Swapping ratios in an overdrive A-833?

[MopaR&D]

My '70 Duster is currently equipped with a 904 and cheap 2600-stall converter behind a built 360 and while it launches the car really hard I would prefer a 4-speed manual overall. I know auto-to-manual conversions on these cars can get pricey, so I was looking into possibly swapping in an overdrive A-833 since they can be found for cheap and having overdrive would be a Godsend for me. However the gear spread on these sucks, mainly the 3.09:1 first gear is way lower than I need esp. if I am going to be running 3.55+ gears in the back. Is there a way to swap a 2.66:1 first gear set from a regular A-833 into an overdrive? I don't have experience with these at all, just looking for a cheap way to be able to slam gears in my car but not give up any performance or 'feel'... I know Passon has an overdrive gear set but I'm not ready to shell out $1500 when I could save that money to put towards his new 5-speed.

 

[mischiefdart]

Nope. The countershaft or cluster gear is one piece so no ratio changes are possible

 

[MopaR&D]

Nope. The countershaft or cluster gear is one piece so no ratio changes are possible

:banghead: damn maybe I'll just look into a different tranny then, I'd rather go through the extra trouble to have a decent spread between ratios and non-overdrive A-833's are pretty expensive and hard to find.

 

[Woods74]

If it helps, I've heard claims that IRL, the spread isn't that bad. Try it out and see if it really bothers you that much first.

See post #16:

http://www.forabodiesonly.com/mopar/showthread.php?t=137732

 

[SirDan]

http://www.kabamus.com/garage/gears.html

you can use that and get an idea of how the gears will be.

It seemed like with a 255/60/15 tire and 3.55 gears that First and second on the OD trans at 6000rpm were 10mph slower than what 904 gears were.

 

[Woods74]

Here is a cool calculator too, and it has a tic-toc-tach!

http://vexer.com/automotive-tools/speed-rpm-calculator

 

[66fs]

The "overdrive A-833 since they can be found for cheap and having overdrive would be a Godsend for me." The OD A-833 is actually pretty sweet on the street. 3.55 are a good ratio since it gives a final ratio of 2.60, and a 1st gear rato around 4.10. Not the best for Racing, but not too shabby on the street. Since you have a built 360 you will have no problem with power and torque from the gear spread. I run one behind my 273 and my biggest problem is keeping a clutch from slipping.

 

[MopaR&D]

Ok maybe i'll give it a shot after all... I looked into other options like a Mustang T-5 swap and while the ratios are better I doubt it would live long behind my 360 (380+ lb-ft). I read up on bushing the aluminum 833 case for strength, how expensive is it to get that done?

 

[R3dplanet]

A T-5 would work perfectly well if you found what is known as a "world class" T-5. It's the one Ford put into the 5.0 mustang in the '85-90s, and perhaps some of the trucks. It's far stronger than the standard T-5 and has excellent ratios. If you go Mustang hunting be sure NOT to get the "world class" model from the 4-cyl turbo model because while strong, the ratios are all wrong.