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2019/2020 Stock Pinion Angle Shims

hotrodz37
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hotrodz37 Senior Enthusiast

hotrodz37

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I checked my stock truck prior to posting this topic and mine is off. The rear end already has shims and they need to come out to put it in spec.


Trans - 5.45*

Shaft - 5.2*

Rear end - 1.56*

Currently has 2* shims with the fat end towards the front of the truck. Taking them out would move it to 3.56 degrees and the operating angle would be back in spec.

I took the passenger shim out this weekend and got to the driver side and my denali has the magnaride bracket in the way so I put the pass shim back in until I can figure out the best way to tackle the driver side.


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  • 3 months later...
Johnny-5 Enthusiast

Johnny-5

Posted
Posted

My 2020 has a driveline vibration that is pretty noticeable during decel from 25-10 mph.  It has factory shims pointing the pinion way down.  I measured the front and rear working angles and the front is about .6 degree, and the rear is 3.8 degrees.  I think they reversed them at the factory. I am thinking of flipping them around and driving it to recheck.

  • 1 month later...
MRP Enthusiast

MRP

Posted
Posted

I have just lifted my 2019 elevation 2 inches to match the spec of the AT4.  I used the Readylift 2.25 inch rear lift blocks and put Bilstein 5100's right round.  Put the front shocks on the middle groove which lifts the front another 0.5 inches.  Bought the shocks for an AT4.  I had spacers machines for the rear bump stops (I have the engineering drawings if interested).

 

The interesting thing is on the rear lift blocks is that they have about a 1.4 degree taper and Readylift said to put the narrow side up front and to leave the factory shim/wedge in.  Factory wedge is about 2.25 degrees.  Having looked at the angles and the angle of the driveline (checked on the front pully of the engine) I removed the factory wedge and put the lift blocks in back to front.  The back axle his now pointing a bit more upwards than what is was from the factory.  The engine and the pinion angle are now the same at about 2 degrees and zero vibration at all.  These measurements were done with a cell phone app so maybe not the most accurate, but worked with the same device on all measurements and you can check that the phone is perpendicular.

SSsierra Enthusiast

SSsierra

Posted
Posted
On 12/12/2020 at 4:21 PM, Johnny-5 said:

My 2020 has a driveline vibration that is pretty noticeable during decel from 25-10 mph.  It has factory shims pointing the pinion way down.  I measured the front and rear working angles and the front is about .6 degree, and the rear is 3.8 degrees.  I think they reversed them at the factory. I am thinking of flipping them around and driving it to recheck.

Did  you get a chance to flip the factory shims? Do you mean by saying you think they installed  them backwards meaning the fat part of the shim was towards the rear of the truck.

  • 1 month later...
Johnny-5 Enthusiast

Johnny-5

Posted
Posted

I did flip them and that created a vibration hnder hard acceleration,  so I removed them altogether and all vibrations stopped.

  • 1 year later...
Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted
2 hours ago, mafd2 said:

Should the rear end be at zero degrees? What should the drive shaft angle be?

Iam wondering also as I have a slight vibration that starts at 60-65 mph. I had new tires put on and road forced balanced but it is still there. Iam just wondering why my factory axle degree shims are fat end to the front and skinny end to the rear no lift is on my truck all stock. Its funny cause all the trucks I looked at on the lot do not have factory degree shims. Maybe newdude can chime in and let us know why some have them and the ones that do to me there installed backwards.

mafd2 Senior Enthusiast

mafd2

Posted
Posted
27 minutes ago, Silverado4x4 said:

Iam wondering also as I have a slight vibration that starts at 60-65 mph. I had new tires put on and road forced balanced but it is still there. Iam just wondering why my factory axle degree shims are fat end to the front and skinny end to the rear no lift is on my truck all stock. Its funny cause all the trucks I looked at on the lot do not have factory degree shims. Maybe newdude can chime in and let us know why some have them and the ones that do to me there installed backwards.

I lowered my 2019 RST to level it.  Had a slight decel vibration between 20-25mph.  I spun the factory shim around 180 degrees and it fixed it. They stopped putting the shims in 2020 for some reason.

  • 2 weeks later...
redwngr Senior Enthusiast

redwngr

Posted
Posted
On 5/2/2022 at 1:50 PM, mafd2 said:

I lowered my 2019 RST to level it.  Had a slight decel vibration between 20-25mph.  I spun the factory shim around 180 degrees and it fixed it. They stopped putting the shims in 2020 for some reason.

PTO shafts are normally designed with the same angle for the universal joints on each end. 

 

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