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I know that driveshaft U joints require some angle applied to them so that the needle bearings have a chance to roll and lubricate as the shaft spins.

360/ number or needles = shaft angle is that fast rule of thumb i am aware of.

But how is this handled (how have you handled it) with an IRS rear. Is the diff set lower to accomplish this angle or is it offset left or right to put the shaft on a horizontal angle.

I am finalizing my 8.8 rear placement and any advice would be appreciated.

-Stu

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-STu

There is no shame in defeat, so long as the spirit is unconquered

My Build Log

Yes.


All of the above or any of the above. Angle is angle

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

If you move the engine a couple of inches to the passenger side you add some angle, improve the cars weight distribution and give yourself more room for the pedals.

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2015 & 2016 EMod Florida State Autocross Champion
2013 & 2014 DSP Florida State Autocross Champion

Scrap Metal Build Log viewtopic.php?f=35&t=14558

Yup, what he said... The U-joint angles can be in any plane. With a stick axle, the angle is usually in the vertical plane and varies as the axle moves. With IRS, you can build in a working angle or angles, vertical or horizontal.

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom

For smoothest operation the shaft angles should match with the axis offset.

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Honey anyone?

This is very sound engineering practice.

With fairly short IRS suspension half shafts, and the suspension in pretty constant up and down motion, you need have no fear about the needle rollers rocking sufficiently for lubrication and even wear.

Braking, acceleration and cornering ( not to mention the odd bump) will keep those needle bearings quite happy even with the half shafts set dead straight at normal ride height.

Its more of a problem with the main driveshaft, but as already mentioned above, you can build in a bit of deliberate angularity, especially if the driveshaft is fairly short.