View Full Version : Alternator???

03-26-2007, 01:00 PM
Looing for a lightwieght alternator that I can run off the output shaft of the rpm FNR. I like it to be a one wire setup. and need some installation photos. if any one has any. Not sure what size pulley to run off the output shaft. The shaft is 1" dia.

The space is somewhat restricted and I need to run as small of a belt as possible.

Need some help here.

For some reason the cbr ignition is not recharging the odessy battery. Just in the short test run, the battery has been almost drained. The only other component running during the initial drive was the cooling fan. *Between the fan, intercom,lights and other components, I'm sure an aftermaret alternator would be the way to go.

03-26-2007, 02:42 PM
Yep the stock system can't keep up.I use a Kubota tractor alternator on the race cars.They are about 4" in diameter and put out 30 amps.These things will take15+K rpm and live fine.Run it at 1:1 pulley sizes if you are running it off engine. Otherwise if you're running it off of some driveline component use a ratio *that will keep it spinning at least 1500 rpm most of the time.One wire hookup and typical 2 bolt mounting.These are not cheap but I have found them to be bulletproof.

03-26-2007, 02:44 PM
On the busas the charging system is just about non-operative below 3000 rpm,BTW.Don't know about others but I suspect the same is true.

03-26-2007, 03:59 PM
Thans for the info since I would be running it off the output shaft of the rpm box it would only be spinning when the car is moving. would this be a problem? Also you mentioned these can handle 15+K rpm (15,000 or 1,500)?


03-26-2007, 05:44 PM

Late model GM truck alternator - 115 amp (I think?), runs about 100 bucks, NAPA will take the old one back and trade out for new one...

I took the original tranny brake that came with my RPM box, turned off the rotor and kept the center, splined section.

The adapter tube welds onto the spline center and the nut that holds the pulley onto the alternator. *Cut a couple windows in the tube so you can get to two of the flats on the nut. *It uses a #45, I believe, torx wrench on the end of the alternator.

The problem is that it (input of the tranny shaft) rotates in reverse direction to the threads on the end of the alternator, so it's always trying to loosen up. *You have to use red lock tite, a lot of swearing and force to make it tight enough - lock washer too.

When the nut loosens up, it pushes the alternator shaft thru the back side of the alternator, which in turn starts to make a bunch of nasty sounds and then eventually dies.

It took three tries before I got it correct, but once I got the adapter figured out, the only time I've lost an alternator was due to what appeared to be a very large rock.

The alternator's single lead. *I just run mine straight to the battery. *I use it in conjunction with the charging system on the RX1 engine and have not seen any problems or issues with charging. *It's nice because when the car's not moving, the GM alternator's not doing anything, but the Yamaha alternator keeps a steady, albeit lower amperage, charge on the battery.

Sorry I don't have a closer picture of the setup. *I can't find any others either.

03-26-2007, 06:02 PM
With the set-up K-fab described above, I would omit the lock washer; it's actually helping to undo the nut! I would just use a drop or two of Loctite and give it plenty of time to go off before trying it out.

You might also want to look at some of the Japanese alternators. Mitsubishi ones have a good reputation in the racing world.

03-26-2007, 06:05 PM
Now that you mention it... *I may have moved away from the lock washer and switched to a set screw in the side of the nut.

Sheesh - it's been through a hand full of adaptations and what ever it is now has proven to work. *I wish the car was here so I could go look.

03-26-2007, 06:28 PM
thans For The Info Since I Would Be Running It Off The Output Shaft Of The Rpm Box It Would Only Be Spinning When The Car Is Moving. Would This Be A Problem? Also You Mentioned These Can Handle 15+k Rpm (15,000 Or 1,500)?


03-26-2007, 06:30 PM
Just wont be charging when you arent moving..... [smilie=biggrin.gif]

03-26-2007, 06:31 PM
Who stops????????

03-26-2007, 07:01 PM
Who stops????????

I assume you do, to get all the shit yoshi blows in your lap, off you, when he smokes by your heavy old ass....lol

03-26-2007, 07:26 PM
When yoshi has his ass in the air jumping all the time I'll be stuck like glue to the ground propelling my ass past him.Can't have both! [smilie=biggrin.gif] I like flat out; he likes jumping.To each his own. [smilie=boogie.gif] Just 3 more days till you guys miss out on the fun. [smilie=blowkiss.gif]

03-26-2007, 07:33 PM
K-fab,why the 115 amps? You know how many HP it takes to drive that thing?30 amps from the engine plus 30 from the smaller auxillary alternator will be quite a bit of power unless you're running high amp lighting.30 amp alternator will suck quite a few less ponies from your drivetrain than the 115 amp'er.But I admit that if not engine driven you won't be able to sit idle for long.On a bike motor there aren't many options for that problem tho.

03-26-2007, 08:29 PM
This may sound stupid to some but does it matter what direction the alternator turns? Will it create charge either way?

Or does it "De-charge" very very quickley! LOL when run reverse[smilie=biggrin.gif] .

03-26-2007, 08:31 PM
It's capable of producing that much - but doesn't always output that.
Cheap, easy to find, easy to replace.

Agreed - does pull some hp out of the system, but it's all okay. *It also varies with the load on the system.

Radio - 110 watts on transmit - 20 a
Fan - 20 a
intercom - 10a
lights - 30 to 40 amps total
I'm missing something...
Anyhow, I'd rather have too much and loose a bit of good ol' hp, than not enough. *The sled side will keep the car running, but when you start playing with the electronic stuff, it's time to make sure the Odyssey battery stays well charged.

All worst case scenarios, but possible.

Sled side of the charging system:

Charging system
System type AC magneto ----
Model (manufacturer) F4T471 (MITSUBISHI) ----
Normal output 14 V/32 A at 5,000 r/min ----
Stator coil resistance/color 0.19 ~ 0.23 Ω at 20 C (68 F)/WW

Not sure what I'll do on the new car. *I need to see what sort of output the 1.6 VTEC Honda alternator puts out. *I still want a secondary alternator for backup.

side note: *the Trophy Truck I navigated in runs a secondary alternator driven off the drive shaft. *There's a pulley just in front of the u-joint on the shaft that runs it. *There's a switch in the truck for selecting either or both of the alternators. *I'll probably do something similar.

03-26-2007, 08:40 PM
I won't argue the point other than it depends on the electric load needed supplied at max draw.That said I agree that a backup alternator is good and when I find room I plan on doing so also.Kinda hard to drive it from anything other than a driveline component with a bike motor.

03-26-2007, 08:45 PM
Keep the trinkets out of the dash and the bike alt will do just fine.... [smilie=biggrin.gif]

03-26-2007, 08:48 PM
Not really with lighting added.

03-26-2007, 08:52 PM
well not if you got 6 baja lights up top no, but they work just fine for a bike headlight, i dont do much dark riding anyway myself.....I may try to put a starter generator on my car for reverse and added amps.....

03-26-2007, 09:00 PM
Yeah,we're back to -it depends on your max. amp load.You gonna make Dog Days? We'll miss ya at LS this weekend.

03-26-2007, 09:09 PM
You wont miss me i promise.... [smilie=biggrin.gif]

03-26-2007, 09:12 PM
Well can they run backwards or not?

03-26-2007, 09:28 PM
well a honda car one can, you got to get the one that runs funky oem tho....not sure what model or year but i know one of them does....

03-26-2007, 09:39 PM
Honda's J Series engine was designed in the US by Honda engineers and built at Honda's Anna, Ohio engine plant specifically to bolt up to GM's clockwise rotating transmissions, so any pre-J Series alternator should do the trick.

03-26-2007, 09:44 PM
looking at the way k-fabs was set up on the left side of the output shaft it appears his would have been running counterclockwise correct?

03-27-2007, 05:59 AM
An alternator itself does not care if it runs clockwise or counter-clockwise.The threaded shaft will be LH/RH threads as appropriate from the OEM but so long as you have the nut positively retained with red loctite on CLEAN threads you won't have a problem with the "incorrect" handed threads coming loose.

03-27-2007, 08:46 AM
That's what I was hoping. Thanks