Lotus Elan

Cv driveshaft query?

PostPost by: Grizzly » Mon Dec 21, 2015 2:32 pm

originalsprint wrote:Interesting "Grizzly" - I think the thing that most impressed me with the Australian system was that all the original character of the car was totally intact! I'm all for originality and indeed I retained all the original driveshafts so it's easy to convert the car back to the original rotoflexes however, the rubber that has to be used now is inferior because they can't use the chemicals they could "back in the day" and I really don't fancy loose rubber and metal ripping into the glassfibre underneath the car, not to mention breaking down miles from nowhere! I have no experience of the other units on the market but I was mightily impressed with how original the car still drove...

I agree, i would not entertain using anything but Genuine Lotus Metalastik rotoflex's and they get checked Monthly. Might just be me but i like the windup :) and the way the Rotoflex's act almost like a rear antiroll bar that you just don't get with CV's.

I drove my +2 daily for years with Rotorflex's there ok just as long as you keep an eye on them, as you say don't cut corners and buy the cheap crap you see for sale so often on places like Ebay (asking for trouble) i've had one fail and ironically it was a Bolt that failed not the Joint but didn't stop it smashing the caliper of the hub casting.

As i say if you buy quality CV joints there great for every day use but i'd want to see a quality makers stamp on the Joints (too much cheap rubbish used in the past) i've fitted a pair of shafts for a friend that had the extra output shafts i was told they where Elantrix but looking at the pictures i think they where RD Enterprises. If i was going to buy some now i'd be going for that type myself they where great quality and performed well (might be my imagination but they seemed longer between the joints so didn't lock up on the 2 seater with stock droop)
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PostPost by: nomad » Wed Jan 06, 2016 1:11 pm

I'm wondering why no one is offering shafts that have one CV and one universal joint. Similarly, a shaft like on the front drive cars. It would seem that they could be made cheaper and that a problem I see with the CV's could be eliminated.
With the two floating CV's it would appear that the shaft between them could be moving against it's limit's, inward and out, at all times with nothing to promote it being centralized but the rubber gaiter's. Spyder's idea of one CV and one rotoflex seems to me to help this problem but I would imagine just increase the stress on the rotoflex. Instead of four to absorb shock you have half that.
Do all modern independent rear drive cars use two CV's that both allow plunge?

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PostPost by: pharriso » Wed Jan 06, 2016 1:18 pm

nomad wrote:I'm wondering why no one is offering shafts that have one CV and one universal joint.

Kurt.


Someone does... If I recall correct it's Spyder in the UK

Just about every current production car, fwd or rwd has driveshafts with 2 CV joints
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PostPost by: nomad » Wed Jan 06, 2016 2:11 pm

pharriso wrote:
nomad wrote:I'm wondering why no one is offering shafts that have one CV and one universal joint.

Kurt.


Someone does... If I recall correct it's Spyder in the UK

Just about every current production car, fwd or rwd has driveshafts with 2 CV joints


Phil, I should have been clearer. What I meant was do all current rear drive independent suspention cars have inner and outer CV joints that both allow plunge.

I'll have to check the Spyder offering's. I thought they offered a CV and rotoflex. Also I know that two universal joints and a sliding shaft have been offered since, at least, the 60's.

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PostPost by: 661 » Wed Jan 06, 2016 4:34 pm

Correct, I've had the Spyder CV/rotoflex conversion for many years. Still a pain to change the rotoflex and I'd recommend the fit and forget offerings.
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PostPost by: TroonSprint » Wed Jan 06, 2016 5:17 pm

What I meant was do all current rear drive independent suspention cars have inner and outer CV joints that both allow plunge.
Indeed they do, and have done for years. My MGB V8 is fitted with Hoyle independent rear suspension which uses shortened drive shafts off the old Ford Sierra from the eighties - and there is a CV joint at both ends of the shaft. Have a look under a current BMW.

On my Elan I used the twin CV shafts from Col Croucher in Australia (Elantrikbits) http://www.elantrikbits.com/. Expensive, but really good. No Rotoflexes to keep an eye on, no snatching, no problem with full droop, and no harshness in the driveline. Fit and forget. You just don't know they are there.

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PostPost by: originalsprint » Wed Jan 06, 2016 6:04 pm

I'd agree with Mike - the Elantrikbits system really is the complete answer and the driving experience remains true to the original. There's a neat video that shows them being fitted at: https://www.youtube.com/watch?v=AWq3FTd ... 0hTp-kYKYF

Hope this helps!
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PostPost by: snowyelan » Wed Jan 06, 2016 7:51 pm

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PostPost by: TroonSprint » Wed Jan 06, 2016 9:50 pm

And for completeness, a piccy of the Hoyle IRS under my MGB GTV8. Note the twin CV joints!

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PostPost by: nomad » Thu Jan 07, 2016 4:27 am

Well, the reason I got to thinking about this is that I have a early used set of a CV conversion by RD. He has now changed the design but these have quite a bit of evidence of the CV's or axle shafts hitting there limit side to side. This got me thinking that if both of the CV's used are the type designed to allow plunge that there is nothing to keep the axle and CV centers [locked together with snap rings] from moving as they please from side to side and therefore up against there limit.
I have not obtained the CV joints for this set up yet but am just a bit curious after I had this thought. Obviously, they are used extensively so I guess its nothing to be concerned about.

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PostPost by: jono » Sat Mar 19, 2016 6:56 pm

My +2 has done just over 6k miles since as full nut and bolt rebuild during which I installed Sue Miller CV shafts.

Increasingly over the last 2k miles or so I have become aware of a distinct 'clunk' when pulling away (driveline shunt) which is very difficult to avoid without careful clutch control.

I tended to ignore it but today I have removed the rear struts to fit new lotocones and noticed that there is considerable play/backlash in the driveshaft assemblies. It's in the order of 10mm rotational 'slackness' before a turn at the hub end begins to react at the diff end. There is also slackness when you articulate the outer CV joint.

Is this normal - should there be any play in the joints? There's no graunching or clunking just an annoying degree of play.

If the CV's are shot (which would be most disappointing after a few thousand miles) can anyone recommend a good quality CV joint which is a direct and reliable replacement?

Cheers

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PostPost by: originalsprint » Sat Mar 19, 2016 7:23 pm

Hi there, I sympathise with your predicament and I suspect the CV Joint/s are on their way out. I had heard of this before with the CV conversion you have fitted. New CV joints should be available from Kelvedon Motors who are now handling the Sue Miller supplied kit. I personally fitted the Elantrikbits kit and the joints they use have grease nipples on and are very good - no wear or complaints at all. They are pricey but they certainly "do the business". Have a look at this nice and clear YouTube video that shows them being fitted - perhaps you could obtain just the joints from Australia to graft onto what you already have? Best of luck!

https://www.youtube.com/watch?v=AWq3FTdlC3E
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PostPost by: a d price » Sat Mar 19, 2016 8:48 pm

Fitted a set of col crunchers c.f. conversion at Christmas .They are expensive but very well made.You only want to do this job once.Highly recommended
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PostPost by: rgh0 » Sat Mar 19, 2016 9:22 pm

jono wrote:. It's in the order of 10mm rotational 'slackness' before a turn at the hub end begins to react at the diff end. There is also slackness when you articulate the outer CV joint.

Jon


Examine the free play in the CV's themselves individually. There is normally a significant free place in the diff itself from the differential gears. you may only need to replace 1 or 2 if they are worn. The Cv's will be a standard unit that a bearing supplier should be able to provide. Make sure they are properly greased before replacement

Even a very badly worn CV will only have 1 or 2 mm of rotational movement

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PostPost by: jono » Sun Mar 20, 2016 11:29 am

Thanks Rohan,

On further inspection there's a very large amount of slack movement between the outer CV and the diff, which is not good after only 6k miles.

I've noticed that the joints appear to have shed their grease from between the join in the aluminium spacer which may account for this premature wear, or perhaps I have the cheap Chinese copy CV joints.

So it would appear this issue is not just confined to the small Elan.

Regards

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