BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
  JWood Auction  
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Photo posting tutorial

Member Spotlight
Roger Gulledge
Roger Gulledge
Oahu Hawaii USA
Posts: 255
Joined: January 2012
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
221 registered members (57nortonmodel77), 1,770 guests, and 551 spiders.
Key: Admin, Global Mod, Mod
Newest Members
XTINCT, Bruce Roberts, Brian Ellery, Jon Andrews, Berni Ernst
9957 Registered Users
Top Posters(30 Days)
btour 190
koan58 100
Stuart 86
NickL 71
Popular Topics(Views)
437,702 mail-order LSR
Forum Statistics
Forums33
Topics65,282
Posts632,294
Members9,957
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate This Thread
#3765 - 08/01/05 12:14 pm B33 sprocket ratios?  
Joined: Jun 2002
Posts: 907
Peter Quick Online content
Sponsor
Peter Quick  Online Content

Sponsor

Joined: Jun 2002
Posts: 907
Jaffrey, NH, USA
During my search to hunt down a big oil leak onto my rear tire (1960 BSA B33) I found my gear box sprocket to be quite worn (previous dummy replaced the chain and rear sprocket but not the front one!). As I am preparing to order a new one I have the following sprocket combination: Engine 20 tooth, Gear box 16 tooth, Rear wheel 42 tooth. The owners manual says the stock set up for a B33 is: Engine 19 tooth, Gear box 19 tooth, Rear wheel 42 tooth. Both the present engine (20 tooth) and rear sprocket (42 tooth) are in fine condition. Is a 20 tooth engine - 16 tooth gear the same as a 19 tooth engine and a 19 tooth gear combination? Is there some sort of formula what one tooth added to the engine sprocket would equal in the subtraction of gear box sprocket teeth (to keep things the same)? My intuition tells me that I should at least go with a 17 tooth replacement (18 or 19?)on the gear box sprocket. Certainly don't want the bike to be geared to go slower than originally designed.

Lastly I know there has to be a special gear box sprocket tool to take off the round nut holding on the sprocket. Does anyone know a part number for one of those (since alot of the parts suppliers are dummies when I ask them these questions without a part number)or where I can get one? Hope someone out there can help me! Peter


check out: www.bsaunitsingles.com
2500 BSA part numbers with inventory in stock just for the unit singles!
Support Your #1 BritBike Forum!
Membership Type! Free
Member
Premium
Member
Premium Life
Member
Vendor
Member
Site
Sponsor
Recognition No Premium Member Premium Life member (5 years) Vendor Member Site Sponsor Membership
Post commercial threads No No No Yes Yes
Custom title No Yes Yes Yes Yes
Upload avatar & photos No Yes Yes Yes Yes
Link avatar & photos Yes Yes Yes Yes Yes
Private Message Storage: 10 100 100 100 100
Length of signatures 255 600 600 600 600
Removes this very advert island between post 1&2 No Yes Yes Yes Yes
Price Free $12.90/year $105.00 No End
$55.00/5 years
$210.00/year
($17.50/month)
Email
Click on button >>
  Premium Member Premium Life member Vendor Member Site Sponsor Membership
#3766 - 08/01/05 3:41 pm Re: B33 sprocket ratios?  
Joined: Oct 2003
Posts: 11,108
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member

Joined: Oct 2003
Posts: 11,108
North Georgia, USA
Our shop has the official BSA gear selector chart on the wall if you need to come look at it! I mean, I thought every shop had one of these. :rolleyes:


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA

"Shop Boy" at Rodi British Bikes
#3767 - 08/01/05 3:48 pm Re: B33 sprocket ratios?  
Joined: Jun 2002
Posts: 907
Peter Quick Online content
Sponsor
Peter Quick  Online Content

Sponsor

Joined: Jun 2002
Posts: 907
Jaffrey, NH, USA
Why I think I'll just hop on the B33 and drive down to look at that chart. wink But wait I need to get that pesky sprocket problem solved first. Would a 20 tooth engine sprocket and a 19 tooth gear box sprocket make much of a difference than the stock 19 / 19 combo? About the only other size I can find for the gearbox sprocket (in my limited searches of the web) is a 17 tooth one. :rolleyes: Peter


check out: www.bsaunitsingles.com
2500 BSA part numbers with inventory in stock just for the unit singles!
#3768 - 08/01/05 5:41 pm Re: B33 sprocket ratios?  
Joined: Aug 2001
Posts: 1,105
J in KC Offline
BritBike Forum member
J in KC  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,105
Kansas City, USA
Here you go Peter.


#3769 - 08/01/05 6:51 pm Re: B33 sprocket ratios?  
Joined: Aug 2001
Posts: 29
Josef2 Offline
BritBike Forum member
Josef2  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 29
Germany
hi Peter,

I try to make the calculation easy to handle for you. Best thing is to compare motorcycle speed.


the sprockets of the usual B 33 are:
Engine 19
Clutch 43
Gear 19
Rear 42

The overall ratio can be calculated by dividing the sprockets:

i= Rear/Gear * Clutch/Engine = 42/19 * 43/19 = 5,003

then you need the perimeter of your tyre, it should be a 3,50 x 19
p = (19 + 2*3,5)* 3,14 * 25,4 / 1000 = 2,073 m

Now you can calculate the speed of your bike, e.g for 5000 rpm

Speed ( km/h) = rpm/i * p * 3,6/60 = 5000/5,003 * 2,073 * 3,6/60 = 124,30 km/h.
For miles per hour you have to divide it by 1,609 = 124,30/1,609 = 77,25 mph.

Now to your special sprockets:

i = 42/16*42/20 = 5,644 thats too short, the bike runs at 5000 rpm only 110 km/h

You should change the gear sprocket to 18, then
i = 42/18*42/20 = 5,017, almost original, the speed at 5000 rpm is now 124,0 km/h.

If you want an excel sheet to calculate, send me a pn.

Josef

#3770 - 08/01/05 7:07 pm Re: B33 sprocket ratios?  
Joined: Jun 2002
Posts: 907
Peter Quick Online content
Sponsor
Peter Quick  Online Content

Sponsor

Joined: Jun 2002
Posts: 907
Jaffrey, NH, USA
Wow, I'm saving this info. bigt Now if I could only find a special wrench that grabs the round gear sprocket nut. I guess I'll just have to smack it with a punch to loosen it frown Ick! Peter


check out: www.bsaunitsingles.com
2500 BSA part numbers with inventory in stock just for the unit singles!
#3771 - 08/01/05 9:49 pm Re: B33 sprocket ratios?  
Joined: Aug 2001
Posts: 1,851
dave - NV Online content
BritBike Forum member
dave - NV  Online Content
BritBike Forum member

Joined: Aug 2001
Posts: 1,851
Elko, Nevada USA
Peter ... There is a 'hook spanner' that fits the sleeve gear/sprocket nut you speak of. However nearly everyone uses a 'soft' brass drift and tap it on/off with a hammer. Don't forget to bend over the tab washer when reinstalling the nut. I dislike using lock tite on this nut which may make it difficult to remove the next time. And as is so typical, if the notches in the nut have been punched/hammered on before and distorted a spanner won't work very well.
Reinstall the rear chain to allow you to hold the sprocket from turning when doing this. Generally just the inertia of the rear wheel will hold things in place, but you may need to reconnect the pedal and hold the rear brake on.

Now is also the time to replace the largish countershaft sprocket seal that's secured by the snap ring behind the sprocket. A hint here, always smear a good coat of sealant around the flat face of the new seal that bears against the bearing race before installing the seal. It's a funky setup. Then of course grease the seal lip with grease when assembling.

The best fix for this pesky seal leaking is to replace the sleeve gear bearing with a 'sealed one side' bearing as I and many (most?) others have done. The complete tranny will need to be removed to allow you to heat the case to remove/install the bearing. But, reinstall the seal under the snap ring for proper location of the bearing.

Now I'd betcha a good part of your oil leak problem is what I and most all other pre unit BSA guys deal with, the 'Official BSA chain oiler'! There is no seal on the mainshaft where it passes through the sleeve gear. As the shaft and sleeve
gear rotate at different speeds except in 4th, oil seeps out between the two.
This is especially bad when the bushings in the sleeve gear are worn, oil continuously seeps out past the main shaft when in neutral or any gear other than 4th. The oil drools onto the sprocket and spews onto the rear wheel.
Overfilling the tranny oil or using too light a grade oil in the tranny will cause even more leakage.
Don't pay any attention to the level plug in the tranny, but with the bike level and not on the side stand, only add enough oil to cover the end of the layshaft as viewed through the oval filler hole. I use 90 wt gear oil but I'm sure 50 wt
engine oil would be OK as was OEM prescribed. Be paranoid, check your oil level often!

Too low oil level is the reason there are so many fragged out bushing layshafts in bikes like your B33, vs the "T", GS tranny setup with Torrington needle bearings on the layshaft which are more forgivable of low oil.

I would suggest you find a 19T countershaft sprocket for riding the bike on the road. It should work just fine with a 19T or 20T on the engine.
I too have had problems locating 19T sprockets for the narrow 520 chain as I/we use to allow fitting a sealed DID "X ring", (good stuff!) chain on the road GS and for the GS racer using narrow chain.
I've had a machinist friend narrow good/new 530 sprockets a couple of times, but....

One of my problems locating narrow sprockets has been simply I don't have a parts book listing them by part number. Can anyone help me with pns for all the 520 sizes made? They must be listed in the B33 parts book... Thanks.
dave - NV


dave - NV
#3772 - 08/01/05 10:30 pm Re: B33 sprocket ratios?  
Joined: Aug 2001
Posts: 1,105
J in KC Offline
BritBike Forum member
J in KC  Offline
BritBike Forum member

Joined: Aug 2001
Posts: 1,105
Kansas City, USA
Dave, might this help?


#3773 - 08/02/05 3:49 am Re: B33 sprocket ratios?  
Joined: Aug 2001
Posts: 1,851
dave - NV Online content
BritBike Forum member
dave - NV  Online Content
BritBike Forum member

Joined: Aug 2001
Posts: 1,851
Elko, Nevada USA
J in KC ... Thanks a bunch for the part number listing. "Ask and ye shall receive". I like that ...
dave - NV


dave - NV

Moderated by  Allan Gill, Jon W. Whitley 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.151s Queries: 14 (0.009s) Memory: 0.8578 MB (Peak: 1.0383 MB) Zlib disabled. Server Time: 2017-11-22 05:40:07 UTC