4speed conversion

-
O

omotz

FABO Gold Member
FABO Gold Member
Joined
Feb 3, 2024
Messages
13
Reaction score
5
Location
Sacramento Ca.
Wondering if a833 overdrive fourspeed will bolt up to a 1963 170 dart with 3 on the tree
 
Anything is possible. I don’t have a slant 6 so I can’t say on bolting up. There is an iron case and aluminum case OD 4 speed, they have different input bearing housing size than a non OD case so you will have to check on the bell housing for fitment. You will also have to mess with the 3 on the tree linkage and modify it to work for a 4 speed. Or do a floor shift which the 4 speed was meant to do from the factory. Most likely will have to adjust the drive shaft length also.
 
as scody21 mentioned the input bearing retainer is larger on the OD unit. the bolt pattern for the 833 is also different than the 230 so you won't be able to use your bellhousing. you'll need to source one for a OD unit, or one for a 4spd and then have the retainer register enlarged to fit the bearing retainer.

i know that there exists a way to convert the 3spd to 4spd on the column, but swapping to floor shift is probably much easier.

so, will it bolt up? yes, with the right combo of parts.
 
^^^^ LIke 66fs said!
There were two early slant bells drilled for the 4 speed I don't have any anymore or the #'s. Hard to find anyway. Just for the std. A833 4 speed. BUT they don't have the hole for the OD unit. Only bell that comes to mind that might work in the truck slant OD setup/? slant in pickup thru what '88?
 
omotz said:
Wondering if a833 overdrive fourspeed will bolt up to a 1963 170 dart with 3 on the tree
Click to expand...
IMO; This is actually a great idea.
The factory gear ratios in the A250/A903 are;
3.18/3.22/2.95 First/1.83 Second/and of course 1.00 Third.
and in the overdrive are; 3.09-1.67-1.00-.73
But whereas 3.23s are singing 65= 2775 with 25.5" tires; the overdrive knocks that down to 65=2026.
However; notice that the Second gear goes from 1.83 to 1.67. This makes Second gear to be a long stretch from First.
The "cure" then, is to install a bigger rear-end to put Second where you need it to be, and let the rest be what it will be.
To see how that plays out, you need to convert the the transmission ratios to roadgears, by multiplying each trans-gear by the rear-gear. So here are the Roadgears with the A903 and 3.23s;
9.53--5.91-3.23; ......................and the A833od is;
9.98--5.39-3.23-2.36; to equalize 2nd gear, would take 3.55s, so
10.97-5.93-3.55-2.59; ..........However, trying to pull a 2.59 cruise gear with a 170slanty, could be a stretch. Yet to go bigger than 3.55s, means the First gear is getting to be pretty low. About the deepest rear-end you might entertain is 3.91s, thus the roadgears become;
12.08-6.53-3.91-2.85, and 65=2445 with 25.5" tires.
However; I'm thinking 3.73s would be a good compromise;
11.53-6.23-3.73-2.72/65=2334rpm
This gives you a really good Selection of gears, except First which is a little deep. That 6.23 Second gear, compared to the current 5.91, is an improvement of just 5.4%, but 3.73 over 3.23 is an improvement of 15.5% for Third.
IMO; The 3.73s are about the best combo of A833od, and rear gear, for a slanty. Any lower a First-roadgear, is gonna put you into Second gear too early.

Happy Hot-Rodding

However, cutting the tunnel open to fit the floor-shifter, is a given; and, with bucket-seats, you get to put the shifter where you want it.
 
Last edited:
barbee6043 said:
^^^^ LIke 66fs said!
There were two early slant bells drilled for the 4 speed I don't have any anymore or the #'s. Hard to find anyway. Just for the std. A833 4 speed. BUT they don't have the hole for the OD unit. Only bell that comes to mind that might work in the truck slant OD setup/? slant in pickup thru what '88?
Click to expand...


The 64-66 slant 6 bellhousing for the 4-speed part number is 2468433
I have one ready to go into my '71 Demon with a 1966 A833
2468433.jpg


14-05-2024.jpg
 
You must log in or register to reply here.
-

Back
Top