Lotus Elan

Other than money, any reason NOT to convert to CVs?

PostPost by: Grizzly » Sun Apr 28, 2019 7:39 pm

Depends which shafts / joints you have as some of the better quality CV joints don't bind (also 2 seater or +2)...... when i first fitted mine (kelvedon/Shafttec CV kit 2 seater) they only locked up in the last 3/4".

I could have done some thing with that but the problem was the CV boot was pulled really tight, i fitted a set of droop reduction dampers but even so i've had two sets of new boots in little over 3 years.... because of how their pulled you only need to nick one and it will rip.
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PostPost by: 74Twincam » Sun Apr 28, 2019 7:44 pm

"Any idea on what those cost delivered from AUS? RD has a $1,600 option which is more than I’ve spent on some of the cars I drive. Gulp."

-The shafts from Elan Trik Bits are $1161 including shipping, but unlike those from Bean and RD though, don't include differential shafts, which if purchased separately are running about $500. Seems you're swinging in the same ballpark cost wise. Guess it just depends on how you want to piece it together and if there's a need for the inner shafts- the second part is where I'm struggling.
There's plenty of discussion as to the need to upgrade to strengthened parts if increasing power, changing tires, etc.- not sure if it's necessary to start replacing the entire rear end if the original goal is to replace the donuts, all other components being left alone (should they?)
I feel the tug between "do it once while I'm in there" vs. "keep it as original as possible, only fix what's broke"...

I do think I've garnered enough from the group that regardless of details and additional parts, CV's are in my future.
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PostPost by: Slowtus » Sun Apr 28, 2019 8:55 pm

gherlt wrote:
Elanintheforest wrote:I’ve never quite understood the idea that without the Rotoflex couplings the shock provided by CVs will somehow wreck the transmission of an Elan. The differential is standard Ford, as is the gearbox, and no Ford has Rotoflex couplings. They are bomb-proof assemblies even in the much heavier cars, and are amongst the last components to fail..

None of the Ford's had 105hp, I think 61hp at most in the Ford Anglia.


All of the Lotus Cortinas had 105hp (+/- a few hp, depending on whose 'specs' you read.)

Mine, as I said had 240hp and yes, I did smithereen the diff as I was heading out of the garage to go to the track one day.
Fortunately it gave way literally as I left the garage. When I pulled the diff I found many broken teeth BUT the majority of them looked like they had been damaged long before I did the deed.

The previous owner had had a very grunty V6 in the car which probably did the nasty as it had almost 3 times the torque of the original engine.
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PostPost by: richardcox_lotus » Sun Apr 28, 2019 9:28 pm

My rotoflex are now 5 years old, and still ok.

I’ve always managed 8 or 9 years on a set, although my mileage is not great - 2 to 3 thousand a year.

So I think the talk of them all failing after only a year, is perhaps overkill. Also do not think CVs are fit and forget, they still require maintenance.

Let us know what you decide.

Regards,
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PostPost by: tdskip » Sun Apr 28, 2019 10:08 pm

$200 versus $1600 on a car that I haven’t driven yet seems like a noteworthy difference....
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PostPost by: USA64 » Sun Apr 28, 2019 10:33 pm

copied from my other post
have read that Chapman had to chose between rotoflex and inboard brakes and chose the rotoflex. The reason was presumeably handling and some subtlety with the geometry.
I have read that the resistance to deflection the donut (4) creates a anti-roll effect on the rear. Thus if the donuts are replaced with CV joints an anti-roll bar must be added or handling will suffer.
I would guess the donuts Lotus used were off-the-shelf. Does anyone know what else used the same spec?
Does anyone know what the specs were? Not just dimensions but stiffness or whatever rubber is specced at? Or, for that matter, what was the -rubber- actually made of?
We are supposed to be having fun, are we not?
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PostPost by: webbslinger » Sun Apr 28, 2019 11:59 pm

As for ripping CV boots, mine have torn twice. They didn't rip driving, they ripped when I was rotating the wheels while the car was on stands and the wheels were at full droop. The second boots ripped as I was tightening things up after putting them on, hadn't even let the car down yet. I then
Macgyvered a limiter that has done the job for 10k miles so far.
Soon though, I'm going to get the limited droop shocks which are adjustable without removing them. If your shocks aren't externally adjustable I think you should figure that as another reason to get new shocks if you go to CVs.
I never minded the donuts. I had some drag-racer friends back when and they called my Elan "the spit wad" because of the rubber band launch. It was just the character of the car and made it more interesting. But I switched. Attached is a horrifying picture of my kluge droop limiter. Don't look if you have a headache.
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PostPost by: tjb0274 » Mon Apr 29, 2019 12:21 am

Steve Taylor of Lotus Marques has some comparison info on his site between the various options.

https://www.lotusmarques.com/parts/data ... conversion

I spoke with Steve and with Col at ElanTrikBits before deciding on cv joints for my S4. I went with the Lotus Marques option because it's slightly lighter, but I've since driven an S2 with Col's c.v. conversion and honestly couldn't tell the difference. Both look and feel very solid and well machined.
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PostPost by: mbell » Mon Apr 29, 2019 1:52 am

My +2 had the rdent shafts on when I got it. I think these are probably the best CV shafts available. As mentioned you get new output shafts but this has an added benefit of making the drive shaft a little longer, which means you get lower angles for the CV joints. So you don't need to worry about droop limiting shocks and the CV boots are at lower risk of splitting.

The downside of course is the cost which is a lot, but $1200 isn't a small sum either. (You could argue they save you the cost of new shocks, so as complete solution aren't they much more $.)
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PostPost by: tjb0274 » Mon Apr 29, 2019 3:25 am

Just an addendum since people are expressing concerns about droop-limiting - the Lotus Marques CV units are machined to cope with the standard droop, at leas in a baby Elan, so shouldn't be a need for extra expenditure/mods to limit droop or change drive shaft length.

Can't remember whether the ElanTrikBits units are the same, but Col is very friendly and responsive to questions, so worth contacting him to ask if you're considering his parts.
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PostPost by: nmauduit » Mon Apr 29, 2019 8:04 am

for the sake of completeness since dealers are being discussed, Sue Miller also offers a CV conversion

http://www.mickmillerlotus.com/parts-cv ... hafts.html

one should talk to her for more information (no affiliation)
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PostPost by: Grizzly » Mon Apr 29, 2019 9:53 am

i was thinking about this last night and two things stood out when i swapped to CV shafts...... First obviously lack of wind up. The second was the lack of rotoflex's seemed to take some thing from the way the back end was sprung, the back end was quite allot softer with cv's / stock springs on and this is some thing i am looking to fix in the near future.
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PostPost by: Grizzly » Mon Apr 29, 2019 10:00 am

nmauduit wrote:for the sake of completeness since dealers are being discussed, Sue Miller also offers a CV conversion

http://www.mickmillerlotus.com/parts-cv ... hafts.html

one should talk to her for more information (no affiliation)

Ironically it was Sue Miller that told me to go see kelvedon as she had stopped making them (i belive there was a bad batch that all came back that put her off making them up)...... kelvedon then told me Sue miller had given them the designs and they had fixed a couple of flaws in the design and farmed construction out to Shaftec. So maybe Kelvedon is supplying kits to Sue Miller now??
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PostPost by: Grizzly » Mon Apr 29, 2019 10:04 am

webbslinger wrote:As for ripping CV boots, mine have torn twice. They didn't rip driving, they ripped when I was rotating the wheels while the car was on stands and the wheels were at full droop. The second boots ripped as I was tightening things up after putting them on, hadn't even let the car down yet.

That sounds about right, my first set went whilst i was setting up my handbrake and the second set went thanks to a hump back bridge on the way home from work.
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PostPost by: rgh0 » Mon Apr 29, 2019 10:06 am

tjb0274 wrote:Steve Taylor of Lotus Marques has some comparison info on his site between the various options.

https://www.lotusmarques.com/parts/data ... conversion

I spoke with Steve and with Col at ElanTrikBits before deciding on cv joints for my S4. I went with the Lotus Marques option because it's slightly lighter, but I've since driven an S2 with Col's c.v. conversion and honestly couldn't tell the difference. Both look and feel very solid and well machined.



You may want to ask Col at Elan Trikbits where the design for the Lotus marques CV conversion actually came from.

cheers
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