Some Vincent projects for John

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Re: Some Vincent projects for John

Postby John H » Thu Mar 21, 2019 6:16 am

Thanks Gordon, I think this engine tops the list for parts. Most parts are available from the Vincent Owners Club in UK.
Pistons and cams are available in the US. Some parts still must be made one at a time.
Here's a sample of quantities.
Crankshaft Assembly: 15 (+ 8 spacers and a large number of individual rollers)
Assembly for one valve: 12 pieces (valve, guide(s), springs, etc.)
Timing chest: 40 +
Clutch: approx. 100
Gearshift mechanism: 34
Amazingly they still hold some land speed records.
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Re: Some Vincent projects for John

Postby ATinkerer » Thu Mar 21, 2019 9:30 am

Good engineering continues to be good engineering.
Materials improve and designers learn things that allow different designs, but if it was well done originally, it continues to be a good design.

Cosworth DFV, Ducati gear drive demo systems also are great great mechanical designs that still work well.

Gordon
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Re: Some Vincent projects for John

Postby John H » Fri Apr 05, 2019 7:49 pm

Finally back to something besides yard work and clearing downed trees and limbs.
The heads are heated to 300º+ while the valve guides are left in the freezer overnight.
The brass lower guide is on the driver. A modified upper guide will get pushed in place just
before the lower guide is driven in place. A small valve seal is inserted in the retaining collar then
it is screwed in place and punch locked.
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Next will be reaming the lower guide, piloting it off a special upper guide so when all is done,
the bores of upper and lower guides are perfectly aligned with each other.
Then it will be time to grind the valve seat concentric with the new guides.
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Re: Some Vincent projects for John

Postby John H » Sat Apr 13, 2019 9:29 pm

The gearbox is buttoned up with new bearings, bushings and two new shafts damaged by rust. Several mods have been done to improve the gear selection. The gears are heavy and tend to over travel when shifting. Some parts have been lightened as well as some centralizing springs have been doubled up. Next is tuning up the gear selector mechanism.
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Re: Some Vincent projects for John

Postby John H » Tue Apr 23, 2019 9:34 pm

There's around 90 pieces in a Vin clutch. They either work swell or horrible, no in between. When working right, it will operate with one finger. The single disk is operated by the clutch lever and when engaged forces the shoes against the drum. The higher the rpm, the shoe is centrifically forced against the drum harder. On decileration the other end of the shoe is forced against the drum to help slow the bike down. I've replaced the material on the shoes and resurfaced the disk as well as the drum. New bronze bushings have been installed.
The fine tuning comes by shimming the end float of the shoe carrier as well as the spring compression disk. With the springs set, the compression is 330#. This causes excessive wear to the clutch rod. This is the time to add a dab of Stellite hard facing to the clutch actuation arm and also temper the ends of the clutch rod.
That's it for now.
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Re: Some Vincent projects for John

Postby ATinkerer » Tue Apr 23, 2019 10:00 pm

Not sure that Vincent design deserves all the credit.
I'm seeing a lot of detail work that the assembling mechanic has to do to make sure it came together "right".

You should put your "master mechanic mark" somewhere to sign the work or art you are producing.

Gordon
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Re: Some Vincent projects for John

Postby John H » Fri Apr 26, 2019 6:45 am

Well, after two days of frustration trying to get the pressure plate to lift off equally unsuccessfully.
As it turns out, the bearing surface of the C20 retaining nut is not concentric with the main shaft causing
the clutch plate carrier to wobble. Hopefully a new retaining nut will be accurately machined.
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Re: Some Vincent projects for John

Postby John H » Sun Apr 28, 2019 3:26 pm

My last post can be better understood with a drawing of the clutch. The revolving clutch parts spin on the C20 retaining nut.
If the nut isn't machined true, this causes the clutch parts to wobble and that makes it difficult to engage the gears.
MO02.gif
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Re: Some Vincent projects for John

Postby ATinkerer » Sun Apr 28, 2019 4:57 pm

Looks like just about everything depends on that retaining nut/sleeve to maintain concentricity of the assembly with the transmission input shaft. Can understand why that would make it hard to shift. Made the clutch grab/release also?

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Re: Some Vincent projects for John

Postby John H » Sun Apr 28, 2019 8:02 pm

The wobble causes grab/chatter and never fully releases and that makes the clunk when trying to get 1st gear.
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