Lotus Elan

Crankshaft sprocket to Jack shaft sprocket relationship

PostPost by: lee_romain » Tue Jul 17, 2012 10:41 am

Hi There,

I have a problem, i am currently rebuilding my Lotus elan big valve engine. I have to an issue with the position of the crankshaft sprocket in relation to the jack shaft sprocket. When i place the crankshaft sprocket on, it is out of alignment with the jack sprocket by 2-3mm. My question is, is there suppose to be shims behind the crankshaft sprocket to space it out to get alignment with the jack sprocket?
There seems to be no mention of shims in the service manual.

Kind regards

Lee
Regards

Lee

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PostPost by: promotor » Tue Jul 17, 2012 10:50 am

Are you sure that you have a twincam sprocket and not a crossflow sprocket - the lotus one is offset to line up with the jackshaft sprocket?
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PostPost by: garyeanderson » Tue Jul 17, 2012 11:06 am

elan-f15/jack-shaft-adaptor-t21051.html

take a look at this post on the jackshaft adapter too.

Gary
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PostPost by: lee_romain » Tue Jul 17, 2012 2:19 pm

Thanks for the swift replies guy's

I have the adapter for the jack sprocket in place.
Here are some pictures of the issue as best i could do. Is it my eyes deceiving me or an optical illusion, but they don't look aligned. Or is that as good as it gets on an old Lotus?

Cheers
Attachments
P1020386.JPG and
alignment issue?
P1020382.JPG and
alignment issue?
P1020379.JPG and
Jack sprocket adapter
Regards

Lee

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PostPost by: promotor » Tue Jul 17, 2012 2:49 pm

The correct parts are fitted so that's that out of the equation!

Could be down to crankshaft thrust washers - if the thrust faces of the crankshaft have been incorrectly ground from factory, or re-ground since then that could have an affect. Be a good idea to check what size thrust washers are in the front and back position.

Is the jackshaft adapter seated correctly onto the jackshaft?

I have seen crankshafts fitted with shims previously to push the sprocket further out. Might be worth pulling the crank sprocket off to see if that, or the crank mounting face itself, has been ground in the past?
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PostPost by: types26/36 » Tue Jul 17, 2012 2:54 pm

I have seen a shim used (from new) on a Xflow crank but not on a TC but if you are unhappy with the alignment just add a shim as necessary.
Also have a look at this thread elan-f15/crossflow-crank-gear-t18221.html
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PostPost by: garyeanderson » Tue Jul 17, 2012 3:06 pm

Here is one of the same engine in the other thread, it hasn't gotten any further in the assembly/disassembly phase. :) It too looks slightly out of alignment, the Elan did quite a few miles just like it is so I don't know what to tell you.

Gary
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crank and jack sprocket alignment.JPG and
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PostPost by: lee_romain » Tue Jul 17, 2012 5:06 pm

Many thanks again for the replies. i'll go away and see whats what.

Cheers
Regards

Lee

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