U Joint Cross Replacement

[Lamedog]

Now I've done it... After greasing the shaft every tire change, and feeling I pretty good about the front zerk, I finally took the shaft out and played with it in my hands. The front U joint is really notchy. Perusing Guzziology, I realize I'm in over my head (too complex/infrequent/risky for me). Local Guzzi dealer has experience replacing these in other models, but using Guzzi crosses & shims. They were off-put by the fact MG does not list crosses for the '02 LeMans. While aware of the after market parts suppliers, they had some concern not following Guzzi's recommendation to replace the shaft and no direct experience with going this route for the specific bike - for whats thats worth.

 

The job looks labor intensive and seems I could end up $160 for replacement crosses (MG Cycle) and another $200 for shop charges. This is only a bit more than half what Guzzi wants for a new shaft. At 21,000 miles the splines look good, but show some wear. So, I'm considering buying a new one from Guzzzi, or ship it to someone who will I can be confident will do a good job. Don't want to worry about this bit as I wander to New Jersey and back this summer.....

 

Any thoughts? And particularly any experience having this done with shops in SF Bay Area?

 

Thanks -

[Paul Minnaert]

look for a shop who does this for cars and trucks.

[Pierre]

look for a shop who does this for cars and trucks.

... or tractors, of course.

[Guest ratchethack]

LD, my first take is that with only 21K miles, you'd be mightily and unusually cursed if you had significant UJ wear even if you'd never had them lubed. Are you sure the "notchiness" you felt isn't just the normal hardened lump of cooked-on grease at the end of maximum roller travel in each bearing cup? Keep in mind that the trunnions only rotate in their bearings in a reciprocating motion thru a ~10 degree max (a guess) rotation. Every time I've checked mine, I felt an initial "lumpiness" at the limits of operational rotation until I worked them repeatedly by hand, rolling thru the lumps as it were -- and then it disappeared. New grease, and Robert's y'er Mum's favorite brother.

 

More 'n likely, you don't have any appreciable wear unless the trunnions are actually getting loose. Absent this, I'd run it as is and continue to lube them on schedule and not worry about it until you detect things getting loose, easily checked by wobbling the shaft by hand.

 

But that's just me.

[twhitaker]

What Ratch says makes a lot of sense.

[dlaing]

At 21,000 miles the splines look good, but show some wear.

Have you lubed your cush lately?

 

Also, be sure to align the index marks when reassembling the shaft.

[dlaing]

The front U joint is really notchy.

How notchy?

EDIT Like Ratchet says, try hand rolling it out

[Lamedog]

Thanks all. Notchy right in the middle where I suspect this usually sits, +/- a few degrees. I'm thinking this is similar to the inner roller bearing on the bevel box/swingarm which I have also found "flat" when I bought the bike. Such a limited existence for noble bearings of semi-infinite potential. But notchy is notchy. Even the wife says "boy this is notchy" - with that "what you gonna do now big guy? You got the bike to wrench on - so wrench". Anyhow, its to the garage and subject the joint to a little "Death Valley summer" treatment - very lightly touching the caps with a torch (really, really, mindful of the seals) and not getting hotter than I could touch. Squirted in grease, moved the joint, squirt, move, etc., until the grease coming out is completely fresh (really mindful of the seals).

 

An hour later, still notchy. How notchy? Notchy enough to throw in a box and ship to Moto Int. I'll trust to Dave and Greg to decide between repair and replace. Going to a local auto shaft guy would be sort of fun, but I'm a bit concerned that the small small differences between available cross-sizes and potential requirement for metric diameter spacers creates an unacceptable risk of bodge on their part to complete the job.

 

Thanks for your help.

[Greg Field]

Thanks all. Notchy right in the middle where I suspect this usually sits, +/- a few degrees. I'm thinking this is similar to the inner roller bearing on the bevel box/swingarm which I have also found "flat" when I bought the bike. Such a limited existence for noble bearings of semi-infinite potential. But notchy is notchy. Even the wife says "boy this is notchy" - with that "what you gonna do now big guy? You got the bike to wrench on - so wrench". Anyhow, its to the garage and subject the joint to a little "Death Valley summer" treatment - very lightly touching the caps with a torch (really, really, mindful of the seals) and not getting hotter than I could touch. Squirted in grease, moved the joint, squirt, move, etc., until the grease coming out is completely fresh (really mindful of the seals).

 

An hour later, still notchy. How notchy? Notchy enough to throw in a box and ship to Moto Int. I'll trust to Dave and Greg to decide between repair and replace. Going to a local auto shaft guy would be sort of fun, but I'm a bit concerned that the small small differences between available cross-sizes and potential requirement for metric diameter spacers creates an unacceptable risk of bodge on their part to complete the job.

 

Thanks for your help.

 

Timely. I'm pulling one of those apart this weekend, just to learn how to do it. Yours won't be the first I repair . . .