Lotus Elan

Plus 2 electric lift motor for headlamps

PostPost by: NYK » Wed Jan 29, 2020 12:29 pm

I’m now rebuilding the car following respray etc. I had previously adapted the headlamp lift mechanism to use a Mazda MX5 headlamp motor. I had done some testing during the body repair/prep stage and had thought it was OK. But..........putting it back together I find it is not quite as hunky dory as I’d thought.
So I’m running the motor through a PWM to reduce the lift speed by around 50% as it all looked a bit too violent for the flimsy lotus fibreglass (just in passing I would mention that I bonded on a new front end and the glass layup on this is a lot thinner and hence more flex than the original).
I’m finding it is smooth to lift the pods, but when they lower there is a lot of juddering. I’m assuming this is a function of the weight of the pods trying to drive the motor and the motor resisting this force. As per the photo you may be able to see a solid link connecting the pivot arms on the motor cam and headlamp bar. This solid link is rose jointed at both ends, so there is really no compliance in the linkage.

Thoughts to resolve the problem include - replacing rose joints with rubber bush, adding some sort of damping or perhaps adding a spring between the actuating arms.

What have other done, do you see this problem?

F951036B-A574-4690-B08E-7A2E469EA859.jpeg and
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PostPost by: oldelanman » Wed Jan 29, 2020 2:08 pm

I think you need to retain the large tension spring from the original vacuum set-up for the system to work smoothly ...can't see it in your photo. Spyder mention reusing it with the kit they supply and I believe others have done so with their DIY installations too. That may be your problem perhaps.
Here's a couple of examples .....

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IMG_4935-410x307.jpg (63.06 KiB) Viewed 483 times

lift1.jpg
lift1.jpg (114.66 KiB) Viewed 481 times
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PostPost by: disquek » Wed Jan 29, 2020 2:48 pm

I didn't use the spring and mine goes up and down smoothly. Juddering sounds like stiction in the linkage to me.

The spring seemed pointless as it acts on the portion of the mechanism that's governed by the MX5 motor. If the spring acted on the pods, it might help. But using it in the factory location felt pointless.

Here's a link to mine with a video showing the action.

viewtopic.php?f=31&t=45665&p=326460#p326460

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PostPost by: NYK » Wed Jan 29, 2020 5:32 pm

Well I can see why the spring is used, it is countering some of the weight of the pods with one effect being that it takes the load off the motor, I do wonder if it also adds a bit of damping. To Kyle’s point I don’t think I have got any stiction in my set up but I do wonder if I took some of the weight off the push rod I might overcome the juddering I’m seeing. I don’t have the original spring so perhaps a small gas strut might work, it certainly should add some damping. It’s clear from Kyle’s set up which looks pretty similar to what I have done that it really ought to work as it is.
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PostPost by: pptom » Wed Jan 29, 2020 7:06 pm

Just to second oldelanman.
I have almost the same setup, DIY with an MX5 motor.
No spring and it's juddery and a bit violent, one spring is nice, two springs were overkill
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PostPost by: NYK » Wed Jan 29, 2020 7:43 pm

So I need a spring then, anyone got a spare one?
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PostPost by: oldelanman » Wed Jan 29, 2020 8:39 pm

NYK wrote:So I need a spring then, anyone got a spare one?


If nobody has a spare SJSportscars and Paul Matty both list new ones.
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PostPost by: NYK » Wed Jan 29, 2020 8:47 pm

oldelanman wrote:
NYK wrote:So I need a spring then, anyone got a spare one?


If nobody has a spare SJSportscars and Paul Matty both list new ones.


Ah, thanks for that probably easiest just to get one off them
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PostPost by: mbell » Wed Jan 29, 2020 10:13 pm

I have no spring and have similar judder...
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PostPost by: The Veg » Thu Jan 30, 2020 1:46 am

Interesting topic.

I took the easy route and bought Kelvedon's kit. Pricey, but I have a high-travel job so I don't have a huge amount of time at home to faff about with engineering things. Anyway, the instructions show a spring but it wasn't included in the kit and neither was a parts-list, although a small clamp to secure the spring WAS included. I've emailed them once and called them twice and so far have received no answer as to whether the spring is supposed to be included, but looks like a delicate little thing compared to even one of the two that are attached to the old vacuum-pod. I haven't got it installed as yet due to other priorities with the car lately, but the lights do seem a bit heavy so using a spring is probably a good idea.
Last edited by The Veg on Fri Jan 31, 2020 9:21 pm, edited 1 time in total.
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PostPost by: LaikaTheDog » Thu Jan 30, 2020 9:13 am

Hmmm... I have mx5 lifter with no spring, I do not have juddering but I do have twice the speed of @disquek
I would prefer a softer landing when closing... I wanted to put a spring on but I threw mine away as too rusty during strip down.... fool, keep everything!!
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PostPost by: Mr.Gale » Thu Jan 30, 2020 5:21 pm

I don't know if this will work on a +2, but here is how I did it on my Elan.
https://www.youtube.com/watch?v=_HLdt4Bhnto&t=9s

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PostPost by: NYK » Mon Feb 03, 2020 3:41 pm

What a difference a spring makes. Fitted and problem fixed. My thanks to George who had one spare.

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