MTFCA Forum

Thinking of upgrading my 1927 Speedster 12v system with an alternator. Gear or belt? Are the gear driven get necessary cooling?

Bill, fitting an alternator is a DOWNGRADE!

Allan from down under.

If your engine is a 1927 you can easely find a good working generator and mount it on the engine the original way. No belt needed!!!

Andre
Belgium

"Upgrading"

The gear driven alternator works fine.

If you are going 12v the Texas T (Birdhaven) alternators work good. I'm running two of them. They cool fine with good customer service also. I'm also running a stock 6v generator with a Fun Projects voltage regulator. Works good and is a quality product.

I'll second Pat's recommendation. The Birdhaven unit is the best unit in my experience available out there at the moment. It required the least amount of shimming to get a great fit and has been reliable. My 6v Birdhaven alternator worked great, no issues. I did, however, remove it and replaced it with a generator I rebuilt. By going to LED lights I no longer needed the extra amps to push the halogen lights, so I went back to a generator and Regan regulator. If I had a 12 volt system, I would probably have stayed with the alternator. Stock generators can happily put out 12 volts, but at only half the rate of 6 volt units.

My Texas T gear driven 12 volt alternator works fine. But because of the gearing the alternator does not turn as fast as it was designed to do. This means that it will not start to charge until about 25 mph with 3:1 gearing or 20 mph with stock gearing. Since all alternators use the guts from off-the-shelf alternators, they all work the same with respect to at which speed they start to charge. A volt meter in place with the ammeter will allow you to keep an eye on the battery voltage. Running all the lights, GPS, camera, and charging my phone, the alternator will put out 15 volts at cruising speed.

I do not have any experience with the belt driven alternator but they may turn a higher rpm so that they start to charge at a lower engine speed. In my opinion the gear driven alternator is a cleaner installation. You can buy an alternator that looks like a generator if that is important to you.

The original T starter didn’t care about polarity when it came to rotation because of the wound field coils. Your new starter may have magnet fields and might be sensitive to polarity and rotation. I would certainly want to check outside the engine!!

To clarify I should have said “permanent magnet fields “!!