Question about A518 transmission swap into a '73 Charger

[Triple Black 73]

My dad has a A518/46RH transmission laying around in Alabama and he's bugging me to do research about swapping it into the '73 Charger. I want to replace the lame 2.73 gears with 4.10 gears but I also want to drive 80 mph on GA-400.

My question is there any changes required to the floor to swap this into the '73 Charger?

These sources below does a great job about the process, but nothing about cutting into the floor. Is the there any floor cutting required?

http://jvxracing.com/Adapters.htm
https://www.hemmings.com/magazine/mus/2006/07/Chrysler-A-518-Overdrive-Transmission/1301453.html
http://www.hotrod.com/articles/43323-mopar-overdrive-transmission-swap/

 

[Dako]

 

[493 Mike]

Everything I've read said the OD unit will not clear the torsion bar cross member so it must be extensively modified which would include cutting the floor.
Mike

 

[customusclegarage]

The drive line angle is the most important thing and you have to cut quite a bit to get it right here is what i had to do to my wife's 71 ssp with 92 magnum and 518 I had to raise the tunnel by 1 1/2 inches and widen on both sides drivers side more cut out the center of the torsion bar crossmember and replace it with 3/4 inch x2 inch flat stock with the bottom of it on top of the original tunnel height you can use the original tranny mount crossmember with modifications lots of work by it runs great and no vibration

 

[Triple Black 73]

The drive line angle is the most important thing and you have to cut quite a bit to get it right here is what i had to do to my wife's 71 ssp with 92 magnum and 518 I had to raise the tunnel by 1 1/2 inches and widen on both sides drivers side more cut out the center of the torsion bar crossmember and replace it with 3/4 inch x2 inch flat stock with the bottom of it on top of the original tunnel height you can use the original tranny mount crossmember with modifications lots of work by it runs great and no vibration

Thanks man! I'll show these pictures to my dad. Clearly, we should've done it last summer before the under-body was painted and the inside coated. I was hoping for a cleaner drop in.

I just noticed your trans mount cross member mounts the transmission a good 2-3" inches higher than the one in the Hot Rod's article. I wonder if a fully custom trans mount would lower the trans enough to clear the floor. Of course, then I would need to shim the rear to make sure the pinon and driveshaft angles are correct. Something to research more.

 

[sebring360]

View attachment 497184 View attachment 497183 View attachment 497182 View attachment 497181 View attachment 497180 View attachment 497179 View attachment 497178 View attachment 497177 The drive line angle is the most important thing and you have to cut quite a bit to get it right here is what i had to do to my wife's 71 ssp with 92 magnum and 518 I had to raise the tunnel by 1 1/2 inches and widen on both sides drivers side more cut out the center of the torsion bar crossmember and replace it with 3/4 inch x2 inch flat stock with the bottom of it on top of the original tunnel height you can use the original tranny mount crossmember with modifications lots of work by it runs great and no vibration

I know this is a old thread but I was thinking about this conversion but another question I have have you hooked up your AC- I have a 72 sebring with a magnum and trying to figure out the best way to tackle the ac Greg

 

[wyrmrider]

use a short tranny mount
GM I think works
so you do not have to drop the x member as much
still worth doing
PM me if you need info on 518 mods
BTW 3 wire 95 and earlier trans?

 

[70-BigBlock]

In the midst of having this done to my 70 Plymouth.

They do make a crossmember:
http://store.uscartool.com/70--74-B-or-E-Body-518-Crossmember-Kit-_p_177.html

And a weld-in tunnel (B bodies should be any day if not already exist...they told me):

http://store.uscartool.com/70-to-74-E-Body-Transmission-Tunnel-Perimeter-Frame_p_233.html

May save some time since this is the major issue.

View attachment 853698

 

[451Mopar]

If connecting to a big block, use the JW Ultra-Bell. It is less expensive than the JVX setup and should give a bit more room because the JVX is a plate adaptor that moves everything back about 1/2", and you have to hole saw the stock bellhousing for the starter anyhow with the JVX adaptor.

https://racewithjw.com/product/ultra-bell-big-block-chrysler-to-tf727-or-a518/

I think it will fit without modifying the Floor pan, but the T-Bar crossmember will likely need to be cut for clearance. Pretty easy with a plasma cutter or torch.

I was planning on doing that swap in my '69 Coronet R/T Hardtop, but now have a GEN3 Hemi and NAG transmission.

The 518 might go behind a small block 360 in another project.

 

[Pilotusmc]

I have a 70 GTX. I want to put the 518 transmission in it. OK from what I’ve read this is what I need of course I need to buy 518 with a three wire connector that I have. The tunnel will have to be modified I understand can I get by with just cutting out the torsion bar crossmember and moving it up by just welding in flat half or three-quarter inch stock? The front of the 518 looks just like a 727 to me so you should not have to modify the front of the title correct? It appears that the overdrive unit is what gives it a hard time fitting in. Also I understand that the crossmember will have to be dropped down a few inches for the transmission mount. What else will I need to have to do?

 

[Photon440]

I have a 70 GTX. I want to put the 518 transmission in it. OK from what I’ve read this is what I need of course I need to buy 518 with a three wire connector that I have. The tunnel will have to be modified I understand can I get by with just cutting out the torsion bar crossmember and moving it up by just welding in flat half or three-quarter inch stock? The front of the 518 looks just like a 727 to me so you should not have to modify the front of the title correct? It appears that the overdrive unit is what gives it a hard time fitting in. Also I understand that the crossmember will have to be dropped down a few inches for the transmission mount. What else will I need to have to do?

The 518 bellhousing is indeed like a 727, but the small block version. See post #9.

 

[493 Mike]

Don't forget to release the tension on the torsion bars before cutting the crossmember!
Mike

 

[70-BigBlock]

I have a 70 GTX. I want to put the 518 transmission in it. OK from what I’ve read this is what I need of course I need to buy 518 with a three wire connector that I have. The tunnel will have to be modified I understand can I get by with just cutting out the torsion bar crossmember and moving it up by just welding in flat half or three-quarter inch stock? The front of the 518 looks just like a 727 to me so you should not have to modify the front of the title correct? It appears that the overdrive unit is what gives it a hard time fitting in. Also I understand that the crossmember will have to be dropped down a few inches for the transmission mount. What else will I need to have to do?

Yes. I went with the JW Ultra-Bell setup. And we welded a half in stock (see pictures above), after cutting out the crossmember. See the link in my previous post since they now make the crossmember (I had mine custom built and powder-coated - but it did not exist last year when I started my project).

The tricky bit is you can get the pressure switch to work so it shifts down when it is supposed to. I have a 522 with a cam and it just did not work. It would shift up and down at certain speeds on the highway....so we went with a carb activated switch and a speedo in-line switch for shifting. And of course, a lock-up type torque converter is probably the best set up (what I have).

You can get this if it works for you from PATC:
https://transmissioncenter.net/shop...ick-here-for-727-to-46rh-swap-wiring-diagram/

I still ran into some clearance issues and we just mounted the tranny direct without mounts (race-car style). Yeah, you get more vibration but mine is a hotrod, so no worries.

 

[Dennis Gunter]

Advice please……..I’m considering changing from a 727 to an A-518 tranny to gain overdrive My Belvedere has a 440 with the shifter on the column ……...can I run the column shifter ? I’m thinking not but not sure…what changes do I have to make? Appreciate any advice thanks

 

[493 Mike]

Both the 500 and the 518 are longer and bulkier in the tail section. So yes the drive shaft needs to be shortened. Any unibody style Mopar will require torsion bar crossmember and floor pan modifications to clear. It’s a fairly complicated swap as far as metal fabrication is concerned.
Doug

Advice please……..I’m considering changing from a 727 to an A-518 tranny to gain overdrive My Belvedere has a 440 with the shifter on the column ……...can I run the column shifter ? I’m thinking not but not sure…what changes do I have to make? Appreciate any advice thanks

 

[Dennis Gunter]

Thanks Doug. Your answer clarified a lot for me ….I’m going to stick with the 727

 

[493 Mike]

Thanks Doug. Your answer clarified a lot for me ….I’m going to stick with the 727

I trust you do not mind my plagiarism here Doug!
Mike