RSinMO
RSinMO New Reader
9/7/24 4:36 p.m.

Hey guys, 1st time poster here. I'm in the process of swapping an AR5 transmission into a 2000 2wd Silverado that originally had an NV3500, and I had some questions regarding driveline angle before I fab up a transmission crossmember. Forgive me for this being long winded, but I want to avoid costly mistakes  

This truck utilizes a 2 piece driveshaft. 

It is my understanding that we want between .5° and 3° of total operating angle. 

With the truck sitting on the ground and suspension under load, I zeroed my angle finder relative to the rear pinion flange. With the gauge zeroed I attempted to match the engine/trans combo to 0° by jacking the combo up or down from under the transmission. 

By the time I reach ~2.5°, the mechanical fan is hitting the bottom of the shroud, and the trans is sitting way up high in the tunnel. As I try to match the pinion angle I am effectively dropping the front of the engine as it pivots at the motor mounts. This truck is stock ride height so my concern is that the engine/trans angle surely did not match the pinion angle from the factory as I never had any issues with the fan contacting the shroud. 

Am I safe to assume that tilting the engine/trans downward at a greater angle that I will be okay as long as I do not exceed 3° difference relative to the pinion flange?

Basically my engine/trans/front driveshaft would all be angled downward roughly ~4.5° relative to the ground, and the pinion flange would be facing upward only ~2° relative to the ground.

Additionally, does the front driveshaft angle need to be between 0°-½° of the transmission output shaft? I am visualizing the front driveshaft as essentially nothing other than a straight extension of the transmission output shaft. The ½° being only for proper ujoint lubrication. 

eastsideTim
eastsideTim UltimaDork
9/12/24 3:43 p.m.

Might get more answers in the main forum, but my understanding with two piece driveshafts is that the rear driveshaft should have u-joints of equal and opposite angles.  The front driveshaft u-joint does need a bit of angle for lubrication purposes, but I think it can safely go over 0.5 degrees.  I would assume (possibly incorrectly), that you could get away with raising the mounting point of the carrier bearing to help line up the u-joints, as long as the angle doesn't get too extreme on the front driveshaft u-joint.

wvumtnbkr
wvumtnbkr UltimaDork
9/12/24 5:38 p.m.

Can't you simple change the pinion angle to get the angles close?

RSinMO
RSinMO New Reader
9/22/24 3:40 p.m.

In reply to wvumtnbkr :

I could, but my confusion stems from the fact that the pinion angle is stock on this truck, and if I match the engine to the pinion angle, the rear of the engine is sitting way too high up and causing it to pivot at the motor mounts, pushing the mechanical fan into the shroud. 

This suggests that GM was not running their operating angle anywhere near 0.5°. Perhaps I won't have issues with running it up to ~3°. 

As of now I'm waiting on some tool purchases so I haven't made much progress yet, but I am happy with my engine placement as it sits and I matched another LS based truck so the engine is facing 'down' by about 4.5°. 

buzzboy
buzzboy UltraDork
9/23/24 1:39 p.m.

I have read lots of articles about driveline angles and this was my favorite

enginenerd
enginenerd HalfDork
9/23/24 3:34 p.m.

In reply to buzzboy :

Came here to suggest this article...glad somebody is already on it!


Basically that entire Spicer drivetrain manual was a great education when trying to make decisions about my swap project.

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