Lotus Elan

Recommended CV Axle Conversions

PostPost by: EricB » Sun Feb 18, 2018 7:18 pm

Presently restoring a '66 S3 SE DHC and the message I am getting is not to worry about using rubber doughnuts as they are unreliable and go directly to a CV axle conversion.

Therefore just wondering what the forum experience is and what choices are out there.

--EricB
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PostPost by: USA64 » Sun Feb 18, 2018 8:39 pm

I am restoring a S4 DHC and am sticking to donuts. I suspect the "unreliability" is more down to driving style. My research found that CV's require a rear sway-bar to compensate for the lost resistance of the donuts but I never hear it mentioned by the CV promoters. Ironically my car has Spyder rear a-arms with a provision for the sway-bar; also elliptic not round cross-section.
We are supposed to be having fun, are we not?
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PostPost by: elated » Sun Feb 18, 2018 11:07 pm

The OE donuts worked well enough though windup was apparent especially prior to the introduction of the interleaved version.
The same would be true today but for the fact that, possibly due to H&S, modern rubber is not up to the task.
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PostPost by: rgh0 » Mon Feb 19, 2018 11:26 am

USA64 wrote:I am restoring a S4 DHC and am sticking to donuts. I suspect the "unreliability" is more down to driving style. My research found that CV's require a rear sway-bar to compensate for the lost resistance of the donuts but I never hear it mentioned by the CV promoters. Ironically my car has Spyder rear a-arms with a provision for the sway-bar; also elliptic not round cross-section.



The roll resistance of the donuts is trivial compared to the rest of the suspension and i dont subscribe to this theory of needing a rear roll bar as promoted by some. What is important is to have the rear Aeon rubber springs in place and in good condition.

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PostPost by: rgh0 » Mon Feb 19, 2018 11:31 am

elated wrote:The OE donuts worked well enough though windup was apparent especially prior to the introduction of the interleaved version.
The same would be true today but for the fact that, possibly due to H&S, modern rubber is not up to the task.
Gordon


Modern rubbers are better than those of the 60's, the problem with current donuts is the cheap manufacture in China or India (where no one is concerned about H&S) not what is possible with modern rubber. Have a look at some of the drive line donuts used in modern cars to see the strength and flexibility of modern rubbers when made as OEM for a major manufacturer.

In the end Cv's are a better solution for the drive axles than donuts. Donuts are good in the propeller shaft for reduction of NVH ( Noise vibration and harshness) which is a key design paramenter of modern cars

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PostPost by: Chancer » Mon Feb 19, 2018 12:25 pm

Very well said Rohan, I nearly spat out my coffee at the thought of H&S being a hindrance to the Chinese and Indian suppliers of playdough/cheese drive couplings.

My car is 17 years old and has done 500000kms, every bit of rubber is as good as new, screen rubbers,door seals, coolant hoses, clutch and brake system rubbers, valve stem seals, not a single one has hardened or degraded, compare that to the rubber parts on new cars back in the day and in only 5 years it was prudent to start replacing them to avoid breakdowns.

A also laugh when I read of people replacing "all the hoses" etc as a precaution, its quite the opposite, you can pretty much guarantee premature failure, I have known people doing restorations when the rubber parts particularly screen and door seals needed replacing a second time before they even finished the restoration, the vehicle not having turned a Wheel or having once seen daylight.
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PostPost by: AussieJohn » Mon Feb 19, 2018 1:37 pm

There are lots of tales where donuts have failed before restoration is finished just from sitting.
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