4x4 Driveline Angles

[Rat72]

I'm putting in an LS2 and 6L90 into my 72 4x4 and am having a heck of a time figuring out the positioning of the engine. I've read a ton of posts on driveline angles and a lot of them say about 2 degrees rear tilt on the engine is good but nobody explains why? After thinking about it the engine will probably run fine at any angle so I'm guessing that it comes down to driveshaft angles. I built a spreadsheet to determine front and rear angles based on engine tilt and both front and rear driveshaft angles improve as I tilt the engine back. I was surprised because the engine tilt adds directly to the driveshaft angle but the lowering of the transfer case (and driveshaft) is more significant. But only by a little. So why shouldn't I set my engine back at 6 degrees? It helps the front and rear shaft angles. The rear angle is negligable and the front angle is 24 degrees and 31 degrees at full droop. The CV joints I use are good to 32 degress. Anyone have some thoughts on this?

Thanks,
Whit

[Longhorn Man]

oiling system.


Oh, and moved to the 4X4 section.

[special-K]

All I know is with a 6" lift kit they supply spacers to drop the t-case an inch or so.So.I`d think you can play with the angle within limits with no adverse affect.I never understood how dropping the t-case could help the shorted front driveshaft angle,the one I`d be concerned with.But,you did some figuring and the drop counters the angle in some way?In my head it just doesn`t jive.But,I believe you.I`d think the lift companies did their homework on it,too.

[Rat72]

It's all about how the transfer case sits in comparison to the pinion. Ideally you want the transfer case to be perpendicular to the pinion. The reason kit manufacturers drop the case is to reduce the rear angle so you don't have to go to a CV joint. Dropping the case moves the pivot point of the front driveshaft down creating less of an angle. However it tilts the case backwards which directly adds to the angle. The two essentially cancel each other out on the front. However, on the rear you get a lower pivot point and the transfer case points down towards the axle. The two changes add together in a good way reducing the angle.

[Rat72]

Originally Posted by Longhorn Man

oiling system.

When you look at the 6L90, the mounts are are not parrallel to the axis of the tranny. They are tilted back about 5 degrees. I assume that means that the drivetrain is tilted back 5 degrees and not that their is a goofy twisted tranny mount. I also checked my Denali which has a similar setup and it too is tilted back about 5 degrees. Maybe 5 or 6 degrees isn't an issue?