Lotus Elan

Are my donut’s distorted?

PostPost by: Fergus » Mon May 09, 2022 10:40 am

Hi I bought a nice Elan s3 with lots of non standard Spider bits last summer and I’m slowly finding my way round it. The car was rebuilt pre 1980 and hasn’t covered many miles, it’s a great runner but I noticed going into reverse sometimes there’s maybe a bit of wobble in the drive shaft. Checking out the “donuts” they look a little distorted, I’ve bought new ones but before I get dirt could could someone please check out my photos…. maybe this distortion is within limits? Thanks
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PostPost by: m750rider » Mon May 09, 2022 2:33 pm

That one looks a little bit out, but maybe this picture is with the suspension not in compression.
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PostPost by: smo17003 » Mon May 09, 2022 4:44 pm

It appears (unless it's a trick of the camera) that there's a washer between the spider and the rotoflex - I don't think that should be there.
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PostPost by: types26/36 » Mon May 09, 2022 5:30 pm

The coupleing bosses have a high and low sides which must be fitted the correct way round.
Its hard to tell from the pictures if they are correct, here is a pic from the manual that explains which way they should be fitted although I'm not sure if it makes any difference with the Spyder set up you have.
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PostPost by: 512BB » Mon May 09, 2022 8:10 pm

It stands to reason that no matter what shaft arrangement you have, if it encorporates a donut or donuts, it needs to run as true or flat as possible, unlike in the picture. It appears that the shaft has been connected to the low bosses, which is not correct, and will seriously shorten the life of the donuts and may cause vibration.

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PostPost by: Fergus » Mon May 09, 2022 8:34 pm

Thanks to all of you. The photo shows the donuts under compression so I was pretty sure they should be flat and running true and yep why’s that big washer there? I’ll dismantle the shafts and probably put in new the new bits. Cheers
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PostPost by: sprintsoft » Mon May 09, 2022 9:27 pm

Hi Fergus,

I think you have a Spyder driveshaft conversion fitted, you can see the sliding spline in your pictures, the outboard end connecting to the disc should be a hook joint, not a second rotoflex.

The inboard end you are showing should have the Spyder fail-safe boss installed between the diff output shaft and the rotoflex, if it is missing or wrongly assembled then its probably contributing to your misalignment.

I'm attaching a pic here of the conversion, I marked in red where you can just see the Spyder internal boss that prevents the shaft detatching in case of a rotoflex failure.
SpyderDrive.jpg and

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PostPost by: Fergus » Tue May 10, 2022 11:28 am

Hi again. It looks like the shaft was connected to the low boss and the head of the Spider “fail safe” insert was rubbing, due to insufficient space. I’ll connect the shaft to the high boss and re-assemble using the new donuts. Thanks again.
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