3-speed manual gear ratios

[Ray Bell <raybell@xxxxxxxxxxxxxxxxx>]

I've posted this on Moparchat as well... 

Basically, I am trying to get a full rundown of all the ratios available 
in all the 3-speed manual transmissions installed in Chrysler cars and 
light trucks from about 1961 to 1975.

The transmissions involved are as follows:

A903 - Used principally behind slant sixes, some small V8s
A745 - Similar to A903, but heavier gears, used behind all V8s
A230 - All-synchro unit introduced about 1971
A250 - Light truck unit of approximately the same era

I know there was also a Borg Warner 3-speed used, the T87 (or was that 
T85?) as fitted to Max Wedges etc... this is outside the area of my 
interest.

Most of what I know about these I've gleaned from websites, in 
particular the Autohobbydigest site which no longer has quite the same 
detail on it. The information there was, however, as incomplete as most 
others.

I'm looking to record all the different ratios (and possibly tooth 
counts) for each of the various trannies.

The A903, for instance, I read came with at least three set of gears. 
For the slant 6 there was 2.95 1st; 1.83 2nd and 1.0:1 top as well as 
another gearset with 3.22 1st; 1.84 2nd and 1.0:1 top. However, for the 
318 'light duty V8' model there was a very close ratioed set with a 
2.12:1 first gear... second was about 1.4:1, but I don't have a record 
of that exactly.

The A745 car with something in the order of 3.09:1 first gear for the 
most part, but big block cars (supposedly) had a 2.55:1 first and 1.49:1 
second. There was possibly yet another option with a slightly lower 
first, but again I don't know.

The A250 is a bit of a mystery to me, but the A230 is of plenty of 
interest. It's a similar build to the A833 4-speed and has some 
interchangeable parts, while I know there was a couple of gearsets with 
first gear just over and just under 3.0:1, I've also read somewhere that 
there was another with a 2.25:1 first. Yet another list shows the same 
2.55:1 first as came in the A745 as an option, so it's possible this has 
caused someone to get a bit excited and get the numbers wrong.

I'd like to sort all of this out if it's possible. Information will come 
from spec sheets for different models, including light trucks, and 
possibly workshop manuals, all of which are unavailable to me.

For those not familiar with these trannies, the A903 and A745 are 'top 
loader' type units, with a pressed steel cover over the top of the cast 
main housing. The A745 is distinguished by having a distinctive lump 
over in the front part of this cover over the 2nd/3rd selector 
mechanism.

As mentioned, the A230 and the A250 look rather like the A833 4-speed, 
but not as bulky. There is a side plate rather than a top cover, with 
the selector levers operating through this side plate.

Those built for cars have two lengths, approximately 33" from the tip of 
the input shaft to the rear seal for the A-body units and about 4½" 
longer for B, C and E-body trannies. There is another length in the 
A745s that I know about, for those fitted to Chrysler models in the 
early to mid-sixties, which have a slightly longer input shaft that 
probably adds about 2" and is easily distinguished by having an increase 
in input shaft diameter just behind the clutch spline area.

I'm trying to get a comprehensive picture of all of these variations for 
the simple reason that it's so hard for anyone looking (as I have done) 
to find them in any one place.

Hope you guys can help... thanks in advance.


Ray 

The stories of youth, of the burden of time, and the death of 
devotion.HCK


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