Going back to Rotoflex

[andyelan]

Hi Everyone

It always appeared to me that, at least in our era, Chapman never liked using metal joints to take driveshaft plunge. On cars with fixed length driveshafs like the Elite and Europa he used hook joints ok but when a wishbone arrangement required a variable lenght driveshaft, Elan, Lotus 47 etc, there he used a donut.

Now, I'm not an expert on the 26R, but I get the impression that this car might have used sliding metal joint, however, while no wishing to upset anyone, was the 26R actually a Lotus design? I had a feeling that this was a conversion done by someone outside Lotus but was then copied when it proved popular.

One finall point on rubbrer donuts and the fact that they have to be considered as a consumable item. Is this really any more of a problem than say the rubber cam on a Zetec (or BDA), If either let go you're into serious expense.

Andy

[Elanintheforest]

My BDA hasn't got rubber cams! But I know what you mean, and probably for that reason, I still prefer chain driven cams. I've driven Elans with Rotfolex (lots of em, and lots of miles), and Elans without...and I can't tell the difference. The two seater doesn't get much in the way of wind-up, but it can be quite pronounced on the Plus 2. The biggest worry for me is that the current crop of Roltoflex couplings only seem to last a year...irrespective of the miles done...they can come apart with the car just sitting still. On the other hand, I fitted new Rotofexes to my S3 in 1979....and after a quick thash last week, had a good look at them...and they're fine.

Until the current manufacturing problem is resolved though, I would use Sue Miller's / TTR's solid shafts.

Mark

[gerrym]

Mark, just to keep your theme running, the Rolloflics are probably more likely to fail with no miles (especially if suspension is sitting) high, due to the "creep" failure modes of elastomers. But then again Rotofloww couplings were probably not tested against todays weekend/summer only use patterns.

Regards

[robcall]

Technical report with/without rubber in driveline
http://members.iinet.net.au/~tduell/rep9.pdf

[andyelan]

Hi Mark

Rubber cam belts, of course

I didn't spot that one. Think I'll have fire my proof reader

Andy

[SJ Lambert]

Is anyone using the 4 & 7/16" PCD Metalastik Rotoflex Donuts p/n 21/979/1 (the ones with the metal interleaves bonded into the rubber elements to provide increased torque capacity)? Our Elfin open wheeler currently sports the 3.78" PCD ones out from the gearbox together with a c/v joint at each end of the half shafts. On an upgrade for higher torque we'd use the larger PCD donuts and discard the inner c/v joint.

With larger PCD (4.44") donuts are there only two choices - Metalastik Rotoflex part no. 21/932/1 or 21/979/1 (the higher torque application)?

Cheers James

[worzel]

Hi

Is it correct that racing spec donuts for the hillman imp are the same as the ones being sold for elans- I paid ?75 each for elan spec ones then found that the hillman aternatives were ?40 each!

John

[ftsoft]

Is anyone using the 4 & 7/16" PCD Metalastik Rotoflex Donuts p/n 21/979/1 (the ones with the metal interleaves bonded into the rubber elements to provide increased torque capacity)? Our Elfin open wheeler currently sports the 3.78" PCD ones out from the gearbox together with a c/v joint at each end of the half shafts. On an upgrade for higher torque we'd use the larger PCD donuts and discard the inner c/v joint.

With larger PCD (4.44") donuts are there only two choices - Metalastik Rotoflex part no. 21/932/1 or 21/979/1 (the higher torque application)?

Cheers James

Hmmmm I don't know if mine are metalastic, but they have metal bonded into the rubber as you describe. I also paid a hell of a lot more than 75 lbs for them.

Frank

[c42]

Hi John

You need to check that the Hillman Imp ones have the metal interleaves in them - the standards ones did not, I used to race an Imp in the historic saloon car championship and the Rotoflex couplings always came in Lotus packaging.

Regards
John

[Steve G]

Hi Andy,
Technically off topic now, but I'll answer.

How many modern cars can you name where you remember the journey?
How many modern cars can you name where you enjoyed the drive

How many "1600cc" Modern cars can you name that do 120(ish) mph and 0-60 in under 7 seconds and properly corner?

If you can find any that cost under ?20k let me know! 'cos I'd probably have one!

Oh dear, can't agree with any of that. I love the Elan and I bought it for reasons of newer cars being too sterile and uninvolving but you can't have old car blinkers. No drive has ever come close to my 10 laps of the Nurburgring in my old Honda Integra Type-R on my stag trip.

By the way, that's 1800cc of naturally aspirated, hand built Japanese perfection that develops 187bhp at 8,000 rpm, the car does 145mph (tested and confirmed by me at the 'Ring), 0-60 in 6.2 seconds (if you like lunching clutches) and 'corners properly', having some would say, the best front drive chassis in the world. On top of that, it did 35mpg on a long trip, used about 100ml of oil between 9,000 mile changes, carries 5 people, has a huge boot, never, ever breaks down and best of all had the steering wheel from a Ferrari 550 and a titanium gear knob.

OK, front wheel drive and/or being Japanese might make you gag, and it is a 1800 cc so how about this 2012 car;

http://www.lotuscars.com/gb/our-cars/cu ... e/elise-16

1600cc - check (1598cc).
120(ish) mph - check (127mph).
0-60 in under 7 seconds - check (6 seconds).
Properly corner - check (better than the Elan I would dare say).

Under ?20K you say?
http://beta.pistonheads.com/classifieds ... ise/235151

So we'll be seeing your Elan in the For Sale section soon then?

[SJ Lambert]

Metalastik rotoflex 21/892 replacement


Does anyone know where I can source a replacement for the above coupling - I have become aware of an alternate part number 21/967/1 which I understand is of same size but heavier load rating - am looking to use the small PCD ones initially before going upgrading to the next size up

[SJ Lambert]

The Queensland Lotus Club has featured an article by John Mihalich Jr utilising Volvo/BMW couplings in lieu as they have the same 3.78" PCD and are rated at 245 a side!

Preferred type is - Febi-Bilstein part # 04435.

http://www.lotusclubqueensland.com/imag ... b-2014.pdf

Imparts in Bayswater might have 'em!

[SJ Lambert]

Lotus Marques in Boronia have the high load rating ones part number 21/967/1 at $160 a pop, am waiting for Mission Supply to get back to me as their stock.....

[gus]

I would caution that in race cars the deflection is much less than in the Elan

[Sea Ranch]

Awesome find, Mr. Lambert. Excellent article and sounds like a great product (looks it, too).

But now, as Gus mentions, we need to find someone who has used them in an Elan (or Plus 2). This would give us some info not only on reliable in a setting with much more flex, but also give us a reading on how the possible extra stiffness affects ride, etc.

Anyone??

Randy