Lotus Elan

Cv driveshaft query?

PostPost by: thorbs000 » Wed Jan 08, 2014 9:14 am

Hi all
My 68 +2 restoration is coming on and with all new rear suspension done it's time to think of ordering new cv driveshafts.
After ringing millers, only to be told by sue that she is not doing them at the moment,I got in touch with Kelvedon.they are struggling to get some of the bits and won't have any till end of jan at the earliest.
I then rang matteys only to be told that They have stopped supplying these parts due to some failures of parts supplied by them. The person I spoke to said it ended up in brake failure??
Has anybody heard any more on this?before I go out and spend a lot of money on these parts
Thanks

Ian
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PostPost by: peterako » Wed Jan 08, 2014 1:40 pm

Hi Ian,

Happy New Year,.

I can only comment on my Miller CV driveshafts which I've had on my car for approx 7-8 years and around 40,000 miles.

No problems of any sort (fingers crossed).

They DID highlight other problems early on like a broken diff mount. But have caused none.

Fit and forget (in my case). Expensive but, IMHO, well worth it.

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PostPost by: TroonSprint » Wed Jan 08, 2014 5:32 pm

From my conversations with her, I doubt that Sue Miller is going to supply these driveshafts again. I bought a pair from Col Croucher in Oz. These are REALLY expensive but are very well made. As my car isn't finished I can't comment on their performance or longevity.
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PostPost by: PeterK » Wed Jan 08, 2014 6:27 pm

Sue is trying to cut out some of the complexity in her life just now, and the CV drive shafts consume more time than she has right now. She has given Kelvedon permission and the drawings to continue production.

As far as I know failures only relate the the Elan. The Plus 2 has longer drive shafts and doesn't suffer from the CVs locking at full suspension droop.

Another option is the SpyderCars shafts which have one CV and a rotoflex.
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PostPost by: rgh0 » Wed Jan 08, 2014 9:57 pm

A well engineered and properly installed set of CV driveshafts will last vitually forever. I have had a set on my plus 2 for 20+ years and more thyan 60 thousand road miles and on the Elan for even longer and for about 30 thousand race miles without failure.

I guess it is possible for a bolt failure in the CV shaft attachement to cause a loose shaft which in turn could damage a brake line or cause one of the rear disks to come loose as they are located by the same bolts thus causing a brake failure at stated by the guy at PM. However the risk of a similar bolt failure with donuts I would rate even higher plus you have the very large risk of donuts themselves failing which you dont have with CV's

The 3 bolts at each end locating the diff and outer hub drive shafts to the CV adapters do need to be properly torqued and locked with loctite and potentially lockwired also just to make sure they dont come loose. The 6 bolts locating the CVs themselves to the adapters are less of a problem with less tendency to come loose but do need to be properly torqued and loctite locked also

The angular binding problem in Elans at full suspension droop can be cured by droop limiting shocks or cables or by higher angle CV joints as used in the Col Croucher Elan Trikbits CV shafts.

cheers
Rohan
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PostPost by: TroonSprint » Wed Jan 08, 2014 10:17 pm

Let's face it, almost all modern cars use that type of driveshaft with CV joints. I would expect them to last well over 100,000 miles, wouldn't you?
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PostPost by: AHM » Thu Jan 09, 2014 10:36 am

Perhaps most modern European, rear wheel drive cars, use this configuration. They are subjected to thousands of hours of endurance testing before they get anywhere near a production car.

The low volume 'Motorsport' parts that we fit are a different kettle of fish.
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PostPost by: TroonSprint » Thu Jan 09, 2014 10:57 am

Are they different? The Col Croucher shafts that I have look identical to the type used on many production cars. He machines them a little so that they can withstand a greater angle of operation, but other than that they seem to be the same equipment.
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Elan Trickbits Driveshafts by Col Croucher.
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PostPost by: rgh0 » Thu Jan 09, 2014 11:17 am

The units used by Col are standard high angle GKN Lobro CV's as far as I am aware. They are polished for smoother performance but otherwise not modified. I believe he modifies the metal end caps on the rubber boots so these do not bind at high angles on the drive shaft. I am sure he will be happy to discuss any details of his current units not covered on his web site to potential buyers

The continuous use at a high angle and high speed will wear a CV faster in an Elan than in most modern cars with more limited suspension travel and longer drive shafts but provided they don't bind, wear does not seem to be an issue in Elans. My Elan has done lots of miles at high speed and maximum droop cornering on the track but the second hand VW Combi CV's I used 25 years ago are still going strong. In a plus 2 the CV angle and any theoretical problems are certainly much less.

cheers
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PostPost by: AHM » Thu Jan 09, 2014 2:59 pm

TroonSprint wrote:Are they different?


Yes very - front wheel drive cars have a requirement for much higher angles due to steering so the outer joint is 'fixed' ie no plunge. This means that the inner joint does double the plunging.

TroonSprint wrote:The Col Croucher shafts that I have look identical to the type used on many production cars.

Rear wheel drive European cars yes. Predominantly German manufacturers as it is a German design.

The ones that Col makes are nice aren't they!
The only things I would do differently are:
1. Do away with the grease nipple - It serves no purpose you either have the correct grease quantity or you don't!
2. I would use Oeteker clamps rather than tie wraps - but the tools and jigs to do it correctly are very expensive, and he probably gets a more consistent and reliable result doing it by hand.

rgh0 wrote:The units used by Col are standard high angle GKN Lobro CV's as far as I am aware. They are polished for smoother performance but otherwise not modified.


He has also done lots of machining on the outside to remove unnecessary weight. Similarly there is no waste on the adapter which is nicely made.
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PostPost by: stugilmour » Thu Jan 09, 2014 4:25 pm

Ian, I think any of the available CV kits will be fine on your Plus 2.

I used the kit from Ray at RD Enterprises. With about 20,000 miles they are fine. I tore a boot at one point, but that was my error while trying to remove the diff for servicing. The RD kit uses shelf VW parts; just had to take the CV in to the VW independent to match it up to get a boot kit. As mentioned above, the Plus 2 shaft length is sufficient to prevent the locking issues. Note the RD kit also includes new high strength splined diff output shafts in the kit, which (I think) adds a bit to the length of the shaft.

Only issue with this conversion is it is pretty expensive. The kit is pretty heavy, so shipping might be a bit dear. No association, just a happy customer. The same kits may be available from other Lotus suppliers in NA.

http://www.rdent.com/

Elan CV Rear Axle Conversion Kits

Each kit includes two uprated differential output shafts with bearings, axle shafts with Lobro CV joints and adapter for outboard (hub) shaft. Installation is not difficult and can be accomplished by the Elan owner/mechanic. Enjoy the increased reliability of cv axles - no more rotoflex couplings to fail! If you're serious about eliminating the rotoflex couplings (donuts) this is the only way to go! Much better than u-joint conversions! Elan CV Rear Axle Conversion Kit is fully assembled and ready to fit. One kit required per car.

Ref. 26RD0034 Elan CV Kit - $1550.00

Ref. 50RD0034 Elan Plus 2 CV Kit - $1625.00



This kit does more than just replace donuts!
It replaces rotoflex couplings, intermediate axle shafts, differential output shafts and bearings, and associated hardware.


HTH

Stu
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RD Elan CV Pic 3.jpg
RD Elan CV Pic 3.jpg (31.88 KiB) Viewed 3010 times
RD Elan CV Pic 2.jpg
RD Elan CV Pic 2.jpg (26.87 KiB) Viewed 3010 times
RD Elan CV Pic 1.jpg
RD Elan CV Pic 1.jpg (24.98 KiB) Viewed 3010 times
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PostPost by: William2 » Thu Jan 09, 2014 5:29 pm

I ran an Elan for many years which had Tony Thompson driveshafts fitted. Good product and not too pricey.
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PostPost by: originalsprint » Mon Dec 21, 2015 11:24 am

Hi all,

I "bit the bullet" and bought the Col Croucher / Elantrikbits conversion and I have to say I'm well pleased. They are pricey plus you have to pay duty and V.A.T. etc. when they arrive in the U.K. but they are fabulous. The car feels taut and there is no limitation on the original suspension travel. This was important to me. I looked at all the others and they do recommend some limiters for the suspension travel whereas the "trikbits" system doesn't need it. Also, there's one U.K. system that still needs one rubber "doughnut" which seemed to be a backward step as the modern day rubber simply doesn't last due to them not being able to use the older style chemicals. I saw a great video on YouTube how to fit the "trikbits" system it's at:

https://www.youtube.com/watch?v=AWq3FTdlC3E

Hope this helps someone!
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PostPost by: Grizzly » Mon Dec 21, 2015 12:33 pm

As already pointed out its all about the quality of the CV joints used, i bought a set of Sue miller shafts just before she stopped selling them for my +2 and they started making a clunking noise after 500ish miles.

Since then i've replaced the CV joints (if memory serves i think they where OE VW) and not had any issues since.

A trick i was told by a guy i work with is to fit a BMW clutch CDV (Clutch Delay Valve) which helps reduce the shock load on alloy parts when you go with CV joints.

I know its very much a personal preference thing but i've gone with Rotoflex joints on my Sprint for the simple reason the CV joints took allot of the character from my +2 and i won't be doing huge mileage in it, yes it made it more reliable and low maintenance (which is good when you use it as an every day or race car) but i missed the eccentricity that makes it a Lotus.... After all if you wanted a car with no character why not just buy an Mx5.
Chris
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PostPost by: originalsprint » Mon Dec 21, 2015 2:06 pm

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...
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