Quote:
Originally Posted by BR3W CITY
Well, there might be room for debate here. Ujoints don't like being head-on, they need a certain amount of flexion to not bind the yolks. Offsetting the motor that tiny bet helps prevent the driveshaft from ever going dead-nuts straight to the output shaft and rear end. Normally, the amount of vertical drop in the driveshaft angle does this just fine, but on bagged trucks with 1 peice ujoints, its possible to get a drive angle so flat that you can actually bind the ujoints up.
I'm guessing this is something thats mostly prevalent on trucks with rear ends which are centered. If you look carefully on late model RWD vehicles, the rear end is actually offset just slightly to one side or the other (in trucks, this is sometimes to ease the angle of departure from 4wd transfer cases).
My $1 on the topic. Holley might have some other crazy reason for doing it, but thats the only logical one I can deduct.
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You did say there's room for debate
I agree with what you said in theory. However, the minimum u-joint operating angle is 1 degree. The source for that is Dana:
http://www2.dana.com/pdf/J3311-1-DSSP.pdf (see rule #1 on page 5)
In a SWB truck application, a driveshaft is going to be in the neighborhood of 60 inches. 1/16 inch offset at 60 inches is 0.0597 degree. That's 1/20 of 1 degree!
I stand by my original statement that 1/16 is insignificant in this case. For the record, with that same 60" driveshaft, you'd have to offset on end by just over 1 inch to get 1 degree of offset.