Post by 90GTVert on May 24, 2013 10:59:34 GMT -5
We know that long case and short case Minarelli/Jog/1E40QMB Chinese CVT covers will bolt up in place of each other. The exception being some Adly engines where the long case is more of a stretched out short case. That is, it uses a short case style gearbox, but has more length between the front and rear pulleys (variator and clutch) to stretch it out and make it a long case to fit larger wheels. Those need a longer CVT cover and a longer drive belt. Genuine Yamaha covers don't bolt up either, other than perhaps some old Jogs. The Zumas and Aerox and others use a different setup than Chinese clones.
Until recently, myself and others thought that short and standard long case Chinese clone CVT covers were totally interchangeable. Here's what challenged that idea...
Well, we had a longcase cover on my cousins FM Linhia. It started making gear noise and leaking oil from the output shaft. He pulled the cover off so we could take the trans cover off and look. I didnt even notice until he pull the drive gear cover off that the drive shaft and bearing had been pushed over, out of the seat about 2mm or more. Bent the retainer washer and all. I grabbed the CVT cover and looked at the driveshaft bearing in it and it was fine but the cover itself had been worn in and chewed up from the driveshaft itself digging in.
I grabbed the FM stock cover and sure enough, its deeper where the driveshaft rides. Im sure this is do to the final drive being "inside" so to speak. We replaced the cover bearing in the FM cover, as thats all it really needed to begin with. We pressed the bearing back in the seat. Lined everything back up and assembled. Now his scoot still needs an output seal but runs better yet. I mean the engine runs the same, but it sure is getting more power to the ground. I was kinda waiting for him to get to speed. Now, not so much
Im sure if you tried the FM cover on a longcase the drveshaft wouldnt go into, or all the way into the bearing.
I took measurements of 2 different vented short case covers and 2 Vento stamped long case covers.
I used a steel ruler across the centerline of the bearing in the cover, then subtracted the thickness of the ruler, when I did the A & B measurements. C & D I just measured from the lip of the cover.
A = Depth bearing race
B = Depth of CVT cover behind bearing center
C = Depth to edge of the cover face, top side of clutch
D = Depth to edge of the cover face, bottom side of clutch
Vento long case covers were :
A) 78.75mm
B) 91.5mm
C) 63.5mm
D) 66.5mm
Vented ATV short case covers were :
A)83mm
B)95.75mm
C)70.25mm
D)68.5mm
I did avg the C&D measurements in each set, but they were really close. I think maybe sanding or casting differences with the angles would cause the very minor discrepancies in those. A&B bearing depths were basically right on.
From what has been found, it seems that you are best off to stick with long case covers for long cases and short case covers for short cases. I've used short case covers on my long case engines plenty of times. I have noticed that the wear marks on the shaft are more shallow, but I never really put much thought into it before. I'm not sure if the depth would make a lot of difference on the longevity of bearings as long as it's supported in the cover. As 2strokd discovered, it's not a good idea to put a shallow cover on a short case. Use caution any time you are swapping covers around.
Until recently, myself and others thought that short and standard long case Chinese clone CVT covers were totally interchangeable. Here's what challenged that idea...
Well, we had a longcase cover on my cousins FM Linhia. It started making gear noise and leaking oil from the output shaft. He pulled the cover off so we could take the trans cover off and look. I didnt even notice until he pull the drive gear cover off that the drive shaft and bearing had been pushed over, out of the seat about 2mm or more. Bent the retainer washer and all. I grabbed the CVT cover and looked at the driveshaft bearing in it and it was fine but the cover itself had been worn in and chewed up from the driveshaft itself digging in.
I grabbed the FM stock cover and sure enough, its deeper where the driveshaft rides. Im sure this is do to the final drive being "inside" so to speak. We replaced the cover bearing in the FM cover, as thats all it really needed to begin with. We pressed the bearing back in the seat. Lined everything back up and assembled. Now his scoot still needs an output seal but runs better yet. I mean the engine runs the same, but it sure is getting more power to the ground. I was kinda waiting for him to get to speed. Now, not so much
Im sure if you tried the FM cover on a longcase the drveshaft wouldnt go into, or all the way into the bearing.
I took measurements of 2 different vented short case covers and 2 Vento stamped long case covers.
I used a steel ruler across the centerline of the bearing in the cover, then subtracted the thickness of the ruler, when I did the A & B measurements. C & D I just measured from the lip of the cover.
A = Depth bearing race
B = Depth of CVT cover behind bearing center
C = Depth to edge of the cover face, top side of clutch
D = Depth to edge of the cover face, bottom side of clutch
Vento long case covers were :
A) 78.75mm
B) 91.5mm
C) 63.5mm
D) 66.5mm
Vented ATV short case covers were :
A)83mm
B)95.75mm
C)70.25mm
D)68.5mm
I did avg the C&D measurements in each set, but they were really close. I think maybe sanding or casting differences with the angles would cause the very minor discrepancies in those. A&B bearing depths were basically right on.
From what has been found, it seems that you are best off to stick with long case covers for long cases and short case covers for short cases. I've used short case covers on my long case engines plenty of times. I have noticed that the wear marks on the shaft are more shallow, but I never really put much thought into it before. I'm not sure if the depth would make a lot of difference on the longevity of bearings as long as it's supported in the cover. As 2strokd discovered, it's not a good idea to put a shallow cover on a short case. Use caution any time you are swapping covers around.