster correction with that 5" lift?

Hopefully some of the folks who have delt with these bigger lifts will chime in.
 
You probably need a cv front shaft, have you checked bearings??
 
Yes, I have castor correction, via the slee stuff. I will try to get a pic tomorrow.

Have I checked bearings??? Which bearings??? the front end is all new rebuilt, with all new bearings, and with shaft off, there is no vibration. Also since there was only vibration when no load at highway speeds, I am confused what it could be. Seems like it would not be a driveshaft balance, bearing or tire out of balance, since it only happens on no load situation. It makes sense it could be u joints or something like that or maybe something on the transfer case.....

Anyway, what bearings should I check, or what is the next test to narrow down the reason this is happening?

Oh, one more thing I want to confirm. With the front driveshaft out, when I park on an incline, it will roll. I assume this is normal without the one shaft it is freewheeling out of the transfer case. Just wanted to mention it if this is not normal.

Thanks,
 
I used to have the exact symptom. Started with the front drive shaft u-joints and balance- no change. Then had the rear fully rebuilt and balanced and bingo: vibes gone. Something to consider....
 
2fpower: with either driveshaft out the CDL should be locked at all times.
 
Ok, I will lock the CDL, and see what happens.
 
Check to see if there is any play in the slip yoke of your front shaft, if it has play like mine did, it will not vibrate under load as the rotational load takes the slop out. But when there is no load the slip is free to vibrate.

This is what happened to my rear, I suspect it was a result of 35's and stock gears putting more stress on the shaft, had a new one made by a local shaft shop and have had no problems. Now my front is doing the same, I will most likely just get a dc shaft from slee soon as I have a little bit of vibs under decel but different than the slip yoke issue.
 
Two things-
If you remove the front driveshaft, you're relying on the viscous coupler to drive the rear. It should feel sluggish, with RPM's going up before the truck accelerates. If it doesn't, you have a locked VC. Not a huge deal- my wife's has been that way for years- but do a search in this forum to understand what's going on.

If your front u-joint has no angle on it, you are in the 'CV zone'. That is, the geometry that can require a CV driveshaft. Usually, both upper and lower u-joints are at the same angle, and they both vibrate, but they cancel each other out. With no angle on the lower u-joint, there is nothing to cancel the vibration in the upper u-joint. A CV joint adds a 3rd u-joint to the top of the shaft, and splits the angle between the top two u-joints. The added u-joint vibrates, and cancels out the vibration of the first u-joint.

Or, you may just need a new u-joint or two in the front shaft.
 
answers

First off thanks for all the help....

Answers: (and more questions)

I don't feel any play in the driveshaft... see picture. It appears to be a CV driveshaft by the way. I seem to recall the PO had an extra driveshaft in the pile of parts.... So, is this a factory thing, or something else? Where to I get replacement U joints for it?

Spike- You must be correct that my VC is locked. It drives better with more spunk than ever without the cdl locked. Would this cause the vibration?
DSC07990.jpg
DSC07991.jpg
 
How can I identify this CV driveshaft as far as origin?

Is there a great thread on these driveshafts? I want to replace all the u joints, so want to know how to get them?

Thanks,
 
I just looked at the pictures again. It looks like the driveshaft is not 90 degrees off. Does this need to happen on the cv driveshafts?
 
First off, let me answer my own question, I could not remove the CV driveshaft end, so no way to make it 90 degrees off.

So, I decided to just try to Re-install the driveshaft with the CV end back by the transfer case. The only thing that I found that disappointed me was that the front axle the thingy that bolts to the driveshaft has about 1/2 rotational play back and forth. Should it have that much? Anyway, regreased all the joints. Looked like they had been neglected. Really found no play on any of the u joints.

I will get some pictures posted up also.

Test it today.
 
really that simple?

I almost hate posting this, but the vibration seems to be gone. (please toyota gods don't make it come back to spite me...)
 
Having the same issue. I replaced my u joints and made no diff. I see that you have a double cardon joint on yours. Mine did not have that. What years have that dc joint.
 
pics

Don't know where the CV joint shaft came from except PO installed it.

Can anyone help on this? I could not find any vendor number on name on it.

Well, still no vibration, so my answer was just incorrect installation of the cv joint axle with the CV section down at my axle.

Note on the pics how straight my driveshaft goes into the axle.

Oh, should I worry about the slop in the front gears of the axle?
003.jpg
001.jpg
 
I have the same issue. I have narrowed the vibe to the frame to axle arm bushings. I have not changed them out yet but am 95 percent sure this is my issue.
 
It is in the correct possition in these pics. If it was installed opposite before it would def give you vibes.
Don't know where the CV joint shaft came from except PO installed it.

Can anyone help on this? I could not find any vendor number on name on it.

Well, still no vibration, so my answer was just incorrect installation of the cv joint axle with the CV section down at my axle.

Note on the pics how straight my driveshaft goes into the axle.

Oh, should I worry about the slop in the front gears of the axle?
 
Happy to report that no more vibes! Thanks for the input.

Does anyone know how much play should be on the front diff?
 

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