I need to change to a 90A alternator. Some are rated 12V, some 14V. It's hard enough getting one that fits and doesn't cost a fortune, nevermind this confusing issue.

Any ideas?
Cheers.

 

12v and 14v alternator will be the same thing. The regulator will be 14v (ish) but its obv for a 12v battery, so people bounce around both names..

 

Thanks. You wouldn’t happen to know a good place to buy one at a decent price. Eurocarparts have Lucas but only up your 70A. Would be handy if it was somewhere I could drop the old one off for the trade-in.

 

I would be tempted to refurbish/or get the old one refurbished.

Sadly, like most things, it's a dying trade, although I have a couple of specialists near me.

You do know the brushes are easily replaced?

70 A is what lesser models and the 3 DR had, 90 A was for high spec MK2 and Granada's.

Martin

 

Old one is only 70. I’m after a 90A or even more due to twin fuel pumps and occasional lamp pod use.

 

I bought a new 90amp alternator recently from ACP All Car Parts run by mr-wiper (475657 ) on E-bay It is a genuine Autoelectro premium 12v 90amp one and was the correct one. Easy to fit and is working fine.

 

Thanks! I'll go for one of those. Cheers!

 

Got it. Now I'm stumped as to where the little red "diode" wire goes. No spades visible. Is it on D+ ?

 

You only have 2 wires (and maybe a ground wire).
The thick wire is B+
The thin wire is D+ (batterylight)

 

Thanks!

 

I was about to give you the same info, you can't go wrong really. Hope you have now got it fitted and it is up and running.

 

Yes, fitted now. The baffling thing is that it's still only kicking out 12.2V same as the battery. It's as if the battery is feeding it and not the correct way around.

I'm near the end of my tether with this.

 

Have you got to the bottom of the problem yet? Have you taken it to an auto-electrician to have it checked out? I would be very suprised if there is anything wrong with the new alternator.

 

Thanks. Definitely nothing wrong with it. I'm going to take the dash out and trace everything back. It's a rebuilt rally car. I suspect the excite wire is maybe broken somewhere or a loss somewhere in the ignition circuit. All earths seem good. It's pretty simple wiring I reckon - a big kill switch on the dash (new one ordered) and a Start button. Twin fuel pumps whirring away nicely.

Problems after rebuild were: Volt meter reading low on fire up then at some point down the road it would jump to 14V at random. It's never revved past 5K without a loud bang and going into limp mode. Made doubly bad as I have a paddle clutch that needs run-in and I can't use proper boost. Arggh!!

 

Now you have said it's a re-built rally car and the wiring has been altered I would say that could be where the problem is. What ecu has it got? The problem with only revving to 5000rpm and going into limp mode could be ECU related. The paddle clutch should be good to go from fitting. I have had 2X 6 paddle clutches and neither of them needed to be run in. I have had a hydraulic system fitted and there was just a bit of adjustment to the length of the push rod to get it just right but it worked straight away. Hope you get it all sorted out without to much hassle.

 

Its an L6 ECU. It's just the voltage that's the problem. I investigated a bit yesterday and succeeded in immobilising the thing. Could be an earth where all the fuse tails and kill switch resistor are anchored.
The clutch is hydraulic but the running-in period seems quite normal with whoever I've asked. It was slipping like mad to start with and now holds better. New flywheel etc. I've only done about 100miles since rebuild but this voltage thing is the overlying issue. It conked out a couple of times and only ran when I attached a booster pack to the battery. It was a race battery and I've now got a new Bosch one.
I can see me stripping back the entire dash and tracing back all the wiring but I'm looking for something more obvious for now. At least I can rely on the alternator.

 

Had a charging problem on my 2WD saph. That turned out to be that the wire from the alternator to the battery, had almost completely burned through inside the heat sheathing. About 5 inches from the alternator.

 

I fitted the drop bracket as used on RS500's to give a little extra clearance between alternator and turbo/exhaust on my 2wd. Definitely worth while as it must help prevent the back of the alternator getting cooked and prolong its life. Something to consider if you have a stock 2wd alternator bracket.

 

You have answered your own question!

The problem is almost certainly the exciter supply missing, which explains the random voltage, the reason being is when revved hard enough, it will excite the field winding's.

That's why I asked what was wrong with the old one as it was unlikely this was the issue.

You simply need to verify you have a switched +12 V supply to the 'D' terminal, I'll happy bet there isn't!

Martin

 

Martin, all bets are off! You’re right! Been on it 4hrs today.
I traced the excite wire to the dash light and the spade connector was crap. Got 14.2V throughout now.
But now the kill switch on the dash is throwing up an issue. Seems it’s not killing anything. But my mate has it sussed apparently so will have another go on Wednesday. Nearly there. Cheers!

 

You have certainly had your patience tested!! What should have been a simple new alternator fitting has turned into a bit of a nightmare!! hopefully now you have got to the bottom of it.

 

can you add the link? would this alternator need also different bracket?

 

Here you go. No need for extra bracket on mine. I use the threaded rod adjuster type.

https://www.ebay.co.uk/itm/Fits-Ford...72.m2749.l2649