Our recently picked up 47 Chevy has a stout 261 with a 3 speed, all new parts, looking to be able to make highway speeds at 70-75mph. I have a 56 Chevy 3.70 car rear to start the conversion. What is the most direct path both for maintaining a manual and for going automatic? Please share parts needed to do both
A T-5 would be the easiest to do,Buffalo Enterprises made a adapter to the existing bellhousing if they are still in business,Lokar makes a parking brake cable that will work woth the original parts.
you'd best get something with over drive. I have 3.70 gears in my 38 Chevy and even with tall tires it's spinning pretty well at 70, over 3000 RPM....since we have snow up the wazoo here I haven't had the car out.....can't remember the exact RPM per mile per hour. Overdrive is your friend.
I described on 1954 Bel Air's Rear End' swap, my conversion to a S-10/Camaro 5-speed. Used a later bell housing so no adapter was needed. I liked the use of somewhat newer parts, thinking of easier replacements if needed. Dyno Dave
28" tall tires with a 3.73 final is 67mph at 3000rpm P235/75R-15's are 28.5-29" tall depending on brand etc.
The 55-57 rear is a bolt in EXCEPT you will have to re-drill the mounting pad to center the rear end. The mounting pins on the 47 springs is about 1-1/16 ahead of center.
I'm running 3.73 gears, and 29" tall rear tires on two different hotrods I own. One is a 1:1 final drive, and the other an OD with .63:1 final drive. The one is doing 3,000 rpm's at 70 mph, and I hate driving long distances at that rpm. The other is cruising at 2100 rpm's and I love driving it ANY distance! Then there's the fuel economy on the freeway that the OD also gets! A 350 with around 375 HP and it gets 18 mpg on the highway all day! I'd do the T5 swap, and put the 3.70 axle in your '47 and never look back! Your straight six will thank you for it!
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