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Discussion Starter #1
I'm looking for some solid motor mounts, but all I can find are poly based ones.

I have a friend that can lathe me up some inserts to replace my poly ones but thought I'd check in to see if other's have done this and/or have a source.

Race application only.

Thanks, Rob.
 

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Discussion Starter #3
I don't know if 95A are too soft, currently using 60A X 4. But in the past race cars I've owned I've always used solid mounts.

Do I4s "need" poly?
 

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Seems like reports here would indicate the need for softer mounts is do to the transmission needing something to dampen the abuse of hard shifts...
 

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Discussion Starter #5
I've heard of those reports, just not a subscriber to them "yet" (need more data) and no idea how they may or may not be relevant to my Quaife box with good NA power/TQ.
 

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solid mounts are a really bad idea unless you want to start considering the chassis as a consumable?
Considering how the Elise/Exige chassis is built (Bonded Aluminum, then riveted for peal strength)…I think this statement is not founded because, when Lotus shock tested this chassis for endurance, it exceeded all previous records of any other chassis design. So, as far as vibration through the chassis is concerned, there is no concern. Why did you make such a statement? Do you have some data/experience to the contrary for this chassis design?
 

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Considering how the Elise/Exige chassis is built (Bonded Aluminum, then riveted for peal strength)…I think this statement is not founded because, when Lotus shock tested this chassis for endurance, it exceeded all previous records of any other chassis design. So, as far as vibration through the chassis is concerned, there is no concern. Why did you make such a statement? Do you have some data/experience to the contrary for this chassis design?
sorry, but your so far wrong is scary.

look, it's an extruded aluminum tub, aluminium had pretty poor fatigue characteristics, if you vibrate the **** out of it, it will crack and fail.

and yes, this is not just theory, I have seen it happen, several times including on Lotus's own cars (back in the Autobytel days) when they solid mounted the gearbox's etc.

but don't let me stop you, go ahead....
 

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sorry, but your so far wrong is scary.
Be afraid…very afraid.
look, it's an extruded aluminum tub, aluminium had pretty poor fatigue characteristics, if you vibrate the **** out of it, it will crack and fail.
All true…so it begs the question; If you already know that, why didn’t you design for it?
and yes, this is not just theory, I have seen it happen, several times including on Lotus's own cars (back in the Autobytel days) when they solid mounted the gearbox's etc.
Did an engineer design the mounting system or did some $tup!d @$$ mechanic just replace one material for another and say he designed something?
but don't let me stop you, go ahead....
I’d be unstoppable if it wasn’t for physics and law enforcement!
 

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What advantage is a solid engine mount, compared to hardened poly mounts, like Innovative ?
You and/or I probably would not perceive a difference… but the reasons for replacing rubber mounts are twofold; 1. As your tires load up and the rubber engine mounts load up (windup), they both wind up in opposite directions. This is stored energy above and beyond the engine HP. The energy in the rubber is released and the tires hop. So when street cars “peal out”, you get this jerky chirping of the tires. The more solid your engine mounts are, the less “windup” you get and less chirping therefore a controllable hard acceleration. 2. As the engine moves back and forth, there is ever so slight a change in the length of the shifting cables that contributes to the sloppy shifting feel that we Lotus drivers get.
 

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OK, like I said, go on and solid mount yours, and tell us all how it goes over time...

and just to be pedantic, the Elise was never designed to have the powertrain solid mounted, it's a road car.

and just to be pedantic, I did not design it, Lotus Engineering did, as a road car.

Seems to me you don't have a clue what you are on about,
 

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Looks can be deceiving…
do you have to work hard to come across as such a tit?

OK, go on, prove me wrong by publishing the detailed analysis and testing you have done around the Elise chassis design & construction and it's ability to withstand the vibration loads placed upon it by solid mounting the drivetrain.
 

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Discussion Starter #15
Simon S,

Any chance you can give me the details of the structural issues you've experience including engine output, PM if you don't want to post here.

Hello Kitty,

Per what has been said, engine motion is wasted energy and has other undersirable effects for a race car.

Thanks, Rob
 

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As the engine moves back and forth, there is ever so slight a change in the length of the shifting cables that contributes to the sloppy shifting feel that we Lotus drivers get.
The engine can flail about with the softest mounts and there is NO change in the length of the shift cable assemblies. There is a cable and a sleeve. Both are mounted rigidly at either end. How the two ends move relative to each other has no effect. All the talk about engine movement affecting shifter feel is hooey. Our shifters are sloppy because of the internal components of the transmission.
 

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I don't know if 95A are too soft, currently using 60A X 4. But in the past race cars I've owned I've always used solid mounts.

Do I4s "need" poly?
I have Sector111 85a mounts. The reduction in engine movement is dramatic compared to stock. I would say about 80% reduction in movement with the hardest shifts. I only have about 200 WHP so your NA setup may see a similar reduction in movement.
 

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Simon S,

Any chance you can give me the details of the structural issues you've experience including engine output, PM if you don't want to post here.
nothing to do with engine output per say, and everything to do with vibrations from the engine/drivetrain.

Let me say I have never had the issue as I have never attempted to solid mount in an Elise, as I said, it's just a stupid thing to do.

As I said, I have seen several chassis with fundamental cranks in them from where they had solid mounted drivetrain components, and were effectively scrap.

Ask any Aero engineer about Aluminum and fatigue in relation to vibration/resonance from engines/pumps/etc. they will tell you the same.

That's not to say I think having the engine bouncing about on floppy mounts is a good thing, it's not, and running 'stiffer' mounts is not a bad idea, but there's a massive difference between 'stiff' and 'solid'.

the mounts we came up with for the Sequential box use big rubber bushes in them, and we have left the std right hand engine mount/damper as is as it works very well.
 

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Discussion Starter #19
Simon S,

Thanks for your information ... engine output does have an affect on vibration and stresses being put on the mounts/chassis - it can't be ignored, both produce the forces that could lead to structural integrity issues.

Do you happen to know the enigne output of those cars with fatigued chassis?

Obviously there are many factors that go into chassis fatigue (curb usage, off track, etc.) and you feel vibration is a contributing factor (agree), I'm just trying to gather as much data as possible and decide what is best for me.

Chassis isn't cheap, but anyone racing a Lotus should consider it a consumable item ... the question is just how long. For example, if I raced my Lotus every year for 5 years every month until the chassis got fatigued, then I'd be OK with that. Now if your data indicates the chassis will be fatigued after only 1 year (using solid mounts), then I wouldn't be Ok with that. So whatever data you can share, I'd appreciate.

Jason,

Thanks for your information, good to know.

Cheers, Rob.
 

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Now if your data indicates the chassis will be fatigued after only 1 year (using solid mounts), then I wouldn't be Ok with that. So whatever data you can share, I'd appreciate.
I'll bet any amount that Simon S(ays) doesn’t have any scientifically acceptable/repeatable data… don't hold your breath.
 
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