1986 Toyota MR2 - We’ve got a damn great hump...

The car not me btw
James

Oh thank goodness!
I'm sure you look proper sexy with your top off (as do I) but I'll stick with the car thanks...



I know exactly what you mean about temporary jobs. I've been saying that I'm going to change the big ends for about 3 years and haven't done it. Point taken.
To me 'doing it properly' involves repainting the whole thing with a gun. I haven't the money, equipment or time for that just now. So it'll have to be patched with aerosols. Maybe I should get it the right colour though... Point taken about panel wipe too. I actually thought about it before I put the black on.

I'm not sure your paint supplier will appreciate this idiot being on the phone though... (Thanks for the link - I'll look them up.) Would you like me to keep your name out of it!?

I've done the odd bit of rattle can stuff in the past - which mostly looked terrible - but I've never done fine filling, painting, flatting, and polishing before. This is very much the front end of a learning curve for me.
Lecture (and advice from everybody else) much appreciated. Thank you! 

James

Yeah but I'm unbelievably attractive in a masculine sort of a way and need to admire myself in well polished paintwork! But not vain, oh no, just properly adjusted...

Am I starting to sound like @quatermass ? Ah well, there are worse people to sound like I guess.




I did look up panel wipe this evening and found that some of it is based on isopropyl alcohol. Now IPA is used as a solvent in the electronics industry which is my neck of the woods. So yesterday, when I was kicking myself for not having panel wipe I realised that I had a tin of IPA in the garage and wiped it over with that. (The contents not the tin.) Seems I might not have been far from doing it properly after all.

@grumpynorthener has probably just winced...

I'm with grumpynortherner here.

I would rub back the whole thing before you spray and make another mess.

The spoiler is just small enough to be rattlecan size but not the rubbish cone spray cans from Hellfrauds. Contact the paint supplier you have had the link for or someone like Paints4U and order a mix-to-order rattle can. These are far better with a slightly higher pressure and have a fan type nozzle so it sprays like a spray gun. The mix-to-order cans aren't much more than off-the-shelf cans. Halfords used to do Holts mix-to-order cans too but the last few i had were not done very well so i've ordered from paint suppliers instead and they have been excellent. You might get a bit more orange peel than if you used a spray gun, but flatting it back will be ok.

Sand it all back uniformly, panel wipe, prime again with grey primer for undercoat but not etch primer (this should only be for bare metal areas really), sand with W&D down to 800, panel wipe,then dust coat with colour followed with a couple of wet coats of colour. With it being metallic i would guess you should then apply clear coat the same way.

Paints4u certainly do a colour and clear coat 'buy together' deal and i'd expect other places would too.

Perhaps not quite keeping up with the plot but does the plan move the high / low beam dash light to the switched side off the relay with an ickle fuse to stop nasties happening ?
James

The Doctor, I hadn't thought about Xenons causing the same problem. LED H4s probably wouldn't have worked either. I don't remember any comments when I was researching it though.

jamesd1972, I thought about rewiring the warning light for half of last night. A lot of the wiring goes through a junction box in the drivers foot well. That'd be an ideal place to do a mod and I considered sticking a relay in it to drive the warning light but...

1, I don't want to modify the car if I can avoid it. As it stands it's a plug in mod which seems like a good plan.
B, I definitely don't want to be running wires from the lights back into the car 'cos it'll look horrid unless I integrate it into the loom and that's hard to do properly.
4, And with regards to adding that relay to the junction box, there isn't a handy 12V feed that's alive at the right time.

Hmmph.

Not to worry, I have a cunning plan and I'm fairly certain it'll work. I'll draw it up later which'll give me another chance to think it through.

The whole thing is complicated slightly by the fact that the switch in the car should be either high or low. But if you move it slowly you can get neither or both so any solution has to cope with that eventuality.

James

Right. So the high beam warning light doesn’t work with the relays plugged in. This is because the relay coils have a higher resistance than the old lamp filaments so aren’t leaking enough current to light the warning lamp.

But also my dip beam relay won’t drop out because there is too much current being allowed by the high beam warning light.

Too much current - holding the relay, yet not enough to light the warning light. I need more and less. I need a new plan.


I wondered about modifying the wiring to the warning light. Maybe a relay in a handy wiring junction box. But there isn’t a suitable 12V feed. I wondered about adding “a thing” to my relay box that would stick 12V down the dip beam wire to light the warning light. But when you go to dip beam, if you don’t get the 12V off quick enough, you short the battery through the light switch… I thought of lots of things. All of them have problems.

One wrinkle is that you obviously have dip beam or main beam. The switch is either in the dip beam or high beam position. Right? Nope. As you move from dip to main the switch actually, briefly, turns both on. And when you pull the switch to the flash position there is a moment where neither filament is lit. So dip, main, neither, and both are all possibilities that I have to cope with.
That’s one reason why I went for the two relay design. Replace a filament with a relay coil and the car win’t notice… Shame it did.

Ok, sorry for spelling this next bit out at extreme length. It’s partly because you might be interested, but also it’s going to make me think it through so I hopefully don’t miss something.

So I’m going to replace the the two relays with a single double throw one like this.





We’ll have the normally closed position bring the dip beam on so the default position is dip (I don’t want main beam on unless it’s commanded to be on).
That means the relay coil is connected to the high beam wire and the dip beam wire is not needed. Great - it all works apart from the high beam warning light which, on the original set up, was connected to the bottom of the dip filament. So lets do that…





As it’s drawn above it’s in dip mode.
My relay is not energised and the dip filament is on. Earth current has two paths to choose from. The original one through the switch and the new low resistance one. Much of the current will take the new fat earth because it’s a lower resistance path so the switch should have an easier life. The main beam warning light is shorted by the switch and my relay so it’s off.

Next - Main beam.





So now the bottom of my relay is earthed and the relay switches over. The high filament lights and the dip one is out. However, just as in the original car, some current flows through the dip filaments to light the high beam warning light.

Next, the car’s switch is between positions.





My new relay isn’t earthed so it’s in rest position and the dip filament is lit. The main beam warning light is shorted by my relay so it’s off too.

Lastly, the switch is in both positions…





This is the one that’s worrying me…
So, my relay is on so it’s earthing the high beam filament via my new earth.
But also the low beam filament is being earthed by the switch so it’s on too. And the switch is carrying the full current. Also the warning light is shorted by the switch so it’ll be off. But this is no different to what the car does without my relay box and it’s only a transient moment. I can live with it.

I think that’s ok? Isn’t it?
Well, at least I’m convinced that I’m not shorting the battery or anything equally horrible.

Guess I’d better build it and see what happens. Wish me luck!

James

How about a 5 pin relay in the dip beam circuit instead of your “new remote relay”?

Wire the W/L to pin 87a (in the centre) instead of the current +ve connection - it becomes +12v (battery live from pin 30) when the relay is de-energised.

I'm going to put a left field idea out there - fit an LED in the tell tale instead of the original incandescent bulb but keep with your relays for the high current stuff. Not one of those special proper bulbs either - just a 10p special (with biasing resistor to set the forward current nice and low).

Logic - the sticking relay syndrome is because the telltale passes too much current? LED won’t pass enough current to keep a relay in. I wouldn’t worry about those transient conditions where both filaments are lit with no telltale either as I suspect it’s done that way to maintain light output on switchover. It’s not the only car that does it either so as long as you don’t end up with a short from battery to earth, don’t worry about it.