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The only place for a coil spring is up Zebedee's arse.
Member
Joined: May 14 2018
Posts: 21

I keep forgetting to fold / unfold my mirror when I park up, and I'm really lazy so I was wondering about the possibility of hacking together a powerfold mirror for my beloved P38. I know a lot of the P38 / discovery 2 parts are interchangeable and, looking at the disco mirrors on ebay the fitting doesn't look a million miles away. I imagine the electric bit operates in some incredbly weird, esoteric way as per usual though.

Has anyone attempted this before? I've done some googling, but can't find anything online.

I'm also considering shelling out for a 3d printer, so if the fitting isn't quite right I should be able to ring something up to make it fit.

Would I be better just buying a motor and trying to fit it into the current P38 housing?

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Joined: Sep 14 2016
Posts: 279

Electric control bit doesn't really matter as its a simple DC motor. Take supply out of an always live when ignition is on feed with the usual bi-directional power on / power off drive and job done. Retracts when the ignition goes off, swings out when it goes on. Basically a change-over relay and two diodes. Need an over-ride for servicing of course.

A potentially hairy issue is if Disco system lacks limit switches relying on seeing the stalled motor current spike to detect end of travel. Still do-able in a retro hack but a pain in the behind to get always reliable right without risking motor burn-out. Correctly done a computerised system can detect difference between hard stop and sticky movement so motor overload is unlikely. Not so easy with a simple retro-hack where stalled current spike has to be greater than maximum overload. I've built such limit stopless drive systems in pre micro days with safe stall current and short overload motion capability but it gets tricky.

3D printers sound like good idea but its a shedload of work to get properly up to speed for real world jobs. Need good one too if the results are going to be strong enough. That said if you do get a good one folk will be forming a queue for good quality sunroof guide bits! Better to design properly and go to a bureau service. Looked at the whole 3D thing more than a few times but as I still can't be arsed to get my CNC mill going ....

Clive

Member
Joined: May 14 2018
Posts: 21

I have a spare raspberry pi with a touchscreen on it and some GPIO pins spare that I can use to rig up a 'proper' control system.... I've been thinking about tying the windows & lights into that anyway so I can (eg) crack the windows remotely when it's hot or whatever, adding the mirror motors shouldn't be too much trouble.

3D printers have dropped loads recently, there's a decently reviewed one on amazon at the moment for around £200. As you say, probably not strong enough for external bits but should be fine for internal stuff like a decent mount for the raspberry pi :)

Member
Joined: May 14 2018
Posts: 21

I finally got round to writing up my attempts to add a powerfold mirror to my P38: https://tall-paul.co.uk/2018/11/15/p38-part-2-folding-wing-mirrors/

Member
Joined: Sep 14 2016
Posts: 279

Congratulations. Glad you got it all sorted and working well.

Clive

Member
Joined: Mar 22 2016
Posts: 968

Excellent Paul, something for the taste buds in the future.
How were the mirrors controlled in the disco ?
Maybe something worth doing as a swap out kit !
I’d certainly be interested..
I park 2 wheels on the pavement as mine get whacked quite often.

Member
Joined: May 14 2018
Posts: 21

no10chris wrote:

How were the mirrors controlled in the disco ?
Maybe something worth doing as a swap out kit !
I’d certainly be interested..
I park 2 wheels on the pavement as mine get whacked quite often.

In the disco there's a plugin controller and a button to trigger them. However the button is an absolute pain I believe (you have to press it for just the right amount of time, or it triggers twice) and it doesn't do it automatically.

At the moment I have a cable running from each mirror to a box in the glove box, which isn't the neatest addon as a kit!

However, at some point I want to work out how to route cables through the existing cable run from the door and tidy it all up. Once I've done that I'll happily put some together for anyone who's interested :)

Member
Joined: Mar 22 2016
Posts: 968

I’m up for that