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  #1  
Old April 13th, 2019, 19:38
rmoorex rmoorex is offline
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Vibrations > 45 MPH... Close to Fix?

1991 Two Door, 5 Speed, 3 inch lift. All drive-line components, steering components, suspension, track bar, control arms, etc have less than 3,000 miles. Totally new/rebuilt front Dana 30 front, 44 rear.

SYE with new Tom Wood's double cardigan front and rear propeller shafts.

At 45 MPH plus, mean vibration. Constant and distinct.

Until last night.

This is round II.

First tried a 1" T-Case drop based upon recommendation from several people. Then did my own research. Learned that A) a t-case drop is more or less a potential solution that is just luck-of-the draw; B) t-case drop can result in accelerated motor-mount damage.

Called Tom Woods. A tech told me about the need for a double cardigan to be within 1 degree of pinion angle on the axle side.

Measured. Did a 7 degree shim install.

Now, with each imperfection in the road, the vibration "stops" for a brief moment. Each pot hole, rail road tracks, less than smooth road surfaces.

Upon research, axle assembly and/or propeller shaft angle will flex 1 or 2 degrees when a vehicle "encounters" uneven surfaces.

Could it be that I am within 1 or 2 degrees of being in-range?

Also, maybe I am measuring wrong? I measured on top of the "collar" on the Dana 44 and on top of the rear propeller shaft. Right now both angles match. Makes me think that I am placing the angle finder in the wrong place on the Dana 44.

Hope that a patron can provide more insight.
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  #2  
Old April 13th, 2019, 20:57
RCP Phx RCP Phx is offline
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Re: Vibrations > 45 MPH... Close to Fix?

You should be placing your angle finder on the back of the diff and on the driveshaft itself.
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  #3  
Old April 14th, 2019, 00:34
rmoorex rmoorex is offline
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Re: Vibrations > 45 MPH... Close to Fix?

I thought that I heard/read, "Place the angle finder on the 'service area'."

Next to the fill plug?

Angle from "the back of the diff" + angle on the propeller shaft should = 90 degrees?
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  #4  
Old April 14th, 2019, 07:07
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Tim_MN Tim_MN is offline
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Re: Vibrations > 45 MPH... Close to Fix?

If you have an SYE installed, then there is no reason for transfer case drop spacers.

The angle finder is placed on a machined flat surface of the differential housing casting. Typically the machined surface where the diff cover is to be installed, or the pinion snout.

The rule thumb for shimming an SYE is about 1° of shim per inch of lift. I would say you have too much shim installed.
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Last edited by Tim_MN; April 14th, 2019 at 07:11.
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  #5  
Old April 14th, 2019, 07:40
trippled trippled is offline
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Re: Vibrations > 45 MPH... Close to Fix?

What are the angles you measured? I typically shoot for 2-3 degrees lower on the pinion. That helps account for axle wrap under load but is still smooth cruising.
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  #6  
Old April 14th, 2019, 08:05
RCP Phx RCP Phx is offline
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Re: Vibrations > 45 MPH... Close to Fix?

Also remember that a 2* shim will make a net change of about 3*.
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  #7  
Old April 14th, 2019, 10:07
trippled trippled is offline
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Re: Vibrations > 45 MPH... Close to Fix?

Quote:
Originally Posted by RCP Phx View Post
Also remember that a 2* shim will make a net change of about 3*.
Yup changing the pinion will have an effect on the driveshaft as well. If you have a 6 degree difference I would start with a 4 degree shim and recheck the angle, for example.
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Old April 15th, 2019, 09:15
md21722 md21722 is offline
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Re: Vibrations > 45 MPH... Close to Fix?

The comments about pinion angle are spot on. Also, don't ignore the possibility that the new driveshaft is out of balance.
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  #9  
Old April 15th, 2019, 12:20
Rockwood Rockwood is offline
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Re: Vibrations > 45 MPH... Close to Fix?

Your driveshafts (front and rear) should look like this:



(Image stolen from: http://www.4xshaft.com/driveline101.asp)

If they don't, you're going to have driveline vibes.
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  #10  
Old April 15th, 2019, 20:14
rmoorex rmoorex is offline
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Re: Vibrations > 45 MPH... Close to Fix?

Quote:
Originally Posted by trippled View Post
Yup changing the pinion will have an effect on the driveshaft as well. If you have a 6 degree difference I would start with a 4 degree shim and recheck the angle, for example.
Thanks to everyone for the info/input!

Put in a 4 degree shim. Worse. Far worse.

When I had the 7 degree in, I placed the angle finder on the top of the snout of the centersection (also called the pumpkin) and on top of the drive shaft. In both cases the angle matched. Have photos. But I guess I cannot post those here.

Now it looks like things are 2 - 3 degrees off.

Pulled the rear drive shaft all together. Smooth as silk up to 55 MPH.

With the rear propeller shaft in, things start shaking at 45 MPH.

Discouraged for sure.

Last ditch effort before I take it to a shop is to send the shaft back to Tom Woods for recheck on the balance. They advised that driving with the angle off, and "exposing" the thing to so much vibration, the shaft could be damaged/out of balance.

Possible, I don't know.

This all started when installing the SYE and the Tom Woods custom shaft.

Crossing my fingers.
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  #11  
Old April 16th, 2019, 09:38
md21722 md21722 is offline
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Re: Vibrations > 45 MPH... Close to Fix?

I have some pictures I can send you for measuring angles. I sent you a PM.
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  #12  
Old April 16th, 2019, 10:23
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Tim_MN Tim_MN is offline
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Re: Vibrations > 45 MPH... Close to Fix?

7° vibes, 4° vibes. No drive shaft - no vibes, kinda makes one suspect the driveshaft.

Simple test of above theory, install the front driveshaft on the rear axle.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....
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  #13  
Old April 16th, 2019, 17:33
Gotrdone Gotrdone is offline
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Vibrations > 45 MPH... Close to Fix?

Send the driveshaft back to tom woods for re balancing - it’s free and then you will know if that’s it or not


Sent from my iPhone using Tapatalk
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  #14  
Old April 17th, 2019, 13:00
rmoorex rmoorex is offline
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Re: Vibrations > 45 MPH... Close to Fix?

Quote:
Originally Posted by Tim_MN View Post
7° vibes, 4° vibes. No drive shaft - no vibes, kinda makes one suspect the driveshaft.

Simple test of above theory, install the front driveshaft on the rear axle.
Moved the front to the rear as advised. Same result. Vibes @ 45 and higher.

Waiting for a SYE yoke to arrive. Tom Wood's advised that maybe the yoke is out of wack. Will see.
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  #15  
Old April 17th, 2019, 15:01
RCP Phx RCP Phx is offline
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Re: Vibrations > 45 MPH... Close to Fix?

What SYE kit did you buy?
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