what gears to use

[hilljob26]

i have asked this before,but i would like some more insight,i have stock 3.08 gears in my 72 4x4 and it seems a little sluggish,oh yeah,i have 35 inch tires,anyway,what do you guys run on yours and how well do they do,any difference in mpg,im thinking 3.73 or 4.10,i dont do alot of off roading at all,its my daily driver,i would just like some more insight......mike

[FormerMember]

With the 35" tires, I would say 4.10's

[crazy longhorn]

I would go 4.10, or 4.56 with a 35" tire. I guess it just depends if you do a lot of hyway driving, or mostly in town? my calculator says 3000 @ 68 mph with the 4.56's.......which isnt really too far out there L

[special-K]

On a 1/2t that would have originally had about 30" max.dia.tires and now has 35s,I`d say you`d want 3.73s to be close to that ratio.You`ll probably come out a little higher(lower no.).I would go with 4.10s.You`ll end up with between the 3.08s & 3.73s.Ratio isn`t the only thing that taller tires change.Figure you`ve added more rolling resistance,taking away a little power.So you want to come out a bit lower than your original mark to keep the same power.

[hilljob26]

so,how exactly do i figure out how to calculate that,in a post above,he said at his calculation3000rpm at 68mph,how would you figure that

[crazy longhorn]

Originally Posted by hilljob26

so,how exactly do i figure out how to calculate that,in a post above,he said at his calculation3000rpm at 68mph,how would you figure that

Here you go....
http://www.1bad69.com/calc.htm You may also find some other calculators that let you compair 2 different setups. L

[stueber68]

What kind of trans are you running?
I used to have a 4x4 77 model with the same gears as yours. I got rid of the 350 trans that was in it and went to a 700r4. This trans has the lowest first gear you can find, even better than the 400. This helped out dramatically for taking off from a light. Normal traffic stopped walking away. Eventually I also went to a 3.73 gear. The combonation of the two made the truck great offroad and on. 16 mpg highway.
With the 35's I had on mine I could run down the highway at 2000 rpm.

[Mudder]

I had the 3.08's like you and went to 3.73's (Running 35's) because with 3.73"s you can just change ring and pinion. If you want 4.10's you will have to change carrier. Mine is a lot better with the 4.10's. Going down the interstate at 70, I'm running around 26-2800 rpm's. I like the 4.10's the best from my 35's. You will tell a big difference going from the 3.08's to the 3.73's if thats the way you go.

We have calculator's over at myoldtruck.com to figure your rpm's.

http://www.myoldtruck.com/calculator...alculator.html

[JIMs70GMC]

I've been there too, 35s w/ 3.08s. then I got my GMC and went 31s w/ 4.10s, sold it with 35s and the same 4.10s. My Chevy had 4.56s and 35s. Now I have 4.10s w/ 33s, and fairly happy, probably go 35s one day.

[Mudder]

I have a friend that tags along sometimes and I mean tags along. He has a 3/4 ton with 4.56's and a 4speed (35's) and he has a hard time keeping up on the freeway. His old truck is wound pretty tight going 70.

[chevy71super]

I have the same problem, 35" tires with 3:08 gears. I will probably go with the 3:73's because it is a pavement pounder though I once owned a 1/2 ton Chevy with 36" tires (measured) with 4:10's and that combination produced better gas mileage than the stock 3:08's with stock tires.

[hilljob26]

ok,so where do i find a calculator to determine what my gear ratio will actually be,once i put the 3.73 in,like right now,w/ my 35 tires and my 3.08 gear,its actually like a 2.42 gear all together,i seen it on here once,but cant seem to find it,also,what kind of mph should i be looking at w/ 3.73,around 10,thats really not bad for me

[53burb]

Try this link...http://www.csgnetwork.com/multirpmcalc.html

[Budweis]

Originally Posted by Mudder67

I have a friend that tags along sometimes and I mean tags along. He has a 3/4 ton with 4.56's and a 4speed (35's) and he has a hard time keeping up on the freeway. His old truck is wound pretty tight going 70.

i have the same set up and yeah at 70 its screaming, 70 is about max speed i ever go.

[b454rat]

one of my trucks has 3:73s and 36' SXs. I drive it on the road, wheel, highway. I think it's perfect. Once I get the VSS hooked up so the speedo and engine stuff, it will run alot better and more mileage, too. The burban that I'm building will have 3:08s in it, with a 4 speed and 33s. This will be a driver, no wheeling here. And if it doesn't sell, an alum head 468 to motorvate it.