hey guys, So lets say you have a roughly 3,ooo pound car, your running a sbc and a th350 butted up to a 9 inch ford rear. rear tires are around a 26/27 inches in height. motor is mild to stock, and the car is for driving...alot. you can pick between a 358ish something ratio and a 3:00 ratio. which set do you go with? Im leaning towards the 3 0' as it seems like itd lend to better mpg but im curious if it being 3k pound car if a steeper gear would make it more bearable to drive? just thinking threw options while things are going together and want to be happy with what i land on. thanx in advance timm
I'll put in my .02. I think you'll be happiest with a 2.75 or 3.00 ratio for highway driving. I'll add that I have over 200k miles in a 65 Chevy pickup with 3.08 gear and want to grab another gear to run with traffic and not being passed all the time by fromt wheel drive shitboxes running comfortably.
thanx guys, thats kind of what i figured. long as it can get out of the way of its own shadow and cruise at 80 with out blowing apart ill be happy for the most part lol
I just went on a couple trips in my 55, first one I had 3.25 gears and pretty much limited to 65 mph, second one I had the 2.75 gears in, 75-80 no problem Having a blower on the big block helps with the low end torque. but with a mild engine in a light car you should be ok.
I know there are more gear/speed calculators out there but this one is useful. http://www.richmondgear.com/101032.html
wow, realy hitting the wall at 65 with 3.25's? man im glad i asked id be pissed if i put all this work into the car and it wouldnt feel like its standing still on the interstate! yikes. its a 1946 ford tudor and shipping weight 1432 kg / 3157 lbs estimated curb weight 1540 kg / 3390 lbs is what i find online for actual weight. for right now im thinking 305-350 with an rv cam and some better exhaust for now for motor-vation. it doesnt make since to have a car get decent mileage if it wont go fast enough to drive the damn thing down the road. so you guys are thinking 2.75 ish?
My driver is a 3700 pound car with a stock Buick 350 backed by a stock Turbo 350. The rearend is a 3.08 and it gets down the road pretty well. If I were driving this car on the highway every single day it would get old, but for "town and country" driving the 3.08 works fine. I wouldn't want it any steeper though...
65 mph with 27" tall tires---2.75 ratio at 2250 rpm and 3.00 ratio at 2500 rpm. 80 mph---2.75 at 2775 and 3.00 at 3100. Wanting to grab a gear that ain't there in a TH350.
How high do you like to buzz the motor when you're going down the highway? that's what it boils down to....I don't really like running over 3 grand, but if you don't mind winding it up to 3200 or 3500 or something then mid 3 gears would be fine
yeah fair enough, its just been a long time since ive run a small block so im a little foggy on where these motors like to be rolling down the highway. i suppose most of the time id be highway driving at 55/60 mph and when doing one or two road trips a summer the interstate is 75mph. seems like unless i add some gears to that transmission ill just have to find a happy medium. it sounds like a 2.75 would be a good spot to land at. thank you for all your guys info and time
I remember having 5.12 gears in a '55 Chevy for awhile. There were 2 tools required in the car all the time, a screwdriver to jump the starter solenoid and a hammer to pound the rocker studs back down into the heads............ Start with 2.75 gears, on the 9in, you can change in one afternoon or a 6 pack, which ever you gauge best. J
What kind of car is this? 3000lbs is not that heavy, but i think aerodynamics really plays a big part with highway driving. For example my truck's drivetrain with 305, th-350 and 2.56 gears with 29" tires (235/75 15) feels like it's laboring at 55-65 and higher---i'm turning 1700-2100rpms. i will have to do some further investigating----maybe the throttle springs are a bit too stiff, 3 of the other wheels need to be balanced etc. But aero is something to think about.
There's always the option of a Gear Vendors unit... that would let you run a steeper set of gears but still let you cruise on the highway without buzzing your fillings loose...
Yeah, that's going too far. With tires that tall and that small of an engine, 3.0 gears would be about right.
you need to look at your cam to find out what rpm it will get the best mileage then use a gear calculator like the 1 above to determine what is the best gear ratio for the driving you do my cam gets the best mileage between 2600 and 2800 but i run a 3.7 gear just because i like to play around and dont go on the hiway very often
My estimate for a 27 inch tire and 3.00 gear is 3300 at 90 mph, 2200 at 60. I run a 3.00 gear, 30 inch tires and a 327/350 in my pickup that weighs not too much different from 3,000, and has the aerodynamics of a barn. Unless you demand dragster performance from the start, it will work fine.
so an obvious newb question, will i need to know what spline axels i have when ordering new gears for this rear?
if you're just getting gears, then no you won't. But if you're buying a complete third member (center section), then you will, and you'll also need to know what pinion yoke you need.
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