Major drivetrain vibration/shudder at 85mph

[tekdeus]

I noticed during the trip to Vegas, my car developed a major drivetrain vibration/shudder at 85mph. It is a full chassis shuddering, that can be felt right in seats. 2 days ago, I installed a new OEM transmission mount, since I knew the rubber on mine was beginning to separate. The vibration did not change. Yes, my car has a 1 piece aluminum driveshaft, and I suspect that might be the cause, even though it never had this problem during the past 2 years. The output shaft on my R154 doesn't seem to have excessive play. I can move the end of the driveshaft at the tranny up and down maybe 1mm or more.

Yesterday I installed a brand new Shaftmasters 1 piece aluminum driveshaft, hoping that it might be tighter and better balanced and solve the problem. I have not driven the car yet, but I did spin the wheels up to 85mph while on jack stands, and the vibration is still there. (my Tein coilvers don't allow the rear suspension to drop very low)

What should I do next? Take it to a driveline shop with a dyno/roller so that they can try to isolate the cause of the vibration? Should I try a BIC poly transmission mount to eliminate the harmonic vibration? Or see if I can exchange the 1 piece shaft for their 2-piece?

I will check the balance of the rear wheels tomorrow, but I doubt that is the cause since the vibration is present when the wheels are off and the rotors are spinning at 85mph with light brake pressure to simulate load. Interestingly, the vibration is dramaticlly less with no load or wheels mounted.

 

[shenronzero]

yeah ive heard of vibrations with the one piece shafts. um maybe you could drive slower? or faster? whichever suits you better :biglaugh:. is it only at/around 85? what about 80 or 90? does it do it at any other speeds?

 

[jdub]

Might want to check the wheel bearings.

 

[dumbo]

u-joints more than 1mm, that would prolly be it no?

 

[Poodles]

Yep, check for play in the wheel bearings...

At least you know it's something from the driveshaft back...

 

[tekdeus]

Wheel bearings are new, but will double check. And I meant to say I can move the end of the driveshaft at the tranny up and down maybe 1mm or more. Basically the play in the output shaft bearing, several inches down from the bearing itself.

The vibration starts around 65 and is worst at 85.

 

[IJ.]

Sounds like a harmonic vibration Brad.

 

[ForcedTorque]

Do you still have, or can you borrow a 2 piece for testing? That would be a logical place to start. If that doesn't solve the problem, you may want to consider Ian's post next.

 

[kingofyo1]

good idea forced, took the words outta my mouth

 

[tekdeus]

Sounds like a harmonic vibration Brad.

This is what I'm worried it might be. The new OEM rubber trans mount is quite soft and has lots of flex; I can move the end of the trans around quite a bit. I'm wondering if a poly mount might be the simplest fix?

I'll see if I can find a stock 2-pce to try as well.

 

[dumbo]

Wheel bearings are new, but will double check. And I meant to say I can move the end of the driveshaft at the tranny up and down maybe 1mm or more. Basically the play in the output shaft bearing, several inches down from the bearing itself.

The vibration starts around 65 and is worst at 85.

ok i thought the u-joints themself had that much play

 

[Muzy]

Is this a commen mod, to put a one piece driveshaft?
Although I not seen the shaft I would sugest: 1, wall thickness to thin
2, joints out of phase
You mentioned up and down movment, but how is the side to side? If the size of the joint
was not increased there may be binnding in the joint.
Anybody know why Toyota went two piece?
Not trying to jack your thead just thinking out loud.
Anybody eles hear that grinding noise, oh it's getting quiter now. Muzy

Oh just reread. Do any hard launches laitly? Or scape bottom over speed bump.
Gusse you would have seen if it were bent when you had it on the hoist.
Perhapes it has twisted some (out of phase).

 

[NashMan]

when i got my shaft master drive shaft it came to me not blanced to well so it got reblanced fixed my issue

all so did you gresh the u joints they don't come gresed

 

[Nick M]

Anybody know why Toyota went two piece?
Not trying to jack your thead just thinking out loud.

Why do you think they should have gone with one?

Guess you would have seen if it were bent when you had it on the hoist. Perhapes it has twisted some (out of phase).

Could be. Out of phase can feel like a dead miss. But my thought is also on the driveshaft/u-joints. Not wheel bearings. Based on vibration in the seats. That is what they do.

 

[IJ.]

Brad: A gumby test for the balance is to tape a section of the shaft with electrical tape to protect it the grab a hose clamp the shaft size, undo it to open it up and slip it over the taped section.

Snug it down and mark where the clamp screw is with a magic marker and go for a drive, move it remark and drive again, do this a few times and if you hit a sweet spot return it to be rebalanced.

Mistakes happen my shaft shop I've been dealing with for 30 years sent me one with the balance off and it drove me nuts trying to solve it.

 

[tekdeus]

I don't believe it is out of balance, because like I said in my 1st post, I have two aluminum 1-pce shafts. The vibration was present with both driveshafts. The old one used to be fine. The new one has weights welded in 2 places so it should be in balance.

 

[IJ.]

Up to you....

At least try turning the shaft 180 in the diff and bolting it back and test drive it.

 

[hvyman]

is it the kinda vibration you feel when the carrier barring goes out. thats supposed to be most noticed at 65mph

 

[tekdeus]

Wow, I had my rear wheels checked for balance today... WAY off! The tire guy said it seemed that the rims had spun within the tires, throwing the balance off. I had these wheels balanced only 2000 miles ago, but I suppose I have enough torque to spin the rims!??! Very surprising.

Anyways, the vibration is virtually eliminated now, but is still noticable at exactly 87mph, which I can live with. I figure the 1 pce driveshafts have a harmonic vibration at that speed, but having my rear wheels out of balance probably shook the subframe enough to cause the chaos I was feeling, possibly affecting the driveshaft.

 

[Who]

Take a wax pencil and make a mark on the tire inline with your valve stem. If the vibration starts to come back you can check the marks and see if the tires have spun on the rims.