Question for you that run an original 3 speed, R10 or R11 OD trans...

[Hot Rod Reverend]

What rear end gear are you using and how do you like it? I installed 3.78s and it runs great. I feel like I can just about pull a stump out of the ground. I have not run the car on the interstate yet so I do wonder what rpm I will be at when I hit 70 or 75 mph.

What y'all thinkin?

[Oldmics]

3:91 s in the Edsel Roundup.


No prob on the hiways.


Oldmics

[Ole Don]

Depending on tire size, about 2250.

[42merc]

I have a 3:40 gear with a R10 OD. Runs mid 70s nicely.

[scicala]

Originally I'm pretty sure V8's with OD in '55 came with about a 3.90 rear gear, so if you like the way it runs now, I would say keep the 3.78's.


Sal

[miker98038]

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I’ve run as low as the 4:27 or 4:30 rear end in tbirds (used a 6 cyl o/d wagon rear end). But that motor had an Isky rpm 300 cam, and 11.25 compression ratio. Long time ago. More recently, a 4:11, with o/d. But you should be fine at 3.78 on the highway if you’re happy around town now. The low and mid range torque numbers on our y blocks make them very forgiving.

[Alaska Jim]

For what it is worth, my 1951 Merc. with a stock Flathead and o/d trans , with 4:27 rear gears, runs about 2300rpm at 65-70, but I don't remember for sure, may be just a little more. the car has a trans problem right now and I have not driven it for about a year and a half. have not been able to pull the trans. and make the repairs due to health problems the last year and a half.

[unclevinny]

where did you find the correct speedo gears ??????

[Hot Rod Reverend]

Originally Posted by unclevinny

where did you find the correct speedo gears ??????

I am 10 mph off, too slow on the speedo. I need a 17 tooth gear I believe.

[Hot Rod Reverend]

Guys! Wow! I got it all sorted out and took the car out on the interstate Monday night. What.a.trip. That 3 speed overdrive is awesome. The low end torque from 3.78's are great when you need to take off, etc, but the overdrive gearing on the interstate ... the engine just purrs with so much power left in reserve as you go down the highway 70 mph. Loving it!

Check out this video of the first run on the interstate after installing the Holley and getting the wiring straight on the Borg Warner overdrive.

https://vimeo.com/340120577

[Oldmics]

Glad you got it all sorted out !

Now,just a reminder to keep tranny fluid in both of those chambers of that O.D.


Happy Motoring


Oldmics

[Hot Rod Reverend]

Originally Posted by Oldmics

Glad you got it all sorted out !

Now,just a reminder to keep tranny fluid in both of those chambers of that O.D.


Happy Motoring


Oldmics

Check! and double-check. Every time I have been under there that has been one of my double-checks since I have heard many guys talk about it. So far, no leaks. knock on wood...

any leads on a 17 tooth gear?

[40cpe]

Modern Driveline spec'd out a 17 tooth gear for my car and it has a 3.25 rear. How many teeth is on the gear you are using now?
https://www.facebook.com/ModernDriveLine/

Does your gear look like this?

[Hot Rod Reverend]

Originally Posted by 40cpe

Modern Driveline spec'd out a 17 tooth gear for my car and it has a 3.25 rear. How many teeth is on the gear you are using now?
https://www.facebook.com/ModernDriveLine/

Does your gear look like this?

I will have to dig up a photo tomorrow, it does not look quite like that one. My current gear is 19 teeth.

[40cpe]

This one is 17 teeth, I think it was in a C4. I'll send it if it will work.