Alternator off rear end....???

So I finally got around to working on this project, I am just going to buy a good Red Top Optima battery and I think it'll work out well.




What do you guys think about this...? Should I worry about road grime and dirt? I realize it's not going to be spinning when I am not moving and only going to be spinning the same speed as a traditional mount when I am in 4th gear and even then its going to be spinning slower since the drive pulley is smaller than the normal drive pulley (crank pulley).

Has anyone else done this? How well did it work?

ModelAMafia

 

I once taught of doing an a/c compressor like that.

 

I have seen several done this way, I'm certain it would work and you already are aware of it's limitations. That alternator can withstand alot of abuse, I doubt that it will be too negatively affected mounted in the driveline. I suppose the wiring/connections would be pretty critical.

I couldn't use that system around here.........'way too much traffic, the battery couldn't take it.

 

Some of the protype race cars of the last years were doing this, AND they also were using a generater in the same setup. It assisted in braking, and when they got on a straight, the driver would hit a button that would spin it up like a short lived "turbo boost" I just cant remember which lemans team was using it...Audi??

Im not sure if its gonna be all that GREAT with your accesories running in stop and go traffic, but It looks like a pretty kick ass idea.

Cant you change the pulley size on the ALT end for a much better ratio very easily?


Cheers and Beers

Hodge

 

probably would work great for a car with low demand on the charging system. I have seen where its run off a shaft driven off a pully on the front of the engine too. Not sure how Alternators deal with shock. give it a shot and let me know how it works out.

I have been trying to think of a way to get mine off the front of the engine too.

 

I cant bring myself to thinking this is a good idea on anything other than a racecar.

 

Just to throw this in the mix. Instead of mounting it off the rear, get a pressed steel bellhousing, modify it to have two starter holes, and mount the alt off that, run a drive gear off you fly wheel/flex plate. Charging all the time! Hidden! and tidy solution.

Or am I just talking crap here? Just an idea.

 

The only load I'll have on the system is the ignition, headlights, and one tail light. So the worst it could get would be if i was stuck in traffic at night.

 

This topic has been discussed multiple times here over the years.

Try a search for some opinons from guys who have actually done it... use Driveshaft, alternator for keywords.

 

Won't charge below 40 mph.

 

Plus, I think its the belt that will get the hardest time, with stuff getting in there and tearing it up. Plus you will pick up anything thats gets flinged up.

 

They run this setup on most left turners around here, I think you need a larger pulley on the diff don't you?

 

you'll only charge when moving. if you get stuck in traffic you could screw youself setting it up that way, also if itslike my alternator it doesnt start charging till it hits 2000 rpm, so you wont start charging till you hit like 40 mph

 

How many amps(output) are needed to charge the battery? During normal driving my ignition system is probably only going to draw 5 amps, this should be making over that even at slow speeds.

 

It's a pretty sweet setup if it works.

 

It will work. I'm running a similar set up on the '33. I also run a second battery with a cut off switch in case I get caught in slow traffic for a while where I can't get much of a charge. I have a dash mounted switch so that I can call up the fresh battery from the drivers seat. Mine's not a daily driver, but I've yet to be stranded by a low battery with this setup.

Doc.

 

Normally it would be about 3:1 run off the crank, this is abut 1.25:1. That was the only yoke that I could find, so that limits me. I could lfind a smaller alternator pulley, however I havent looked into it yet.

 

old guys [like me] used to run it off the drive shaft..close up to the tranny..plan to do it on my 32 pick up

 

But then you could do a BURNOUT to charge the system!!!

Maybe the COP would "Understand" LOL!!!!

Cheers and beers
Hodge

 

I don't understand the advantages of this...

 

I like your thinking.

 

I'll have no power steering pump or other accessories, so the only thing I'll need to drive is my water pump, it'll really clean things up under the hood and make people think...dare to be different yo.

 

it cleans up the front of the motor...and if you run a mag no probs

 

it is a lot cheaper that a racemate waterpump alternator combo, those go about 600 bucks ,alt is built in the pump you only run one belt also, but they are only 15 amp i think,

 

If you're running a standard, then so what if the battery dies and won't turn the starter. Just park on a slight incline whenever possible. ::shrugs::

Also, depending upon the ignition system you're running, once the motor is running the battery isn't necessarily 'needed' to maintain function, is it?

And... isn't the Red Top the deep cycle battery that'll self charge anyway?

I think the only thing I'd change is to maybe add a small skidplate under the pumpkin to give a bit of 'flinger' protection and keep short stuff off the road from just openly flipping up into the belt itself. I've contemplated doing this to my AA project, but I'm going to run AC and PS anyway, so screw it - I'll fit it all off the front anyway.

 

I see... a visual mod

Run an electric water pump and traffic will be your best friend...

 

I like the idea ! I think the alt. in the engine bay of a rod looks like crap , so go for it ! and let us know how it goes .
BTW the best solution i've seen so far was a solid mount in the frame just next to the gearbox driven by a flex cable , not sure how it drove off the engine cause it was'nt in the frame in the pic I saw . maybe someone else knows what thread I saw it in ?

 

It'll work, but you need a larger drive pulley for sure. I would go with a 4-1 ratio to get the system up running quicker. At 4-1 the driveshaft only has to turn 350-400 rpm to work. For example 2.2 ratio first gear, 3.3 ratio rear gear, 28 inch rear tire, 860 engine rpm, equals 9 mph @ 350 driveshaft rpm. So basically, anything over 10 mph will work, with this gear combo.

 

O/k so the alternator needs about 2,000 tailshaft rpm before it even begins to charge, and about 6,000 tailshaft rpm before the alternator reaches rated output. So you need to be going fairly fast to charge the battery at all and probably well over 100 mph to get reasonable charging rate. What sort of vehicle is this fitted to anyway? It is certainly not going to work on a street car driven around the suburbs.

 

I would worry about the movement of the wiring to the starter. I'm not so sure that I would enjoy dropping a driveshaft to replace the belt either. It is a novel idea. Keep the ideas flowing.