Lotus Elan

Electric Elan

PostPost by: Bombay Racing Green » Mon Feb 10, 2020 11:12 pm

I kept the transmission on my Elan and Europa conversions. It means you can get away with a smaller motor. Mark’s motor is a beast and will, I suspect, pull away easily in fourth. Mine is much smaller but will do it but it is sluggish. In first and second it’s quite sprightly even with a small motor.

Unless you’re willing to do serious modifications or get a lotus 47 chassis then you’re pretty much stuck with the transmission on a Europa. It forms part of the rear suspension. Not an issue with the Elan.
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PostPost by: LotusElon » Tue Feb 11, 2020 4:05 am

David1953 wrote:Mark
Great work.
I see you have gearbox but no clutch. How necessary do you think the gearbox is?
What is the performance from 0 like in 3rd or 4th?
David

Thanks David,
The motor is not a monster as say a (heavy)Tesla motor with 400+ hp, where gearing not necessary, its a lighter 120+hp motor, but with lots of torque from zero. There are lighter and more powerful motors than the hyper9 but I couldn't find one that worked with relatively low 120v (for 5 light tesla modules) and had a suitable, proven matching controller.

So I really like the choices the gearbox gives.
It is reasonably easy to change gear, if necessary, on the move but I tend not to.
The motor spins upto 8000rpm so:
1st is ~ 45mph max ... good for childish stuff :-) eg smoking wheelspin starts, and in the right place, drifting.
2nd ~70mph is the gear I use most on twisty stuff with max acceleration (even at 70/8000 the motor is quiet and doesn't sound strained).
3rd can set off and should do ~100, bit less acceleration from 0 - probably a good trackday gear.
4th can set off, but quite gently - probably my least used gear atm - unless it turns out to be more economical.
...... Matching best gear/rpm/torque/efficiency curve on an electric motor is a different 'kettle of fish' I'm still getting my head round - the controller software has a multitude of inter-related settings.
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PostPost by: 2cams70 » Tue Feb 11, 2020 6:01 am

Sorry if you have already explained but why did you retain the transmission? I wouldn't have thought it needed in an electric car. Would make it more fun though I must admit !
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PostPost by: David1953 » Tue Feb 11, 2020 11:44 am

LotusElon wrote:...... Matching best gear/rpm/torque/efficiency curve on an electric motor is a different 'kettle of fish' I'm still getting my head round - the controller software has a multitude of inter-related settings.


Makes sense, projects always looks easy to someone who has not done it.
Are you on a 3.7 diff.
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PostPost by: LotusElon » Tue Apr 14, 2020 4:02 pm

Sorry I missed those Q's.
@2cams70 I kept gearbox as 2/3rd gears probably most useful, and easier than making a custom 1 speed gear.
TBH I'm finding (before lockdown) 3rd is most useful, but 2nd has its uses (best off the lights :-) )

@David1953 Yes the Diff is standard 3.7:1 .. and yes its been quite a challenge (but very rewarding).

Now in Lockdown I'm planning some 'lotus' work ..

Question for you guys
[Background: the car was one of the last out of Miles Wilkins workshop, where it was languishing/rusting for over 25yrs before Miles put on new Chassis, Bushes, Springs and rebuilt engine].
Miles is a stickler for original parts so the new Springs are exactly the original spec: Correct wire Ø, turns, lengths.

BUT the front of the car is about 1" too high, and the rear is 1.5" too high (and yes, its driven ~ 1000 miles to settle, and bushes/Joints tightened with suspension loaded - well loaded, to try and lower these heights). The weight ended up much the same as before the mods, only ~20Kg lighter, and same F-R distribution [Result :-) ]

I've had/rebuilt several elans over the years, and prefer the standard suspension set up with original springs giving the ride / grip / feel I like for twisty, bumpy B-roads and occasional track days (with Lower F & Rear wishbones approx. Horizontal) . I could get shorter/harder springs, and even adjustable seats, but prefer not to.

So maybe someone could enlighten me:
a) WHY do factory spec springs make an Elan sit high ? (Youngs Modulus / stiffness of steel has not changed !).
b) Did new Elans always sit high ? (I could only afford them when they were 10-20yrs old, and the springs/ lotocones / spring bushes had settled, and rust had settled in ).
c) As an experiment, I could cut 1 coil from the rear, and 2 coils from the front (Face off, re-anneal etc.) which would give the correct fitted length - but that would theoretically put the spring rate up... I cant square this
d) ... Assuming the experiment doesn't work (correct fitted ride height, but wrong spring rate) .. I'll get Paul Mattys 1" shorter "Standard" rear springs, and Kelvedon adjustable height shox.

Insights and suggestions welcome. (Project is > https://www.instagram.com/lotus_elon/ )
Last edited by LotusElon on Tue Apr 14, 2020 8:25 pm, edited 1 time in total.
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PostPost by: David1953 » Tue Apr 14, 2020 7:58 pm

When you say sitting high is that above the 6 1/8" Lotus manual quotes? The setup instructions are to load weights into the car till it comes down to this height, so I assume empty it was always above this.
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PostPost by: LotusElon » Tue Apr 14, 2020 8:20 pm

David1953 wrote:When you say sitting high is that above the 6 1/8" Lotus manual quotes? The setup instructions are to load weights into the car till it comes down to this height, so I assume empty it was always above this.

Yes, it sits (even before conversion) about 7.25" with driver, at the rear, (to rear bottom of sill) .. which is over an inch higher than all my previous Elans (on original Springs) .
Elan High.jpg and
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PostPost by: benymazz » Tue Apr 14, 2020 11:17 pm

LotusElon wrote:Yes, it sits (even before conversion) about 7.25" with driver, at the rear, (to rear bottom of sill) .. which is over an inch higher than all my previous Elans (on original Springs) .


Wow, practically a monster truck!

Been following you on instagram for a while (my tag is morrbenj). It's a joy to follow along with the conversion and I'm glad to see you on the forums now too, lol.

Regarding the max speeds in each gear you posted above, those are almost exactly what I get now in my S2 with the gasoline engine. It has the factory close ratio gearbox and 3.9:1 rear end. My spreadsheet tells me redline in first gear is 46mph, 2nd gear is 70mph, 3rd is 94 and 4th is 115.

The ratios in the box are 2.51, 1.636, 1.23, and 1. I love how ridiculously tall first gear is... fun fact, if you change to a 3.55 diff with the close ratio box, and raise the rev limit to 7000, you can get to 54mph in first. It's insane. And that's still with stock diameter tires (73in circumference)...

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PostPost by: rgh0 » Wed Apr 15, 2020 4:09 am

If you loaded with the Lotus specified weights and loosened and re-tightened all the bushes at the normal ride height and its still to high then assuming all the rest of the suspension is standard dimensions including tyre diameters then the springs are to stiff or to long or both

You need to then remove the springs and measure free length and spring rate to see what the problem is and determine how best to fix it. Spring winders can normally rewind a coil spring to correct the free length if its to long (or to short), alternatively you can cut off a bit less than an inch off the free length to lower the car by the inch your looking for. The impact on spring rate of cutting that small amount off especially at the front will be small and not really noticeable, given the number of coils. Once you have carefully measured up the removed springs you can calculate precisely how much you need to cut off to get the needed compressed normal ride height length wanted

A very experience suspension tuner once told me most race drivers can only detect a +/-50% change in spring rate and below that most don't notice it.

cheers
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PostPost by: LotusElon » Wed Apr 15, 2020 8:39 am

Thanks Rohan, that's helpful ... even if the number of coils, and wire diameter are all correct, the free length may be wrong. [I guess I was a bit in awe of Miles, and his supplied springs :D )
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PostPost by: LotusElon » Wed Apr 15, 2020 1:00 pm

@Ben Thanks for comments and insta heads up .. great set of pix - I'm now following you too (as 'Human_Amp', Lotus_Elon is just the project page).

And yes having the option of gears is fun if only for 2nd and 3rd. 2nd at the electric motors 8000 rpm red line is a bit odd, you dont hear it just the acceleration stops :mrgreen:
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PostPost by: LotusElon » Mon Jun 08, 2020 11:44 am

Just posted a walkaround video of 'Lotus_Elon' .. still work-in-progress (which 50yr old Elan isn't ? :-)
https://www.youtube.com/watch?v=53WO-Oo2REU

and how it works (testing -- someone has to do it :-) )
2Mb.gif
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PostPost by: HCA » Tue Jun 09, 2020 6:45 am

Brilliant! Well done :D
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PostPost by: rgh0 » Tue Jun 09, 2020 10:14 am

You need and LSD in that :lol:

cheers
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PostPost by: LotusElon » Tue Jun 09, 2020 10:42 am

rgh0 wrote:You need and LSD in that :lol:

I wish :D
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