Lotus Elan

Mainshaft Grooved?

PostPost by: S2Jay » Fri Jun 24, 2011 4:27 pm

Hello to all,

Original S2 Elan with three rail 4 Speed Trans, 42K miles.

As I was inspecting transmission components prior to final assembly, I noticed a groove and some ?scars? [for lack of a better term] on the back half of the Mainshaft. This is the part of the mainshaft that runs through the Tailshaft Housing, where there appears to be nothing that could be rubbing on the shaft to cause the groove shown in the pic below, and nothing that would cause any of the other marks.

Is this groove common? It does not appear to be a new condition, there are no obvious fresh rub marks or discoloration.

Is this just part of the shaft since new?

I still have a concern about shaft strength, especially since the shaft has a relatively long and unsupported length with no intermediate bearing.

Does anyone have any experience with these shafts breaking or twisting in higher HP applications?

Would it be useful to have this section of the shaft shot peened, or even more drastically, reinforced with a sleeve?

Any observations, experiences and suggestions are welcomed.

Jay
65 S2 DHC LHD
Attachments
P1040668A.jpg and
Groove and Scars in Mainshaft, Elan S2, 3 rail 4 Spd Transmission.
Last edited by S2Jay on Fri Jun 24, 2011 10:10 pm, edited 1 time in total.
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PostPost by: john.p.clegg » Fri Jun 24, 2011 4:42 pm

Just a quick thought but is that where the speedo drive gear should be?

John :wink:
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PostPost by: garyeanderson » Fri Jun 24, 2011 6:37 pm

I don't see any grooves in the six pictured here.

They are two kinds shown in the picture.

From top to bottom

Junk semi-close main shaft
Desperation wide/close ratio (rust pits), from a Cortina
semi-close with rust pits on the output
Wide/close main shaft
semi-close main shaft
Wide/close main shaft
EnFo main shaft.JPG and
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PostPost by: S2Jay » Fri Jun 24, 2011 8:06 pm

Thanks for the input guys.

John, although it does not really show the location in the pic due to the close-up, this groove is spaced well behind the speedo drive. The "groove" is about half way between the speedo drive & the Tailshaft Housing seal. This area appears to be empty at all times to me.

P-A, Thanks much for showing so many other shafts! There does appear to be just the hint of a groove on the top shaft in a location similar to mine, but it does not seem to be as deep. This is seen almost on a line from the ".5" printed on the cardboard box above the shaft and the "UL...." letters printed below.

The 4th shaft seems to have some of the same "half moon" shaped nicks that I see in my shaft behind the groove.

Perhaps it is just excessive paranoia on my part?

Jay
just looking for clues at the scene....
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PostPost by: garyeanderson » Fri Jun 24, 2011 9:30 pm

All shafts have the lathe tooling marks of the last cut except the 5th one down in the original picture. There is a few "transitions" in diameter that are shown as steps in the attached new pic. The differences that you are seeing in the middle transitions are on the order of a .001 difference.

I'd re-use your shaft, its lasted 40 plus years so far.
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EnFo main shaft1.JPG and
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PostPost by: S2Jay » Fri Jun 24, 2011 10:05 pm

Well, of course I should have posted dimensions to begin with, sorry.

My shaft measures a bit thinnner than yours at 0.834, but in the groove, it measures only 0.826. Ok, maybe not a big diff.

You are probably right, there is no real problem with this shaft, but I am expecting a few extra HP now, and as long as it is out, and I hope never needs to come out again [!!, knock wood?], I will check into having the shop shot peen that section of shaft along with the 125 E rods I just got. I'm thinking it can do no harm & will not cost much.

Jay
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