Transmission - 5 speed main shaft

Moto Guzzi V700, V7 Special, Ambassador, 850 GT, 850 GT California, Eldorado, and 850 California Police models

Created: 2022 December 14

Updated: 2023 January 09

Thanks to Dan Eberhardt for sending me this discussion between he and Charlie Mullendore of Antietam Classic Cycle. In their own words and photos:

Hi Charlie,

Was wondering what your thoughts are on relocating the 2nd/1st gear cluster on the main shaft on a 5 speed. I have had several of these transmissions apart and inevitability find that the 2nd/1st gear cluster has slid to the rear and in most cases enough so that I had to first move it forward to be able to move the spring loaded pin to remove 5th gear. I always remove the cluster completely, clean every thing up ad re-install it tight to the 4th/3rd cluster with some close tolerance Loctite product like the Green 638. In doing so I've always noticed that the 18.35 mm to 18.5 mm tolerance could not be adhered to. I always ended up somewhat bigger than 18.5 mm. Since I am currently going through another transmission I am thinking about not completely closing the gap between the two gear clusters and adhering to the 18.35 mm to 18.5 mm dimension. By doing so 5th gear won't have as much room to wonder about on it's needle bearing which I think might be a good thing. Any thoughts you might have regarding this matter is greatly appreciated. Sorry for the sloppy notes I made on the screen shot but at least it should help you understand what I'm referring to.

Until later,

Dan Eberhardt

Hi Dan,

I currently have four 5 spds. apart and another two waiting for me to do. To tell you the truth, I never paid much attention to that 18.35 mm to 18.5 mm dimension. In long conversations years ago with Charley Cole we discussed shaft separation and the issues it causes. He always stressed that there should be zero gap.

I'm not sure which causes which, whether shaft separation causes divots to be worn into the 5th gear inner bearing race, or if the bearing race wears allowing separation. I'm guessing the former. I have a bunch of 5th gear inner bearing races that look like this:

Really not reusable at that point. I'm looking for a few of them in fact.

4 spds. are so much more simple...

Charlie

Thanks for getting back to me Charlie,

Upon further investigation I have come to the conclusion that the 1st/2nd gear cluster movement and the 5th gear inner bearing race wear are mutually exclusive! Since the inner bearing race has a depth of 18.25 mm and the space it resides in is greater than 18.35 mm (usually 18.5 mm ++) and the gear is spirally cut every time 5th gear is engaged and power is applied , the inner race is driven a distance of 0.1 mm to 0.25 mm ++ causing the rearward facing flange to Bang up against the front of the shaft splines and overtime creates the indentations we always seem to find on the face of the inner race. If I recall correctly I have taken at least one of these transmissions apart where there was no 1st/2nd cluster separation but there was still the wear occurring on the inner race. It should be noted that the inner race does not spin on the shaft but rather with the shaft providing the spring loaded pin is in place. It is my understanding that this spring and pin didn't make it in to some of the earliest production 5 speeds and that there was a recall on some Eldos and 850 GT's.

I think the gear cluster movement is more of a creep rearward over time also due to the way the gears are cut and by the time the cluster moves back far enough to lessen the 18.35mm to the 18.25 mm depth of the race then the race starts getting trapped into the wear indentations which have previously occurred and hence needing to move the cluster forward just to be able to remove the inner race!

One could install the gear cluster maintaining the 18.35 mm distance and maybe even an 18.35 mm - distance as long as you could still get the spring and pin in properly and this would probably help reduce the inner race wear but in so doing you would be perhaps creating issues in the 3rd to 2nd shifting etc., so I am just going to continue to close the cluster gap and consider the inner bearing race wear a normal occurance based on the design.

I know now that I will always be looking for that elusive main shaft that has no gear cluster separation but still has the 5th gear inner bearing race flange wear indentations. I hope you'll keep an eye out for 1 or two yourself.

When you have some time let me know what you think regarding the above. Your thoughts are always greatly appreciated.

Until later,

Dan

Hi Greg,

As promised here is a picture of a 5th gear inner race which has been repaired by laser welding along with a picture showing the typical damage these races incur.