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Alpha One Universale Joint Parts

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Merc1100sc

New member
Hello all.

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

  2. Do I replace just the cross bearings and associated hardware, or do I need to replace the yoke and center sockets?
  3. 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.
 
Ayuh,.... Ya just replace the u-joints with u-joints that fit,..... ain't gotta be Merc parts,....
 
Just the U joints unless the yokes are damaged. Use the Merc. or Sierra equivalent. There are Spicer, etc out there that have the same dimensions as the Merc. and will fit, but they won't last long. The Merc and Sierra cross journals are much larger that auto/truck U joints. The others have a thicker wall in the needle end caps to fit the yoke bores. The Sierra is identical, and runs $55-$60. You can put in a $13-$20 Spicer, but the damage it could cause if it comes apart will eat up the savings many times over.
 
harringtondav said:
Just the U joints unless the yokes are damaged. Use the Merc. or Sierra equivalent. There are Spicer, etc out there that have the same dimensions as the Merc. and will fit, but they won't last long. The Merc and Sierra cross journals are much larger that auto/truck U joints. The others have a thicker wall in the needle end caps to fit the yoke bores. The Sierra is identical, and runs $55-$60. You can put in a $13-$20 Spicer, but the damage it could cause if it comes apart will eat up the savings many times over.
Click to expand...

Thanks for the feedback. I will go with the Sierra's rather than take the chance of the cheaper ones wearing out.
Can you recommend where to order them?

Thanks
 
At this site is as good as any Go to the top of this page, Boat Engine parts>mercruiser stern drive parts>shop all engine and drive models>jump to drive models and find your year and drive. Once you get the p/n buy it , or Google it for a better price elsewhere.
 
Merc1100sc said:
Hello all.

I have a 97 Sea Ray with a 4.3, Alpha One, I believe Gen IIbased on the year.
I believe the U-Joints are bad. Sort of a knocking noise atmost 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? If no damage to the yokes and center section, just replace the bearing crosses.
  2. What brand parts should I buy, and from where? I assume Merc parts are rebranded OEM’s from somewhere else. That is correct!

Thanks for any input.
Click to expand...


Although the industry refers to these as U-Joints, the term U-joint represents the entire assembly.....(i.e., universal joint..... i.e., male yoke/bearing cross/center section/bearing cross/male yoke)
You will be replacing the Bearing Crosses only.

Most all of the marine bearing crosses are originally from the automotive industry.
These all share an approximate same trunion diameter and bearing cap ID. The quality of the steel and manufacturing makes the difference.

Spicer is a good brand.
The Spicer 5-1306 X should be a direct replacement, and without the $$$$ mark-up used for the alleged Marine brands.
If you have access to, and can purchase from a good truck drive-line parts supplier, they should have these for around $16 each.


Your call! :D
 
The Spicer will fit, but the cross bearing journals on the Merc/Sierra are 15% larger. Others make up the difference with thicker walls in the needle caps. Boat U joints operate at 4800 rpm at full torque at 27 degree bend angles. If a truck u joint fails, you unbolt the yoke caps and replace it. If a out drive U joint fails, you pull the drive and the input shaft assy, and hope the U joint is the only thing that has failed. $34 more each for real thing is peanuts compared to the hassle of replacement, and possible replacement of your yokes.
 
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harringtondav said:
The Spicer will fit, but the cross bearing journals on the Merc/Sierra are 15% larger.
May I assume that this would be the trunion and it's diameter that you claim is 15% larger?

Keep in mind that the bearing cross cap OD cannot be changed for a certain application. In other words, if the receiving bore within the Yoke and/or Center section is 1.XXX", then the cap OD must also be 1.XXX" (minus clearance).

If strength or longevity is to be gained by increasing the trunion diameter, then one or more of several other things must occur:
..... the needle diameter must become smaller
..... the wall thickness of the cap must become thinner
..... somehow the C clip groove depth is unaffected by the larger bore (remember.... these are internally clipped)

Others make up the difference with thicker walls in the needle caps. Boat U joints operate at 4800 rpm at full torque at 27 degree bend angles.

If we are operating at 4,800 RPM, then we will have an issue with Engine longevity..... therefor bearing cross life expectancy will take second seat!
(I know of no one who operates their Marine Cruiser Engine @ 4.8K RPM in a constant fashion)

Also...... and many do not consider this.... most of the heavy load occurs while piloting straight ahead and with the drive trimmed IN.
This creates very little trunion and cap articulation, of which creates "point loading", of which accelerates wear.
This is also why average Joe will rotate his universal shaft and think that the crosses are nice and smooth feeling.

If a truck u joint fails, you unbolt the yoke caps and replace it. If a out drive U joint fails, you pull the drive and the input shaft assy, and hope the U joint is the only thing that has failed. $34 more each for real thing is peanuts compared to the hassle of replacement, and possible replacement of your yokes.

So.... may I summize that by paying more for the exact same bearing cross labeled "Marine", quality is magically increased?
Click to expand...
 
For sure the trunion, (I retired from drive train mfg. engineering, so by habit I call a precision ground bearing OD a bearing journal) is larger on the marine U joints. The marine trunion is .700" dia. I measured one as I'm typing this. I remember going to to a truck power train store and looking at an exact fit replacement. The trunion was close to 1/2" OD. Last winter I was still trying the beat the $55-$60 price and spent time researching Spicer and the others. I finally got on the phone with an application engineer, he pulled the print for the cross on their HD - M (for marine), and told me the trunion was .600" dia. 15% smaller.

I see hoople heads doing full steering turn, full power donuts. Merc. knows what people do, so they build the stern drive to take it -with beast U jonts. Merc also designed the engine for 4800 rpm max. Miss use or abuse will shorten any machine's life. I'd never take a full torque (3500-3800 rpm), full 45 Deg. steering turn, but if I did, the drive will handle it.

So I advise people to save their pennies elsewhere than on a critical part of the innards of their out drive.

ps. The Alpha Gen II can handle a 350 Mag at it's torque. If someone owned a 3.0L boat and wanted to save $70, and knows how to avoid U joint abuse I think they'd be fine with the $20 truck U joint. I just checked Bravo U joints. The Sierra $55 Alpha joint costs $100 in that big block Bravo drive. So I'm sticking with the Merc. engineers on this one.
 
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Harringtondav, my apologies for my previous post sounding rather gruff!
Your info is good.... and I don't doubt your findings.
It's just that during my years of performing marine work, I've seen how the Marine application trunions wear in a rather point-load fashion.
This point loading wear area is what causes these to create the vibration that gives us the first warning.

Rarely have I ever seen a bearing cross trunion break off due to extreme torque loading.... but I must agree with you in that if one did break off, the damage could be catastrophic.

In a car/truck, the universal joint is constantly articulating, causing the needle bearings to consistently change positions on the trunion. This action reduces wear on the trunion. In other words, with the articulation the needles are rolling, so to speak, and are changing positions.
Whereas in the Marine application, the universal joint may not articulate to the same degree, nor in a consistent fashion...... hence my comment regarding "point-loading".

More articulation = forces spread out over a larger area, effectively reducing confined wear.

The next time any of you pull one apart for a replacement, look closely at the old cross trunion surfaces. You will see the wear marks being confined to a rather small area only......... I.E., point-load patterns at the trunion's "drive" side, and point-load patterns at the trunion's "driven" side.

harringtondav said:
For sure the trunion, (I retired from drive train mfg. engineering, so by habit I call a precision ground bearing OD a bearing journal)
Yes, I can go with that. (However, I think that technically that portion of a bearing cross is referred to as the trunion.)

is larger on the marine U joints. The marine trunion is .700" dia. I measured one as I'm typing this. I remember going to to a truck power train store and looking at an exact fit replacement. The trunion was close to 1/2" OD. Last winter I was still trying the beat the $55-$60 price and spent time researching Spicer and the others. I finally got on the phone with an application engineer, he pulled the print for the cross on their HD - M (for marine), and told me the trunion was .600" dia. 15% smaller.

I see hoople heads doing full steering turn, full power donuts. Merc. knows what people do, so they build the stern drive to take it -with beast U jonts. Merc also designed the engine for 4800 rpm max. Miss use or abuse will shorten any machine's life. I'd never take a full torque (3500-3800 rpm), full 45 Deg. steering turn, but if I did, the drive will handle it.

So I advise people to save their pennies elsewhere than on a critical part of the innards of their out drive.
Understood!

ps. The Alpha Gen II can handle a 350 Mag at it's torque. If someone owned a 3.0L boat and wanted to save $70, and knows how to avoid U joint abuse I think they'd be fine with the $20 truck U joint.
Actually, the Spicer 5-1306X is from an old Chrysler auto application. The X designation places the zerk fitting in the apex of the cross, preventing it from contacting the interior of the drive shaft bellows.

I just checked Bravo U joints. The Sierra $55 Alpha joint costs $100 in that big block Bravo drive. So I'm sticking with the Merc. engineers on this one.
Understood!


Also, as good as it sounds, I believe that greasing them does little to no good. Once they have begun the inevitable point-loading process, no amount of new grease is going to reverse that process!

One last thing........ our Marine stern drive bearing crosses are wear items. We should all be preemptive by replacing them before we have trouble.
Click to expand...
 
Yes to all of your comments. Our job is to share our knowledge w/newbies seeking help. Looks like there is plenty of that between us. The bending loads required to break a single hardened 8640 forged steel trunion would probably far exceed the torque it would take to twist off the prop pinion drive shaft at the water pump key flat. I see that as the torque weak point in the Alpha. There are eight working trunions in the Alpha cardan U joint set up.

So yes again, trunion needle bearing failure is the failure mode in a U joint. In machine design, higher side loads, which get huge in a pivoting U joint, are resolved with a larger bearing for increased bearing contact area. That 15% larger dia. = 15% more needle contact area.

My concern is when a U joint bearing starts to go, things get loose in the drive shaft assy. If it gets too loose the gimbal brg. and engine coupler see stresses above the design intent, as well as those two massive pre-loaded timken tapered roller bearings supporting the gear end yoke and input spiral bevel gear.

Hopefully the operator notices the racket before things get this far, and the yoke bores start to wallow out.

Keep on sharing your knowledge.
 
Guys. Thanks for all the feedback. I finally got around to getting the serial number off my drive to make sure I order the right parts. I'm going with the Sierra's just to be safe. I will hopefully swap them out as soon as the parts get here. If there are any tips or tricks that are good to know before-hand I'm all ears.

Thanks again
 
You can change them with the drive shaft assy. in the out drive (much easier if you remove it, but you'll need a special spanner and other reassembly torques, etc), but you should use or rent an automotive ball joint heavy duty C clamp press. Use a socket OD just smaller than the bearing cap as a press adapter, and a socket just large enough to swallow the cap as a receiver on the push through side. Be sure to keep the trunions partially engaged in the caps when pushing in the second new cap. If you get cross wise and have a needle fall under the trunion end, you'll bust the hell out of one of the caps. (Been there). Insert the snap ring on the first cap, and push the second cap and cross until it's snap ring groove is exposed enough to pop in the snap ring. This may require pushing the first cap back until it's snap ring is tight against the inside of the yoke. When you're finished there may be some stiffness in the assembly. Smacking the yokes with a dead blow hammer will loosen this up.
 
..ps. You will have to modify - ruin the receiver socket to get it centered under the needle cap. So buy a cheap Harbor Freight, Menards, etc. socket. Center it over the cap next to the castle retaining ring on the nose of the upper case and mark it with a sharpie where the retaining ring keeps the socket off the yoke. Then set it on the yoke and mark the height of the castle. With a thin parting disc on your angle grinder or die grinder make a series of cuts thru the depth mark until you've cut a notch that allows your socket to center over the needle cap.
 
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harringtondav said:
You can change them with the drive shaft assy. in the out drive (much easier if you remove it, but you'll need a special spanner and other reassembly torques, etc), but you should use or rent an automotive ball joint heavy duty C clamp press. Use a socket OD just smaller than the bearing cap as a press adapter, and a socket just large enough to swallow the cap as a receiver on the push through side. Be sure to keep the trunions partially engaged in the caps when pushing in the second new cap. If you get cross wise and have a needle fall under the trunion end, you'll bust the hell out of one of the caps. (Been there). Insert the snap ring on the first cap, and push the second cap and cross until it's snap ring groove is exposed enough to pop in the snap ring. This may require pushing the first cap back until it's snap ring is tight against the inside of the yoke. When you're finished there may be some stiffness in the assembly. Smacking the yokes with a dead blow hammer will loosen this up.
Click to expand...

If I may......

Everything that you need in order to do this:
........ A large Bench Vice
........ Short heavy wall steel tubing sections (1 with an OD slightly smaller than Cap OD, and 1 with an ID slightly larger than Cap OD)
........ Brass hammer

When inserting the first bearing cap onto a trunion, push the cap into the yoke's bore 1/8" to 3/16" further than need be.
This will cause the opposite side trunion to protrude some past the yoke's bore, making it much easier to slide the cap over and onto THAT trunion without loosing a needle bearing.
Now as you continue pressing THAT cap into it's bore, install the C clip onto the first installed bearing cap.
Continue pressing in THAT cap until the first cap's C clip makes contact with the inside of the yoke's cap bore.
Now install the second cap's C clip.
You can use this technique at all areas.


When finished, do not forget to "relax" the new bearing crosses by tapping on the drive shaft components at the appropriate areas.
 
RicardoMarine said:
.....................


If I may......

Everything that you need in order to do this:
........ A large Bench Vice
........ Short heavy wall steel tubing sections (1 with an OD slightly smaller than Cap OD, and 1 with an ID slightly larger than Cap OD)
........ Brass hammer

When inserting the first bearing cap onto a trunion, push the cap into the yoke's bore 1/8" to 3/16" further than need be.
This will cause the opposite side trunion to protrude some past the yoke's bore, making it much easier to slide the cap over and onto THAT trunion without loosing a needle bearing.
Now as you continue pressing THAT cap into it's bore, install the C clip onto the first installed bearing cap.
Continue pressing in THAT cap until the first cap's C clip makes contact with the inside of the yoke's cap bore.
Now install the second cap's C clip.
You can use this technique at all areas.


When finished, do not forget to "relax" the new bearing crosses by tapping on the drive shaft components at the appropriate areas.
Click to expand...

Merc1100sc: This works just fine. But if you keep the drive shaft assy. assembled in the complete out drive, you'll have to lift the beast onto your workbench, and block it up even with the vice jaws.
 
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