Lotus Elan

Engine mounts for the twin cam

PostPost by: JimE » Wed Sep 06, 2017 4:24 pm

I know there is often talk about the longevity of the rubber in the rotoflex but the engine mount (on the passenger's side) on my Sprint has been on the car for no more than a 1000 miles and has collapsed. Thankfully it didn't happen while at Brands last weekend. The rubber has pulled away from the metal. Hopefully a bad batch and the pair I've just ordered from Miles Wilkins last longer! Jim
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PostPost by: john.p.clegg » Wed Sep 06, 2017 4:44 pm

Mine delaminated a few months ago causing a knock on taking up the drive , searches on Fleabay show a variety of prices but the quality ??

I purchased a pair and filled them with high modulus silicone....let's see if that makes a difference...

John :wink:
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PostPost by: Grizzly » Wed Sep 06, 2017 6:25 pm

I had a similar issue....... i went through one every few months during my daily use of my +2, turns out the stainless manifold i fitted was putting to much heat into the engine mount causing it to prematurely fail. Fitted a heat shield and ceramic coated manifold that seems to have fixed the problem, engine mount is cool to the touch and isn't showing any signs of failing.
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PostPost by: JimE » Wed Sep 06, 2017 7:03 pm

Heat shield sounds like a good idea.
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PostPost by: Gopherit » Wed Sep 06, 2017 9:16 pm

Why persevere with a design that is bound to fail? When we first got our +2 the signs of failure were present and having thought about it I went looking elsewhere, eventually finding this bunch:
http://www.miltonrace.co.uk/
Wonderfully old school, confirmed by the great pic on the front of the brochure, but also keen on providing kit that works.
See P10 for the engine mounts I fitted. If it's not obvious, unlike the shear failure in every direction Lotus mount, IF this were to fail it does so in a failsafe way. The likelihood of this happening however is about 0 as the polyurethane bush is in compression.
The first set I fitted from Milton I was worried that they might be a bit too stiff and decided to soften the bush by drilling radial holes - see pic. These were then fitted and lasted 5 years until I had an engine fire that destroyed the front of the +2 - now still in rebuild! Worked perfectly.
Over time we acquired a Vegantune Evante - couldn't afford a baby Elan. Trying to sort the carbs out when we first got it discovered they were supporting the engine. With no time to get from Milton it was into the workshop and a short time later a pair of mounts using spare polyurethane suspension bushes - not radially drilled. This helped solve the carb problems and we do not get any more vibration. Easy to make and fit.
Many thanks to the Milton brothers!
(you may have to work out the pics, I cannot see how to re-order them and they are reversed from my upload sequence!)
Attachments
p1270363c.jpg and
p1270362c.jpg and
p1270355c.jpg and
p1140534c.jpg and
p1270347c.jpg and
It's not a rehearsal
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PostPost by: Lincoln62 » Thu Sep 07, 2017 12:41 am

Just in case you weren't aware the mount on the exhaust side is a standard Ford item.

The mount on the carb side is a Lotus only mount which looks the same on casual inspection but is designed to lift the carbs about 3/4 inch.

My Elan had a Ford mount on the carb side when I got it and the airbox would hit the footwell under acceleration.

The Lotus mount cured it.
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PostPost by: JimE » Thu Sep 07, 2017 8:47 am

Lincoln62 wrote:Just in case you weren't aware the mount on the exhaust side is a standard Ford item.

The mount on the carb side is a Lotus only mount which looks the same on casual inspection but is designed to lift the carbs about 3/4 inch.

My Elan had a Ford mount on the carb side when I got it and the airbox would hit the footwell under acceleration.

The Lotus mount cured it.


I use to have the same problem of the carbs touching the bodywork when I had a Sprint in the seventies. It use to drive me mad.
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PostPost by: collins_dan » Fri Sep 08, 2017 6:09 pm

lotus-twincam-f39/engine-mount-heat-shield-t17722.html

From the post, you can see that I made this heat shield in 2009 and the mount is still going!
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PostPost by: JimE » Fri Sep 08, 2017 7:18 pm

Thanks Dan. I'm going to make one. Jim
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PostPost by: mark030358 » Fri Sep 08, 2017 7:59 pm

kelvedon already sell mounts like this...

cheers
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PostPost by: JimE » Wed Sep 20, 2017 1:17 pm

Well today I got round to changing the engine mount on the passenger side. Turned out the rubber was sound but the adhesive used to bond the rubber to metal was the cause of the mount collapsing. Jim
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PostPost by: Chancer » Wed Sep 20, 2017 2:46 pm

There should not be an adhesive, it should be a rubber to metal bond done under precise conditions of temperature, pressure, time, surface preperation and treatment, rubber compound etc etc. - My father ran a rubber/metal mould shop and my mother the personnel department.

Over 20 years ago I bought an aftermarket X/flow gearbox mount, looked like it had been made by a chimp and it had been glued together with contact adhesive, lasted all of 50 metres :cry:

Actually that is unfair to chimps :D

Things havn't got any better since then, someone soon is going to be killed by rotoflexes letting go in the same way.
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PostPost by: Grizzly » Wed Sep 20, 2017 4:15 pm

Yep that sounds about right, mine were exactly the same..... Rubber looked ok but had separated from the metal. My money is still on heat being the cause.
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PostPost by: david.g.chapman » Wed Sep 20, 2017 5:51 pm

I have been thinking about firming up my engine mounts by putting a bolt through a standard mount with rubber around it. I posted something along those lines a while back.

I might still try it this winter and will post if something comes out of it.

I was told by a guy at a Lotus dealer to be careful making the engine mounts too stiff, as too much force would be transferred to the chassis with possible cracking...hmmm.

Dave Chapman.
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PostPost by: JimE » Wed Sep 20, 2017 6:17 pm

david.g.chapman wrote:I have been thinking about firming up my engine mounts by putting a bolt through a standard mount with rubber around it. I posted something along those lines a while back.

I might still try it this winter and will post if something comes out of it.

I was told by a guy at a Lotus dealer to be careful making the engine mounts too stiff, as too much force would be transferred to the chassis with possible cracking...hmmm.

Dave Chapman.

Yes. There is probably enough torque being transferred to the chassis as it is. I am going to make a shield as per the template on this thread. Here's a pic of the offending mount.
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