Small Alternator

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Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Small Alternator

Post by Westfield 129 »

FYI:

The alternator number for the small, forklift style alternator is ND 18504. This number will lead you to the much less expensive copies that cost around $80 new. I have been using both Chinese copies and the original ND produced 18504, and have found all to be excellent so far as performance and longevity. BIG difference in price, though. Chinese copy is about 1/3rd the price, works just as well, so far as I can tell.

There is an album on the Westyxiownersbuildersdrivers site that covers the modification that aligns the alternator with the crank shaft damper/pulley. This works for both the standard unit, as well as the racing unit from MED, and the Aussie racing damper. I will try to expand this over the weekend to include the full installation.

The alternator mounting hole will require drilling, as well as the mount tab on the water pump. There is no back bracket, as required for the larger Suzuki or Lucas alternator.

I drill and tap the lower mount tab of the alternator to match fractional hardware. I hate to bring two sets of tools to the car when I have to work on it.

Making the lower mount turnbuckle is pretty easy, and requires a pair of inexpensive rod ends in LH and RH threads. Use hex material for the connecting tube and it becomes very easy to adjust the tension with fingers, or with a 1/2" spanner, and a couple of jam nuts. I will try to get some pictures of the entire installation with the lower turnbuckle bracket.

Wiring is also simple, using a three wire scheme. The alternator plug is a standard part, available from any auto electrical supply or rebuilder. One wire to the battery (alternator side terminal), one to the switch, one to the indicator light (back plug).

There are also "one wire" versions available, which have only the indicator light and the battery leads.

This all results in about a 3KG weight reduction, and a much cleaner cold side of the engine, with the elimination of one alternator bracket, and an alternator less than half the size. Adjustment of the belt tension can be done without a pry bar, and may require only fingers to set the tension. Jam nuts fix the adjustment. I have run this setup for more than 15,000 miles, on a very old water pump. No problems, and the belts stay properly tensioned. It doesn't seem to mind being attached to the vibrosonic BMC A series, and doesn't mind being twisted to 7000 RPM. Of course there are reduction drive pulleys available, and you can put the thing on a switch as well, for that little extra bit of HP without alternator drag...

Main Battery Cut Off Switch for Racing: Remember that when you use an alternator, install an alternator inclusive battery main cutoff switch if you need one. This will cut the alternator and the battery power, ensuring that the thing turns off, and that the alternator is not damaged by a voltage surge.
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Small Alternator

Post by jonclancy »

"Making the lower mount turnbuckle is pretty easy, and requires a pair of inexpensive rod ends in LH and RH threads. Use hex material for the connecting tube and it becomes very easy to adjust the tension with fingers, or with a 1/2" spanner, and a couple of jam nuts. I will try to get some pictures of the entire installation with the lower turnbuckle bracket. "

Do you have any dims/specs for the rod ends and length of stock, please Jan?

Once I have these, I'll find the UK suppliers parts numbers/stock suppliers, tap details and post info here. It'll be useful if anyone wants to mod their cars with the leggera alternator version.

BTW, I take it that the standard single-groove pulley that comes with the chinese Denso copy works without modification.

ETA: McGill Motorsport supply everything we'd need in a kit - including turnbuckles etc

http://www.mcgillmotorsport.com/rod-end ... cessories/

or their eBay shop:

http://www.ebay.co.uk/itm/Turnbuckle-3- ... 5894308a1c

Longer lengths are in darker carbon steel and will need painting or coating.
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Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Small Alternator

Post by Westfield 129 »

The hex stock I am using is only 2.5" long, plus the thickness of the thin jam nuts (You can order longer bar hex stock and send it to your friends once you work out the measurements, and have the stock drilled and tapped), drilled and tapped to fit the LH and RH thread rod ends. This part will have to be cut to fit, depending on the rod end threaded area. Pick the stock to match your rod end's requirements. All thread sizes are bored to fractional. I only like to carry one set of tools to the car...
I am using the forklift type, small alternator listed as a replacement for ND 18504.

Rod end size will match the fasteners.

Thread the lower mount of the small alternator to eliminate the nut, and align everything with washers. The original stand off mount for the original alternator/generator works fine or you can use a stack of washers.

My setup uses the standard lower mount point for the generator/alternator, attached to the engine's motor mount plate.

Any angle on the lower mount rod is of no consequence. It will be angled somewhat when mounted, but this is handled by the rod ends.

The standard V belt pulley supplied with the alternator works fine. You may find that some of the suppliers of BMC A competition parts may have other "under drive" pulley sets. If you decide to use one of those, it may require additional change to the alternator case mount tab.

I used the standard pulley that came with the ND copy alternator, and cut the alternator mount tab (the top one, mounted to the water pump alternator mount tab) by 1/8" to move the alternator back slightly. Any additional adjustment forward can be done with shims (though I didn't have to use any). See pictures in my build album at Westfieldxiownersbuildersdrivers. Just figure that everything will be cut to fit the individual car. The measurements that I used for the lower mount worked for three cars, so that should work out for you.
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Small Alternator

Post by Westfield 129 »

One additional note: The lower alternator mount may not clear the alternator body without spacing from both the alternator and the lower mounting point on the engine plate. Moving the strut (mount) assembly forward with washers should help. If not, you can move the lower mount on the engine plate by drilling a new hole.

So far, I have not had to drill any holes in the engine plate. This adjustment is also dependent on having the correct belt length, which may depend on the pulley combination you are using. Sometimes, the belt length needs to be changed.
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Small Alternator

Post by jonclancy »

I had the shot. There was no danger, so I took it.

Got a 60A Denso on the way. This seller seemed to have more than one, as he relisted one I thought was sold.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0810680575

Once it's here, I'll look at installing it and post a HOWTO with links to parts suppliers as well.

How's that?

Jon
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Small Alternator

Post by jonclancy »

Here's an update:

My Denso is 3.1Kg - only a couple of hundred grammes lighter than the Lucas LRA100 alternator. The Denso is smaller, though, and has a much greater output. Handy for my heated seats, sunroof and stereo. ;)

I wanted to find a way to merely bolt the new alternator on, but it seens that grinding around 1/8" off the threaded alternator tab (or filing, if you're patient) is the way to go. The Denso battery stud is M6. The top threaded mounting lug'ole is 8mm. The other lug'ole is 10mm (smoothbore).

I've ordered some A2 part threaded M8x50 bolts and nylocs etc. I'm intending to sleeve the waterpump lug'ole with some heatshrink on the bolt shank. That'll take care of any play there. The rod/turnbuckle will be M10 to make things easier. Once I get the alternator hanging and pulleys correctly aligned fore/aft, I can measure the lenght of turnbuckle assy required - might need a longer fanbelt, but hoping to use stock.

WRT wiring, I'm reasonably happy, but need to confirm the details. Don't forget that your loom will probably have a voltage regulator somewhere (under the scuttle). This will need to be bypassed, as the Denso is internally regulated. If you follow your wiring from the alternator to the solenoid, it's reasonably clear that the brown wires go to the "battery" side of the solenoid (might beef up the skinny brown one, though) and the alternator output stud. The L (light) wire is as stated. You will need to run a new wire (12v) from the switched side of the coil to the Ig (Ignition) connecotr on the alternator. This is the exciter/engergiser circuit that turns the alternator on.

:o WARNING!! I need to fully research this. Please check your alternator and your own loom. Bugger this up and you may set fire to something. WARNING!! :?

That's all for now - I'll post some pics up later on.
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Small Alternator

Post by Westfield 129 »

I use a cut off tool to make the initial cut, and a hand file to level it. Washers can be used to adjust alignment.

I also bore the alternator top mount to take fractional bolts, so I don't need separate (additional metric) tools in the engine compartment. This also makes fabricating the lower bracket easier, as both RH and LH threads for the rod ends can be the same fractional size.

The alternator's lower bracket was threaded for the fractional bolts I was using, eliminating another nut for the fastener.

A heavier wire from the battery lug on the alternator to the battery (or start solenoid) is an easy conversion (the heavy wire from the old generator is perfectly good). Another wire that is switched power (white circuit) can go to the alternator plug, while the remaining wire goes to your GEN/IGN warning light.

Removing the regulator is straightforward once you have disconnected the generator. You can check any of the later Spridget wiring schemes for alternator wiring as a guide.

The one thing that you don't want to do is to hook up the plug backwards, as that blows out the warning light circuit. The alternator will still work, but you will need an volt meter to confirm. The fix, should you make that wiring mistake, is to replace the voltage regulator module in your brand new alternator.

I made this particular mistake for you, so you would not have to.
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Small Alternator

Post by jonclancy »

Just for clarity - the Lucas alternators (17ACR etc) have an internal regulator. It's the dynamo which has a separate control unit, field switching relay and warning light control unit.

Which fractional sizes did you settle on in the end, Jan?
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Small Alternator

Post by Westfield 129 »

3/8" Fine thread. The rod ends will be 3/8" as well with thin jam nuts.

Use 9/16 hex stock for the lower mount. That way, you only need a single wrench to adjust the belt tension.

If you have an older chassis, your took kit already includes a 9/16" open end wrench, and probably a 9/16" socket as well. Tension will be easily adjusted with fingers, or the open end wrench on the lower hex rod mounting. Very easy, and it will never slip.

This just keeps all the fasteners in the engine compartment uniform. No surprises, and no rounded off bolt heads when one picks up the wrong wrench.
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