small block overdrive

[trevor74]

hey i have a 360 small block in a 1974 charger and i was wondering of anyone that knew an automatic transmission that would work in my car. right now i have a 904 thats junk. and i figured might as well try and get an overdrive one.
thanks.

[RD]

yes they will work... but.. you will need:

a new driveshaft (or yours shortened)
a new trans mount, or  yours modified
the tunnel reworked, or the trans case modified
a new flywheel and torque converter
and lastly, you will need to hook up your OD trans to accept either the electric or hydraulic actuated solenoids that activate the OD and converter lock up (which is based upon the year of the transmission you would be using as they switched from hydraulic to electric in the late 90's).

all of this can be done.. just requires either (1) the right shop or (2) research and know-how on  your part.

any 42/46 RH/RE transmissions will work as long as they are for 2WD vehicles.  42 being 904/999 style and 46 being 727 style.

[THMPN73]

I put a 518a in my 73 charger a couple of years ago.. the tranny was out of a 1990 dodge 1/2 ton and has the electronic OD.

I did not have to modify my tunnel but i did need to shave off some of the brackets on the top of the transmission. It fits very tight but i have not had any problems with clearance. I have my driveshaft from my 904 shortened for quite cheap $30 or something at a driveline shop. I used the original bracket from the 904 but it needs to be a few inches lower to allow the OD to fit through it so I just cut two U shaped plates which did the trick and have not had any clearance issues with that either.
For the electronic shift it was fairly easy to rig up. It just has a plug with a positive and a negative prong.. just put the battery to one side and ground the other. I have a switch on my b&m shifter for the positive side and you just turn it on whenever you want OD.

The only problem that I have had with it is that it will automatically shift into OD about 3-4 seconds after it shifts into 3rd gear no matter how hard or soft you are on the throttle. But its not really a big deal cause i only ever turn it on when i get up to cruising speeds on the highway. Makes a huge difference with 4.10s in the back!

Also I bought a new 2200 stall and b&m flexplate(120$) when i did the install

I have some pictures on my other computer of the brackets I made for it that I will post later

[RD]

great post thmpn.. here are some pics of a modified trans housing...

[THMPN73]

Thanks RD...I did this install while I was still back in highschool and had never really done too much modification before, so I know my install is a bit sketchy but I have no complaints about it haha. I was wondering if you know if you can still use the speedo for these transmissions? I believe mine I left the electronic speedo plug in just to seal the hole as i could not run the old school one because the frame gets in the way. I thought I had some better pictures but i found these ones that kinda show what I did. Above I said 2 u-shaped plates but looks like i just used one on the back side and 2 squares on the front just to drop it a bit. You can see the pan hangs quite low but i havent dinged it yet, the headers always hit first haha.

Oh and i got a Lokar cable throttle/kickdown kit because the mechanical (lever?) kickdown wouldnt work with the new carb but I think that I was able to get it to work with the old carb.

[RD]

to be honest.. i have not addressed the speedo issue as of yet as all of my vehicles take a standard 727 (well except for the upcoming v10 swap i will be doing).  in that one i have the computer so i am not too worried about it.

I know the inner part of that speedo pinion is mechanical and turns the rotations into an electrical current to the connection via a magnetic pickup i assume.  I will see if I can take apart my speedo pinion and see if it can be modified for a standard speedometer cable.  I think  your access issue is specific to your trans mount configuration on the 73.

imo.. it looks really low due to the deep pan you got (which are stock), and because you didnt modify the case or the tunnel that is probably necessary... be careful over speed bumps (dont ask me how i know LOL ).

is your pinion angle good on your rear diff?

as far as the kickdown issue.. your one carb's geometry may be a lil off at the throttle lever... just requires some tinkering to get it to align good.  I had that issue with my Demon carb after i put it on my 400... fixed it with tinkering.