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#848155 05/05/21 6:08 pm
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KeithM Offline OP
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Hi
Does anyone know if all the LH gear change T140 crankcases are the same? I have a T140ES with a damaged RH crankcase. Will the none ES crankcase RH side be a direct replacement so that I can retain the original engine number?
Thanks
Keith

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Yes and no... The intermediate pinion (and sprag) spindle on an ES runs on bearings in the block and cover, as opposed to the age old layout with the pinion rotating on a fixed spindle. Easy enough for a competent machinist to replicate though.

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Doesn’t the timing side crankcase on an ES have an extension to accommodate the starter (similar to the magneto extension on a pre-unit)?

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Quote
Doesn’t the timing side crankcase on an ES have an extension to accommodate the starter (similar to the magneto extension on a pre-unit)?

i think most of the E-parts are part of... or bolt onto the timing cover , which i presume the OP has ?
[Linked Image from cdn.myonlinestore.eu]

https://www.britishspares.com/catalogs/show-catalog-page/triumph/PCT140-82/025
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Last edited by quinten; 05/05/21 8:40 pm.
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Thanks for that Quinten, I've learnt something!

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Originally Posted by koan58
Thanks for that Quinten, I've learnt something!
yeah , so did I .
I guess it brings up the point
that any T140 (and maybe T120 ? ) could be converted to an E-start with
the later/last E-start cover and assorted bits .

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Originally Posted by quinten
I guess it brings up the point
that any T140 (and maybe T120 ? ) could be converted to an E-start with the later/last E-start cover and assorted bits .


What it couldn’t be converted to is a good, long-lasting electric start.


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Originally Posted by quinten
Quote
Doesn’t the timing side crankcase on an ES have an extension to accommodate the starter (similar to the magneto extension on a pre-unit)?

i think most of the E-parts are part of... or bolt onto the timing cover , which i presume the OP has ?
[Linked Image from cdn.myonlinestore.eu]

https://www.britishspares.com/catalogs/show-catalog-page/triumph/PCT140-82/025
.
Look at the intermediate gear bushing in the cover, you need a bush/bearing in the timing chest as well.
To me, cranking the engine through the timing gears was never a good idea.

SR

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I'm in the process of putting together an October 1980 engine with a model designation of TR7RVS which has no electric start, but has the bronze bush in the crankcase only. It may have been converted from electric start, but either way it's a PITA, as the spindle comes out with the outer cover. I've glued the spindle in place!

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To the original question, if you replace on case half you have to insure the case dowel does not misalign the halves. Square up the drive side case on the primary and locate the crank and cam bores. Put on the right case with the dowel and align the cylinder face. Now measure the crank and cam bore locations. From there and the cam bore tolerance you can decide if the dowel has to be moved.

KeithM #848324 05/07/21 10:05 am
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KeithM Offline OP
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Thanks for all your comments guys. This site is amazing, and simply the best place to get help and advice for old bikes!
My original query regarding replacing the RH crankcase was because the needle roller on the layshaft (clutch end) has disintegrated and the shaft has eaten into the aluminium casing causing an egg shaped hole. Anyone else had this happen? Only had the bike for a few months. Think I'm going to get it sleeved as the chances of finding an ES RH crankcase are slim.
Thanks again for all you advice.
Keith

KeithM #848325 05/07/21 10:22 am
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That must have sounded horrendous as it was eating up the bearing! I think you're right about repairing, never mind about the matching numbers for originality, the crank halves will be machined together, must be a good thing.

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Missed something here, if the layshaft bearing on the clutch end disintegrated that is the left hand case. The right side of the layshaft is held in the inner gearbox case which you should be able to find. What is the reason for replacing the right hand case?

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A little brain fade here! The gearbox layshaft bearing on the left is in the right hand case, the layshaft bearing on the right is in the inner gearbox case. The L/H mainshaft bearing is in the R/H case too. There is no bearing related to the transmission in the L/H case, just the L/H crankshaft main bearing - unless I have been too much on the beer (fat chance).

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Yes, faded off into the sunset. Layshaft bearing is on the left side of the right hand case. Still, no reason to junk the case because the bearing hole is damaged. Either have the case welded and rebored or bore and fit a steel housing.

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