E: Engine Main bearing outer race width

[Phil Arundel]

I am rebuilding my 1952 Rapide and find that when fitting the crank into the crankcases that the cases will not close fully.
It appears the flywheels are rubbing against the outer race of the main bearings.
Is there a solution to this? Narrower outer race?
The outer race of both timing and drive side of the crancases protrudes by about 3 mm.

 

[stumpy lord]

I am rebuilding my 1952 Rapide and find that when fitting the crank into the crankcases that the cases will not close fully.
It appears the flywheels are rubbing against the outer race of the main bearings.
Is there a solution to this? Narrower outer race?
The outer race of both timing and drive side of the crancases protrudes by about 3 mm.

you have Answered your own question, fit the correct narrowed main bearings et92

 

[Pete Appleton]

Stumpy answered the question as I was looking it up...

From 'Richardson' - 'Vincent Motorcycles' - "NOTE ET92 is used with 5/8 in wide outer race."
The best Vincent book you will ever buy. The club shop is currently showing out of stock but you will soon find one.

The spares company stocks the narrowed bearings. Not particularly cheap but if you haven't got a surface grinder they will work. http://new.vincentspares.co.uk/index.html

 

[Bill Thomas]

Surely it's only Drive side that has narrow outer track ?.
If you have not had the bearings out before, They do sometimes "Walkout a bit " Because of a bad crank ? and could be pushed back, With heating the cases.
They should both be flush with the cases.
Also you can use the wide outer track bearing on the drive side ,With a modified Alloy spacer, Which is more narrow , Where the outer track touches it, And is sold by the Club Shop.
Good Luck, Bill.

 

[Simon Dinsdale]

I always use a full width roller bearing on the driveside. My thoughts are the extra fit of a full track must be good. You will need a modified spacer ET19/1 as Bill states which is available from the VOC spares or you can take your current ET19 and if you have access to a lathe turn a step on the outside to allow for the extra width of the bearing outer track. this should be 1/8" off the width of ET19 to a diameter that just allows the bearing outer sit in. Do not remove 1/8" from the full face of ET19. You should see the difference in the attached screen shot for VOC spares.

You have to use a reduced width bearing on the timing side though.
Simon

 

[Bill Thomas]

Thank's Simon, After all these years, It looks like I should get the book out again, The Wife says I have lost it !. Cheers Bill.

 

[greg brillus]

I've found that the full width 3/4 wide bearing makes no difference at all due to the larger outer chamfers on each edge, meaning that the actual grip width of the bearing is no better, if not worse than the stock 5/8 one as used in the timing side. The wider bearing is cheaper to buy, but not if it means buying another alloy distance spacer to match. Some of the new bearings have a very narrow ( in radial thickness) outer race, which I feel has less strength............... Which I do wonder about...............

 

[Bill Thomas]

The reason I got it wrong is because I have lipped outer tracks, on the inside, For my next build, So they can't walk out, I had forgot, I will have to have them ground down, I fitted some a long time ago to a friends Twin, But he got them ground. Cheers Bill.

 

[Phil Arundel]

Thank you all for your replies. Some really useful information here.
I purchased my Rapide as several boxes of bits with new crankcases and 3/4" wide outer race main bearings.
Having not rebuilt a Vincent before I am finding the challenge very interesting and enjoyable (although a bit expensive!). This forum is so helpful!
By the way, I have sourced a pair of 5/8" main bearings from Conway Motors at £50 each plus vat. Conway have also proved to be very helpful especially with technical advice .
Regards
Phil

 

[Phil Arundel]

Stumpy answered the question as I was looking it up...

From 'Richardson' - 'Vincent Motorcycles' - "NOTE ET92 is used with 5/8 in wide outer race."
The best Vincent book you will ever buy. The club shop is currently showing out of stock but you will soon find one.

The spares company stocks the narrowed bearings. Not particularly cheap but if you haven't got a surface grinder they will work. http://new.vincentspares.co.uk/index.html

View attachment 19396

Thanks Pete, I have the Richardson book so I need to read a little closer !!
Cheers,

Phil Arundel