rear end gears

[tphsmith]

everyone this stumps me, how do you check and what all gears were in 72 swb in a in line 6 cylinder and what is a good gear set to run in a daily driver for having a little wheel spin fun once in awhile and the same breath good highway driving gears, now the truck has a LT1 sitting next to the truck to put in it and hopefully apply power to the truck this spring for its first start up.please explain this to me about the rear end gear stuff

[rage'nrat638]

well there is some trick about spinning the wheel and counting the spin's of the drive shaft but...
i would just pull the rear cover and look on the ring gear edge it's stamped there...your truck will be happy to have a new drink of rear end fluid.

[tphsmith]

thanks Rage, but what is a good set of gears to run with a 350 LT1 and a bump up COMP CAM in the motor with a 700R transmission? any one

[msgross]

3.73 seems to be a good all around gear, doesn't kill mileage or acceleration I hear.... don't take my word for gospel, i'm into 4x4's so spinning wheels is done in the dirt!

[chuck1960]

I'm no expert but usually a 3 speed trans with a v8 will be a 3.73 and a auto. trans will have a 3.07 ratio, the 6 cyl. trucks with a 3 speed were 3.73 also. not sure what it would be if it's a 6 with a automatic trans. Also if you pull the rear cover the ratio is stamped on the ring gear I think 11:41 is a 3.73 and a 14:43 is a 3.07. Someone else will probably have a little more info. I think the 3.73 would be alright with the overdrive.

[LockDoc]

-
Ratio 2.56:1 Tooth Combination 41,16
Ratio 2.73:1 Tooth Combination 41,15
Ratio 3.07:1 Tooth Combination 43,14
Ratio 3.08:1 Tooth Combination 40,13
Ratio 3.08:1 Tooth Combination 37,12
Ratio 3.31:1 Tooth Combination 43,13
Ratio 3.36:1 Tooth Combination 37,11
Ratio 3.42:1 Tooth Combination 41,12
Ratio 3.55:1 Tooth Combination 39,11
Ratio 3.73:1 Tooth Combination 41,11
Ratio 4.10:1 Tooth Combination 41,10
Ratio 4.11:1 Tooth Combination 37,9

LockDoc

[jamon8]

the lt1 intake had horsepower in mind when it was changed over from the torquey tpi

with a 700r4 and a nice cam you should get a 3.42 for the best of both worlds senerio

[71chevylowrider]

I have a mildly built 350 & a TH350 with a 3.73 gears & mine hauls A$$ & burns the tire (non posi, but not for long) in all three gears on dry pavement if i punch it at 20mph, I have a friend who builds transmissions & he tells me that with the lower first gear of a 700R4 you could go with a 3.07 & it would still have good launching power, you also have to determine what your wheel/tire height is gonna be (28" 30" 31") ect. that will effect what rpm range your in on the freeway, my current setup is great around town, but it sucks on the freeway (3500 RPM's at 60MPH) I am plannning to go to a 700R4 one day soon & I am really leaning towards the 3.73's, or I do like the above recommendation of 3.42's but I haven't seen any posi units in that ratio, I suppose you would have to change out the ring & pinion to get there. I care more about burnouts & launching ability then I do gas mileage on the freeway since i don't drive mine on the freeway all that much anyway. Good Luck! I'm sure you'l get some more responses, I know there's plenty of people out there running 3.07's that maybe can shed more light on the subject.