727 Overdrive

[whitey]

The tunnel on a GTX is quite a bit bigger than an A-body. Looks like some sheet metal work was necessary on this car http://www.moparts.org/Tech/Archive/auto/28.html was I believe was a Dart....just to give you an idea on how much smaller an a-body tunnel is the trans that is in my car fit into an e-body with out any surgery at all.....another 518 swap article into an a-body http://www.hotrod.com/howto/hrdp_0706_hemi_swap/photo_07.html

This topic is getting thrashed around alot. I've seen articles on thiw topic and the big question is 'Does the floor need to be cut?' My question is why? Why would the hump have to be cut, Chrysler put the same trannies in all cars, 4 speed, 904 or 727. Why would the hump be bigger from B body to A body to E body if a 4 speed or 727 would go in it? The mount locations didn't change (just bolt patterns fron BB 727 to SB 727 and the bell housings)

 

[inkjunkie]

B and E bodies are completely different cars than an a-body. I am in the dark as to what it is you do not understand. Are you saying that all the tunnels are the same size? They are not. For what it is woth a gm4l80 e will fit into a Challenger with NO cutting of the tunnel, into an a-body it requires MAJOR surgery. Let me try to find the pictures of the Challenger......the first picture is of a Challenger with a 4l80 in it. Notice how the area near the mount is not cut in anyway. The second is of my car from the bottom, notice how much farther back the trans mount is in relation to the where the torsion bar is mounted, which is the location of the factory trans mount. Being that the trans mount area is the same from the bellhousing to the trans mount on both cars, that shows you how much longer the Challenger tunnel is than an A-body. That is why the 518, or in case of the pictures, a 4l80 will fit into a Challenger with no cutting yet require a ton of it to get it into an a-body. Last picture is of my car from the top. notice how close my hole is in relation to the gas pedal? Go look at your car and see the difference from the edge of your tunnel to the pedal in relationship to mine? On a Challenger, the tunnel was not modified at all. Sure, you could just drop the tail shaft down to clear everything, but what will that do to driveline angles??

 

[fishy68]

B and E bodies are completely different cars than an a-body. I am in the dark as to what it is you do not understand. Are you saying that all the tunnels are the same size? They are not. For what it is woth a gm4l80 e will fit into a Challenger with NO cutting of the tunnel, into an a-body it requires MAJOR surgery. Let me try to find the pictures of the Challenger......the first picture is of a Challenger with a 4l80 in it. Notice how the area near the mount is not cut in anyway. The second is of my car from the bottom, notice how much farther back the trans mount is in relation to the where the torsion bar is mounted, which is the location of the factory trans mount. Being that the trans mount area is the same from the bellhousing to the trans mount on both cars, that shows you how much longer the Challenger tunnel is than an A-body. That is why the 518, or in case of the pictures, a 4l80 will fit into a Challenger with no cutting yet require a ton of it to get it into an a-body. Last picture is of my car from the top. notice how close my hole is in relation to the gas pedal? Go look at your car and see the difference from the edge of your tunnel to the pedal in relationship to mine? On a Challenger, the tunnel was not modified at all. Sure, you could just drop the tail shaft down to clear everything, but what will that do to driveline angles??

Great pics and explanation. I thought A-body tunnels are smaller than E and B body tunnels but I've never really measured them so I couldn't say positively. You've cleared up that question.

 

[inkjunkie]

Great pics and explanation. I thought A-body tunnels are smaller than E and B body tunnels but I've never really measured them so I couldn't say positively. You've cleared up that question.

I have never measured them, just going by what the pictures say. All of the Mopars I have crawled under had the transmission mounted at the torsion bar crossmember, and given the fact that the b & e torsion bars are 5.3" longer than the a-bodies things have to be different. I need to check the web site where I got the Challenger pictures. Pretty sure there is one of the bellhousing/firewall relationship. On the CHallenger picture, if I remeber right, the top 2 bolts are very accessible, on my car clearance holes were needed as the top 2 bolts are right against the firewall.....

 

[inkjunkie]

First picture is of the quicktime bellhousing to adapt the 4l80e to a Mopar r/b. Notice how the sticker pretty much covers the flat area where the adapter will bolt to the motor? The second picture isof Bryans Challenger, looking down at the firewall. Notice how all but the bottom of the sticker is visible? Third picture is of the Dart with the 4l80e adapter bolted to an empty case. Not the best view but you can see a good portion of the sticker is under the firewall, which shows that the tunnel lengths are different.

 

[grassy]

Has anyone done this conversion ? Ca you do this by yourself or is this a trans dealer install ?

With a 318 or better..it seems like great addition.

Grassy

here ya go.. you can buy the switches as a kit.. http://www.redrider.us/518_parts.htm

PATC 727 to 518 Conversion Kit​

#727518. With these four parts you can convert your 727 transmission to a 518 overdrive transmission with locking torque converter. [FONT=Arial, Helvetica, sans-serif]Lets say you drive an average of 400 highway miles per week, at that rate you could save as much as $1000.00 per year on gas, not to mention the 31% reduction in RPM. Your new 518 will have automatic shifts into overdrive and lock-up, no toggle switch needed. Now with adjustable vacuum switch. The instructions are at the bottom of this page. [/FONT][FONT=Arial, Helvetica, sans-serif](11-25-06. I just saw this kit on the Internet by the copy cat competition for $1654.00.) [/FONT][FONT=Arial, Helvetica, sans-serif]Cost $85.00 Qty 12345
Overdrive 44 MPH48 MPH
Converter Lock-Up 50 MPH52 MPH[/FONT]