Lotus Elan

Is this Rotoflex coupling bad?

PostPost by: 7skypilot » Fri Nov 09, 2018 10:28 pm

It's not too much trouble to jack the car up on the A-frames.

I've made a couple of wooden boards (courtesy of this site) which snug tightly into the A-frames and allow clearance for the discs. It really isn't much more trouble than jacking up on the sills.

Maybe worth a try?
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PostPost by: reb53 » Fri Nov 09, 2018 10:45 pm

7skypilot wrote:
IMHO a contrubutory cause of donut failure is the donut being stretched unreasonably when the car is jacked up on the sill and the rear suspension is fully extended.


I suspect that this isn't the only bad thing that comes from prolonged jacking.
25 years ago, after a crash, my car was carted off to the local "sports car expert" repairer.
By the time I'd sorted the paperwork, and retrieved it to work on it myself, it had, unbeknownst to me, been fully jacked up at the rear for about 6 weeks.

When finally back on the road both left, and right, rear wheel bearings failed within weeks of each other.
I keep good records and it was way before their time for both sides, which had been replaced at different times as well.
I think the prolonged pressure on them, without them moving, put small "dents" in the races.

Ralph.
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PostPost by: Matt Elan » Mon Nov 12, 2018 11:17 am

Just reading Tony Rudd's autobiography 'Its been fun' and he sys that the Rotoflex failure were on the top of the warranty claims list. So Rotoflex failure was an issue in 1970, and Rudd replaced them with stronger ones which were 'already under test' when the Sprint was introduced. And he describes how the Sprint engine was based on the BRM Phase II engine used by Mike Spence BRM Loti....
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PostPost by: Andy8421 » Mon Nov 12, 2018 12:30 pm

reb53 wrote:
7skypilot wrote:
IMHO a contrubutory cause of donut failure is the donut being stretched unreasonably when the car is jacked up on the sill and the rear suspension is fully extended.


I suspect that this isn't the only bad thing that comes from prolonged jacking.
25 years ago, after a crash, my car was carted off to the local "sports car expert" repairer.
By the time I'd sorted the paperwork, and retrieved it to work on it myself, it had, unbeknownst to me, been fully jacked up at the rear for about 6 weeks.

When finally back on the road both left, and right, rear wheel bearings failed within weeks of each other.
I keep good records and it was way before their time for both sides, which had been replaced at different times as well.
I think the prolonged pressure on them, without them moving, put small "dents" in the races.

Ralph.

A related problem - I had searched for ages to locate the cause of a long brake pedal. I checked disc runout but all was fine. Can't remember why I did it, but on one occasion I had the car supported on the bottom of the rear uprights rather than the sills. One rear wheel bearing was clapped out, the disc was wobbling all over the place. The reason I hadn't spotted it before was the preload applied to the bearing by the rotoflex when the car was jacked on the sill and the wheel was on full droop - it had masked all the play in the bearing.
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PostPost by: jimcast » Thu Nov 15, 2018 10:31 am

Many years ago I had a doughnut let go which then unwound itself and wrapped around the handbrake rod causing the back brakes to lock on suddenly. Luckily I was travelling at low speed at the time and got away with it but could have had a nasty accident.
An acquittance also had one go on his +2 at 80mph and it destroyed a whole back corner instantly but he was able to walk away from it.
Please therefore do not ignore the "Horror" stories! It could happen to you.
Any doubt change them!
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PostPost by: Famous Frank » Fri Nov 16, 2018 2:55 am

Back in 1969 I was Autocrossing my VW almost every weekend. I was watching this beautiful Elan on the track. Suddenly the back of the Elan swung around and came to a stop. I ran up to see what happened. i noticed all the gas coming out of the tank. A closer look exposed a broken inner Rotoflex. The axel flailed around, bent the lower A-arm, tore the fiberglass in the bottom of the trunk and sliced a hole in fuel tank. At that point I said to my self "OMG, I'm glad I don't have one of those cars!"

Little did I know then that from 1972 onwards I wouldn't ever be without one. Buy the CV's now. It might be a lot less money and a lot safer.

Frank

Oh, remember, Lotus Elan 26R's never had Rotoflex's. That was in 1965 / 1966. They used Sliding Splines. And the super powerful (46 HP) VW Beetle had CV joints in 1969.
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PostPost by: StressCraxx » Fri Nov 16, 2018 4:39 pm

While I agree with Frank about the CV axles, the donuts you have are the earlier ones with solid bolt inserts, not the modern ones with folded sheet metal. Unless you flog your Elan through the gears at the intersection, run sprints or gymkhanas, I would have no problem keeping them in service. Simply inspect them and check bolt torque carefully whenever you perform other service on your car. The usual root cause of donut failure is a loose bolt that fatigues and breaks.
There is no cure for Lotus, only treatment.
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PostPost by: Foxie » Sun Nov 25, 2018 8:59 pm

Many years ago, I was late heading in to work one morning. I came on a long queue of 2 lanes of traffic stopped at the lights. The 'turn right' slip lane was empty, so I took pole position, confident in getting out in front and pulling in ahead of all the traffic on my left.

When the lights changed, I redlined the engine and dropped the clutch. There was a tremendous bang and racket from the rear of the car. I was still sitting at the lights, while the traffic disappeared in front. I had no drive, and no brakes either.

The outer rotoflex had burst, and in doing so completely broke the rear caliper, lugs and all, off the hub

I was very late for work that day.

I think that was around the time I changed to CVJs......... :)
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PostPost by: Donels » Mon Nov 26, 2018 4:44 pm

I am currently rebuilding my +2 and have found the LH boot floor, associated boot front wall and inner wheel arch have been replaced/repaired. There is no other repair work to show it’s been rear ended, so I’ve concluded it’s had a doughnut failure at some point in its life.

It’s now got solid driveshafts!
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PostPost by: AussieJohn » Sat Dec 22, 2018 8:53 pm

Those who knew Owen Wuilleman may have heard his tongue in cheek remark about this, "At least the driveshaft probably knocked you on the back of the head so you you wouldn't feel anything as you were burnt to death"
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PostPost by: elansprint71 » Sun Dec 23, 2018 12:40 am

I know that every time one gets into an Elan there is a temptation to blast off (for me it was like this in 74 and still is now). Drive like it's a normal car and when you decide to make the change, do not fit Rotoflexes, they are rubbish compared to period rubber.
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