Lotus Elan

Rotoflex couplings

PostPost by: Orsom Weels » Sat Mar 19, 2016 1:13 pm

I'm in the process of helping a friend put his S3 back on the road & whilst bleeding the rear brakes, I was shocked to find that the NEW Rotoflex couplings we had fitted only recently had already started to fall appart, all four of them. They came from Sue Miller, as she no longer offers her CV conversions, due to problems with them, so not un-known internet purchases. They had been fitted & the car had only been rolled about in the workshop, they had never had any power through them. Sue has refunded my friend, as we now have absolutely no confidence in trying another set, so what's the recomendation now ? UJ conversion or CV conversion ?

Regards, Tim
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PostPost by: Grizzly » Sat Mar 19, 2016 2:10 pm

It's a well covered subject so if you do a search there is everything you need to know.

BUT.... Arguably the best quality Drive shafts are http://www.elantrikbits.com/ and you could get away with not changing the struts but personally i'd do it as a matter of course with a CV swap.
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PostPost by: EPC 394J » Sat Mar 19, 2016 5:25 pm

I believe if there is insufficient weight on the rear suspension, the couplings can be hyperextended, and damaged. Almost certainly exacerbated by rolling the car around.

Just a thought?
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PostPost by: pereirac » Sat Mar 19, 2016 6:21 pm

Grizzly wrote:It's a well covered subject so if you do a search there is everything you need to know.

BUT.... Arguably the best quality Drive shafts are http://www.elantrikbits.com/ and you could get away with not changing the struts but personally i'd do it as a matter of course with a CV swap.


At that price, I should hope they are :-)
Carl

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PostPost by: KevJ+2 » Sat Mar 19, 2016 7:25 pm

EPC 394J wrote:I believe if there is insufficient weight on the rear suspension, the couplings can be hyperextended, and damaged. Almost certainly exacerbated by rolling the car around.

Just a thought?


I hopefully agree. I have kept my rear springs compressed during my rebuild to avoid the hyperextension. Without this, the couplings have a lot of constant distortion. I intend to keep the spring compressors on until the rebuild is complete, occasionally rotating the rear wheels to even out the stress.
I also bought mine from Sue Miller so fingers crossed :roll:
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PostPost by: Orsom Weels » Sat Mar 19, 2016 11:00 pm

The couplings haven't really been left without weight on the back of the car, it's been sitting at it's normal ride height & they were not unduly distorted or stressed. Also the fact that the car was moved arround in the workshop means they were not just left in one possition, so spreading the load a bit. The bonding between the plates & rubber had completely let go, there was no trace of rubber left on the plates, just clean metal. I still have do-nuts on my +2, they've been on since I restored it between 1987 & 1991, done thousands of miles & other than the usual stress marks, still look in good condition & I still happily drive fairly spiritedly with them, so I'm not against them, but my confidence has been knocked somewhat with regard to new ones. I really don't think they should have fallen appart like that under those circumstances.
I have searched through the archives, but everything I can find is quite a few years old now. I know there were a few problems with some CV joints locking up on full suspension drop on Elans, & also that some say sliding splines can lock on the UJ shafts, but wondered if there was any up to date thinking. We don't really want to change the dampers, as they are new std replacements, so were erring toward UJ's. The elantrickbits CV's look & sound good, but would prefer to keep it local if poss.
Thanks for the replies so far,

Tim
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PostPost by: Sea Ranch » Sun Mar 20, 2016 5:25 am

Tim,

I hear that you would rather keep the driveline solution "local". I would, too, if someone made a driveline solution local to where I live. Don't know any, so I bought what I thought was the best: Col's Elan Trikbits halfshafts. One of our forum members has had sets on multiple cars, put many miles on them, and loves them.

Having said that, I gave rubber donuts serious thought for a long time and have been intrigued by the following option:

http://www.ebay.com/itm/400561897083?_t ... EBIDX%3AIT

In the next couple days I will lay my hands on an article from some years ago that documents an owner/racer using the above BMW/Volvo rubber discs on a formula ford, I believe, to great effect.

I am sincerely hoping someone on our forum will run this down and try them out, see what happens. First thing that comes to mind is that they are stiffer than rotoflex couplings and may well stiffen up the rear suspension response, perhaps unduly. But just an initial observation.

Anyway, perhaps food for thought. Oh, and I have not installed/used my shiny new trikbits halfshafts yet. About 2 years away from that in my build. But will certainly be reporting results when I have them :mrgreen:

Regards,

Randy
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PostPost by: john.p.clegg » Sun Mar 20, 2016 7:02 am

Any news from the chap who was experimenting with material to make up new rotoflexes?

John :wink:
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PostPost by: john.p.clegg » Sun Mar 20, 2016 7:03 am

Edit

Bugger key bounce.....

John :oops:
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PostPost by: theelanman » Sun Mar 20, 2016 8:23 am

Just a thought on the cv conversion......did I hear that Kelvedon were doing them?
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PostPost by: theelanman » Sun Mar 20, 2016 8:32 am

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PostPost by: Elseezed » Sun Mar 20, 2016 9:38 am

image.jpg and

?Ricky Evans? to The Hillman Imp Group
23 January ? Brean ?
"Two stages bmw couplings don't work on a rally car period".
Above taken from Facebook.
Lots of discussion on Imp sites.
Merc, BMW couplings used on prop shafts and not designed to take the greater angles that rotoflex drive couplings take, hence above.
For my +2 I have used the Spyder set up, I had some old stock rotoflex couplings.

Les.
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PostPost by: TroonSprint » Sun Mar 20, 2016 9:48 am

I put Elantrikbits drive shafts on my Sprint last year and am delighted with them. Even at full droop with the car jacked up the shafts still turn without problem. They look good and are beautifully made. I don't notice them at all when driving the car. Yes, they are very expensive, but you really do get what you pay for.

Mike
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PostPost by: a d price » Sun Mar 20, 2016 12:47 pm

Agree with Mike I fitted these to car and am delighted with them.Your only going to do this job once.Expensive but we'll worth it
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PostPost by: Grizzly » Sun Mar 20, 2016 1:33 pm

pereirac wrote:At that price, I should hope they are :-)

If their good enough to run without reducing Droop then you could argue that you don't have to spend that extra ?200 on Struts? so maybe not as bad is they look on face value.

I'm with the guys above, if your going to do the conversion do it properly and fit quality parts.
Chris
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