Rear Axle Tag

[highlander61]

3.36 would be better with OD. 3.08 may load the 1st 3 gears enough to make it a pig for city drive stop n go gigs. Also with a 3.36 a taller tire could be used in the future if desired with little adverse effect on mileage and driveability. 150 RPM more at your predicted 70mph target really means very little. It may serve to keep the motor closer to peak TQ which means better manners and better MPG.

 

[black58]

Thanks for posting all of the ratio information! I have a 3 speed w/overdrive that I just put in my '58 Impala, behind a 348 with 3x2's. I checked the differential code, and it looks like I have 3:36 gears. I used the chart from this website to read the casting code on the rear end. http://www.348-409.com/differential.html

I had been thinking that I should look for a 3:55 or 4:11 rear end to work better with the overdrive, but from what you have found, sounds like the 3:36 should be fine for cruising. I haven't had my car on the road yet, so I can't say how it works, but I should be road ready this fall.

Here's a website I had found with some good info on the 3 speed overdrive: http://www.classictruckshop.com/clubs/earlyburbs/projects/t85n/rebuild.htm Somewhere I had downloaded pdfs of the manuals for the Borg Warner overdrive (operators, service, troubleshooting,) and I can email them if needed.

I still need to wire my overdrive, since the transmission didn't have the wiring when I bought it from the junkyard. I've been just driving around the yard with the lockout cable engaged to keep it out of overdrive. Are you using the stock type of wiring, with the kickdown switch? Is the switch below the gas pedal, or mounted on the carb?

 

[SonOfThomp]

I had been thinking that I should look for a 3:55 or 4:11 rear end to work better with the overdrive, but from what you have found, sounds like the 3:36 should be fine for cruising. I haven't had my car on the road yet, so I can't say how it works, but I should be road ready this fall.

My experience is that with the 3.70 gears I have now, first gear is practically unnecessary. Seriously, I shift in seconds, before or at about 10 MPH, normal driving mode. So, I am curious as to how your experience will be with the 3;36 axle. Since you've been "driving it around the yard", how does 1st feel to you, as in, when does it feel comfortable/natural to shift to 2nd? I am in no big rush, so I'm gonna wait and see how it works for you!

Here's a website I had found with some good info on the 3 speed overdrive: http://www.classictruckshop.com/clubs/earlyburbs/projects/t85n/rebuild.htm Somewhere I had downloaded pdfs of the manuals for the Borg Warner overdrive (operators, service, troubleshooting,) and I can email them if needed.

Thanks for that!

I still need to wire my overdrive, since the transmission didn't have the wiring when I bought it from the junkyard. I've been just driving around the yard with the lockout cable engaged to keep it out of overdrive. Are you using the stock type of wiring, with the kickdown switch? Is the switch below the gas pedal, or mounted on the carb?

The switch is mounted on, but not attached to in any functional way, the carb. Page three, post #33, of this thread has an image:

http://www.348-409.com/forum/showthread.php?t=13654&page=3

Since the car came with OD, everything is stock. I keep the unit engaged at all times, per advice from members at this site. Works fine, must say though that it's weird engaging it. Let off the gas a bit at speed, and it does it by itself. Seems advanced for what is practically WW2 technology! Any other questions, I'll do my best - I have had enough of mine answered here!

CHEERS
SoT

 

[black58]

Thanks for the info. The Suburban website that shows the rebuild of the overdrive also has some detailed instructions on wiring the OD without using the kickdown switch, so a switch on the dash can be used to control when the overdrive downshifts. I like that idea, as I think the 348 may be too hard on the OD if I have to floor the throttle to get it to shift down. They didn't put the OD on 348's, but I got a good deal on the transmission, and thought it would be something unique to mess around with.

 

[SonOfThomp]

I like that idea, as I think the 348 may be too hard on the OD if I have to floor the throttle to get it to shift down.

I've heard they aren't hi-perf units. I don't drive that way (any more), but then I don't have a 3x2 set up to tempt my right foot. It would work every time.

How does it act in 1st? When do you shift, as you putter around the yard?

if I have to floor the throttle to get it to shift down.

Didn't know that's how you shift out of OD. Have to try that.

Cheers

 

[black58]

I got the 58 running again on Saturday after changing the rear seal (no oil leaks now!) and I took it for a little drive down the road. I had the overdrive locked out, and the speed for 1st gear seemed to be good. I didn't remember to look at the speedometer when shifting, since I was a little nervous being the first time I had the car on the road (also no front fenders or bumpers, and in need of a front end alignment after changing tie rod ends.) I just had to get it on the road though to see if the secondary carbs work (and they work good) The shift point for 1st gear seems to feel pretty good, as I could wind it out for a ways before shifting. I can't wait to get the fuel tank in and get the front end put together so I can get more miles on it.

 

[rstreet]

I got the 58 running again on Saturday after changing the rear seal (no oil leaks now!) and I took it for a little drive down the road. I can't wait to get the fuel tank in and get the front end put together so I can get more miles on it.

I can't resist this one but the last time I knew someone who drove without his gas tank was a car built by Smokey Yunick I think at a NASCAR inspection years ago because of his laps per fuel stop. Anyway things got so heated they drove the car away and left the gas tank!!!:eek::eek: Later learned that the roll cage assembly held several gallons of gas
robert