Alpha One U-Joints

[merc1100sc]

Hello all,

I have a 97 Sea Ray with a 4.3, Alpha One, I believe Gen II based on the year.
I believe the U-Joints are bad. Sort of a knocking noise at most trim levels and when turning.
My questions are:

1. Do I replace just the cross bearings and associated hardware, or do I need to replace the yoke and center sockets?
2. What brand parts should I buy, and from where? I assume Merc parts are rebranded OEM’s from somewhere else. Would like to not pay the inflated Merc prices if possible.

Thanks for any input.

 

[harringtondav]

Unless Your U joints have failed so badly that they have damaged the yoke bores, only replace the U joints. Merc. 805536A2 Is a Rockwell HD truck U joint, but I've never found the Rockwell p/n. Also, be careful if you cross reference the Merc. parts based on a dimension chart. There are a lot of 'M' (marine) suffix part numbers, but none have the same cross journal bearing size as Merc. The cheaper ones will fit perfectly, but the torque load capacity is inadequate because of the smaller journals. So buy the Merc, or Sierra 18-2097. The Sierra joint has the same beefy large journal dia., and is 2/3 the cost. It is a high quality Koyo product. Sierra's use to be the same Rockwell part, but their Koyo joints have worked well for me for 22 yrs. iBoats has the best price I've found on both. Also, both are sold a 'permalube'. I advise adding a grease zerk instead of the plug, pull the caps and pump the cross full of Merc. U joint grease, or Penzoil red syn. EP grease. Then replace the caps and pump more grease until the caps start to move. Squeeze the caps back seated, and wipe off the squeeze out grease. You'll be surprised at the amount of grease you can add to a 'permalube'

 

[Alumarine]

Welcome. Here's a link from the stickies that might help.

https://forums.iboats.com/forum/eng...outdrives/244162-u-joint-part-number?t=238091

 

[harringtondav]

I've checked out the link marc c shared. I'd avoid the Spicer and others like the plague, unless you pull the needle caps and measure the cross journal dias. The Merc, Sierra and maybe GLM journals are .706" if I remember. Others are less than .675", some at .630". There is a reason you can get these for $13. But if a cheap U joint comes apart, you'll $pend hundred$ in driveshaft assy. parts. The Spicer and other are HD truck joints, but they run at low rpm., and low angles. Your Alpha U joints operate at 60 - 90% of engine speed at WOT, and can handle a 45 deg turn at full torque and speed. There is a reason they cost from $50-$90. Don't scrimp here.

 

[stang32]

im with Mark, i have put plenty of the less expensive joints in drives over the years, the joints are the sam that are used in cars, light and heavy duty vehicles. i have put the caps onto the cross joints and it fit just as snug as the one removed. they do not engineer new u joints just for marine.
and as for spicer and rockwell, there is a reason they have been around for years, they know their stuff