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Gas prices Hike. Time for an Overdrive Tranny
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Author:  Pyper6970 [ Thu Mar 06, 2003 10:31 pm ]
Post subject:  Gas prices Hike. Time for an Overdrive Tranny
What will it take for me to bolt a a500/a518 trans to the back of my slant, i have a 904 on it now, Custom work isnt a problem. Do I need to install a computer? Cut my tranny tunnel? lengthen/shorten my driveshaft. Im gonna need an adapter plate im sure, does anyone make one to bolt a /6 to a 500/518? im pulling 14 street and 19 fwy....wouldnt mind pulling 25 on the freeway. It will also save my engine from high revving to go faster. 3.23 peg leg, 4bbl Offy alum. Manifold, 390cfm Holley, stock rebuilt head, stock rebuilt lower end 8.5:1 cr.

What can i see as far as this project?

<img src="http://members.aol.com/_ht_a/Pyper70/Dartpack.jpg"width=400>
Author:  Eric W [ Thu Mar 06, 2003 11:20 pm ]
Post subject: 
I know Gear Venders makes an over drive unit, don't know about the cost or what kind of modifications are required.
Eric W
Author:  DusterIdiot [ Thu Mar 06, 2003 11:53 pm ]
Post subject:  List of stuff....
Just from perusing the various posts on this subject:

You'll have to cut the tunnel, since the A-518 is like a 727 but with a fat tailsection.
You'll need to custom fab a new crossmemeber.
You want an A-518 out of a 1989-1993 Truck or similar year A-500 from a Dakota,etc... these are not electronically shifted or regulated, but you do need to hook up a dash switch to manually turn on/off the lock-up and the O/D.
You need the adapter plate from a 1967- truck with the slant six and A-727 tranny...or you can have your favorite machinist make one for you but he'll need the specs for the bolt pattern on your tranny/engine, and the LA-block bolt pattern for the donor tranny.

I think you'll need to shorten the drive line a smidge depending on the unit.

Just FYI, I have two dusters:
One modified Feather Duster, before I rebuilt it it got 14/25 with a very tired drive/power train with the stock 1 barrel engine and the A-833 OD manual and 2.94:1 rear gears, with a comp cam 252s, 9.22:1 compression and super six I get 13/21 on 'plus'. My other driver is a 1974 Duster stock motor with A-230 wide ratio manual 3 speed and 3.21 rear gears it got 13/19.5, I goofed up 3 rod bearings and replaced that motor with a 'high miler/road oiler 225' got the same mileage. Changed the exhaust to "Feather Duster" exhaust got 14/20.5...changed the rear end from the 8 1/4" 3.21 to a 7 1/4" 2.94 due to a bad bearing and went to 14/21.3...wasted that rear end and put in another 7 1/4" with 2.76 gearing...got the same 14/21.3 but got more top-end out of it, and more clutch burning to get it motivated.

Not sure what mileage advantages you'll get from this swap.

If you do it, I'd be curious about the results. :)

-D.Idiot
Author:  Loghead [ Fri Mar 07, 2003 4:59 pm ]
Post subject:  do you have another tranny to install?
(SWEET looking Dart!)

Weren't those A-500's and 518's made for V6's and V8's?
I realize that you don't object to custom work, but between the price of the tranny(not cheap) and the price of getting one to fit a /6...
That'll buy alot of fuel...

my .02 cents :lol:
Author:  Dart270 [ Sat Mar 08, 2003 9:34 pm ]
Post subject: 
I really need to write an article about this...

I have an A500 in my '68 Dart, got me about 10-15% mileage. DusterIdiot pretty much outlined what it took to do it. Another fun way to get mileage is to put a 5 speed in it. I also put a Mustang T5 in my '64 Dart and picked up at least 15% in MPG - more in the city, but I haven't fully tested that yet..

The OD autos are BIG, so you at least need to cut a bunch of the upper X-member away (what I did), and probably cut up the tunnel too (what I should do). I made an all-custom lower X-member and moved the motor forward 1/2" too. The stock shifter linkage hooked right up, although it probably wouldn't if the motor were left in the stock location.

Lou
Author:  AutoTrans [ Sun Mar 09, 2003 7:03 am ]
Post subject: 
Quote:
I know Gear Venders makes an over drive unit, don't know about the cost or what kind of modifications are required.
Eric W
If I recall right, the Gear Vendors unit is in the neighborhood of $1500. Don't know about the 500 or the 518, I've seen a lot of them go bad in the trucks. Something to do with the OD unit on the tailshaft.
Author:  Dart270 [ Sun Mar 09, 2003 8:28 am ]
Post subject: 
IF you can find an A500/518 cheaply, then that will be more work but cheaper than a GV unit. I have about $400 in my project with me making all the custom parts for free, and not including the high-stall TC I bought for $500. I was pretty lucky to find a good trans for $150. If you can afford the $2200 price for the GV unit, that would be a LOT less work.

Lou
Author:  Jopapa [ Sun Mar 09, 2003 10:48 am ]
Post subject:  Re: do you have another tranny to install?
Quote:
(SWEET looking Dart!)
Every time I see that pic I get insanely jealous. The one I'm working on is in no where near even adequate condition at this point.

PSSSST, hey Pyper you gonna take some pics of that dash so I can try and copy it for my friend's Swinger? :D
Author:  YeahBut [ Wed Dec 14, 2005 12:07 am ]
Post subject: 
But will this be viable in a truck. that is my big concern
Author:  flight704 [ Wed Dec 14, 2005 3:35 am ]
Post subject: 
i was looking at the gear vendor unit 2 weeks ago and it was around 2200. I must admit i had a little sticker shock at the price myself. thats alot of jingle for a working man.
Author:  dakight [ Wed Dec 14, 2005 4:33 am ]
Post subject: 
$2200.00 will buy a lot of gas... 1000 gallons or more at current prices. You would have to save 1000 gallons to pay for it; the thing to consider is how long will it take at a (very generous) 15% mileage improvement to save 1000 gallons? I just did a quick calculation... if you currently use 10 gallons a week and net a 15% saving that's 1.5 gallons a week or 78 gallons a year. At that rate it would take 12.5 years to pay for the overdrive at today's prices. Even if prices double fairly soon it will take over 6 years to recoup your investment.

Now, if you want to do the project for the pleasure of doing it, the satisfaction and sense of accomplishment or to sharpen your skills then it might be worthwhile but I find it hard to justify from a pure economic standpoint.
Author:  YeahBut [ Wed Dec 14, 2005 9:02 pm ]
Post subject: 
Quote:
$2200.00 will buy a lot of gas... 1000 gallons or more at current prices. You would have to save 1000 gallons to pay for it; the thing to consider is how long will it take at a (very generous) 15% mileage improvement to save 1000 gallons? I just did a quick calculation... if you currently use 10 gallons a week and net a 15% saving that's 1.5 gallons a week or 78 gallons a year. At that rate it would take 12.5 years to pay for the overdrive at today's prices. Even if prices double fairly soon it will take over 6 years to recoup your investment.

Now, if you want to do the project for the pleasure of doing it, the satisfaction and sense of accomplishment or to sharpen your skills then it might be worthwhile but I find it hard to justify from a pure economic standpoint.
Thirty years ago I traded a 63 Studerbaker PU with a thrown rod for a running VW bug. It seemes like I got the best out of the deal, until some time later the guy told me that the tailshaft overdrive was worth a fleet of old Bugs. The funny thing was that I bought that truck from a junkyard for $85.00 and drove it home. Actually it was an under/over Low Low was way low, and sixth gear was only good on the flats. the littlest hill and I down shifted to 2nd high or 3rd low. I had no idea what I had at the time. My father had a 53 Merc with the same setup. I would love to find something like that.
Author:  Guest [ Tue Dec 20, 2005 8:57 am ]
Post subject: 
OK, I've given this a lot of thought and here's my best suggestion:

You'll need a "donor" 904 and an A500 from a V6 or V8 truck. You'll also need a spare front pump housing, a thick (3/8" at least) aluminum plate larger than the bellhousing bolt pattern and a piece of tubing slightly larger than the center opening of the front pump seal area.

Take all the parts out of the pump and bolt it into the case. You'll have to make a careful copy of the bellhousing bolt pattern on the thick plate. Make sure that the dowel pins holes are ACCURATE and use them to align the plate, then bolt it down securely.

Now the tube must be turned down in a lathe so that it JUST fits into the front of the pump. Make sure there is enough length left to reach the plate after you've welded the tube to the pump.

So, now you have the pump bolted into the 904 with a tube sticking out to at least where the front face of the bellhousing is. Cut the tube to length so that it just touches the front plate when it's bolted on. Now weld the plate to the tube. You've now made a cheap and sturdy jig that gets you correct front to rear placement of the bellhousing to the front pump - this is the critical part!

Now comes the fun part! Cut off the bellhousing from the 904. This will take a large bandsaw - probably at your local machine shop. You'll also need to cut off the bellhousing from the A500, but first you'll need to look at where the two shapes intersect. If you place the cut bellhousing in front of the A500 it should be pretty clear as to ABOUT where to cut.

After both cuts are made, bolt the jig into the A500 and then fit the bellhousing into place. Weld it up inside and out, and (in theory) you now have an A500 for a slant 6!

I haven't done this yet, but I've put a lot of thought into it. If what I've typed isn't clear, e-mail me at marc@marcmedina.com and I'll see if I can do some pictures.

Thanks,
Marc
www.marcmedina.com
Author:  mcm95403 [ Tue Dec 20, 2005 8:59 am ]
Post subject: 
oops - wan't logged in when I typed all that!

Marc
www.marcmedina.com
Author:  mcm95403 [ Tue Dec 20, 2005 9:39 am ]
Post subject: 
Also,
The A500 is basically a heavy duty 904 (what they called an A998 or A999) with and OD unit hung on the back end.

It also give you deeper first and second gears - 2.74 and 1.54 - instead of 2.45 and 1.39. So, getting moving is a little easier although you do have slightly more of an rpm drop between gears. The long stroke of the 225 should work great with that though. Third is still direct and the od ratio is .69 I believe.

You also get a lockup converter, so you can use a looser converter for a better launch and then still have the efficiency benfit of the lockup. All you need is a ground switch of rhte od unit on the dash (pirate it from the truck you get the tranny from) and you're up to date on the transmission scene!

The A500 shares the same light weight internal parts that the 904 has, so you're not spinning all that extra mass and wasting power. The V8 drag guys usually pick up about .3 in the 1/4 mile just going to the smaller trans becasue of the reduced rotating mass.

Marc
www.marcmedina.com
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