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Pre unit gearbox serial numbers #112740
03/24/07 7:46 pm
03/24/07 7:46 pm
Joined: Mar 2007
Posts: 215
Southern California
Geoff Patrick Offline OP
Life member
Geoff Patrick  Offline OP
Life member
Joined: Mar 2007
Posts: 215
Southern California
Is there a guide that identifies the year and model based on gearbox serial number?

thanks!

gp


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Re: Pre unit gearbox serial numbers #112741
03/25/07 5:09 am
03/25/07 5:09 am
Joined: Aug 2001
Posts: 6,923
Vermont
Jon W. Whitley Offline

BritBike Forum member
Jon W. Whitley  Offline

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Joined: Aug 2001
Posts: 6,923
Vermont
Have never seen a guide. You can usually determine the year of manufacture by two cast numbers on the case and innner gearbox cover.

When I obtained the factory info on my 1957 6T, the transmision numbers were included in the report and match what I have on the bike.

beerchug


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project

Re: Pre unit gearbox serial numbers #112742
03/26/07 7:15 pm
03/26/07 7:15 pm
Joined: Mar 2007
Posts: 215
Southern California
Geoff Patrick Offline OP
Life member
Geoff Patrick  Offline OP
Life member
Joined: Mar 2007
Posts: 215
Southern California
Thanks! The cast dates are a help.

gp


Watch "American Triumph" at www.americantriumph.tv
Re: Pre unit gearbox serial numbers #112743
03/29/07 2:12 am
03/29/07 2:12 am
Joined: Aug 2001
Posts: 6,923
Vermont
Jon W. Whitley Offline

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Jon W. Whitley  Offline

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Joined: Aug 2001
Posts: 6,923
Vermont
Hi Geoff,

You're welcome. As far as the numbers go,I would think that anybody who knew the sequence of numbers has long retired frown

As far as inner covers go,depending on the year the earlier (mostly rigid frame models..but not the late rigid frame models)outer covers have one bottom screw hole in a different location than the later models...although the cast number stayed the same T411.

What year transmission do you have and what year is the bike?

beerchug


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project

Re: Pre unit gearbox serial numbers #112744
03/29/07 3:35 am
03/29/07 3:35 am
Joined: Mar 2007
Posts: 215
Southern California
Geoff Patrick Offline OP
Life member
Geoff Patrick  Offline OP
Life member
Joined: Mar 2007
Posts: 215
Southern California
Hi Jon,

Working from a completeley disassembled inventory of 16 or so transmissions, I am trying to match the closest one for a 49 TR5 project I am working on now. The rest will be for 9 future projects.

gp


Watch "American Triumph" at www.americantriumph.tv
Re: Pre unit gearbox serial numbers #112745
03/29/07 1:53 pm
03/29/07 1:53 pm
Joined: Aug 2001
Posts: 6,923
Vermont
Jon W. Whitley Offline

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Jon W. Whitley  Offline

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Joined: Aug 2001
Posts: 6,923
Vermont
I imagine with that many, you'll most likely have an early one that you will be able to see the difference in.The early rigid boxes also had a mount that the later rigid and swing-arm models didn't have. Unfortunatley, I don't know what the changeover year was. Nonetheless, they will work.

beerchug


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project

Re: Pre unit gearbox serial numbers #112746
03/29/07 1:55 pm
03/29/07 1:55 pm
Joined: Aug 2001
Posts: 6,923
Vermont
Jon W. Whitley Offline

BritBike Forum member
Jon W. Whitley  Offline

BritBike Forum member
Joined: Aug 2001
Posts: 6,923
Vermont
Geoff,

Also, the late 1940's inner covers where the numbers are stamped can be preceded by T.F. for example....I believe a 1949 would have that on the transmission.

beerchug


Jon W.


1957 6T Thunderbird 650
1968 T100R Daytona 500
1971 TR6R Tiger 650
1970 BSA A65F 650
1955 Tiger 100 - Project

Re: Pre unit gearbox serial numbers #112747
03/29/07 3:54 pm
03/29/07 3:54 pm
Joined: Jul 2006
Posts: 77
Port Townsend, WA
A
Amaranth Red Offline
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Amaranth Red  Offline
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A
Joined: Jul 2006
Posts: 77
Port Townsend, WA
G,Day
The early post-war, rigid frame gearbox mount castings are noticeably different than later models. The early boxes were prone to cracking so they beefed up the mounting areas. Also the early boxes have large numbers stamped on the exterior. In 1948 they began to tap the two bosses on the back of the box, just behind the drive sprocket, in order to accomdate an external speedo drive due to the introduction of the sprung hub wheel which could not accomodate a speedo drive. In the early 50's the boxes were changed to accomodate an external speedo drive. Hope this info helps. With so many boxes you should be able to group them according to the changes described.
Cheers Dan O.......


1948 3T Deluxe
1948 5T SpeedTwin
1948 Tiger 100
1954 TR5
1955 6TAC Thunderbird (Blackbird)
1956 TR6 Trophybird
1965 T120R Bonneville
1967 T100R Daytona
Re: Pre unit gearbox serial numbers #112748
03/29/07 3:56 pm
03/29/07 3:56 pm
Joined: Jul 2006
Posts: 77
Port Townsend, WA
A
Amaranth Red Offline
BritBike Forum member
Amaranth Red  Offline
BritBike Forum member
A
Joined: Jul 2006
Posts: 77
Port Townsend, WA
oops, I meant to say the early 50's boxes were changed to accomdate an "internal" speedo drive


1948 3T Deluxe
1948 5T SpeedTwin
1948 Tiger 100
1954 TR5
1955 6TAC Thunderbird (Blackbird)
1956 TR6 Trophybird
1965 T120R Bonneville
1967 T100R Daytona

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