Lotus Elan

uprated diff output shafts

PostPost by: seniorchristo » Fri Apr 15, 2016 12:08 am

I recently acquired a pair of uprated Lotus diff output shafts for my Elan in anticipation of boosting engine HP to about 140-150. Shaft increase in diameter is about .010". Does anyone have experience with the strength/reliability of these units? I will have a final drive ratio of 3.55 and I am currently running 155/80 X13 tires. :)
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dsc00413.jpg and
uprated axles on right
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PostPost by: bitsobrits » Fri Apr 15, 2016 1:52 am

I would think with stock or near stock size tires the strength of the output shafts is largely immaterial. It's with wider/stickier tires when shaft twisting becomes something to worry about.

Though I suppose if you drove like a hooligan :roll: on skinny tires you just might be able to twist a stock output shaft.
Steve

Elan S1 1963-Bourne bodied
Elan S3 1967 FHC pre airflow

Formerly:
Elan S1 1964
Elan S3 1966 FHC pre airflow
Elan S3 1967 FHC airflow
Elan S4 1969 FHC
Europa S2 1970
Esprit S2 1979
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PostPost by: rgh0 » Fri Apr 15, 2016 10:43 am

The later uprated shafts had better steel as well as the bigger diameter section between the spline and bearing mount. The earlier shafts tended to fail in the spline section not normally in the reduced diameter section so I think the improved material strength was more important than the diameter.

I have not seen a later shaft fail while I have seen many of the earlier ones break. I would think your later shafts should be OK for 150 hp road use.

cheers
Rohan
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PostPost by: elangtv2000 » Fri Apr 15, 2016 5:19 pm

I previously had two stock shafts fail at the root of the spline. Upgraded with TT shafts, and as Rohan indicated, these are not only larger stock without a reduced diameter below the spline, but of better material.
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Greg
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PostPost by: seniorchristo » Fri Apr 15, 2016 9:41 pm

Elangtv
These are upgraded shafts from Lotus. The TTR shafts are said to be made of stronger material but the pictures I've seen show a reduction in diameter from the splines on down. :)
http://shop.tonythompsonracing.co.uk/tt ... -298-p.asp
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PostPost by: elangtv2000 » Fri Apr 15, 2016 10:05 pm

Interesting - the TTR shafts I bought previously were not waisted like this. They may have found that superior metallurgy allowed them to add lightness!
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PostPost by: seniorchristo » Sat Apr 16, 2016 12:04 am

Elangtv
You added lightness and replaced your wasted shafts with waisted shafts. :)
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PostPost by: bill308 » Sat Apr 16, 2016 2:18 am

In the end I went for the DBE differential output shafts supplied as part of his CV joint system. I did not ask about the metallurgy but should have. I was told his early version of the system, as I used on my S2, would not be sufficient for my later 165 lb-ft engine.

Now I'm curious as to what the material really is?

Bill
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