Alternator off rear end....???

Appreciate your comments but this isn't the first time i've done this job, Thanks.

 

We put one on our race car off the rear end. We run a 6.5 pulley to a 3.3 and it works great.--TV

 

exactly, i hate the alt on my 58, but in a full bodied car its hard to mount em low.

 

My way of trying to make a point .

 

If this works that's cool .I looked at the photo of the pulley welded to the yoke made me nervous .My 2 cents

 

So yours is basicly a 2:1 ratio and works fine....

I did some figuring today and came up with this....

At 2500 engine RPM, using my current 1.25:1 ratio. the following is alternator RPM in each gear.

1st - 932 rpm
2nd - 1570 rpm
3rd - 2348 rpm
4th - 3125 rpm
5th - 4596 rpm

In 1st gear at 2500 RPM, with 3.50 rear gears, 28'' tall tires.... These are the speeds I would have to go, in order to spin the alternator the RPM listed above.

1st - 18 mph.
2nd - 30mph
3rd - 43 mph
4th - 60mph
5th - 87mph

So it seems that I do need to change my gear ratio. However most of the time I will have less than a 10 amp draw on my system. I need to figure out how many RPM the alternator needs to spin to output enough to keep up with my system draw.

keeping the comments coming...

ModelAMafia

 

I suppose it depends on the electrical load on your system. Modern cars with airconditioning, electric radiator fans, and four powerful headlights, can be very power hungry. But a street rod, maybe not. It should work though, but I still have two reservations about this. The first is ground clearance. There will be a limit to how big a pulley you can fit before it starts hanging down really low to the ground. If it catches a speed hump, you are screwed. The other potential problem is spline pumping. As the rear end does it's thing, the splines on the transmission output allow this in and out movement. That means your tailshaft pulley is moving sideways in and out of alignment. That may be o/k as long as the drive belt is reasonably long. With a very short belt, it may try to jump off, if one pulley gets too far out of line with the other.

 

that would only happen if the alternator was mounted to the frame, mine is mounted directly to the rearend.

 

Well if all else fails at a long red light and your battery is low you can always do a burnout to start charging.. haha.. I actually would like to know how this works out for you but to me why fix what is not broken.keep us updated.

 

Anyone remember the GREEN GRENADE?????

Chris (Loud Pedal) ran his off the back of the crank, with a belt thru the bellhousing.
I searched for photos, couldn't find any.

 

You just described the BEST solution ever!!!!

 

FWIW, I saw this pic in Dreadmans Hollywood Hot Rods open house photo thread. Cable driven from I believe a tach drive distributor. Pretty slick.

 

just noticed that the pedals are on the wrong side of this car

 

You can also use a jackshaft to increase the ratio at the alternator, without changing the yoke at all. The original yoke pulley drives a very small pulley at one end of the shaft, and a really big pulley on the other end of the shaft drives the alternator much faster. The final ratios is both ratios multiplied toogther. The shaft doesn't have to be in direct line between the 2, it can be offset to the side for more clearance.

Re: "so what if the battery dies and won't turn the starter. Just park on a slight incline whenever possible"

But... you'll have to coast to over 20 mph (luckily - the clutch can be in, so the engine doesn't have to turn) to have any alternator output, and then you have to energize the fields.

"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?"

Always, except real magnetos.

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

You're kidding, right?

 

Yep! If memory serves I think there was mention made that this one was being exported to Oz.

 

Cable driven yes,but prolly' not from the dizzy,as the dizzy shaft already has quite the load on it,what with spinning the oil pump and all.

 

exactly what i was thinking

Im thinking of trying this method - Im running a powerglide with bell adapter tp a sb mopar - so will be running a chevy flywheel instead of the mopar flex plate - wonder if i try to spin a gear drive off that, or go to the back of the crank like someone else just said

 

That cable drive is awesome..... I would like to know where/what it is actually driven off of.

Anyone else know anything about it?

 

I am sure it has been thought of before, and there will be a few things to consider, like flywheel spin direction compared to Alt and stuff like that.
I hope it works for you though!

 

it doesn't make any difference which way your turn the alternator , it will charge just fine. i mounted an alternator on the rear once and it was just fine , and would charge going forward or in reverse. why i did it i don't know , maybe because i could

 

I was talking about running it off the flywheel/flexplate, not the rear end.

 

yeah , i know....i was responding to your concern of flywheel / alternator rotation

that will teach me a lesson to stick my nose it where it doesn't belong

 

OH, cool, thanks.
Dawn at 20 paces? LOL.

 

Me either, why would one do this?

 

I don't get the concern about the charging system not charging while the car is stationary. Any battery worth it's weight in lead can run your car for hours without a charge, then take a charge and be just fine. Mind you if you take 5 amps out for 2 hours you have to put the same back in, but you can put in 20 amps for 30 minutes and catch up. It would be the same as starting your car and shutting it off 2 minutes later over and over, eventually the battery will die because you haven't replenished the charge. Put a Interstate or a red top in it and go

 

'cause it looks cool...

 

Exaclty, alternators are like balls on a chick..............unless you like that kinda thing

 

I think that the bouncing to helll the alt would get from being on the articualting rear end would end the life of the thing pretty quick. Mount it to the frame up front, at the tranny.

That cable set up looks cool, I bet he has a small belt and pulley set up front, maybe hidden down below the water pump to spin that cable. Could MaGuyver a cable out of a roto-rooter or something...

 

I have seen very large cable drives like on concrete vibrators. that would have no problem spinning an alternator, just have to run a pulley up front on an idler arm, belt driven off the pump and find a coupler for the alternator shaft and your in luck. I guess you would still end up with a 6 inch pulley up front on your engine.

 

I don't know how/if it's gonna work, but I sure like your work, good job, looks great.