Lotus Elan

S3/SE diff cooling duct

PostPost by: Famous Frank » Fri Feb 04, 2011 5:32 am

My diff scoop isn't finished but I believe the forward section that is still missing will be lower that the one Bluesbrother has. Gordon, let us know if there is still one on your S2SE???
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PostPost by: ceejay » Fri Feb 04, 2011 5:35 am

The side air scoops look nice on the 26R to, but I always thought the
side scoops were designed to feed air to the rear brakes?
The side air scoops would be less of a problem as far as speed
humps and other things that may happen to snag on the lip of
the under body air scoop.
The sound of breaking & tearing fibreglass is not nice!!
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PostPost by: Famous Frank » Fri Feb 04, 2011 5:38 am

TTR catalogue describes the side rocker scoop as a diff scoop.
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PostPost by: ceejay » Fri Feb 04, 2011 5:41 am

Thats interesting, both would be very effective for the intended
purpose, side scoop would be less prone to damage.
Thanks for feed back and details on this.
Col.
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PostPost by: ardee_selby » Fri Feb 04, 2011 9:59 am

So....We have cooling "scoops" if they're fitted to the side, cooling "ducts" if they're fitted to the underside and "funnelythingys" if they're fitted in the Netherlands.

Guys, this forum is great! (But why the h*ll couldn't it have been around in 1976!)

Cheers to one and all - rd
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PostPost by: gordont » Fri Feb 04, 2011 10:26 am

did we have the www in 76? I was 10!
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PostPost by: ardee_selby » Fri Feb 04, 2011 11:48 am

gordont wrote:did we have the www in 76? I was 10!


No, but if the guys working on ARPANET had been Elan owners, who knows what application priority they might have had.....

But back to my original question...

With the help on here, and on Frank's thread (with excellent photo's...thanks, Frank) I now know the fit & form it should take. I also conclude that it is a wise thing to have for any road car (that is to be used in earnest), and that the modern diff lubricants needs consideration.

What I'm not clear about is whether it's the 3.55 diff that is particularly effected. Or all other ratio's, as fitted on other Elan's including +2's. But since I can't see myself having anything other than an S3/SE Coupe, it's academic to me.

Don't know what happened to the S3/SE Coupe on ebay... but for those who didn't see the write-up it included:

"another odd detail that came out during the full rebuild was some scraps of glassfibre under the passenger side. I?d always thought they were an old exhaust mounting, but it turned out to be the remains of a type 26R differential cooling duct. There?s a lot of old paperwork between owner, AA and Lotus concerning repeated differential failure with high-speed cruising and perhaps it was fitted by the factory to cure that. I?ve restored a replica one, using the original screw-holes as a guide"

Cheers - rd
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PostPost by: jimj » Fri Feb 04, 2011 2:27 pm

Now I know nothing about aerodynamics though I did write to Colin C. in 1976 suggesting the venturi effect to suck air out from under an F1 car........but I think he probably never even read my soppy letter. My opinion then was based on, not science but, common sense, and common sense suggests to me that as you drive along there`s lots of fresh air wafting about around the diff. Wouldn`t the scoop in Gordon T`s photo just be scooping air that would have draughted up around the diff. anyway? It doesn`t seem to collect and direct any extra air to an area lacking in fresh air, but what do I know?
Jim
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PostPost by: ceejay » Fri Feb 04, 2011 9:24 pm

I like the idea of keeping things cool, I have three diffs, 4.1,3.9, 3.55, I have been using
the 3.55 for several years simply for the longer legs it gives on the open road
(I live in the country)

On one occasion about 15 years ago I experienced a Diff failure while returning home
from the Far South Coast of NSW via the magnificent "Snowy Mountain Hwy", most
Aussies with performance cars know about this great driving road.

The diff problem reared it's ugly head on the descent down to Corryong along some
long sweeping downhill bends, initially, everything was OK until an almighty
protesting howl & wail came from from the Diff region.

I backed off immediately, stopped the car, got out and had a look underneath, the
streak of oil from the Diff region and out the back indicated I was in deep Do Do's.

I limped into Corryong just a few Ks down the road, found an accommodating
bloke in a servo, we put the elan up on the hoist, then we discovered a seal had
blown out on the RHS Diff output shaft... my first question was why?

I bought a couple of litres of Diff oil from the servo bloke, re filled the diff, we
poked the seal back in as best we could, lowered the elan off the hoist, I thanked
the guy with some moola $$, and gingerly set of for the slow trip home.

To finish this article, yes, I had been driving the elan damn hard, did the Diff
overheat? If I had an air cooling duct fitted would it have saved the day?
It is hard to say yes or no to either question, but I'm sure it would have helped.

I have a floor pit in my workshop, and out of curiosity one day after
a very long hard run in the elan up in the Alpine country, I parked it
over the pit, jumped out, went down into the pit under neath and felt
the temperature of the Diff casing... Jeez, it bloody near burnt my hand,
I could not believe how hot these things run.

So, we need the best of the best in lubricants for the Diff, and yes,
my thoughts of fitting a Diff air duct are very positive, but which one?
The under body type? Or the 26R side sill mounted type?
I must also remember to replace the broken Diff oil temp gauge.

Any thoughts out there.
Col.
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PostPost by: robertverhey » Fri Feb 04, 2011 10:01 pm

I'll jack up the S3 SE and take some pics when it cools down a bit in Sydney....(41C today and has been like this for a week!). I don't think the scoop would achieve a lot....pretty small intake area. But I've never had a diff overheat in either Elan or +2. But obviously there was a reason for the scoop being fitted. Snowy Mts Hwy....yes it's a beauty. Robert
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PostPost by: ceejay » Fri Feb 04, 2011 10:23 pm

23C & 85% humidity here in North East Vic, and we are about to be deluged
today by the remnants of Yassi... not the kind of day for a fang in the lotus.
Will look forward to seeing the pics.
Col
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PostPost by: Famous Frank » Sat Feb 05, 2011 3:04 am

I'll look forward to seeing those pics too. Won't be long I'll have replacements ready! After all this, i still think they look "Cool!" The side sccop that mounts on the rocker may work as good or better but once I get this body work done and lay down a beautiful paint job, I don't want to cut a hole through the side, and through the interior.

Would the bottom scoop not only add downforce?

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PostPost by: Famous Frank » Sat Feb 05, 2011 3:26 am

Mike asked to post some of his pics earlier in this thread and Gordon posted two of Mike's (Bluesbrother). Here is the 3rd. Mike's scoop is a reproduction. The dimensions look correct although the originals were made with fiberglass mat, not fiberglass cloth. The cloth may be stronger, although I'm not sure, but I think I want mine weaker so when I hit that speed bump or whatever, it will tear or break off.
Attachments
Mike's diff pic 3.jpg and
Mike's 3rd diff scoop pic
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PostPost by: ceejay » Sat Feb 05, 2011 5:23 am

I would agree with your comment re fibreglass strength... better
to have the scoop let go if it got snagged rather than something else.

The 26R side air scoops do look cool, but involve a bit more work
in cutting the holes through the sill for the ducting etc.
The under body scoop is probably the way to go...
and what was that you said.... a ground effect
elan... Mmmmm... maybe kidding ourselves a little.

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PostPost by: Jens » Sat Feb 05, 2011 12:31 pm

ardee_selby wrote:So....We have cooling "scoops" if they're fitted to the side, cooling "ducts" if they're fitted to the underside and "funnelythingys" if they're fitted in the Netherlands.



I wish... I am in the Netherlands but the Elan is located in a garage in snowy Sweden. Just heard that the neigbour cleared the roof from just over 80 cm's of snow. He was getting a bit worried that things would come down... Hence the distance. So, the fynnelythingy is Swedish, in the Netherlands we'd call it a "Trechterachtig iets".

Still, for a regular roadgoing car, is it necessary to have a Trechterachtig iets?

Cheers

Jens
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