4 speed what gears

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tyler_s18

tyler_s18

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in my car i have the non od a833. the motor should put out about 360 horse at the flywheel. i am going to go with a 8 3/4 rear. it will be on the hiway a lot so around 80-90mph for hour long drives. what rear gear would work with this? i want it to still be fun in town so if i need to i can slow down on the hiway but would perfer not to lol. 3.23 gears look pretty good but how do they do in town?
 
tyler_s18 said:
in my car i have the non od a833. the motor should put out about 360 horse at the flywheel. i am going to go with a 8 3/4 rear. it will be on the hiway a lot so around 80-90mph for hour long drives. what rear gear would work with this? i want it to still be fun in town so if i need to i can slow down on the hiway but would perfer not to lol. 3.23 gears look pretty good but how do they do in town?
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Take the GEAR x MPH x 336 / TIRE DIAMETER = RPM

Example:

3.23 x 90 x 336 / 28 = 3488 RPM

4.10 x 90 x 336 / 28 = 4428 RPM
 
whats the biggest tire i can fit under it with out mini tubing it? i will put ss springs under it so it will sit up a little taller but would like to get some 27.5s under it

lol anyone wanna trade my non od 4 speed for their od unit? lol
 
i would be afraid of that od 4 speed not holding up to that power, especially if you ever plan opn running some sticky tires on the back.
 
ok. is just the od mopar unit week? or any od? i want to go with the richmound od 6 speed some day but if it is week i wont lol
 
My opinion the OD unit is not weak. If you want to up grade it to handle more check out passon performance. You can also get a different gear set that changes the ratios. I've got a stock OD in my truck but wouldn't use if for performance because the gaps between the gears are not performance oriented. For my car I have an early slant six gearset that is a wide ratio. It has a 3.09 first which will get you off the line even with 3.23 or 2.9 rear. You don't get OD milage but its not a bad deal. Mopar Action Magazine green brick uses this set up with a small block. Check them out.
 
Another thing to consider is your first gear ratio as well as you final drive ratio , car has to take off in first gear. Your horsepower is not as important as how much low end torque your engine produce.

Basically if you have a light car with a torquey engine (like a stock 340), then you can use a non OD 4 speed with a higher first gear ratio of 2.4 or 2.6 to one and a rear end gear of 3.23 with a 26" tall tire and have some driveability( and still have the ability to cruise at 80 mph down the road without wearing out your engine).

If you go with more cam and less low end torque you will have to run a 3.55 or 3.91 gear to maintain some reasonable driveability, but will lose your ability to make 80 - 90 mph hour long cruises down the highway.

ou sort of need to make these decisions for yourself, since my idea of reasonable cruise speed of the engine (RPM at 80 MPH may be different from yours!).

I think a cast iron case non OD A-833 can handle 350 HP all day long and a cast iron OD A-833 can handle street /strip use ( and will give you the higher cruising speed with a low first gear). The down side of using an OD trans is the RPM drop when shifting gears, this is why HP cars came with close ratio transmission,

Bob
 
first gear ratios are as follows,,

in a non O.D. mopar manual box 2.66 up to 1970

after 1970 first gear is 2.46

any mopar O.D boxes ive ever seen have a 3.09 first gear,,all years,vans,aspen,volare

the early 1965 formula S boxes also have a 3.09 first gear, with a standard 1 to 1 final 4th gear, thats what i use in my cuda a 1965 S box,,

1964 box may be the same i never checked in to it,,

if your not bolting slick on your car,,and driving ,like a wild man, a factory mopar O.D box wil be fine providing its in good shape to start with...
 
My '64 4 speed had a 3.09 1st gear. I once read a magazine review that said the rpm drop from 1st to 2nd was like "stepping off a cliff, there's nothing there."
 
'64 Cuda said:
My '64 4 speed had a 3.09 1st gear. I once read a magazine review that said the rpm drop from 1st to 2nd was like "stepping off a cliff, there's nothing there."
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that may be true on paper,,but i do not notice it in my car,,
 
I noticed it some, but that was with my stock 273. It was by no means a torque monster. I think the same article said the car did 0 to 60 in a "yawning" 12 point something seconds. By the time I was done with my car that had changed a bunch!
 
the 3.09 first gear is to get low powered cars up and running quicker with out using a ton of horse power,,it just works in my combination, snap your neck if i launch it hard LOL
 
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