Leveling engine and trans?

[wayne]

I repowered my 1990 Setra a quite a few years ago but now I am putting the finishing touches on the drivetrain and suspension. I noticed something recently when I was under the bus, the tailshaft on the trans was tilted toward the ground. After taking a closer look at the engine and trans I could see an approximate 12 degree tilt.  Does anyone know if this is normal, common, or just irrelevant?  I did not change the motor mounts when I repowered because they all matched up but changing transmissions from a 748 to a World 6 required fabricating new trans mounts and a new driveshaft. I checked the manuals but there isn't anything about leveling the engine or trans. Any reason for this or should I not worry about it, if I need to change it it's now or never.
1990 Setra 215. Came with 8V92TA DDEC II w/ Allison 748
Repowered with 1994 8V92TA DDEC III w/ Allison World 6

[Utahclaimjumper]

You would like as minimul as possible angle for longevity.>>>Dan

[challenger440]

Well I'm not to sure on buses but on a light vehicle the angle of the engine and trans should match the angle of the rear end.  5% tilt on engine should be matched by an equal  tilt from the rear end.  As I understand it you'll get weird vibrations and eat u-joints for lunch.

John M.

[bevans6]

Well I'm not to sure on buses but on a light vehicle the angle of the engine and trans should match the angle of the rear end.  5% tilt on engine should be matched by an equal  tilt from the rear end.  As I understand it you'll get weird vibrations and eat u-joints for lunch.

John M.

my understanding as well.  U-joints are not constant rotational velocity, they surge up and down as they rotate.  The matching input and output angles make the changes cancel out and eliminates vibration.

Brian

[wg4t50]

When I repowered, I kept the driveline within 2 deg, left/right, and at normal ride height the up/down was also within 1.5 deg, of course that would change slightly due to bumps etc.  Never had a U Joint issue in many miles.
Key is to not have a zero deg line up, you need a slight out of alignement for the U Joints to work correctly.
Dave M

[HB of CJ]

Could have something snapped or broke, causing the droop?  Yeah....drive shaft angularity very important.  Must be ideally within one degree or less of matching the rear end angle.  Does your rear end droop 12 degrees also?  If soos, you will need to fix them both. We used long straight edges and measuring tape to true up the driveshafts with the rear end and tranny.  Yep...you will eat U joints and the vibs will drive you crazy.  They must not be exactly centered, just off set the same just a little bit.  HB of CJ (old coot)

[robertglines1]

What Dave said: Just set my new eaton/60series at 2 degree--  with bus at proper ride height.  Reason: while I was changing things around might as well get as close to best performance as possible.       How much longer was the new transmission/engine combo?   About 3 inches come to mind. Need to check my book tomorrow unless someone knows now.  Would sure change angle a bunch on such a short drive shaft.   Bob