Automotive ujoints

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jakwi

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Hi all, I'm new to the forum and wondering if someone might be able to help. I found this list for automotive u joints that will cross with the Sierra Sierra 18-6406

I keep searching for the Spicer 5.4x but I can't find any reference to it anywhere. I did find that the Spicer 1300 crosses to the Precision 344.

So my question is has anyone tried the spicer 1300 in a Mercruiser Alpha 1 Gen 2. My s/n is OM468354

Thanks for the help

Neapco 1-005 NOTE: This ujoint may have grease zirks in caps. DO NOT use if they do.
Spicer 5.4x
Precision 344
Rockford K4
 

Scott06

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I haven’t had to replace yet but it is my understanding that MOOG 344 or Spicer 5-1306X will fit the gen 2

i would have have gotten this somewhere on this forum, have you tried a search for someone with firsthand experience
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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go to the stickies. the answer you seek is in the stickies
 

jakwi

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Thanks guys I did find this in the stickies, but I'd also read that there were different parts depending on the SN of your Alpha 1 gen 2. My S/N is OM468354.

Spicer 5-1306X It seems that this is the right part number though, so I'll give it a shot.
 

harringtondav

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Fitting in the yokes doesn't make a U joint equivalent. If you pull a needle cap on that Spicer and a Merc OEM or Sierra equivalent you'll see a much smaller trunion diameter on the Spicer. I've done it and measured it. Less bearing area in a high torque, high rpm, high bending angle application. I spend the extra $$s for the peace of mind that my drive shaft assy will stay in one piece.

Sierra18-2097 has the same .700" diameter trunions as the Merc, and can be found for <$53.
 
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Mad Props

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if your drive is off, look at the castings and see what numbers are on it. The standard auto u-joints didn't fit my drive, I HAD to order the mer/sierra u-joints as they were slightly different on bearing cap spacing from the 5-1306X joints.

Check out my u-joint video around 13:30
 

jakwi

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harringtondav thank you for that information. I was running under the assumption that they were exactly the same. Although I find it hard to believe there isn't an equivalent. These sorts of parts are typically all made in the same plants, so often there are equivalents. It would be nice if I could find a drawing of the sierra part with dimensions so that I could start searching for a true equivalent.

Madprops, thanks for the video, I'll check it out.
 

harringtondav

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harringtondav thank you for that information. I was running under the assumption that they were exactly the same. Although I find it hard to believe there isn't an equivalent. These sorts of parts are typically all made in the same plants, so often there are equivalents. It would be nice if I could find a drawing of the sierra part with dimensions so that I could start searching for a true equivalent.

Madprops, thanks for the video, I'll check it out.

Merc unis were Rockwell at one time. Sierra are Koyo. I've tried to find an auto/truck equivalent with the same .700" cross bearing diameter with no luck. I've called application engineers at Spicer. Their "M" suffix marine U joint has a .600" diameter. 14% less bearing area. Merc packs a lot of torque capacity in a small package.

The Alpha II covers the 3.0 L (160 hp?) up to the 6.2 L +- 300 hp. So if you have a 3.0 L, and are easy with the power in hard turns, etc., the automotive unis should be OK. But for a 180 hp 4.3 and up, I'd play it safe and stick with a true marine uni.
 

jakwi

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Hey man, I'm impressed, it looks like you've already taken the path I was just thinking to take.

I have a 357 Mercruiser Repower, supposedly 275 hp, so I'm at the higher end of the range.

I guess I'll stick with the Sierra's damn seems ridiculous.

Thanks for the info and explanation
 

dingbat

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I've tried to find an auto/truck equivalent with the same .700" cross bearing diameter with no luck. I've called application engineers at Spicer. Their "M" suffix marine U joint has a .600" diameter. 14% less bearing area.
Dont t care about the size of the bearing area. What is the unit rated for?

Bearing surface is a function of the load bearing capabilites of the bearing material. You can cut the bearing surface in half by doubling the strength of the bearing material.

Why apply 30 year old standards to modern part design?

Materials and design tools have changed significantly in the past 5 - 10 years. Parts are now designed and produced to tolerances and strengths unheard of before. Developments in HSLA, AAHS steels allow mfg. to make parts smaller, stronger and lighter

Some of the alloys currently in development have properties that one could only dream of just just 5 years ago.
 

wellcraft-classic210

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This may be old news but a few added thoughts

These U-joints tend to wear differently than automotive with metal surfaces getting deformed from heavy loads
( Often referred to as a point load ) so surface area and hardness are certainly important factors. Any detailed inspections should include a visual inspection of the finish and condition on the bearing surfaces.

Also -- I used some automotive U-joints on a prior boat & found I had to grind some material from the cross body to get proper clearances.

I love to save a buck where I can but -- It seems in this case the added cost does provide a better part.
 

harringtondav

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I love to save a buck where I can but -- It seems in this case the added cost does provide a better part.

Sorry to beat my point to death, but that is where I'm coming from. A pickup with 265/70R17 tires and 3.55 rear end has a drive shaft speed of 2642 rpm @ 70 mph with drive shaft angles of maybe seven degrees split between two U joints.

An Alpha drive shaft has a max angle of 45 degrees, plus trim angle. WOT 4600-4800 rpm, with max. torque at 3500-3800 rpm. shared between tow unis. Bending failure of the crosses is not an issue. The torque is shared between the eight journals. But that 22.5 degree high speed, high load oscillation requires more bearing surface for the needle bearings to live. That is why Merc engineers designed their unis with larger diameter cross bearings.

I'd never do it, but I've seen boat jockeys doing full power hard turns. Merc designed their drives to live under all conditions.
 

aimlow

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Bigger is not always better. The bigger the diameter, the higher the bearing speed. You want the rollers to roll, not slide. The greater the angle, the more the needles roll.
 

wellcraft-classic210

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Yes --- But when your dealing with something known to fail from point load force -- AKA pressure -- surface area is very important -- along with hardness.

Speed is a variable to consider in the design -- But its only a problem if friction creates excessive heat leading to wear.
 

bman440440

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for me it was a no brainer... I was able to get OEM mercruiser off of fleaBay for $30 each
u_joint.jpg
 

Mad Props

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I have to agree that these are not OEM u-joints. The ones I removed from my drive looked exactly like this... They had an M symbol and "SPORE" ??? and L15N.
It looks like KOYO is cast on the ones u bought. They look like a decent bearing manufacturer, but you didn't get OEM parts.

Capture.JPG
 

harringtondav

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I have to agree that these are not OEM u-joints. The ones I removed from my drive looked exactly like this... They had an M symbol and "SPORE" ??? and L15N.
It looks like KOYO is cast on the ones u bought. They look like a decent bearing manufacturer, but you didn't get OEM parts.


Sierra uses Koyo, and they're fine with me. They have the same cross dimensions (.700" dia bearing journals). Higher strength, more needle bearing area than the auto "equivalents".
 
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