Alright I am calling all you tech savvy kustom building gurus! Is there anything out there to re-gear the rear end of my 1951 Buick special so that i get better highway driving out of her. i am keeping the the original straight 8 and 3 speed manual and torque tube set up. Are there any companies or other rear end gears i can put in to mine to improve the drivability of her? Thanks in advance to all of you who are willing to respond! Nick
Up through '55 third members will fit your axle housing. I believe there is a 3.36 ratio around '54/'55 models.
It might be best to start with figuring out what rear gears you have now if you don't already know. That would give you a better idea of what change you wanted to make to get the rpm in the range you want with the gear ratios that might be readily available. A 3.7 rear end should cut your road rpm by 10% while a 3.30 something should cut it around 20% if my calculations are right.
http://richmondgear.com/index.php/gear-transmission-calculators Try this calculator. It's pretty helpful.
You are lucky to have a 51 as it means you can use all the Buick differential gears from 1940 to 1955. A good friend of mine is an oldtimer Buick guy, and has lots of experience with changing rear end gears. Anything 'before,' 1940 will need some modifications. He says that he has found that you can find just about any torq tube Buick ratio's in these rear ends but most specials have 4.11, 4:40. So it could be a crap shoot, in my estimation anything is better than the 4:40,s. I dont know if the torq tubes are all the same length but I think many are.