Re: replacement U joints
I talked to a GM powertrain engineer about this.
He knows his u joints.
The ones with fewer, bigger rollers will take shock loads better.
This is because of roller angularity.
On a u joint running at an angle the rollers track slightly skewed to the axis of the joint.
The more rollers the more skew because there is more total clearance between a bunch of little rollers than fewer big ones.
When a shock load hits the skewed rollers are bent a bit, the more skew the more bend.
On the other hand the smaller rollers have more line contact area and are not as heavily loaded.
His bottom line...if you have a race boat running hi HP use the ones with bigger rollers.
If not, don't worry.
I put NAPA ones with small rollers in my boat last year and they were as new this year on winterization.
His main concern was precision, heat treat and metallurgy.
With cnc production machines precision should not be an issue.
With Chinese stuff, heat treat and metallurgy is always an issue.
I'm not worried about it with my small block Ford.
If they start clickin' I'll change them.
Volvo won't even sell you their OEM joints, just the whole shaft assy.
I'm not big on permalube joints in the marine environment.
I did take my $15 ones apart and repack them with synthetic grease.
This eased my mind while I saved nearly $100.
