I just installed a remanufactured 50DN from Kirk's in Detroit and I'm looking for clear, step by step instructions on how to align the belts. I've read "use a straight edge", but from which side of which pulley? I'm guessing the rear of the accessory pulley to the rear of the 50dn pulley? The manual is a joke! Any other advice? Its been years since I messed with my old 50DN that turned out to have a bad frame. It was time to move on to a good one! Thanks in advance!!
As one pulley faces one way, and the other faces opposite, and is 4 valleys wide...
The straight edge gets employed to help your eye. Everything looks crooked, or straight in there, when it isn't.
V engine banks, tilt on drivetrain, compartment door edge doesn't match the bulkhead... Nothing gives you the right reference.
Put the straight edge to both pulleys in turn, and see whether it appears aimed towards the other.
With the pully overlap, it's still a whole bunch of scientific wild @$# guessing, but using the straight edge reduces the error of the wonky "lines" in the compartment.
Hang the belts, and start taking the variables of adjustment out, square to one another and straight across. The mount can wobble around a bit with the bolts loose.
If you are way wrong, it just throws the belts off, so you get to re-adjust it again.
Eye protection!
Run it and watch them run with a good light. Centred in the valleys on both pullies? And both top and bottom to defend against the mount sitting twisted. Fiddle as you feel necessary, you end up with something that looks to be in the middle.
I threw mine off a couple times until a mechanic friend told me to get the carpenter's square in there.
All the difference.
Happy coaching!
Buswarrior
THANKS BW!!
I used a short straight-edge as a guide on the outside face of the alternator pulley, and looked at it as it pointed up towards the drive pulley on the engine. You have to judge it by eye to some extent, as BW says, but the idea is in line and square, both at once.
That's how we did it on the 4104 when we changed over to a belt drive alternator.
Just to follow up, the straight edge did great. No problems to report. Thanks guys!