Driveline phase question (real time)

[EricE]

I just finished replacing my rear driveshaft u joints. I drove it and now I have bad vibration. I marked everything and thought I put it back together the same way but I must have screwed up. The question now is how do I fix it? I am thinking the drive flanges are out of phase but what does that mean. How do I tell phase by looking at it. If it is out of phase, do I have to press a u joint back out to fix it or can I slip the yoke off and just rotate by 90 degrees? Advice?

 

[Kernal]

Slip the yolk off and rotate 90 degrees. Here's a photo and a link with some good information and more links. Note how the flange yolk ears line up in the (Edit: rear) driveshaft diagram.

https://forum.ih8mud.com/80-series-tech/80904-drive-shaft-pm-drive-train-troubleshooting-faq.html

 

[Mark W]

Look at the "ears" that hold the Ujoint caps to the driveshaft. The ears at each end of the driveshaft should line up.

If not, pull the slip joint apart and rotate and reinstall.

Do not get mixed up and align one end looking at the shaft and the other while looking at the flange side of the joint.

Look at the ears that hold the joint to the shaft.

Line 'em up and you are good.


Mark...

 

[-Spike-]

At this point, with vibrations and being unsure of how you put it together, it should probably go to a driveline shop to be balanced. Or you could try the different orientations until something works. Make sure you're not one spline off.

 

[Mark W]

I gotta disagree with this advise. All he did was replace ujoints. Why would the shaft be out of balance?

How hard is it to look under the rig and see if it was put back together wrong at the slip joint?

This is about as rock simple an operation as you will find.

Trying different orientations is pointless. It will only work if the ends are aligned straight. There is no reason to even consider lining them up any other way.


Mark...

 

[Mark W]

Slip the yolk off and rotate 90 degrees. Here's a photo and a link with some good information and more links. Note how the flange yolk ears line up in the front driveshaft diagram.

https://forum.ih8mud.com/80-series-tech/80904-drive-shaft-pm-drive-train-troubleshooting-faq.html

That picture is misleading. The top driveshaft is 90* out of phase.
major vibration will result.

The bottom picture is correct.


Mark...

 

[Kief]

front DS alignment

That picture is misleading. The top driveshaft is 90* out of phase.
major vibration will result.

The bottom picture is correct.


Mark...

I have 3 different 80 series I've checked out and the yokes are all 90 degrees out, just like that illustration.. I don't notice any vibes on mine. I thought it wasn't supposed to be that way but they are all the same-I know its possible they could have been redone and misassembled but I just thought that was weird..

 

[Mark W]

I'll see your "three different '80 series thast you have checked out"... and raise you to 6.... 4 of them here now (all mine) and 2 at the house... and toss in every one I have ever worked on.

And for that matter, since there is nothing special about the driveshafts on an '80.... ALL the rigs I have worked on, and all the other rigs on the road.

It is how a driveshaft works.


Now... in the case of an unlifted '80, the deflection of the joints is minimal. So it is possible I guess that the vibration is minimal enough that you have not noticed it.

But it is still gonna be there unless you have no deflection of your ujoints at all.

A Ujoint delivers power in a pulsing manner if it is deflected... the shadft speeds up and slows down twice for each revolution. The joint at the other end has to be in phase so that this is canceled out.


Mark...

 

[OGBeno]

Mark...the FSM is correct.

The front shaft is supposed to be 90 degrees out of phase. It was a change that occurred in 1993.

The rear is in-phase.

This discussion was fleshed out 7 years ago.

EDIT: switched it up on accident. Front outta phase, rear in phase....

Damn, it's been a long day.

 

[Mark W]

I guess the laws of physics must be different under the back of an '80? Apparently not under the back of '80s in Alaska though I guess.

Never seen one 90* out and never put one in that way. None of mine vibrate, none of my customers do either.




Mark...

 

[Cruiserdrew]

Mark-

The front shaft, in stock form, is meant to be run 90 degrees out of phase. The rear shaft runs normally.

When people lift 80s and swap in DC front shafts, they run in phase with variable degrees of success.

But seriously, as counter intuitive as it is, the stock 80 front drive shaft is 90 degrees out. It's just the nature of it.

 

[Mark W]

I am willing to be convinced.... anyone have an explanation of how this 90 degrees out of phase is supposed to work?

And why it would be done, when "in phase" works perfectly, just as it does in every other rig out there?

BTW, there is no "in phase" with a double carden shaft. There can't be since one end is basically two ujoints locked in phase with each other inside the unit. The other joint is on it's own.


Mark...

 

[OGBeno]

Clarification

The phase change was in 1993. Front went from in-phase to out of phase.

The first two pics show a 1997 schematic and a 1993 schematic.

In the early 1991-1992 FJ80's, the front was in-phase as the 3rd picture shows.

Hope this clarifies. I need a beer!

 

[Kernal]

I'm out of my league, not a driveshaft expert. Had a typo in my response, meant to say the rear driveshaft flange yolks line up. Originally had it right when I wrote a long paragraph, but then edited that to show the FSM page as it's easier to just look at a photo (Beno has better photos). Can U-joints be installed wrong to cause binding/vibration from ?? lost pin bearings, or----?, IDK. Could a counter weight have fallen off??

 

[Mark W]

The most likely reason is that when the slip joint was put back together it was installed with the ends not lined up (I'll skip arguing about which orientation is correct for now ) You can miss it by a spline or by several if you don't realize that it matters, or if you just get careless/distracted.

You can screw up a joint if you loose a needle/roller somehow. Doubtful that this would cause vibration until the joint had time to wear and begin to fail.

You can knock one loose and get it pinned inside the joint. It is almost impossible to get the joint into the shaft if this happens though.

The odds of a weight coming loose... especially while you are working on the DS... are pretty slim.


Mark...

 

[Kief]

Toyota must have had a new engineer in charge for a couple years..

 

[-Spike-]

The FRONT driveshaft is out of phase, probably because it is a broken-back configuration. Mark, I guarantee every post-92 80 series you have worked on was like this from the factory. Maybe someone changed all of them. Pirate4x4.Com - Extreme Four Wheel Drive has an explanation of broken-back geometry in a driveshaft.

I suggested the the OP have his driveshaft checked because obviously he isn't sure he's getting it back together correctly. A driveshaft shop could guarantee it's right. He may have lost a weight somewhere, or dented it, or whatever, leading to his current problem.

 

[EricE]

I figured it out. I had replaced the u joint on the front of the rear shaft recently ( like a year ago). It turns out that the older u joint had been damaged by the failure of the other. When I mounted it back on the truck I did notice some play in the older u joint. Well, that play is what caused the vibration. I replaced that one too and all was good. I had mounted everything back correctly( in phase).

I want to thank everyone for the responses.

 

[Kief]

The FRONT driveshaft is out of phase, probably because it is a broken-back configuration. Mark, I guarantee every post-92 80 series you have worked on was like this from the factory. Maybe someone changed all of them. Pirate4x4.Com - Extreme Four Wheel Drive has an explanation of broken-back geometry in a driveshaft.

I suggested the the OP have his driveshaft checked because obviously he isn't sure he's getting it back together correctly. A driveshaft shop could guarantee it's right. He may have lost a weight somewhere, or dented it, or whatever, leading to his current problem.

stock 80's have a pretty straight configuration, especially with worn springs. The "W" or Brokeback diagram shows the yokes aligned.

Glad you got your problem worked out. It is good when things like this come up as I tend forget about things like this and it is good to check into things that just don't look right.

 

[Mark W]

You guys need to look closer at your reference sources. Pirate4x4.Com - Extreme Four Wheel Drive http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html


The "broken back" geometry has nothing to do with being in or out of phase. In fact it still requires that the joints be in phase and aligned as I have stated.

It may be that the front shafts are supposed to be 90* out in the later '80s. But nothing here provides any explanation of it.


I have worked on more than a couple of FJZ80s. I find it hard to accept that every single one of them was changed from a factory "90* out" configuration.... and since none of them has had any vibration or other problems... I then have to ask.. again... why?


Mark...