Hot Rods 56 Chevy Rear Axle Ratio

A friend of mine has a 56 Chevy with a speed box and overdrive, 4.11 ratio rear axle and at 50 mph the engine is doing 3000 rpm. He would like to know if putting a 3.7 ratio would be a good idea. He knows he would loose some acceleration I said I would ask on here for him as I know you guys are clued up on this sort of thing. Thank You

 

Depends on what he wants, 3:70s would be great but if he has OD it seems odd that it does 3K at 50. Something seems off to me.

Pat

 

That sounds more like it Moriarity.

Pat

 

Sound's like the speedo is off. 50 mph with a 4.11 and 28" tall tire's should be 2500 rpm. 60 mph should be 3000 rpm.

 

28" tall tire is 2960 rpm with 4.11 gear at 60 mph, in od 2132.

 

He needs to find one of us Ford guys show him how the o/d works. Or show him how to troubleshoot it. Probably tougher in the UK.

 

If it’s a stock ‘56 Chevy transmission, Speedway has a good book on the Borg-Warner overdrive. That, and the factory manual might be good sources on the proper operation of the OD.

 

Thank you very much for the replies guys will pass this info onto him.

 

From what I have read in this thread that what I was wondering. Am waiting for him to reply to my message and will let you know. Thanks

 

Here’s a link to the originals o/d manual. I think it’s just the R-10, but the operation is the same as the R-11. Should be enough for anything short of a total rebuild, and it would get you thru the R-11 too if you’re mechanically experienced. Covers the electrical side too.

http://www.oldwillysforum.com/forum/TechData/BWOverdriveManual.pdf

 

Thanks for that "miker" will pass it on. Waiting for my mate to reply to what I have sent him already.

 

Every overdrive I've seen, you have to push the cable in to allow the OD to work. Pulling it out locks out the overdrive. It slides the sun gear into the planet carrier effectively locking the OD gear set.