120 amp alternator

[Kevin Bacon 5]

I have aquired an 120amp alternator but it has a larger pulley than usual on it. Must have been from an A/C / heated seats / 3 bar electric fire equipped car.

 

Do I need to put my pulley onto it, or does the 120amp have a specific pulley size regardless of car?

 

I don't want to over or under drive it you see!

 

My guess is it needs the normal 70/90A corrado pulley since it's correctly geared for the water pump /crank / pas pulleys and belt length, but I have a nagging doubt.

 

Anyone know for sure?

 

EDIT: The slip rings on it look well worn. Are they DIYable to replace?

[Supercharged 2]

Would have thought it would need the same size becuase of the belt length - unless that is different for the 120a alts...

 

Pop round next week if you want to use the Snap-On gun to get it off...

[Kevin Bacon 5]

Cheers dude, I'll try the smaller pulley then.

 

I got a new diode pack from Nacton Autos and it's got a resistor in it. The old one didn't. What's the difference? He said resistor regulator packs are better, but didn't say why, LOL!

[davidwort 0]

Should use the original Corrado pulley, the larger alternator should just have bigger windings and a bit harder for the engine to drive when you really need that extra current.

Only reason I've seen different sized pulleys is for engines with a different diameter crank pulley (to keep ratio the same) or on a higher/lower revving engine.

[Kevin Bacon 5]

Cheers David

 

I answered my own question about replacing the slip rings.... looks like a big job! http://www.oichan.org/mods/alter/alter2.htm

 

I was quoted £60 to replace the slip rings and rectifier etc etc, so may aswell just get it done properly :D

[davidwort 0]

nice how-to though, very similar to the old 4 cylinder bosch ones really, I guess an alternator is an alternator :)

I like the bearing heater 8)

 

In my usual bodging approach I've simply sanded down worn/grooved contact/slip rings before,

the bearings can be done with small pullers, but like you say it's a darn site easier to pay a starter/alternator repair place to do it, the biggest issue I've come across is the rectifier diode plates are soldered to the windings on the bosch ones, well it looks more like brazing!

[Kevin Bacon 5]

I thought about sanding the slip rings but the grooves are really deep and I'm concerned the brushes will wear right through, LOL!

[Kevin Bacon 5]

Picked up my 120A alternator from a local auto electricians this morning and I'm impressed! Cleaned up and repainted casings, new bearings fitted, new slip rings fitted and new diode pack (resistor type) fitted. £60+VAT all in.

 

Considering VAG want over 250 quid for a 120A, exchange, that is a steal.

 

Anyone in Suffolk, I highly recommend Nacton Auto Electrics in Ipswich. Good blokes and fast turn around.

 

Oh and the resistor in the diode pack is an excitor. Apparently if dashboard warning lights go, the alternator stops charging, so the resistor is just a constant low load to stop that happening.

 

Now, my 100W Philips Rally bulbs should no longer trouble my battery :D

[dr_mat 0]

They might not trouble your alternator .. but 120 amps down those cables might make for an early bonfire.. ;)

Knowing you you've done the right thing and uprated all the cabling too, of course!

[Kevin Bacon 5]

Of course! Even my fuel pumps are fed with 30 Amp wire, when 10 is more than enough :d