Factory gear ratio?

[6061Apache]

What rear gear ratio would a 1962 half ton Chevy with a 283/Powerglide have? To my knowledge, the truck is all factory. Maybe 3.38 or 3.90? Is there any markings to tell what ratio? Thanks

[Roll'nSlo]

Not without popping the cover off

[windsurfsam]

Put the truck on jackstands, put it in neutral and turn the tires. Count the tire rotations against the driveshaft rotations to get your gear ratio.

[crhyno]

I had 66Submarine post this reply on a question I posted:

'62's had the Eaton rear ends; a smaller version of the HO-52/72 that came under 20 and 30 series trucks until '72. 3.90 was the standard ratio for them.

Later Captainfab added this:

The only other gears available for the Eaton HO32 differential are 3.38's.

Hope this helps.

[6061Apache]

The truck is in a junkyard. I was thinking the automatic trucks were 3.38 and sticks were 3.90. I am trying to lower my rpm's in my 61 as cheap as I can.

[LVPhotos]

RPMs not much different between the two. Are you looking for rear? Gears? Over drive? Foot off go pedal? In town or highway? Taller tires are the cheapest way!

[6061Apache]

Looking to drop rpm's on the highway. My thought was to swap out third members. My truck is just a cruiser. Mine is lowered 3 inches in the rear and run a 29 inch tire, running 2800 on the tach at 60. I have the original 3 speed. I appreciate any suggestions.

[Roll'nSlo]

I have a '72 rear end in my '63 for the 5 lug and it came with 3.08. If u wanna keep the 6 lug try anything pre '72. Point I'm saying is try 3.08. Lol

[Captainfab]

Turning 2800 @ 60 isn't too bad. That 283 will do that and more all day long. There should be a build code stamped on the passenger side axle tube that will tell you how it was built......52 years ago. Who knows what may have been done/changed in that time. There is a thread in the 60-66 FAQ index that has the axle build codes listed. Myself, I would just pull the cover and have a look. It doesn't take long.

[padresag]

if it has a wa code it is a 3.90 and if it is a wb code it will be 3.38 if they are original. the wa or wb should be stamped on the r/s axle housing close to the centre section
ron

[kieth]

3:08s' would be the ticket with 29" tires, you would be doing 65mph at 2500 rpm, the only way to change it more would be to go to a 700r4 with your 3:90 gears this would be 63mph at 2000 rpm the torque would be ok, if you currently have 3:38 you could not go to the 700r4 because the torque to the ground would be too low.

here is the chart where my information came from....keep in mind one needs around 460ft/lbs of torque to the ground to have a truck that will be a good highway cruiser (what I have) but it will not be a race truck....Kieth

TORQUETOGROUND_Master_r.pdf




If you have 3:38 r/a ratio then a transmission swap to a t5 with a .76 OD ratio would work. 451 ft lbs of torque 67mph @ 2000rpm (there are other ratios of t5's that could be selected to make sure your 283 was happy with the operating rpm.

[TJ's Chevy]

If it's a powerglide then I would think the rear gear would be 3.90...Far as I know 3.38.1 was a "special package." I don't remember the gear split in the Powerglide trans.....I think it was something like 1st gear 1.86.1 and 2nd gear at 1.1...correct me if I'm wrong...my chevy has 31 inch 15's and the stock GM 12 bolt truck axle...at 2500 in 4th I'm going around 55..so I'm guessing my rear gears are 4.10.