Gearing Question

[88trailblazer]

I'm currently running 35's with a th350/np208 and 3.07's If i was to move up to 4.88's, would i be worse off on the highway? How about in city traffic?

The calculator i used puts me at:

3.07's and 35's --------------- 1768 @ 60mph or 2210 @ 75mph
4.88's and 35's --------------- 2811 @ 60mph or 3514 @ 75mph

3.07's and 31's (stock?) ------ 1996 @ 60mph or 2496 @ 75mph

Thanks,
Alex

 

[loafer]

4.88's would be great if you had overdrive.

 

[88trailblazer]

Thats what i was worried about. Would i need to run 37-38's to make up for the gearing?

I would rather not get into changing out the gears if possible, but it's allways an option.

 

[jonrpick]

I'm currently running 35's with a th350/np208 and 3.07's If i was to move up to 4.88's, would i be worse off on the highway? How about in city traffic?

The calculator i used puts me at:

3.07's and 35's --------------- 1768 @ 60mph or 2210 @ 75mph
4.88's and 35's --------------- 2811 @ 60mph or 3514 @ 75mph

3.07's and 31's (stock?) ------ 1996 @ 60mph or 2496 @ 75mph

Thanks,
Alex

Why not 4.10's or 4.56's?

 

[88trailblazer]

You weren't kidding about the overdrive. With 4.88 and a 700r4, it puts you almost at the stock RPM number.

Also with my current trans, i would have to go to 3.73's to stay close to stock RMPs. But it looks like i may have to look for someone with 4.10's that wants to upgrade to 4.88's.

 

[88trailblazer]

Why not 4.10's or 4.56's?

Well i might be picking an OX-locked D44 and Detroit-locked 12-bolt with 4.88's. to upgrade from my open 10-bolt and LSD 12-bolt. But i don't have enough money for bigger tire and a bigger lift.

 

[jonrpick]

Well i might be picking an OX-locked D44 and Detroit-locked 12-bolt with 4.88's. to upgrade from my open 10-bolt and LSD 12-bolt. But i don't have enough money for bigger tire and a bigger lift.

You may want to do what I'm doing, and learn to swap your own gears. I'm in the midst of my first differential setup as we speak.

 

[88trailblazer]

Yeah, i probably have to do that. Luckily this isn't my daily driver. But eventually i want to be able to hit the highway with it and 4.88's and 35's won't cut it. And i went through too many 700's to go back now.

I'll just have to save up for new gears or taller tires and sawsall blades.

 

[GruntHunter]

I'm running Pro-Comp 31 x 12.50's and just swapped out my 3:08 gears for 4:10's and it runs fine. I'm actually getting better gas milage also. I would have to believe your 3:08 and 35's are really putting a load on the engine, like you were driving up hill all the time.

 

[obijuan]

and towing a trailer

 

[88trailblazer]

It hasn't really been too bad since the engine was built. I know i'm not going to get the full potential out of the truck until i get rid of those gears, but 4.88's might be overkill. I'll try it out for a while and see how bad it really is.