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Discussion Starter · #1 ·
Hi

Having trouble finding any info on this stuff.

Is the clutch system (complete system) from a Unit triumph in any way compatible with a Pre Unit triumph transmission ?

I know the Pre U uses a single chain between engine and trans, where the Unit uses 2 or 3, but is the rest useable as a straight swap ? or maybe by switching a couple of components ?

I'm finding it hell on earth to locate a complete Pre unit clutch system, I got a trans without, and I've got the opportunity to get a Unit clutch system. Hence my wondering.

thanks for any input

J
 

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Pretty much no concerning clutch basket and drive sprocket. You should be able to use a unit hub and I have done so on one of mine.

I don't know where you are looking but you should start with posting a Wanted ad in the swap meet section of this forum. Also, there are quite a few suppliers out there. British Only Austria, Peters Classic Bike Parts in the Netherlands, many, many suppliers in the UK and eBay the world over. Take your pic and good luck..
 

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Discussion Starter · #4 ·
Yeah I found loads of suppliers of new parts. Are you just advising that regardless the second hand/old stuff I might find will need renewing anyway so I might as well just buy every single part new from a dealer ?
 

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I believe you can use a 6 and 4 spring clutch on a PU gearbox, but not a later 3 spring clutch. You can switch from BSA to Triumph clutches using an adaptor available on e-bay and at SRM. Pre units cases and covers are designed to fit a single row primary chain, but not a triple chain (too wide).

Do a search on Britbike.com for clutch compatibility.
 

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3-spring cush-drive and pressure plate fit.That's no problem,and it allows you to use 6 friction plates.A new 3-spring cush-drive to suit a T140 is a good investment.They do wear,and you get runout and imbalance.

Everyone says you can't fit duplex sprockets and chain on a pre-unit.I've fitted duplex to a rigid pre-unit with D.C.generator. It just fitted,not a lot of clearance.It may not fit if you have an alternator.
 

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Discussion Starter · #8 ·
Hi

Thanks for this precious info.

I might add that this transmission is supposed to be going on a non triumph motorbike, in fact a pre war 350cc single French bike. So i guess clearance and such is not so much a problem seeing as it has a Magneto and no generator whatsoever.
 

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You can wait until you have found some good used parts but it sounds like you have been waiting a while already. Buying new stuff clutch components shouldn't break the bank.

There is good used parts to be had. I have found plenty of them in the past. It really is up to you though on how long you want to wait and as mentioned in another post, you might not get an ideal part and then you are set back and looking again.

Sure, if you can afford it, buy new in this case. Get that project moving and onto another part. Time to get that bike fired up !

Yeah I found loads of suppliers of new parts. Are you just advising that regardless the second hand/old stuff I might find will need renewing anyway so I might as well just buy every single part new from a dealer ?
 

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If using duplex chain isn't a problem,you can use a complete T140 clutch with triplex sprocket.The duplex chain will just run on the inner 2 rows of teeth.You could cut off the outer row,or just leave them.
It can be easier to find T140 parts in good condition.Apart from the extra row of teeth,the clutch basket is the same as duplex.
 

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Discussion Starter · #11 ·
Hi

the clutch I've confirmed I'd take after reading your comments is a Duplex chain clutch from a T120 unit. It was removed from a daily driver in order to fit a belt drive, so was fully functional.

If anything it will allow me to be able to mockup the transmission support plates I need to custom make for the bike, as well as figure out the line up and get the sprockets made to fit.

I might start a topic once the job gets interesting ;)
 
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