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General Discussion / Re: U/J Carrier bearing collapse
« Last post by izzug otom on September 28, 2023, 10:03:09 PM »Many many many moons ago I tried to find U joints to fit the Guzzi when I work for an auto parts supplier for repair shops. Never could find the right ones back then. I did take one apart just to see if I could.
The Guzzi U joint IMHO is not repairable, though it can be done. I just came to the conclusion that I just need to bite the price and get a complete U Joint ready to install.
Yes, I'm inclined to agree with that myself, but at the same time, I think we must both be wrong. Otherwise you've got to ask the question, why are the crosses supplied for them, including from a renowned specialist Guzzi parts supplier, if it's practically impossible to refurbish them, or at least impossible to recover from making a simple, common, sometimes unavoidable problem, of a fallen needle/s. I'm sure that would fail some laws on the sale of an item that doesn't fit the description. I mean, can you sell parts for something that isn't quite the right size for something that isn't even serviceable? In most areas of business you can't do that.
I can see that it might be possible, but to take on the job as a mechanic, you'd have to be pretty damn certain that a needle won't lie down, and I don't think there's anyway of knowing until it's too late. Having to tell the customer that you've fkd the job and the parts up, or have to fork out cash to replace the parts damaged, would be embarrassing, and costly They're going to tell the customer to get a new uj, or worse still just turn around and start running at the mere mention of a Guzzi uj repair/replacement.
I was thinking, it may be a lot easier with the 49mm crosses that are also listed fo Guzzi's, if that is, that the circlip grooves are deep enough in for them to be held snuggly, because, if a needle laid itself down, you'd maybe, but only maybe, have enough room to maneuver and remove the cross to correct it, which is the most impossible thing about the 50.2mm ones. I'm not convinced that 1.2mm would make enough difference though.
Also, I just can't see any reason why the new cup needs to be so tight in the yoke, that it needs driving off again with damaging chisel blows if something needs resetting. I know it needs to be a good snug fit, but only tight enough so that the path of least resistance in the designed movement is always found in the needle bearings. The pressure that these cups are cramped under when pressed in, seems excessively over the top by a high degree to accomplish that, and certainly tighter than many other vehicle manufacturers spec.
I think the holes in the yoke must be able to be opened a tad, so they're still a tight, but not a totally immovable grip. It is simply this one aspect that makes the uj's unserviceable by any home mechanic. If you could, with some reasonable effort, remove the cup again in the event of a fallen needle, there would be no problem at all. I'm no expert mechanic or engineer, but this seems so glaringly obvious, even to me, after my experience in this.
Another thing I don't find very acceptable, is that Guzzi specialists will sell the uj crosses for a specific bike, supplied with circlips that are absolutely impossible to fit in the uj's that they're supposedly purporting to fit. I can't see as that would pass in many other areas of commerce. Ok you may think I'm being a grumpy fkr here, but just based on the straight up logic that if you buy a direct replacement part, especially when it's a part of vital precision engineering, one doesn't expect to have to modify the parts to make it a bodge fit. Not an unfair appraisal really, I feel.
I'm pretty sure a court of law would agree with the plaintive if such a case was heard, not that I'm contemplating, or suggesting, that as a good idea, I just mean from the point of view of reasoned logic as to whether something is deemed reasonable or not.
If cash wasn't a problem, I'd buy a 49mm, just for curiosity's sake to see if it's more doable, but ah well it's not going to happen. Unless I can talk a company into giving me one to try, on the basis that it's crazy to sell both the 50.2mm and the 49mm crosses on the basis that they're both sold to fit the same uj, a glaring anomaly that exists on multiple supplier's product lists. Another anomaly is that one supplier lists the 49mm cross for the Guzzi Spada 900, a model that has never even existed
I did run a sanding post around the inside the yoke orifices to get them to bare steel, but I didn't have the balls to try and open them out to loosen the holes any. I imagine proper lining up on a lathe would be the safe bet for that, but unless you have your own, it wouldn't be worth the expense. I perhaps should give it a try by hand though, on the other half of the now useless uj and now just as useless new unharmed cross, which if successful would give me the option of buying another cross and making up a spare uj (unlikely to need in the foreseeable) or more likely, scrap it and used to make tools for locking the lay shaft or pinion shaft. I remember reading somewhere, that can be useful for some job or another.
Cheers, Guzzi Grump Mart
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