I am looking at a Chevy part #3705261 Ring and Pinion set with a 3.70 to 1 ratio... told it was used on standard shift cars but in a powerglide would help the car cruise at higher speeds... I seem to have always heard that a powerglide torque tube rear in a standard shift car is optimal... My 1954' chevy drivetrain has the stock cast iron powerglide and rear end and a good ol' 235... I am told that this ratio (3.70 to 1) would allow me to cruise at a higher speed than the stock rearend... So I have two questions... 1) what is my stock rear ratio? I have looked thru my shop manual and could not find it... I seem to remmber 4.11's but I certainly could be wrong.. OK I DID A SEARCH< SHOULD HAVE Earlier.. but seems as though my chevy has 3.55 gears in the rear end, is that right? 2) Would the 3.70 give me a higher top end with lower rpm's for highway cruising? right now the engine (235) turns high rpms at 65 to 70 if i coud get lower rpms this would be great... if this ratio does help, do i sacrifice my low-speed acceleration? anotherwords, with a higher top-end capability, do I put more strain on my powerglide when starting out or running under load a low speeds? SO GIVEN MY 3.55 Gears, seems like a 3.70 gear set would be worse for me ??? Any help would be much appreciated... and for all of those good natured folks who will tell me to drop in a 350/350 combo and go faster, etc... thanks for your advice, but no thanks, not interested in swapping the drivetrain, I love my little 235.... I would appreciate it if you would stick to the topic of my question, thank you in advance for any advice!
I dont remember what the stock ratio is, dont think its exactly 4:11 but its up there. And the ratio's on the power glide rears are lower then the ratio's on the manual trans rears Patricks sells a new center section kit with better ratio, thats if you want to keep the torque tube. Or you can always just swap to an open drive rear. Still keep you 235, with a modern tranny and rearend, s10 T5, Th350, 700r4
thanks, I know about patricks.. this is from another source... jsut wondering on the pros and cons of swapping the ring and pinion.. MOTOR, TRANNY, and TORQUE TUBE REAR STAY, period... if i wanted a modern drivetrain, I'd have a modern car.... thanks for the advice though
I don't kinow what your stock rear end is so I'll just talk about changing your gear ratio. First, your assumptions are all correct, if you lower the rear end ratio you will get a higher top end but will lose some low end performance and put a little more strain on your tranny getting started rolling. That's just the nature of the beast. Here is a web site with some calculators to play with to see where your rpm's will be for different gear ratios and speeds, you can also change tire sizes to get the same effect. A taller tire will do the same as lower gears. http://wahiduddin.net/calc/calc_speed_rpm.htm
I believe the ratio in the Powerglide cars was 3.55. I'm also quite certain that this is as low numerically as was offered in the torque tube rears. So as far as top speed you have the best available. You could see some additional improvement with a larger diameter rear tire(say from a 670/15 to an 820/15) but it would be minimal at best. Hope this helps.
perfect guys, both of you, that all makes sense, thank you very much for your time... I guess I'll have to look at other things to get the gears in motion.. cheers!
Not what you want to hear, but you could swap out the whole rear end to give you more gear options, maybe drop down to a 3.23 or something like that. Also maybe do an external overdrive to your existing transmission. Just thinking outloud here.... how about a 502/700R4... it's not a 350/350 and it will make you go faster, a lot faster...
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