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Discussion Starter · #1 ·
I am brand new to this forum...please be kind. I am trying to build a Triumph "bobber" out of some bits (2 factory hardtail frames and three partial engines) I have laying around. Not as easy as it seemed it would be and I don't think my local British shop has been correct on some of the advice given. Please do feel free to correct me if my assumptions are incorrect.

Since my frame is a factory hardtail, I found that I need to use a long primary case which I was told was not available in alternator configuration. OK, so bought one for a dynamo from him. Two of the engine cases I had were for dynamos so I was covered there. My local guy told me I must also have a drive sprocket with the shock absorber system built into it. That I did not have and purchased most of that from him and got the remaining pieces elsewhere. I did ask if the cranks were the same and was told yes.. something I now do not believe is correct. I only had one clutch assembly and it had rubber shock absorbers in it. I asked if I had a shock absorbing clutch, did I still need that special sprocket...answer yes. Hummm?

I had two crankshafts, both the same, with the replaceable threaded stud for the alternator nut. My dealer knew this as he sold me a new stud because both of mine were damaged. When I went to install the shock absorbing sprocket, it has no place to thread on to that crankshaft. It seems that the cranks are indeed different.

So, can I use a preunit engine sprocket from an alternator engine and drive the clutch with "cush" under that primary case? I do not have one of the drive sprockets (or my primary chain yet) but it seems like it would fit and there would be a shock absorber in the system? Any modifications I will need to make that work?

I hate to keep buying parts I don't need and yet also want to stay on the good side of my local guy who doesn't seem to favor returns.

Thanks for any suggestions.
 

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Welcome.

The good thing is you've got lots of spare parts you can offer in trade for what you need.

Building a bitsa can be anywhere from the easiest thing in the world, to the most frustrating thing you'll ever do.
 

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eya caferacers!

i love the old rigid frame triumphs.

yes there is an alternator inner and outer primary chaincase. they came with the speed twins and the Thunderbirds

there is a special collar that goes on the end of the engine shock absorber that has the right threads for the crankcase snout.

the rigid alternator fastener is a flanged nut for the same snout.

the rubber shock absorbers in the clutch are in all the rigid drive trains, the single row outer hub is the rigid and early swing arm.

heres the early 1945 to 1955 manual:

http://www.classicbike.biz/Triumph/Repair/45-55/45-55TriumphRepair.pdf

heres the 1947/ 1948 parts manual:

http://www.choppedtriumphs.net/files/Parts_1947_48_Twins.pdf

the rigid alternator case numbers are in these, let me know if you can't find em theres some other rigid frame stuff on the net.
 

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Discussion Starter · #4 ·
Thanks for the links

Sunshine Jim,

Thank you very much for the links you provided. They were a great help and reinforced the notion that just because someone, like my local old school Triumph shop, is in a position to know and acts like they know their stuff, doesn't mean that they do.

Thanks again.

Jesse
 
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