The Spares Company
Club Shop/Regalia
Parent Website
Contact Officials
Machine Registrar
Club Secretary
Membership Secretaries
MPH Editor and Forum Administrator.
Section Newsletters
Technical Databases
Photos
Home
What's new
Latest activity
Forums
New posts
What's new
New posts
Latest activity
Information
Bike Modifications
Machine Data Services
Manufacturers Manuals
Spare Parts Listings
Technical Diagrams
Whitakerpedia (Vincent Wiki)
The Club
MPH Material Archive
Flogger's Corner
Obituaries
VOC Sections
Local Sections
Local Section Newsletters
Miscellaneous
Club Assets
Club History
Club Rules
Machine Data Services
Meeting Documents
Miscellaneous
Essential Reading
Magazine/Newspaper Articles/Letters
Adverts and Sales Brochures
The Mighty Garage Videos
Bikes For Sale (Spares Company)
Log in
Register
What's new
New posts
Menu
Log in
Register
Install the app
Install
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
drive-side bearings
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="timetraveller" data-source="post: 15965" data-attributes="member: 456"><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">I started riding Vincent twins in either 1957 or 8 so at that time the bikes were only a few years old and yet even at that stage it was known that the drive side main bearing could walk its way inwards until it fouled the crank pin nut. Once I started racing and sprinting a Vin, about 1960, I always tried to prevent this by grinding two small hollows on each side of the outer race of the drive side inner roller bearing and then fitting two large headed screws each side which fitted into holes sunk into the crank case. All this was done by hand as in those days I had no access (or the skills needed) to machine tools. The screws were punch locked to stop them rotating and the screw heads stopped the outer race rotating and working its way inwards. I never had a bearing come loose after doing this and all my engines both for others to race and for road use have had this mod done if the crank case was split. More recently my advice to those with access to the required machinery and skills is to grind two small flats into the edge of the outer race of the drive side inner main bearing and then place two flat pieces of steel into milled shallow slots which take the small metal plates and are held in place by punch locked countersunk screws. Even more recently it has become the fashion to use a full width outer race for the inner roller bearing, rather than the narrow special item originally used, and to thin down the outer edge of the spacer between the drive side bearings to allow this outer race to fit further in to the bearing housing. This gives a larger area to create the required friction between the outer race and the crank case casting. </span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">At about the same time, late fifties and early sixties, it became clear that the drive side main shaft was likely to come loose in the flywheel with high rev use and sheer if it was used in sidecar racing.. Stopping the rotation of the main shaft in the flywheel was undertaken by drilling a hole, half in the main shaft and half in the flywheel, and forcing in a quarter inch diameter roller bearing and then peening over the surface to keep the roller in place. Several of the sidecar racers went for oversized main shafts following Picador engine development. I believe that the Picador main shaft was 1.125” diameter, as opposed to the one inch standard and more recently several of the racers have even taken this up to 30 mm diameter and I think that Patrick Godet might use that size as standard.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Times New Roman'">It seems to me that the Robert Watson/Dan Smith modification is a particularly elegant way of reducing potential problems in this area. Given the fact that the large flange is on the outside of the bearing housing and that there is an outer locator machined as an integral part of the new flanges tube there can be no way that the bearings or their housing can work their way inwards towards the flywheels. Additionally the sandwiching of the inner taper roller bearing between the flywheel boss and the outer spacer means that the outer race of the inner bearing also cannot move inwards. Given the fact that this mod can either be used in new cases, as Roy the Mechanic is going to do, or to rescue already damaged cases means that it might at some stage be of use to any of us which is why I am happy to now see it in the public domain.</span></span></p></blockquote><p></p>
[QUOTE="timetraveller, post: 15965, member: 456"] [SIZE=3][FONT=Times New Roman]I started riding Vincent twins in either 1957 or 8 so at that time the bikes were only a few years old and yet even at that stage it was known that the drive side main bearing could walk its way inwards until it fouled the crank pin nut. Once I started racing and sprinting a Vin, about 1960, I always tried to prevent this by grinding two small hollows on each side of the outer race of the drive side inner roller bearing and then fitting two large headed screws each side which fitted into holes sunk into the crank case. All this was done by hand as in those days I had no access (or the skills needed) to machine tools. The screws were punch locked to stop them rotating and the screw heads stopped the outer race rotating and working its way inwards. I never had a bearing come loose after doing this and all my engines both for others to race and for road use have had this mod done if the crank case was split. More recently my advice to those with access to the required machinery and skills is to grind two small flats into the edge of the outer race of the drive side inner main bearing and then place two flat pieces of steel into milled shallow slots which take the small metal plates and are held in place by punch locked countersunk screws. Even more recently it has become the fashion to use a full width outer race for the inner roller bearing, rather than the narrow special item originally used, and to thin down the outer edge of the spacer between the drive side bearings to allow this outer race to fit further in to the bearing housing. This gives a larger area to create the required friction between the outer race and the crank case casting. [/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Times New Roman]At about the same time, late fifties and early sixties, it became clear that the drive side main shaft was likely to come loose in the flywheel with high rev use and sheer if it was used in sidecar racing.. Stopping the rotation of the main shaft in the flywheel was undertaken by drilling a hole, half in the main shaft and half in the flywheel, and forcing in a quarter inch diameter roller bearing and then peening over the surface to keep the roller in place. Several of the sidecar racers went for oversized main shafts following Picador engine development. I believe that the Picador main shaft was 1.125” diameter, as opposed to the one inch standard and more recently several of the racers have even taken this up to 30 mm diameter and I think that Patrick Godet might use that size as standard.[/FONT][/SIZE] [FONT=Times New Roman][SIZE=3] [/SIZE][/FONT] [SIZE=3][FONT=Times New Roman]It seems to me that the Robert Watson/Dan Smith modification is a particularly elegant way of reducing potential problems in this area. Given the fact that the large flange is on the outside of the bearing housing and that there is an outer locator machined as an integral part of the new flanges tube there can be no way that the bearings or their housing can work their way inwards towards the flywheels. Additionally the sandwiching of the inner taper roller bearing between the flywheel boss and the outer spacer means that the outer race of the inner bearing also cannot move inwards. Given the fact that this mod can either be used in new cases, as Roy the Mechanic is going to do, or to rescue already damaged cases means that it might at some stage be of use to any of us which is why I am happy to now see it in the public domain.[/FONT][/SIZE] [/QUOTE]
Insert quotes…
Verification
What was Mr Vincent's Christian Name?
Post reply
Home
Forums
Forums: Public Access
Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
drive-side bearings
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
Accept
Learn more…
Top