Lotus Elan

Time to decide between donuts and CV joints

PostPost by: lotusjohn » Thu Sep 12, 2019 10:45 pm

On a further note:
The diff stub axle is a known weak part on the Elan and the current replacements are about $500ea.
I do not know of a failure on a street car of my CV inboard stub axles. The Vintage racers or slick shod autocrossers will occasionally break one.

John
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PostPost by: 1owner69Elan » Fri Sep 13, 2019 6:49 pm

I'm glad to see that the CV kits available in the US (LotusJohn) don't have the droop limiting issue. When I bought my kit from DBE I was unaware of the issue. Only heard about it after I installed my kit and it caused me some worry about whether I needed to install limiting straps. Glad these are not needed. I have not had any issues to date.

I had a long discussion ("argument") with Tony (TTR) regarding the CV kits. He felt that the kits were made with sub-standard Far Eastern CV's and were vastly inferior to the TTR sliding spline U-joints. Based upon this input, I verified that the kits were made with genuine GKN Lobro parts prior to my purchase. I figured a road car would be better off with the CV's rather than the TTR sliding spline u-joint units given the range of road conditions (not a smooth track) that would be encountered.

Not sure of the difference between the Lotus John and Col Croucher kits but both seem to be great quality. The included uprated diff output shafts on Lotus John's are a plus and help explain the price differential. I suppose these can be uprated on the Elan Trikbits kit as well.
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PostPost by: Tmac897 » Fri Sep 13, 2019 7:39 pm

I verified with Ken at DBE. No bottoming issues with the CV joints. He was a bit more technical than that in his explanation, but the conclusion is the same.

BTW, he also said one could reasonably expect 10-15 years of life with Rotoflex Couplings. I thought it worth mentioning, given the bad rap they generally receive.
Tony
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PostPost by: snowyelan » Fri Sep 13, 2019 10:26 pm

I believe John uses a longer shaft than the elan trikbits so proceed with caution if you plan to use a mix of the 2 suppliers. I suppose the CV joints themselves may be different too.
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PostPost by: Andy8421 » Sat Sep 14, 2019 6:02 am

1owner69Elan wrote:I had a long discussion ("argument") with Tony (TTR) regarding the CV kits. He felt that the kits were made with sub-standard Far Eastern CV's and were vastly inferior to the TTR sliding spline U-joints. Based upon this input, I verified that the kits were made with genuine GKN Lobro parts prior to my purchase. I figured a road car would be better off with the CV's rather than the TTR sliding spline u-joint units given the range of road conditions (not a smooth track) that would be encountered.


I have had similar conversations with TTR who seem to be in denial about the risks of the splines in their driveshafts binding under load. As I have posted earlier in thread, the suspension movement on a race prepared Elan on a smooth track is limited, so maybe splines are OK in that application. I wouldn't use splines on a road car.

Andy.
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PostPost by: Craven » Sat Sep 14, 2019 10:27 am

Rhetorical question, How do CV shafts shorten and lengthen if not on sliding splines.
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PostPost by: vincereynard » Sat Sep 14, 2019 1:07 pm

Plus Hooke Joints aren't constant velocity! Hence the need for Constant Velocity joints.
1owner69Elan wrote:I had a long discussion ("argument") with Tony (TTR) regarding the CV kits. He felt that the kits were made with sub-standard Far Eastern CV's and were vastly inferior to the TTR sliding spline U-joints.


He's spouting bollo**s.
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PostPost by: Andy8421 » Sat Sep 14, 2019 2:01 pm

Craven wrote:Rhetorical question, How do CV shafts shorten and lengthen if not on sliding splines.


Like this?

https://www.merlinmotorsport.co.uk/p/gkn-plunging-joint-size-10-fford-gkn-ms3j001
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PostPost by: Andy8421 » Sat Sep 14, 2019 2:11 pm

..and while we are at it, this is how you do it if cost isn't a problem.

http://www.aston-v8.co.uk/blog/sliding-halfshaft-joints/
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PostPost by: steve lyle » Sat Sep 14, 2019 2:25 pm

Craven wrote:Rhetorical question, How do CV shafts shorten and lengthen if not on sliding splines.


If you Google "How does a CV joint work?" - you get this: https://en.wikipedia.org/wiki/Constant-velocity_joint

And for an extra bonus, if you Google "What is a rhetorical question?" - you get this: https://examples.yourdictionary.com/rhe ... mples.html

:-)
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