67 Cuda 5.7 Hemi Tranny Advice Needed

-
M

msmrinc

Member
Joined
May 24, 2011
Messages
24
Reaction score
8
Location
Madisonville, TN
Hello All,

I'm looking for some advice and input on my tranny dilemma. I'm doing a full-on 1967 Barracuda 5.7 Hemi swap. I'm going with the RMS Alterktion front k-member suspension setup.

I already have my 5.7 Hemi donor engine. It came out of a 2004 Dodge Ram 1500 pickup. It came with a Mopar 5-45RFE 5-speed automatic with two overdrive gears, with final ratio being .67 I do want overdrive.

My chief concern is the tranny tunnel. I really don't wanna cut up the floor, and I know my 5-45RFE isn't gonna fit without serious cutting and fabbing up a new hump. My 67 originally came with an A727, which are excellent tranny's and would fit right in there, but no overdrive. I understand that Chrysler basically upgraded the 727 in the 90's to add overdrive and called it the A518.

I'm open to anything at this point. I've got a couple months before I'm gonna install the engine and tranny. What would you guys do? Any advice here would be greatly appreciated.
 
I recently asked if anyone had tryed movint the engine forward an inch or more to aviod cutting the tunnel. No reply yet. That was keeping the stock K with front sump pan and altering its motor mounts. Your AlterK is a different animal.
One meber said he grafted a section of the Dakota pick up tunnel in his a-body rather than hand fabricate the expansion.
 
If you do some research on the tunnel mods, you'll see that there is NO WAY that the 545 is going to fit without major surgery. You won't be able to move the engine far enough forward.

Also, yes, Chrysler did make a 727 variant with an overdrive, the early 90s versions are almost all hydraulically operated. You do however need to cut the floor a little to get it to fit. Over at Hot Rod they have an article about the installing both the new hemi and the A-518.

http://www.hotrod.com/howto/hrdp_0706_hemi_swap/index.html

The only three ways to get an overdrive without cutting the floor are to use a Gear-Vendors unit, or you can use one of the New Passon Performance new five speeds manual. I am dubious about Kessler's kits.

Regards,

Joe Dokes
 
Since you are using the alter-K, it is not that big of a deal to modify the tunnel to fit the 545. You don't have to worry about the cross member for the torsion bars, because you won't be using them. I'm sure you could get a piece of floor out of a ram which might make it easier. The nice thing about the 545 is you can adjust shift points, tire size, etc. with a Predator tuner along with your engine. If you want to see how I did it, check my build in Members restorations. Plus you have more room in your 67 than I did in my 63, and it fits fine.
 
Differences shown here. 727/Nag1/RFE545
 

Attachments

  • trans_diff2.jpg
    72.1 KB · Views: 1,055
  • conversion transmission.jpg
    96.4 KB · Views: 1,255
Wish the A-500 was in those pics. Probably wouldn't help much without a tape measure pictured too though. Good luck to all.
 
C:%5CDocuments%20and%20Settings%5CGerryS%5CDesktop%5CMopar_trans.jpg
A few more pictures and some dimensions:

Left to right: A518, A727, A500
View attachment Mopar_Automatic_A518_727_904.jpg

Length and mount dimensions:
View attachment Mopar_trans.jpg

C:%5CDocuments%20and%20Settings%5CGerryS%5CDesktop%5CMopar_trans.jpg
 
I did all of the cutting, well actually my 15 year old son did it in about 30 minutes. When I got around to putting it in I decided to let someone else do it 110 degrees in the garage. I found a shop to put in motor tranny headers and they made me tranny cross meember and used a GM truck mount that bolted up. They did it in about 6 hours. Well worth the money at 45 an hour. Yes i even tried moving everything forward no luck.
 
It's more than just cutting the tunnel, 545RFE uses pulses for speedometer signal, no cable. However, the 545RFE having the .67 overdrive means you can run a very steep rear end gearing and still lope along at 2-2.5k RPMS at 70. Stock 2011 Ram hums along at almost exactly 2000 rpms with 3.91 gears. Gas isn't going to get any cheaper :sad5: There are some pictures floating around the forums of how much members had to cut out of their tunnels. Just adding more info to the pile :D
 
So, if I understand correctly, if I go with an A518 or my 5-45RFE, I'm gonna have to cut up the floor. I'm not terribly concerned about that, but what about the Torsion Bar Crossover Brace, going from one side of the front frame section, over the tranny tunnel, then on to the other side of the frame. Is this crossover square tubing structurally important to the floor or the car in general? This square frame-like tubing is definitely gonna be in the way and will have to be cut out. If all it's there for is the torsion bar front suspension, and doesn't offer support to the car in general, then I'll cut it out, no problem.

Lemme know.
 
I would imagine it ties together the frame rails in the front. I'm putting a 5.7L and a 545RFE in my 73 duster with the RMS kit. I didn't feel right about taking that cross member out until I put in frame connectors, torque boxes, and US Car tool's front suspension stiffening kit...but I'm also crazy about not having the twists in the turns. I'm no structural engineer, but without some sort of stiffening, I would be hesitant to remove the whole cross member without help elsewhere.
 
Okay, I am right in the middle of welding in my replacement cross member tonight. I tired to reuse the formed cross member peices and added a 2x1 tube across the top, but it became too big. It looked like I was going to be infringing on the bucket seat property, so I went and purchase a 3 x 3/8" flat bar to heat, bend and trim up and over the trans. I am trimming the two ends to just under 2" across and 2" in depth, these will slide right down into the cutoff ends of the stock cross member. I will grind and trim until I get a nice tight fit, then heat up the two bend areas, bend to form the tunnel shape I need (I have template made to match to). Then, I will test fit, tack in-place and roll the trans over to test fit, when all is good, I will weld up solid. I reused the sheet metal tunnel, but beat all the inverted bumps out of it to create more room. It welds in nice at the firewall, but only makes it to the cross member barely, after that it becomes difficult and time consumming. Cut pieces of cardboard to fill the slices that are left, transfer to sheet metal, cut, fit and weld inplace. We are running a 6.1 Hemi with stage two chip, so at 480HP they told us we needed to run the 545RFE, so we went with 3:73 posi in an 8-3/4" Mopar.
Good luck
 
Look at the GM 200r4, it is an overdrive tranny and is actually smaller than a 727. You will need to have it beefed up. I've seen this tranny live quite well behind a 1100hp buick grand national without any problems.
 
69DarttoArt said:
Okay, I am right in the middle of welding in my replacement cross member tonight. I tired to reuse the formed cross member peices and added a 2x1 tube across the top, but it became too big. It looked like I was going to be infringing on the bucket seat property, so I went and purchase a 3 x 3/8" flat bar to heat, bend and trim up and over the trans. I am trimming the two ends to just under 2" across and 2" in depth, these will slide right down into the cutoff ends of the stock cross member. I will grind and trim until I get a nice tight fit, then heat up the two bend areas, bend to form the tunnel shape I need (I have template made to match to). Then, I will test fit, tack in-place and roll the trans over to test fit, when all is good, I will weld up solid. I reused the sheet metal tunnel, but beat all the inverted bumps out of it to create more room. It welds in nice at the firewall, but only makes it to the cross member barely, after that it becomes difficult and time consumming. Cut pieces of cardboard to fill the slices that are left, transfer to sheet metal, cut, fit and weld inplace. We are running a 6.1 Hemi with stage two chip, so at 480HP they told us we needed to run the 545RFE, so we went with 3:73 posi in an 8-3/4" Mopar.
Good luck
Click to expand...

pics ? If you can.
 
The issue with the NAG trans is it needs feed back from the abs system to work. No wheel spped signal no go. 5.7dart did put one in his 68 cuda and had it mobile but he had a sensor built to mount on the driveshaft and was using the complete electronics out of the donor car.
 
toplscuda said:
The issue with the NAG trans is it needs feed back from the abs system to work. No wheel spped signal no go. 5.7dart did put one in his 68 cuda and had it mobile but he had a sensor built to mount on the driveshaft and was using the complete electronics out of the donor car.
Click to expand...

Behind a new Gen engine or old school small block ?
 
I was going to do a NAG1, but there are a laundry list of issues that aren't there with the 545RFE. Things like no slip-yoke on a NAG1, wheel speed sensors, ABS computer and CAN BUS connectivity, etc etc.
 
68-GTS said:
Behind a new Gen engine or old school small block ?
Click to expand...

5.7dart put in a 6.1 and trans out of a 07 magnum. He pulled the complete wiring out of the donor to do the install but found out about the need for feedback from the wheel speed sensors after thrying to get it to move.
 
I know tci has a od six speed for a small fortune that is a heavily modified GM 4L80e, not sure how big it is in relavance to the other transmissions but its an option and it comes with a programmable tcm.
 
A basic test light will kill a wheel speed sensor. Diagnose with multimeter only.
The more you know :)
 
You must log in or register to reply here.
-

Back
Top