nasty driveline vibration. need help

[Degnol]

but no mater which way i put the ds together it would never be in phase.

Well then at some point, like Mark pointed out, your drive shaft has been retubed and not jigged up properly before reassembly. I am guessing you are having them retubed again for the proper length? When you grease the slip joint, goose it full, then remove the zerk and drive it around before reinstalling the zerk. Too much grease can kinda hydro or really petro-lock the slip joint.

 

[lostmarbles]

Just so we all know we're talking about the same thing... This is correct yoke alignment:

 

[Degnol]

Just so we all know we're talking about the same thing... This is correct yoke alignment:

View attachment 340474

You're just showing off that sparkling undercarriage!

 

[zachary g]

okay i have the ds in and in phase. and this was not the problem. i still have the same vibrations. I NEED HELP. i am stupmed with this one. any ideas?

 

[Degnol]

Get a magnetic angle finder, put it on the TC output and the pinion flange to measure angles of both. Ideally they are the same, but at least within 3* of one another.

 

[zachary g]

can anyone tell me how i could eliminate the slight amount of play i have in the rear output shaft. i thightend the e-brake nut to 100 ft/lbs but it still moves. i drained the oil took the ebrake off and the output still moves? is this a problem? and how can i eliminate this slight movement. it doesnt move much but enough were i can feel it. thank you

 

[zachary g]

i dont have an angle finder but it looks more then three degrees off.

 

[Degnol]

Magnetic angle finder = $10-$15....and a very handy tool fo many things. Get one.
Read this.....................................Tom Wood's Custom Drive Shafts - Driveline 101

 

[Degnol]

can anyone tell me how i could eliminate the slight amount of play i have in the rear output shaft. i thightend the e-brake nut to 100 ft/lbs but it still moves. i drained the oil took the ebrake off and the output still moves? is this a problem? and how can i eliminate this slight movement. it doesnt move much but enough were i can feel it. thank you

Radially or axially? IOW can you turn it with a little play? No problem. If you can move it up-down-left-right.....no good

 

[Mark W]

Are your Ujoints both good? Worn out joints will cause vibration too.


Mark...

 

[zachary g]

the outputshaft moves in all directions. i knw that this is a problem but is it my problem? it doesnt make sense that it would happen when i rebuilt the rear end or it is a hell of an odd coincidence. I am 19 and have put alot of time and money into it, this is my dream car but if it doesnt drive i'll be forced to sell it . is there a way i can test either if it is the rear end or the t-case? I really need help with this one, zac

 

[dargreg]

Unless you have had the DS shortened or lengthened and it was done wrong. It WILL go together correctly. This is your problem. your joints are out of phase. Debate will not change this. This IS the problem.


Mark...

Like ive told you but got stuffed in the below current depths column.If you lowered your rig you brought the two flanges closer together,It sounds like your shaft was to long anyway now its really to long and binding under wrap conditions.That has to be addressed,that in turn has most likely taken your bearing out in the t case ,that has to be adressed.In my experiance with all kinds of small to heavy duty off road vehicals I see no alternative to those problems.

 

[zachary g]

*bump

 

[lostmarbles]

Like ive told you but got stuffed in the below current depths column.If you lowered your rig you brought the two flanges closer together,It sounds like your shaft was to long anyway now its really to long and binding under wrap conditions.That has to be addressed,that in turn has most likely taken your bearing out in the t case ,that has to be adressed.In my experiance with all kinds of small to heavy duty off road vehicals I see no alternative to those problems.

*bump

It is hard to offer fresh advice when you don't appear to have responded properly to previous good advice. (See dargreg's posts.)

I believe he is saying:
'Lowering your rig (as you said you did at the start of this thread) will tend to compress both drive shafts. And if there was insufficient compression-movement available in either driveshaft's spline/slip-joint beforehand, this "lowering" would have caused that driveshaft to RAM the relevant output shaft(s) into your transfer case (damaging internal bearings etc in the process) - as the relevant axle/differential moves up in response to a bump in the road.

And damaged bearings on the transfer g/box output drives = driveshafts no longer running "true" = vibration (And the unusual force on the gearbox will produce vibration by itself - even without the bearing damage.)

So have you actually checked that your driveshaft splines/slipjoints aren't able to transfer axle/differential-movement into this damaging/vibration-causing "longitudinal force"?

And you can't really expect people to offer fresh ideas on what is causing your driveshaft vibration when you admit to having "an output shaft that moves in all directions" (even if it has been like that for some time).

 

[zachary g]

I am not ignoring Antibes advice. For ever suggestion made I have tried to trouble shoot. I do admit that tcase might have a bad bearing. I also asked if there was a way I could check this. I am extremely short on money butwish to keep the car. I am sorry if it looks like I am ignoring advice but in no way am I doing such a thing. I am trying my hardest to get the fj going but am having no luck. So is there a way I can determain if it is either the Axel or the tcase?

 

[Butt Ugly Chuck]

when i put the axle in i lowed the car becuz i changed leaf springs, and the output on the t-case is a little loose.

One of the classic causes of driveline vibration is a loose output from the t-case

Did you fix the t-case output problem?

Sounds like not

Welcome. Slop in TC output can cause DS to go off centre and vibrate..

Yes

If you lowered your rig you brought the two flanges closer together,It sounds like your shaft was to long anyway now its really to long and binding under wrap conditions.That has to be addressed,that in turn has most likely taken your bearing out in the t case

Probable cause

'Lowering your rig (as you said you did at the start of this thread) will tend to compress both drive shafts. And if there was insufficient compression-movement available in either driveshaft's spline/slip-joint beforehand, this "lowering" would have caused that driveshaft to RAM the relevant output shaft(s) into your transfer case (damaging internal bearings etc in the process) - as the relevant axle/differential moves up in response to a bump in the road.

And damaged bearings on the transfer g/box output drives = driveshafts no longer running "true" = vibration (And the unusual force on the gearbox will produce vibration by itself - even without the bearing damage.)

So have you actually checked that your driveshaft splines/slipjoints aren't able to transfer axle/differential-movement into this damaging/vibration-causing "longitudinal force"?

Well said

I do admit that tcase might have a bad bearing....
So is there a way I can determain if it is either the Axel or the tcase?

Not saying your axle or pinion are perfect, but all signs are pointing to t-case.

Butt

 

[yotawheeler]

hey man...where u located at? iv been in your shoes many times and faught with my '74 FJ40 for the past few years (since i was 16)...dream truck and refused to sell it, never had the money to pay a mechanic to do any work on it so i had to learn how to do things on my own. if it were me...i would consider dripping the x-case and prolly the trans with it and seeing if anybody in the area has a spare that you could put in to try and decide if thats the problem, if you are anywheres near me, (doubtful but hey, the offer is open) i just took my 4spd trans and case out for a SM420 swap...its kind important to figure this out before you drive it too much (i know, if its your dd you dont have much choice) but the viberations if bad will thrash the bearings in that newly rebuild diff....best of luck

 

[zachary g]

thanks for the advice. I will try my hardest to see if i can get a spair t-case, byt they are uncommon. i am trying hard to find ways to tell what is wrong. i have no reason to belive it is the rear end other then i rebuilt it myself(under the supervision of an instructor). so i have a self doubt of my work.i will see if i can find either a rearend or a t-case.