Drive shaft alignment

[MonstaS4]

I'm running an LS3 with TR6060 and IRS. I need to fabricate an adapter for the transmission mount as the supplied mount was to suit a TKO. My understanding is that from a side view, the tranny should be pointing down at the same angle that the IRS pinion is pointing up (faces are parallel) so that the output speed remains constant as per the pic below:
11-driveshaft-alignment[1].jpg
The closest I can get is within 0.5 deg difference which I believe is acceptable. If I drop the tranny any further, I'll risk hitting the shaft on the chassis.

My question relates to alignment in the other plane - looking front to rear. It appears the IRS pinion is offset to the RHS by approx 20mm (3/4"), while the engine and tranny appear to be centered in the chassis. If I try and shift the tranny mount 20mm to the RHS, then the face of the output shaft is not parallel with the face of the IRS pinion. Am I better to keep the tranny mount centered so the output shaft face and IRS pinion face are parallel even though I'll end up with 20mm offset?

[progmgr1]

The guys at the driveshaft shop told me that you want to have an offset in both planes. 2* is optimal, 1*-3* is acceptable. I'm running a Coyote with 6R80 and the Mustang IRS. Centering the trans and the offset of the IRS pinion gave me 2* tilt in the horizontal plane with no adjustments. I am not familiar with the GM hardware, but my guess is that you will have similar results. Keith HR#894

[GoDadGo]

Gentlemen,

You need some angle in you driveshaft to cycle the U-Joint Needle Bearings, but you do need to get everything properly aligned and in phase.
Shown in these videos below will help you better understand how critical, yet simple it is to get your brain into the game to easily handle this task:

U-Joint Phasing Video:
https://youtu.be/Idk3BVDVHq4?t=17

Mechanics Explanation Which Deals With A Multi-Piece 4-WD Driveline:
https://youtu.be/dt69zYAcXME

Here Is An Inexpensive Angle Finder That You Can Buy At Ace, Home Depot, Lowes & Other Stores:
https://www.acetool.com/Irwin-179448...B&gclsrc=aw.ds

Just remember that having a little angle in your drive shaft dangle is actually a good thing as long as your driven member is in phase with the receiving member.
Hope This Helps & Good Luck From The Dark Dart Side!

Steve

[NAZ]

To answer the OP's question on lateral alignment: The same rules on angle relationships apply to lateral alignment.

Imagine drawing an extended center-line through the engine/trans ***'y and one through the pinion shaft of the rear end. These two lines should run parallel when looking from the top and from the side. If you nudge the output shaft of the trans laterally you will skew that extended center-line through the engine / trans and it will no longer run parallel to the extended center-line of the pinion shaft (looking from above).

This is why it is so important to establish a chassis center-line before assembling the car. It is a datum used for aligning drive-train and suspension components.

[MonstaS4]

Thanks guys, all great info.

Brad