Transmission suggestions

[bbrasseaux76]

I have a newly purchased 1974 Charger. My plan was to do a 5.7 Hemi swap with an automatic trans with an overdrive gear. I'm not a welder, but I do have a few friends that could help. I really would rather not cut the tunnel to make the trans fit, so I'll settle for a 727 if I have to. What are my options? Do any auto-OD trans exist that will fit without cutting?

 

[70chall440]

An A518 (basically a 727 with OD) should fit but they are (I am told) very hard to come by. You could go with a gear vendors OD behind the 727 but if you run 2.76 gears or even 3.23 gears highway speeds should not be an issue.

Remember that 3 speed ATs were roaming the highways for decades before ODs became a thing. Unless you intend to do a lot of Hwy/interstate driving a 3spd will get it done fine. I know that everyone these days want 4, 5, 6, or 8 speeds but much of that is hype and not necessary especially on a car that is not a daily driver especially one that does not see a lot of hwy/interstate use.

All this said, its your car and build it how you want but keep in mind what you are really going to do with it. I seldom ever follow my own advice and go down deep/expensive rabbit holes to acquire some function or capability only to park the car in the shop 99% of the time.

 

[bbrasseaux76]

It will get interstate miles. I plan on driving it to Cruisin the Coast once a year (300 mile round trip), and there's a couple of road trips that I'd like to take with my dad while I've still got him. Other than that, it will mostly be just driving around town on the weekends. The 904 that I have needs to be rebuilt, so I figured I'd upgrade to at least a 727, but not sure what other options were out there.

 

[BeepBeepRR]

Isn't the 46RH the non electrical version of the A518 pretty sure the 46RE is electronically shifted and the RH is hydraulic is that correct? Below is the 46RH

 

[ruffcut]

46RH is hydraulic and 46RE is electric

 

[BeepBeepRR]

I believe the 46RH can be found in early V8 Dakotas and dodge full size vans from the era. 86-96 maybe? I know my Dakota RT had a 46RE which mine was a 1999.

 

[sam dupont]

I seldom ever follow my own advice and go down deep/expensive rabbit holes to acquire some function or capability only to park the car in the shop 99% of the time.

Me too. I have to consciously remind myself that good enough is sometimes just fine. The low hanging fruit here is: a 727 and 3.23's gets the car on the road sooner with acceptable rpm's for occasional trips. Later, you can decide if it works for you or if you need an overdrive.

Nobody sells a tunnel kit for a 5.7 swap? Should be able to glue anything that's welded.

 

[Dave6T4]

RH is identifiable by a 3-wire plug, while RE has multi-wire plug. I understand that the OD chunk interferes with the T-bar crossmember, so some surgery is required here.

 

[#41]

I have a newly purchased 1974 Charger. My plan was to do a 5.7 Hemi swap with an automatic trans with an overdrive gear. I'm not a welder, but I do have a few friends that could help. I really would rather not cut the tunnel to make the trans fit, so I'll settle for a 727 if I have to. What are my options? Do any auto-OD trans exist that will fit without cutting?

I think you are way better off in many ways using the OD automatic trans that originally came with the 5.7 than trying to adapt some other automatic transmission. Cut the tunnel if you have to. I'm not sure why you are shying away from cutting it. The path you are embarking on has many challenges more difficult than a little sheet metal cutting and welding.

 

[451Mopar]

The part of the torsen bar crossmember that is inside the tunnel can be cut back and boxed in to fit the 518/46RH/RE transmission. You don't have to cut into the floor pan.
I'm not sure on the NAG1 transmission? It looks shorter so it might fit?
I'd like to hear of anyone running the NAG1? I looked into it many years ago and there was not much in the way of an aftermarket transmission controller?

 

[sam dupont]

I think you are way better off in many ways using the OD automatic trans that originally came with the 5.7 than trying to adapt some other automatic transmission. Cut the tunnel if you have to. I'm not sure why you are shying away from cutting it. The path you are embarking on has many challenges more difficult than a little sheet metal cutting and welding.

I've had HVAC shops bend things for me.

 

[m79ded]

An A518 (basically a 727 with OD) should fit but they are (I am told) very hard to come by. You could go with a gear vendors OD behind the 727 but if you run 2.76 gears or even 3.23 gears highway speeds should not be an issue.

Remember that 3 speed ATs were roaming the highways for decades before ODs became a thing. Unless you intend to do a lot of Hwy/interstate driving a 3spd will get it done fine. I know that everyone these days want 4, 5, 6, or 8 speeds but much of that is hype and not necessary especially on a car that is not a daily driver especially one that does not see a lot of hwy/interstate use.

All this said, its your car and build it how you want but keep in mind what you are really going to do with it. I seldom ever follow my own advice and go down deep/expensive rabbit holes to acquire some function or capability only to park the car in the shop 99% of the time.

That has to be the best take I've heard. I always see car guys that go around the block and want a 6 speed and go through all kinds of headaches to do it. One guy had a nice healthy big cam, Single plane engine and when he put 6 speed he said it litterally killed the car. He had to be going over 85 to enjoy it. Words from him "The biggest waste I ever did"

 

[70chall440]

I completely agree and I have to admit that I am guilty of doing the same thing. So many times I have gotten an idea in my head and went after it which ended up costing a lot of money and time but in the end, probably not worth it but I get what I want.

Great point in case here is that while building my 71 Charger with a 5.7 I decided I wanted to run a Mopar oval air cleaner which required a new intake, spacers, adapters etc. not to mention the very expensive air cleaner itself.