GEM Car Motor swap

I purchased a new DD Motors 7.5 HP motor from Monster Carts in Costa Mesa, CA. I did the installation myself. Was told to use the old bumper inside the 19 tooth Dana spline and to make sure it wouldn’t be to thick with the new motor. I measured the depth of the
old and the new spline, before I installed the new motor. The old
spline measures 7/8" deep and the new one 1" deep. I used the same bumper I took
out, even though the depth of the new spline was deeper. I figured it was better if the
armature end play were a little loose that tight.
Now, I hear a “clunk” sound when I accelerate and decelerate. Most likely from the armature end play.
Will this be a problem or should I pull the motor and add a thicker
bumper? I am really not looking forward to pulling the motor out
again.

hi… I don’t have an answer… I bought my motor from another place and went to the list of aftermarket items… followed the suggestion and picked up a new bumper at a golf cart place… call D&D at 315-701-0635… they are good guys and quick to answer questions…

Bob