Tranny Overdrive

[George G. Leverette]

I want to add another gear to the 727 in the 74 Duster. Which is the better option the 518 or Gear Vendors? Some factors: total cost for the conversion, ease of installation and modifications to A-body that will be needed for either combination.

[TK]

george, i think mopar performance sell a 518 and the kit for a A body, they didnt say anything about the tunnel mods or the likes.

[dwc43]

The A518 wont fit without some serious frame and tunnel mods. Not really worth it in my opinion. Plus if it's not done right, you'll never get the doors to open again. The front frame is not under those cars very well at all. We learned that when building our big block car and removed the front fender wells. Of course it did not matter since it was getting a full cage anyway and that braced back up the front end even better than the factory did.

[TK]

im glad you said that, i was considering a 518 in my duster!

[ehostler]

There is a complete article in the tech archives of the performance talk area.

Honestly, I would go with the GV OD unit. It's alot easier to install and only requires a small dimple, in the floor pan, just under the rear seat. The GV unit is also much stronger than the 518.

[George G. Leverette]

thanks for the comments, still open for more suggestions.

[dwc43]

Originally Posted by dodgetkboy78

im glad you said that, i was considering a 518 in my duster!

Welcome, anytime.

[cutting torch]

I just completed a 518 swap into my '68 Dart. If you can fabricate and weld, and are motivated, you can do it. If I had to quote a price to do it for someone else, they might just want a gear vendors unit (it's time consuming to do it right). I also did the same basic thing to my Barracuda to clear my clutchflite, I just didn't need as big of a hole. If you decide to do it and/or have more questions, just ask.

torch

[dwc43]

Originally Posted by cutting torch

I just completed a 518 swap into my '68 Dart. If you can fabricate and weld, and are motivated, you can do it. If I had to quote a price to do it for someone else, they might just want a gear vendors unit (it's time consuming to do it right). I also did the same basic thing to my Barracuda to clear my clutchflite, I just didn't need as big of a hole. If you decide to do it and/or have more questions, just ask.

torch

Can you still get a clutch flite from sonewhere. I'd like to try one just for the awe and shock effect ... LOL!!

[cutting torch]

Not that I know of, it's got a lot of custom stuff by myself and Mark Williams. It is a hoot though! I love having an adjustable stall!

torch

[dwc43]

That's what I figured. Wonder what a Lenco cost ? No prices on there site.

[bbeckwith]

George, my man at the local speed shop just called me to let me know my Gear Vendors unit just arrived. I waited about a month, maybe a few days less. Obviously haven't installed it yet, heck he called me only 10 minutes ago, funny this thread comes up. Some timing. Will let you know later on how the install goes, will prolly take some time tho as I just bought a 68 Barracuda fastback and am totally stoked over it right now.

[cutting torch]

Originally Posted by dwc43

The A518 wont fit without some serious frame and tunnel mods. Not really worth it in my opinion. Plus if it's not done right, you'll never get the doors to open again. The front frame is not under those cars very well at all. We learned that when building our big block car and removed the front fender wells. Of course it did not matter since it was getting a full cage anyway and that braced back up the front end even better than the factory did.

That reminds me..... If you do this, block the car up under the K-frame and back off all preload on the T-bars. Also, support it under the rear of the front subframe rails and under the front of the rear subframe rails (read that twice!). This will support the car so it can't move, unload the suspension, and let the car relax. When I cut out the center of the crossmember, it didn't even move enough to bind my sawzall blade!

torch

[dwc43]

Originally Posted by cutting torch

That reminds me..... If you do this, block the car up under the K-frame and back off all preload on the T-bars. Also, support it under the rear of the front subframe rails and under the front of the rear subframe rails (read that twice!). This will support the car so it can't move, unload the suspension, and let the car relax. When I cut out the center of the crossmember, it didn't even move enough to bind my sawzall blade!

torch

I'd have to agree with doing exactly that if not more to keep it from moving. A surface plate or frame machine will work wonders too, but I know most wont have access to such.

[Clair]

Originally Posted by ehostler

There is a complete article in the tech archives of the performance talk area.

Looks like those files are toast. Do you have them saved elsewhere, or do you know what months/years they were published? I have a pretty good supply of old HPM's on the shelf. Was it part of their Roach Runner series? I only paid about half attention to that one... never have had a B-body, and didn't have an auto trans until recently...

Clair

[cutting torch]

Originally Posted by dwc43

I'd have to agree with doing exactly that if not more to keep it from moving. A surface plate or frame machine will work wonders too, but I know most wont have access to such.

In my opinion, whatever you do to keep the car from shifting during the work, and supporting it as the suspension would, (but without the suspension holding any weight) is the way to go. As far as stuff to do this with, I consider myself lucky. I have a 4 post drive-on lift that is a good, stiff platform for this project. I have some long sticks of 5" square tubing that makes great supports for the car when you lay them across the ramps.

torch

[Stoga]

Guys, this has been a killer thread! I just figured it belonged more in the performance forum than the restoration forum. Don't let that stop ya, it's been a good read so far!

[ehostler]

Originally Posted by Clair

Looks like those files are toast. Do you have them saved elsewhere, or do you know what months/years they were published? I have a pretty good supply of old HPM's on the shelf. Was it part of their Roach Runner series? I only paid about half attention to that one... never have had a B-body, and didn't have an auto trans until recently...

Clair

That's right. I forgot that freeyellow stopped being free, so I let it die. It looks like part 1 was July of 1998. I can email you the series, if you would like.

[dwc43]

Originally Posted by cutting torch

In my opinion, whatever you do to keep the car from shifting during the work, and supporting it as the suspension would, (but without the suspension holding any weight) is the way to go. As far as stuff to do this with, I consider myself lucky. I have a 4 post drive-on lift that is a good, stiff platform for this project. I have some long sticks of 5" square tubing that makes great supports for the car when you lay them across the ramps.

torch

Something else that you might find useful is to take old wheels and weld a tube in them. THen make a threaded adjustable top to hold things up like muffler and tranny shops use to support other things while under a lift.

[Clair]

Originally Posted by ehostler

That's right. I forgot that freeyellow stopped being free, so I let it die. It looks like part 1 was July of 1998. I can email you the series, if you would like.

Let me see if I've got them, if not I'll email you. Mainly, I was looking to see if I had part 6/6 so I could add it to the series. Maybe that's about when MM took over...

Clair

[rumblefish360]

I've seen this done twice. The tunnel mod isn't as bad as one might think. It is a job to do, and do it right. The 500 fits better with minor mods.
The structural integrity isn't compromised that much. The best thing to do as someone said is to tie the subframes together before you do anything.
The gear vendors is much more money, but alot easier.

[cutting torch]

Originally Posted by rumblefish360

The 500 fits better with minor mods.

The 500 and 518 use the same overdrive case, so they are equally fat where the crossmember lines up. By the time you rebuild the tunnel in the floor, you could use either tranny.

torch

[Clair]

I assume that the trans mount is in the same location as the 727/904, correct? If so, it would seem to be pretty easy to get the right amount of tweak on the crossmember if you had it all in place. I sure wish I had some confidence that the C-barges had a bunch more trans tunnel space, but I don't know why Ma Mopar would use anything but the one template for all their drivetrain tunnels across the lines. An OD 440 Sport Fury Vert sure would be a nice cruiser...

BTW, Ehostler, I got nada for High Performance Mopar in all of 1998. I have March, May, July, Sept, Oct., Nov. in 1999, though. If you don't mind sending those articles, I could use them.

clair.davis
at
charter.net

Thanks!

Clair

[ehostler]

I don't have part 6 for some reason. I couldn't find that issue. I know that they had skipped a month or two, before printing the last part. I will send you what I do have.

[rumblefish360]

Thanks torch.

[ehostler]

Originally Posted by rumblefish360

The gear vendors is much more money, but alot easier.

By the time you buy a used 500/518 and then have it rebuilt, you are close to the cost of the GV unit. Then you still have to deal with all of the fabrication work on the tranny hump. Don't forget, you need a different drive shaft as well.

[rumblefish360]

I was thinking new 518 or 500 and ethier way, you'll need a new driveshaft. The cutting and fab work is the bummer work with the Chrysler O.D. Not the expense. From what I've seen on the cutting, it isn't that bad.
For the people that are OK with cutting, it may be the way to go if the dollors aren't there for a GV unit.

[ehostler]

The last time that I looked, a new 500/518 was not much cheaper than the GV OD. The you have to kill the value of your car by butchering the floor and the the tranny frame. At least with the GV OD, you can simply remove the unit and put the correct driveshaft back in and it's like it was never there. You can't say taht about the 500/518 swap.

If you don't care about possibly taking the car back to original, then don't worry about the cutting and welding. I know that when I go for the Keisler conversion, in my 69, I will have to make a couple of mods to the floor. Then again, my car started it's life as a lowly 318 car. It currently has a 440 in it. The original 318 is long gone. It was removed 2 owners and over 10 years ago. That was also in Canada. So, I'm not concerned about mine being original or being able to go back to original.

[cutting torch]

I have recently gotten two A518 lockups for builders, one for $85, one for $150, both in good shape. The places to go are you-pull-you-save type yards that have a set price for whatever part, regardless of make. If you rebuild them yourself, the only cost is the parts, which should be well below $250. The expense of modifying the car is minimal cash-wise, just some steel for building stock (this assumes you have the tools to do it with). The money is not a big issue with this project, but the time and commitment is.

As far as the strength of the A518, remember that this unit can be upgraded to the diesel truck specs (internally), which is strong enough for 90% of the hotrods out there. The 47RH specs are easy to get to, and are rated for 700 foot-pounds of torque. Keep in mind that this torque spec is as-installed in a vehicle that has a GCWR 4 to 5 times the weight of your car! I would think that is on par with the GV unit.

torch

[cutting torch]

Originally Posted by ehostler

The last time that I looked, a new 500/518 was not much cheaper than the GV OD. The you have to kill the value of your car by butchering the floor and the the tranny frame. At least with the GV OD, you can simply remove the unit and put the correct driveshaft back in and it's like it was never there. You can't say taht about the 500/518 swap.

If you don't care about possibly taking the car back to original, then don't worry about the cutting and welding. I know that when I go for the Keisler conversion, in my 69, I will have to make a couple of mods to the floor. Then again, my car started it's life as a lowly 318 car. It currently has a 440 in it. The original 318 is long gone. It was removed 2 owners and over 10 years ago. That was also in Canada. So, I'm not concerned about mine being original or being able to go back to original.

Personally, I have no problem cutting up and modifying my Mopars, but I would never consider doing it to one that has value as a restoration, or is the least bit rare. If I got my hands on one that fit that criteria, I would do bolt-on mods only, NO cutting or welding.

torch