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General Site Info => General Discussion => Topic started by: Zac.richardson1 on November 10, 2016, 08:24:59 pm
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really basic question but i didn't know the answer. for my 1/2ton truck with 35 inch tires(soon 38s) what is an impressive amount of ftibs? I'm looking to build a motor and i understand that horsepower isn't a big deal for my truck because of the gearing (3.08) but i want my truck to getup and go. basically I'm looking for a fast take off and to be able to do i mean burnout. what amount of ftibs should my truck have to be able to do so and how much money would this motor cost? any suggestions on where to start? Thanks
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Change your gears! Do you have a 700R4 or a TH350 transmission? or a manual tranny? Bigger tires hurt your take off, maybe keep the 35's
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basically I'm looking for a fast take off and to be able to do i mean burnout. what amount of ftibs should my truck have to be able to do so and how much money would this motor cost? any suggestions on where to start? Thanks
After just spending around 7 bucks on new stock 235 x 75's, i cringe when I hear them chirp between 1st an second........lol
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Agreed, 3.73:1 at least if you want to be able to achieve your desired results.
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i don't know; For a street driven vehicle i'd say 400ft/lbs or more? And really maybe it's not so much how much but how low rpm-wise it happens?
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get up and go + 38s on ½ ton axles i dont see them lasting too long. go for ¾ton axles (14 bolt full floater) with the ratio like they said or 4.10.
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700r4 tranny and its an automatic. planning on going to 3/4 ton axles soon but was wondering where should i buy? online? whats the procedure on changing the gearing? would a professional have to do it or..? also what is the pros and cons of the different gears(3.08, 4.10, 3.73, etc.) and what should i get for my truck with soon to be 38s? i'm hoping to eventually convert to a 4spd as well
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the 700r4 wont hold up for long imo unless its been build for it with some power and those tires. i would go to a junkyard get the axles then get rims and tires as they should be 16" you can fit 15" rims but takes a little grinding
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So what transmission should I look for? This would also be a good time to convert it to a 4spd wouldn't it? What all do I need for that?
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1/2 ton axles with 3.08:1 gears are not going to like 38" tires. Burnouts will kill the axles even with 31" tires.
3.73 or even 4.11 rear gears.
Burnouts will kill a TH700R4 pretty quick. If you want to have a chance of the trans lasting through a fair amount of abuse get a TH400.
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So what are your plans for this truck? Is it a toy or daily driver? What are the speed limits where you drive it? My daughter's pick up Bedazzled has a 700R4 with 4.56 gears on 33's. It mostly runs on 55 mph roads. It doesn't have a tach, but it works really well. I'd guess you might want to put 35's on it if running 70 mph. If it's a daily driver, you'll want a transmission with overdrive. Check PATC for upgrades to your current tranny. I don't think the 700R4's are weak and they have a lower 1st gear. You'll have to pick a transmission and then match gears and tire size according to it's intended use.
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Speed limits around here are 55. It is a daily driver
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th400 4.10 and 38s sound nice if you stay under 60 you could get 10 mpgs. i got 10 with a sm465 and that setup driving easy. if i drove it like a kid i would get 7
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ok thanks, one more question. whats the difference between the 3.08 gear and the 4.10
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1.02 8)
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4.1 revolutions of the axle shaft vs 1 revolution of the drive shaft input. Higher engine rpm for same rotation speed of the tire gives you more power and torque at the wheels with the same size tire as with the 3.08 which is 3.08 turns of axle shaft to 1 turn of the driveshaft. Hence 3.08:1 (3.08 to 1)ratio or 4.10:1 ratio
35 inch tire with 4.10 gears would be say 2200 rpm @ 55 mph vs say 35 inch tire with 3.08 gears would be 1800 rpm pm for the same vehicle speed. Higher rpm for a given speed gives you more power from the engine.
When you go with a bigger tire and the same gear ratio you are effectively lowering the gear ratio causing lower rpm and power from the engine for any given speed.
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(http://www.southwestpowersports.com/gear-chart.gif)
yellow is better mpgs (usually) black is generally close to stock and blue is more power
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What do those numbers represent? Not the ratio or tire diameter.
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your rpm. find what tires you want then go over to you hit the yellow, black or blue then go up. it will then tell you what ratio you would need with a 1:1 transmission (no overdrive). if you have a OD trans then just take that rpm x it by .073
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The chart is based on 65 mph
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Ok thought it was rpm, but I guess I needed to know what speed as well, pretty sure I had calculated a 2100ish rpm at 55 with 31's and 3.42, so it caught me by surprise a little to see I was a few hundred rpm off.
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Yes rpm is the result of size and gear ratio, 65 mph is the constant.
Also with automatics the Rpm's will be slightly higher due to internal slippage.
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what does that 1.02 difference mean
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what does that 1.02 difference mean
Diff between 4.10 and 3.08 is 1.02 which means with 4.10 gears the tires will turn 1.02 times more per 1 revolution of the driveshaft than with 3.08 gears for the same vehicle speed.
Which means higher engine rpm for the same speed resulting in more power at the wheels and less MPH.
Changing to a larger diameter tire size has the same effect as numerically lowering your gear ratio( less rpm for a given speed and power) and vice versa.
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Changing to a larger diameter tire size has the same effect as numerically lowering your gear ratio( less rpm for a given speed and power) and vice versa.
most time when people put 38+ they change their ratio. if they just drive on the streets 4.10 is common if they want to go mudding (a lot and generally dont drive on the streets) 4.56 is their choice
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38s on a stock 10 or 12 bolt axle will kill the axle in a few months
The 10 and 12 bolt axles are not strong enough to hold up to stock tires
I bet if you look closely at the junkyard that has all the squares
Quite a few will be mostly complete except for the back axle is missing
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Ok I guess that's an answer. Your not wrong either but I was kinda asking in less of a mathematical sense lol