"But like a dumb a** I reused the old coupler." Coupler?
A u-joint will be visible when it fails. The little pins inside will disintegrate. so the joint will be loose, visible rust etc. Grab the shaft and look for movement. I don't think there is a zirc fitting on this one so you would have to remove the caps to lubricate. Lubing it won't fix the problem, it just prolongs the life of the joint.
V-drive alignment is critical. You need to be within +/-.003 inch of perfect. There are numerous how to threads on this site.
1850 rpms? Is that at full throttle?
A u-joint will be visible when it fails. The little pins inside will disintegrate. so the joint will be loose, visible rust etc. Grab the shaft and look for movement. I don't think there is a zirc fitting on this one so you would have to remove the caps to lubricate. Lubing it won't fix the problem, it just prolongs the life of the joint.
V-drive alignment is critical. You need to be within +/-.003 inch of perfect. There are numerous how to threads on this site.
1850 rpms? Is that at full throttle?