idaholc

I have a 1949 Olds Coupe with a built 425 Olds and a 700R. The Stock '49 rear end has 3.64 gears. At 75mph I am turning 2378 rpm. I would like to install 3.23 gears for 2110 rpm at 75mph and better MPG. Is there a point of diminishing returns on rear end gearing and cruising fuel efficiency? Does anyone have a set of 3.23's?

idaholc

The 3.64 gears I have have a 40 tooth ring gear and 11 tooth pinion, thus 3.64 ratio. The 3.23 gears I am looking for has 42 tooth ring gear and 13 tooth pinion, thus 3.23 ration.

Question, could I mate a 13 tooth pinion gear to the existing 40 tooth ring gear and get a 3.08?

monzaz

I have a 3.42 complete center section...actually the whole rear if you need axles and or backing plates you might want to get extras if you need.

I can send pictures of the rear if you are interested...yes, I can and will ship to you also.

I think about 65-70 pounds fed ex ground would be- about 45-50 dollars to ship

idaholc

I am shooting or at least a 3.23 if I am going to the trouble of changing. they were only found in 1949 88's. Thanks anyway.

jaysun

Gleason hypoid generator? does that take 1.21 gigawatts to operate?

sorry i'll be quiet now.

Jason

jaysun

There always something to learn.thanks CW

idaholc

thanks for your help. I found a 3.23 gear set locally, so no shipping costs. Now I will soon have a set of 3.64's available.

idaholc

By the way you guys, I have acquired a list of all 1949 and 1950 Olds rear end
ratios and what models they came in, in case anyone is interested. I could pass it along.

mo381

I would be interested in learning about the rear end in my 51 Super 88. Any info would be helpful.
Thanks

monzaz

you can not mix and match ring and pinion gears! They are match sets.... Even mixing 3.23 ring and opinion with 3.23 ring and pinion gears might have issues with noise etc.

Ozzie

If Hollander is accurate, the choices for late '49-'52 on the 8 cylinder with Hydramatic were 39-10, 40-11, 41-12, 42-13, and 40-13. Your choice might depend a bit on the type of terrain you drive and the loads you move. I have a '55 which I drive mostly on flat terrain. It has the 40-13 and can pull a trailer with boat and the A/C running without any distress.

Jimmy Davis

Sent you a message ... wondering if you're still looking for a gear ratio change!

Mark Davis

I have a stock 50 olds 88 fastback, What is the differential ratio?. Im trying to figure out what speedo gear to put in the 700R4 that Ross Racing sent me.

Tedd Thompson

I myself would not build a rear end from a early 50's Oldsmobile that had a engine that produced somewhere around 400 HP. besides being a peg leg doubtful it would stand up to the HP should you ever hook up.... Just a thought....Tedd