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Discussion Starter · #1 ·
Guys - my 500 pre-unit has a belt drive fitted and it is leaking quite alot of oil from the crank end. The belt drive front sprocket just buts up to the end of the crank bearing and has no seal of any kind.

Is it the case that the crank case should never have enough oil sitting in it to reach the level of the case crank hole and thus never running out - I think the bike has been wet-sumping a little.

Any mods, help would be appeciated.

Cheers

Jamie
 

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You will need to fit an oil seal behind the front pulley. If your starting it after wet sumping and not draining the sump, you may experience oil coming out of places you don't want it to. Could be the excess pressure is forcing oil out that crank bearing until oil gets pumped back into the tank. I got a front bearing seal to fit under the front pulley with belt drive kit for a unit 750. One would think you would get oil coming from that bearing with no seal wet sumping or not.
 

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Thanks Coco.....will see if it's possible to fit a seal. At the moment the belt drive sprocket boss is a pretty close fit into the cases.

Jamie
Mine is similar. I fitted a Newby belt drive to a T140 engine. That boss or raised area on the back of the pulley fits nicely into the seal. What brand of belt drive do you have?
 

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http://triumphday.com/britech/parts.htm

Click the "Pre-Unit Main Shaft Oil Seal" link. Nice kit.

-Shaggy
Their outrigger bearing kit interests me. I never could get much info out of those guys. Never replying to e-mails about pricing ect. They do an o-ring chain conversion too but I could get zero info from them about it.

Either way, it looks like they have just what the thread starter is looking for.
 

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we make our own version of the crank seal using the 1959 crank/fork seal and a 1/8" thick stainless plate bolted to the case. We use Bob Newby belt drive and turn the pulley down to fit the seal.
 

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I have a '68 Triumph 650. Can the driveside crank oilseal be changed without disassembling the engine? I have the primary sprocket off. I can't see the condition of the seal and don't want to fiddle too much unless I know it can be replaced easily(i.e.while still on the bike).
The clutch basket is also off, so I suppose the same question apples to the gearbox seal.
I'm installing a Newby beltdrive.
 

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I am currently diagnosing an engine seal leak from my 58' (oil leaking on the dry belt drive). According to the parts book and shop manual, Part H1168 (current part number 97-1168) is a seal that will work for my year. Oddly enough, this same seal is the same for the forks (fork oil seal). I would do some digging, you may find something that works. Currently i'm waiting for the part to show up ands see if it works...
 
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