2mm vs 4mm clutch spline

[amamet]

when did guzzi switch from the 2mm shallow spline to the 4mm?
thx
allen

[Dave Swanson]

The deep spline (4mm) clutch design holds up much better over time than the 2mm.  The 2mm has been known to leave riders stranded in the old days.  Whenever you have the transmission out of the frame it is always worthwhile to perform the upgrade to 4mm. 

[amamet]

Yup, I know that.  Just wanted to know when guzzi switched from 2mm shallow to 4mm. If there is a specific model and year they started  with  the 4mm

[Frenchfrog]

According to guzziology it happened in april 89 from vt 032542 cali 3, vt 024596 mille and le mans vv 016375.I bet there was some old stock kicking around though.

[brider]

I can't believe the original 2mm spline depth was the result of an original design, and lasted so long in production. 2mm is just under .080", just waaaaay too small for such a small contact area, I wonder how it was determined.

[Frenchfrog]

Worked well enough for nigh on 25 years...one of the main  problems seemed to be the hardness or lack of on the gearbox hub.

[Antietam Classic Cycle]

Worked well enough for nigh on 25 years...one of the main  problems seemed to be the hardness or lack of on the gearbox hub.

Exactly. It wasn't really a design issue in my opinion, but rather a manufacturing (heat-treating) issue.

[brider]

Now I remember, I had 2 Eldos that wore the hub excessively. So what drove the move to 4mm? Higher horsepower?

[moto-uno]

  What ever the reason I'm glad they finally did it ! After 4 decades and numerous clutches (and hubs) my Le Mans 2 has a trouble free
4mm spline  . No reason on earth to stick with the old 2mm spline . Peter

[cliffrod]

Bring me up to speed….  Are the 2mm and 4mm designs both v-spline or is the older 2mm a square-spline and 4mm a V-spline?  I upgraded the badly worn original square spline input hub on my V7 Sport to a v-spline input hub & clutch in early 95.  Big improvement and it’s been great ever since.

But if that’s probably a 2mm v-spline and a 4mm v-spline is even better, I’ll probably go with a 4mm version on subsequent projects.

[Antietam Classic Cycle]

Bring me up to speed….  Are the 2mm and 4mm designs both v-spline or is the older 2mm a square-spline and 4mm a V-spline?  I upgraded the badly worn original square spline input hub on my V7 Sport to a v-spline input hub & clutch in early 95.  Big improvement and it’s been great ever since.

But if that’s probably a 2mm v-spline and a 4mm v-spline is even better, I’ll probably go with a 4mm version on subsequent projects.

2 mm is square spline, 4 mm v-spline.

111,000+ miles on the original clutch on my '69 Ambassador and it still works great... 

[cliffrod]

2 mm is square spline, 4 mm v-spline.

111,000+ miles on the original clutch on my '69 Ambassador and it still works great... 

Thanks, Charlie.  My V7 Sport was “well-enjoyed” by previous owners and the input hub was really buggered when I got the bike.  If the clutch & input hub on my V700 looks ok when I take it apart, I’ll probably leave it as is.

[EldoEVert]

I think that one of the issues with the 2mm spline wear was due to miss-alignement between the engine and the gearbox on some bikes. I have a 73 Eldorado that was bought new, in the crate, by my dad. I purchased it from him in 08/75. It has the original gearbox. It always seemed to have premature wear on the clutch hub. Back around 89 I upgraded it to the 4mm clutch and hub. About 3,000 miles later the rivets sheared and the facing came of the plates. Moto Guzzi replaced the parts free of charge (even though I installed it myself). A few thousand miles later, the same thing happened.  The rivet holes were elongated. I then installed a good used 2mm clutch. The 4mm unit has much less play between the hub and plates than the 2mm so alignment is much more critical. The bike now gets very little use so the 2mm clutch should last a long time.

[Antietam Classic Cycle]

I think that one of the issues with the 2mm spline wear was due to miss-alignement between the engine and the gearbox on some bikes. I have a 73 Eldorado that was bought new, in the crate, by my dad. I purchased it from him in 08/75. It has the original gearbox. It always seemed to have premature wear on the clutch hub. Back around 89 I upgraded it to the 4mm clutch and hub. About 3,000 miles later the rivets sheared and the facing came of the plates. Moto Guzzi replaced the parts free of charge (even though I installed it myself). A few thousand miles later, the same thing happened.  The rivet holes were elongated. I then installed a good used 2mm clutch. The 4mm unit has much less play between the hub and plates than the 2mm so alignment is much more critical. The bike now gets very little use so the 2mm clutch should last a long time.

Misalignment is a possibility and it's best to check to see if that's the cause if having clutch issues. It doesn't take much misalignment (less than one millimeter will do it) to cause issues. I've also found one transmission that was cocked slightly at an angle in relation to the engine. Really bizarre wear pattern on the clutch on that one.

[EldoEVert]

Misalignment is a possibility and it's best to check to see if that's the cause if having clutch issues. It doesn't take much misalignment (less than one millimeter will do it) to cause issues. I've also found one transmission that was cocked slightly at an angle in relation to the engine. Really bizarre wear pattern on the clutch on that one.

Charlie,
  At the time I was getting ready for a trip so I installed the 2mm unit. Then I got a later 1100 and didn't put many miles on the Elso hence the clutch has been holding up ok. This summer I'm giving that bike to my son. I'm not sure what all we're gonna get into. The first thing I want to do is upgrade the brakes to a better type of lining and we'll probably be contacting you about that.

Dave W.