U-Joint Phasing Video & Why It Is Important

[GoDadGo]

Hey Gang,

I just want to share this video with everyone in an attempt to get this information out to the masses regarding U-Joint Phasing.

https://youtu.be/gmV4qwLfOMY

The reason why I posted this topic is because I picked up my drive shaft on Friday afternoon, for the Go-Dad-Go Chevy Cobra, and it is out of phase by 3-degrees so back to the shop I'll be heading on Monday.

https://youtu.be/UJwM5godh88

Please make sure to check that your drive shafts are phased correctly in order to avoid unnecessary drive line vibrations.

Steve

[mikeinatlanta]

Great video. Can't make it any clearer than that.

[CraigS]

Wow, how do you measure 3 degrees on a drive shaft? Mine looks fine but I haven't tried to measure it.

[Mike N]

Wow, how do you measure 3 degrees on a drive shaft? Mine looks fine but I haven't tried to measure it.

I checked mine with a bubble level across the U joint cup. Level one end then move the bubble to the other end it should also be level. Much easier to do this on a bench that on the car but not impossible.

[phileas_fogg]

If three degrees is too much, what's tolerable?

Nice video, by the way; thanks for posting.


John

[GoDadGo]

Wow, how do you measure 3 degrees on a drive shaft? Mine looks fine but I haven't tried to measure it.

When you eyeball your drive shaft, looking down it like a gun barrel, you should be able to see if the U-Joint yokes on both ends of the shaft are in alignment.

To measure the degrees that it is out, all you need is a simple angle gauge and something to hold the drive shaft securely. Place the angle gauge on each end to see if the angles vary any.

Believe it or not, you will see as little as 1-2 degrees just eyeballing it, but you need an angle gauge to determine the actual amount.

If it looks fine, it likely is fine, but I can see that mine is messed up, so that's why I measured it.

NOTE: You can use a level to see if you are out if you don't have an angle gauges, but it won't give you the degrees.

[mikeinatlanta]

How to see: Before installing, clamp a broom handle into each cup and any misalignment will be obvious.

[GoDadGo]

If three degrees is too much, what's tolerable?

Nice video, by the way; thanks for posting.


John

On drive shafts 36" and longer, you can suck up about 3 degrees, but on super short shafts like we have they really need to be spot on or within 1 degree.

[Gromit]

Well I've learned something today... I knew U joint phasing was important I just never knew why now I do. Of course I also already knew that there is a U-Tube video for everything

Thanks for the education
Chris aka Gromit

[GoDadGo]

I went to the drive shaft shop this afternoon and showed them the issues and they were surprised about my concern until:

1. I gave the spreadsheet that I showed engine RPM, MPH and driveshaft RPM for each gear and they were shocked and promptly agreed to rework the piece.
2. At 3,250 RPM the GoDadGo MK-4 will be traveling at 137.54 MPH with a drive shaft RPM of 6,632.65.
3. Since the operation range for my 383/SBC is 2,300 to 6,500 RPM, this car will be faster that I am willing to ever drive, though I have gone 163.4 MPH at the Dale Jarrett Driving Experience.
4. Basically, the .49 final 6th gear overdrive really calms the heck out of that 3.73 geared Moser rear.
5. This Factory Five should be able to make it to an insane 201.02 MPH @ 4,750 Engine RPM with an equally insane drive shaft rotational speed of 9,693.88 RPM

So all I can say is where will John George be when I need him to do the test flight?

[Vette1972]

Great video and info. Small things make a huge difference. Thanks!!

[Crawleyscobra]

Well... I know what I will be checking on over the winter.

I do not have any vibration, but I now realize I mis-understood pinion angle when I set mine and I had no idea about drive shaft phasing.

This is now on the top of my winter project list.

Thanks for the info.

[NAZ]

Karlos provided a great detailed look at driveline set-up back in NOV.Driveline Setup (aka, Pinion Angle) Take a look at this thread for more info.

[GoDadGo]

The drive shaft has been reworked and it is perfectly in phase and it is not more that .010" out from end to end.

 Centerline to centerline measurements look good and are within .010-.015” so it is quite tight.
 Overall length looks good at full suspension compression and full suspension droop since we’re running a live axle.
 Yoke movement in and out is about .25-.30” and is spot on with the factory wear ring since this is a Used C-4 Corvette Yoke.
 The drive shaft is in as far as it can be at full compression and the furthers out at full droop with the wheels hanging free.
 I’ve got about .50” (1/2-5/8”) of additional room to spare that the yoke can slide into the tail shaft of the transmission.
 Drive shaft angle look good to allow U-Joint Cycling and my pinion angle is perfect and set to Factory Five’s specs.

This Makes My Week Since My Carb & Alternator Arrived Yesterday Evening Too!