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Old 08-08-2012, 08:24 PM   #1
AussieGreg
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Default Triumph Pre-unit Big Journal Crank

Recently I found out that the guy who had rebuilt the engine I bought had put a big journal crank (late pre-unit/early unit) into the 52 6t engine. I am still using the original early rigid big hump primary case.

So I decided the best thing was to use the later cush drive in the clutch and run the standard crank to sprocket fittings up front for the unit model, minus the alternator. I am not running an alternator because I want to keep the rigid primary cases.

I am about to try and source the parts and order them up. But looking at the disagram it shows the rotor after the crankcase. Because I am not running an alternator I was wondering if I should just put a spacer in there instead.

If so, how wide is the standard rotor and also how big is the diameter?

Cheers, Greg
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Old 08-08-2012, 10:05 PM   #2
Rubone
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Default Re: Triumph Pre-unit Big Journal Crank

The spacer is a standard item and is splined to fit the shaft. Easy to do, no fabrication required!
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Old 08-09-2012, 12:05 AM   #3
'59
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Default Re: Triumph Pre-unit Big Journal Crank

'scuse me butting in, but I've also heard that having the rotor / spacer fitted should be dne when/if balancing the crank.

true/false?
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Old 08-09-2012, 04:10 AM   #4
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Default Re: Triumph Pre-unit Big Journal Crank

1.385'' wide 2.920'' diameter. at least the one I measured is.
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Old 08-09-2012, 06:15 AM   #5
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Default Re: Triumph Pre-unit Big Journal Crank

Quote:
Originally Posted by '59 View Post
'scuse me butting in, but I've also heard that having the rotor / spacer fitted should be dne when/if balancing the crank.

true/false?
They'll normally hand the rotor back to you and say "we can't balance that part (it's already balanced),we just need the crank."
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