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1959 VBA / VBC motor
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Posts: 6
Location: Richmond, VA
 
Member
1959 VBA / VBC motor
Joined: UTC
Posts: 6
Location: Richmond, VA
UTC quote
I have been having trouble getting my clutch to work. No matter how tight I made the cable;, it would not actuate the clutch. When I bought the parts for a rebuild, the brass bushing I ordered was too big. I realized, with some research, that the clutch I was using was the wrong one. I ordered a complete clutch unit and compared it to the old one; it was about 4mm taller. I installed it, adjusted the cable and now the kickstarter is not working. It has a mushy feel to it and the flywheel makes a quarter turn or so then stops. I checked cable tightness and it is fine. If I disconnect the cable altogether, it has the same feel.

Thinking I had made an assembly error, I removed the clutch. Everything looked fine, so I put the old one back on and the kickstarter had it crisp rachety feel back.

I am using a super engine in a VBA. The clutch that came on the super engine is identical to my VBA clutch. The new clutch seems to be an exact fit. Cable adjustment and lever feel are super easy and nice.

Any ideas?
@ginch avatar
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Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
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Location: Victoria, Australia
 
Veni, Vidi, Posti
@ginch avatar
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8676
Location: Victoria, Australia
UTC quote
When the kickstart has that feel, it means the clutch is partially on (plates very slightly separated) and what you are feeling is the friction of the plates.

If you want the 4mm taller clutch to work then you need to decrease other stuff... the brass bush, or the washer/spacer under the clutch. Also make sure there is free play at the lever on the clutch housing (brass bush not touching pressure plate).
If it's not possible to do that then consider swapping the new parts into your best basket.
OP
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Member
1959 VBA / VBC motor
Joined: UTC
Posts: 6
Location: Richmond, VA
 
Member
1959 VBA / VBC motor
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Location: Richmond, VA
UTC quote
Thanks, Ginch for your reply. It does feel slightly engaged. I can put a smaller spacer washer in. I am using the gear for the auto-lube system, which is not in use. There shouldn't be a space issue though, since this is the clutch designed for the scooter. When cabling up, I used an allen wrench spacer at the lever, and there is a gap between the press plunger and pressure plate. I set the cable so that you have an 1/8th of an inch or so lever pull before you feel the plunger hit the plate.

I bought this clutch new from Maskes, It came well oiled. Should I take it apart and soak the corks. Is it just sticky?
@rob_hodge avatar
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Molto Verboso
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Posts: 1924
Location: Seattle
 
Molto Verboso
@rob_hodge avatar
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Location: Seattle
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fit on clutches can be confusing; for the sprint/super era bikes there are two different 'correct' clutches, and they are not interchangeable without making other changes. and there are a few other similar clutches that are different, but look like they aren't.

here's the history of those changes.

very early largefrmames (VNA/VBA) had a few unique clutches have the same basket, springs, but the backplate, gear cog and in some cases the plates are different. these are based on earlier handlebar bike clutches. the brass bushing is smaller in diamiter, the corks and steels have the engaugement bits swapped, and on some versions the gear cog does not have a riveted on backplate. there are a few wierd clutches of this era, and a few that are the same except for clutch thickness.

the main thing is, these clutches are thinner than later clutches, and need a thin thrust washer to work in their inteneded case.

Vespa standardized the clutch in the VBB/VNB era. this clutch is thicker than the earlier ones, and was used with slight changes to the drive gear and backpalte right up until the 80's.

however, these changes didn't happen all at once, leading to a few variations, some that overlap for many years.

the big change is the thickness, while this clutch started out as a thick clutch with a thin thrust washer, a thinner version of this clutch was developed and used when oil injection was added, to compensate for the thicker oil drive gear that replaced the thin thrust washer. for a decade or so, these were used simultaneously, with oil injected models getting a thinner clutch / thicker drive gear and non oil injected models getting a thicker clutch / thinner washer . Late in production, a thicker thrust washer was used, and all models got the thinner oil injected clutch.

because of this, the most common thickness clutch is the late oil injection style thickness.

to confuse things, this thinner oil injected style clutch is thicker than the VNA/VBA style clutch, and while the VBA/VNA clutches can be made to work ( sort of) in a late engine, the reverse is not true.

as you can see, it's more complicated than "this clutch fits this model"
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Veni, Vidi, Posti
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Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
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Location: Tega Cay, SC
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And I always thought these were simple little machines.
@ginch avatar
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Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8676
Location: Victoria, Australia
 
Veni, Vidi, Posti
@ginch avatar
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8676
Location: Victoria, Australia
UTC quote
Rob, great info as always. When are you going to write the book?
Trevor Davis wrote:
Thanks, Ginch for your reply. It does feel slightly engaged. I can put a smaller spacer washer in. I am using the gear for the auto-lube system, which is not in use. There shouldn't be a space issue though, since this is the clutch designed for the scooter. When cabling up, I used an allen wrench spacer at the lever, and there is a gap between the press plunger and pressure plate. I set the cable so that you have an 1/8th of an inch or so lever pull before you feel the plunger hit the plate.

I bought this clutch new from Maskes, It came well oiled. Should I take it apart and soak the corks. Is it just sticky?
Nah just change the spacer underneath for a thin one.
Tierney wrote:
And I always thought these were simple little machines.
You haven't believed that since about a month after you bought your first Tierney! Razz emoticon
@blank avatar
UTC

Hooked
65 VNC Super, Series 1 50n (136), 50s, PX150, Douglas G, Ciao, Si, PX200E, PX vespacross project, Douglas Rod
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Hooked
@blank avatar
65 VNC Super, Series 1 50n (136), 50s, PX150, Douglas G, Ciao, Si, PX200E, PX vespacross project, Douglas Rod
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Location: Victoria
UTC quote
The Best of clutch differences I've seen anywhere Rob. Really useful to know!
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Veni, Vidi, Posti
Joined: UTC
Posts: 6860
Location: Tega Cay, SC
 
Veni, Vidi, Posti
Joined: UTC
Posts: 6860
Location: Tega Cay, SC
UTC quote
Tierney wrote:
And I always thought these were simple little machines.
You haven't believed that since about a month after you bought your first Tierney! Razz emoticon[/quote]

You're right about that!
OP
UTC

Member
1959 VBA / VBC motor
Joined: UTC
Posts: 6
Location: Richmond, VA
 
Member
1959 VBA / VBC motor
Joined: UTC
Posts: 6
Location: Richmond, VA
UTC quote
Thanks, Rob for the history; it really helps a lot. I believe I have the right one, but if I don't, would changing the shoulder washer to the non-injected spec do the trick.The difference has to be just a millimeter or two, Right?
OP
UTC

Member
1959 VBA / VBC motor
Joined: UTC
Posts: 6
Location: Richmond, VA
 
Member
1959 VBA / VBC motor
Joined: UTC
Posts: 6
Location: Richmond, VA
UTC quote
problem solved
I took apart the clutch and the order of the cork and metal plates was wrong. works like a charm.
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