Gearbox upgrade

David C · #1 (**permalink**) 20-08-21, 04:32 PM

Hoping to upgrade my Torqueflite to a later box with locking torque converter and overdrive. Andrew Atherton reports excellent results from his. Sadly with Martin Barnes passing I cannot ask about the details of parts ordered for this.
I think I have identified a suitable unit but need to know if it will work with the original flex plate and whether bell housing bolt pattern is the same. Apparently gearbox extensions with manual speedo drives are available as are kits to switch overdrive and lock torque converter automatically.
Has anyone else done this who can help?

peter dowdle · #2 (**permalink**) 21-08-21, 04:33 AM

David is it your 410 , it always pays to tell people what car you are talking of ?

David C · #3 (**permalink**) 21-08-21, 11:54 AM

It is indeed. Good point well made!

Geoff Kingston · #4 (**permalink**) 22-08-21, 04:37 PM

David,
Browsing one of the mopar forums I came across this company, seemed to be getting good comments and an interesting and informative website.
Geoff.
NUTTY PROFESSOR TRANSMISSIONS

David C · #5 (**permalink**) 22-08-21, 08:09 PM

Thank you. I will give him a call.

jalli · #6 (**permalink**) 21-09-21, 08:34 PM

did you find any info. I am considering doing the same

David C · #7 (**permalink**) 21-09-21, 08:42 PM

As far as I can tell the original flexplate will be ok.

Waiting until I can find out how much modification is required for the mounting but I hope to get moving on the project this Winter.

jalli · #8 (**permalink**) 21-09-21, 08:56 PM

did you speak to nutty professor?

i have a 411 that needs a gear box rebuild and it seems an opportunity to improve things.
I have neither the time , knowledge or skill to do myself!!!

bw

james

Philip · #9 (**permalink**) 22-09-21, 08:56 AM

The four-speed A518/46RH is essentially a three-speed 727 Torqueflite with an overdrive fourth gear in a slightly longer housing, the bellhousing pattern etc is the same so will bolt to what a small block727 did (a big block will need an adapter or the bellhousing cut off and replaced). With a “three-wire” lock-up A518, the operation of fourth gear and the lock-up can be controlled via oil pressure and vacuum switches.

peter dowdle · #10 (**permalink**) 25-09-21, 02:41 AM

Back on the 21/05/2014 Member GOFFJASON started a thread about fitting a 4 speed box to a 412. Jason, last I contacted him, was well on the way to doing the conversion. I have not been able to contact him for some time but you will find some good infomation in these posts. From what I learnt from Geoff it isnt a five minute job.