One Piece Driveshaft Angle? Weird Vibration problem.

[Janz99]

I have a one piece drive shaft, mated to my 2jz, th400 supra. We are getting a weird vibration in the car. The vibration osilates and gets worse as you reach hiway speeds. Someone had mentioned checking the driveshaft angle to make sure its correct. My question is, what is the angle suppose to be on these cars?

At first I had thought it was the solid engine mounts in the car, but I wouldn't think that would cause an ossilating vibration, more of a constant vib. The trans is poly mounted with a custom mount, but drivetrain angle was never measured.... Opps...

Any thoughts?

 

[Janz99]

I had a look through the service manual, but it doesn't specify an angle, or any sort of tolerances on the drive shaft angle.

 

[oldsking]

Possibly the driveshaft wasnt balanced properly looks like? Did you have it custom made of purchased second hand?

 

[te72]

I would recommend checking to make sure the u-joints are in series as they should be. If it's not that, then I'd think your shaft wasn't balanced very well...

 

[Poodles]

Well, for starters you're using a one piece driveshaft when stock is a 2 piece, so there is that issue.

This might help, but it's for the A80 and for a stock 2 piece driveshaft: http://www.supramania.com/forums/sh...aring-for-50&p=1688521&viewfull=1#post1688521

 

[Janz99]

I would recommend checking to make sure the u-joints are in series as they should be. If it's not that, then I'd think your shaft wasn't balanced very well...

Can you elaborate on "in series" ?

The driveshaft is made by Bears Performance. Its a chromoly shaft, fully tig welded and high speed balanced. Thats not to say that mistakes aren't made and it could still be out of balance, but it looks to be a quality piece.

With that said, there is a few things on my end that could definitely be checked to ensure that everything is aligned properly. It seems that we may have over looked this when building the trans mount for the th400.

I realize that a one piece shaft is going to create more vibrations then a 2 piece, but this isn't a small amount I am talking about. It shakes the whole car at hi way speeds. Its also odd that it oscillates, its not a constant vib, like I mentioned earlier.

What angle does the factory engine/trans sit at, and what is the factory pinion angle spec, and lastly what is a typical angle for a one piece driveshaft? Im sure many other guys have swapped in a th350/th400 and one piece driveshafts, maybe one of those guys could chime in?

 

[Another MkIII]

The thing to keep in mind here is, you have a single piece driveshaft. You can take any stock specs on that and wave bye bye. Even if you are at stock specks, chances are you have changed what the spec should be by modifying the car. I'm with the other guys on this, I would check to make sure the driveshaft is in phase and balanced.

Edit: Here is an article with some general information. http://jniolon.clubfte.com/drivelinephasing/drivelinephasing.html
-AM3

 

[Janz99]

Thanks for the information guys. I did some research tonight, and generaly speaking for most IRS cars, you would want no more the 3-4 degree's on the drive shaft. Tonight I'm going to go out and check the angle of my engine/transmission, and the pinion angle to make sure they are parallel. If not, ill shim the trans until they are, and then check the drive shaft angle.

I also found a few helpful tips on how to diagnose the vibration. I'll post up the results once I'm done.

Ryan

 

[IJ.]

Vibration is rarely a pinion angle issue, just look at some of the retarded angles Offroaders run, more often than not it's a balance/phasing problem.

Angle usually becomes a problem under power and will cause windup in the driveline.

 

[Janz99]

Which is the exact opposite of my problem. If I get on it, the vibration goes away. Its only when your cruising do you feel the vibs. I can feel them even at slow speeds, they are just VERY faint. Once you reach hi-way speeds though, it gets pretty bad.

 

[IJ.]

I'd be looking at the Uni Joint phasing then balance.

I have a shop I've used for 30+ years never had an issue then I did, somehow not balanced correctly and a brand new shaft built with the best parts $ could buy...

Had me scratching my head for days...

 

[Janz99]

I'll throw this one out there as well just for informations sake. I am using a billet hub adapter for the th400:

I designed and machined this part. Just to make sure it wasn't the problem, I put a dial indicator on it and spin the engine over, and it has less then .001" run out. So unless the material itself is grossly unbalanced in the part, I don't see it being a problem..... but what do I know !

 

[Janz99]

So after spending some time out in the garage tonight, I've discovered a few things that could be causing/contributing to the problem.

First off, and the biggest problem I see. When we set the trans in place, it looks like we leveled the th400 off the pan rails..... Well if you've ever seen a th400, you'll notice that the pan rials and the tail shaft are not parallel to one another. So when I put an angle finder on the output shaft, its angled towards the ground 5*. The pinion looks like it is angled approx 1* towards the ground as well. Here is a quick paint sketch of what I have going on:

The other problem I seen right away was that one of the ear mounting bolts was missing. Now, I dont think this is causing the problem I'm having, but it definitely isn't helping.

 

[te72]

Can you elaborate on "in series" ?

IJ said it properly when he said "in phase". If your U-joints aren't in line with each other, things get wobbly. Lay on your back under the car, follow the driveline from one end to the other. the U-joints should look like this:

o---o

The circles representing the pins that hold everything together. Hopefully that makes sense...

 

[Dylan JZ]

I never could get rid of vibrations (highway speeds) in my car with one-piece shafts.. it would always go away 100% after returning to stock, even after trying different companies.

 

[Janz99]

After checking everything, I am confident I can get rid of the vibrations. I checked the u-joints and they are in series like mentioned up top. Checked transmission and diff angles. Once I re-set the transmission angle I'm hoping the vibs will be gone.

I'll report back once I get the new mount fabbed up. I'll have to re-adjust my exhaust and charge pipes to suit now, since the trans needs to come up 2" lol.

 

[te72]

Let us know how it works out for you. Nobody likes reading through a dozen threads on the problem they have, when not one of them mentions that what they did actually helped their case.

 

[Janz99]

I will for sure, you have no idea how many threads I've read through over the past few days. Everyone wants help with their problems, but never take the time to come back and describe what actually fixed the problem. Doesn't help anyone else in the future if you don't come back and say what finally ended up fixing the problem.

I think the problem is, most times its something silly or user error, and no one wants to admit when they've done something stupid In this case I don't mind, If its something I over looked due to inexperience I have no problem admitting it.

 

[IJ.]

I always man up and admit if it's something stupid I've done as it may help the next guy NOT make the same mistake, it also sets it in my mind with a bit of a sting so I don't make the same error again.

 

[Janz99]

The transmission is out, and Ive been doing a ton of dialing on the adapter plate, my converter, the billet hub adapter, and it seems that there might be a couple problems. First was the driveline angle mentioned above, but it also seems that there is an engine to transmission alignment as well. Something is moving, because I had dialed the adapter plate in before the trans install and it was 0/0.

I dialed it again last night and it was out .016" ??? I'll have to investigate further and find out whats going on. This could definitely cause the vibration I'm experiencing.