Rear Gears Which Ones?

robertmagni · May 10, 2009

I have an 08 Silverado V6 auto with 275/55-20's 3.42 rear gears. which would be the better combo all around 3.73 or 4.10? I do not drive it everyday so mileage is not the most important. also there presently are not any tunes for the new V6 ECM but how would I get the speedo adjusted and does it need any computer programming for the lower gears.

Thanks

Robert

MS3DALE · May 10, 2009

For the 4.3 I would say 4.10's would be a better choice.

Check with Hypertech to see if they have a power programmer out for the 4.3's,It will let you adjust for the gear ratio change.

Zembonez · May 10, 2009

4.10 might be a little extreme for that truck. You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75. I've driven a RCSB GMT800 truck with a 4.3 and 3.73 gears. They seemed to be good all around gears for that truck. The current 3.23s MUST suck! I had them in mine originally with a V8 and they sucked.

2000DV4.8 · May 10, 2009

4.10 might be a little extreme for that truck. You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75. I've driven a RCSB GMT800 truck with a 4.3 and 3.73 gears. They seemed to be good all around gears for that truck. The current 3.23s MUST suck! I had them in mine originally with a V8 and they sucked.

He's got 3.42s right now, not the 3.23s like you had. That makes me wonder if going to the 3.73 will be enough of a difference to justify the cost.

Robert, where do you do most of your driving? In town or on the highway?

Zembonez · May 10, 2009

4.10 might be a little extreme for that truck. You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75. I've driven a RCSB GMT800 truck with a 4.3 and 3.73 gears. They seemed to be good all around gears for that truck. The current 3.23s MUST suck! I had them in mine originally with a V8 and they sucked.

He's got 3.42s right now, not the 3.23s like you had. That makes me wonder if going to the 3.73 will be enough of a difference to justify the cost.

Robert, where do you do most of your driving? In town or on the highway?

Good catch. I missed that. That isn't enough to make a huge difference. Have to keep in mind that no gear is really gonna change the fact that the engine is a six. I still say 4.10s are too extreme for that truck.

robertmagni · May 10, 2009

4.10 might be a little extreme for that truck. You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75. I've driven a RCSB GMT800 truck with a 4.3 and 3.73 gears. They seemed to be good all around gears for that truck. The current 3.23s MUST suck! I had them in mine originally with a V8 and they sucked.

He's got 3.42s right now, not the 3.23s like you had. That makes me wonder if going to the 3.73 will be enough of a difference to justify the cost.

Robert, where do you do most of your driving? In town or on the highway?

Mostly in town, I have a miser car for highway, right now I have a take home g-ride so my mileage (daily driving) is very low. But I do drive from South Carolina to Florida once a month, for at least a couple more months.

Thanks

Robert

2000DV4.8 · May 10, 2009

4.10 might be a little extreme for that truck. You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75. I've driven a RCSB GMT800 truck with a 4.3 and 3.73 gears. They seemed to be good all around gears for that truck. The current 3.23s MUST suck! I had them in mine originally with a V8 and they sucked.

He's got 3.42s right now, not the 3.23s like you had. That makes me wonder if going to the 3.73 will be enough of a difference to justify the cost.

Robert, where do you do most of your driving? In town or on the highway?

Good catch. I missed that. That isn't enough to make a huge difference. Have to keep in mind that no gear is really gonna change the fact that the engine is a six. I still say 4.10s are too extreme for that truck.

Yeah I've never driven a 6 cylinder in a full-size truck, so I really offer any more input.

Zembonez · May 10, 2009

4.10 might be a little extreme for that truck. You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75. I've driven a RCSB GMT800 truck with a 4.3 and 3.73 gears. They seemed to be good all around gears for that truck. The current 3.23s MUST suck! I had them in mine originally with a V8 and they sucked.

He's got 3.42s right now, not the 3.23s like you had. That makes me wonder if going to the 3.73 will be enough of a difference to justify the cost.

Robert, where do you do most of your driving? In town or on the highway?

Good catch. I missed that. That isn't enough to make a huge difference. Have to keep in mind that no gear is really gonna change the fact that the engine is a six. I still say 4.10s are too extreme for that truck.

Yeah I've never driven a 6 cylinder in a full-size truck, so I really offer any more input.

No gear ratio is going to change the fact that the 4.3 makes about 200HP. 3.42 / 3.73 gears will make the best use of the power while still being driveable on the highway. Next would be making more power out of the 4.3, It would really wake up with a blower or turbo system.

robertmagni · May 10, 2009

wynjammer makes a supercharger for 2500 bucks unfortunately there is no support for the 08 up 4.3's they now have no distributor and the throttle is now computer controlled, there is a pcm and separate tcm computer. So I am patiently waiting for Blackbear to be able to tune the pcm for me.

Robert

thecraft · May 11, 2009

4.10, without a doubt.

You'll have gret 0-30 grunt even with the 4.3 but revs will be up there at highway speeds. You'll think it gonna grenade at about 75.

It will be running about ~2,300 rpms at 75 mph... I don't think it's going to explode...

jhoff8487 · May 11, 2009

If you're upgrading, I'd go to 4.10s. I've been toying with the idea of upgrading but doing front and rear just is so pricey since it's a 4x4. I've got 3.42s and am thinking that jumping to 3.73s just wouldn't be enough of a difference if I'm going to do it.

09Jimmy · May 11, 2009

I have a 2009 RCSB 4X4 285/55R 20s with 4.10s, a 2000 RCSB 4X4 285/75R 16s with 4.10s and a 1955 RCSB 4X4 35X12.50R 15s with 4.10s. I wouldn't go with anything less.

By the way, it doesn't matter whether you have a 4 cyl, 6 cyl, 8 cyl, or 12 cyl, they will all rev at exactly the same RPM at a given speed. It's mathematics, not HP or torque. Assuming 4th gear (OD) ratios on all the transmissions are the same and the tire diameters are the same the revs will be exactly the same.

Another misconception is that the new 6 speeds with 3.43 gears will out pull a 4 speed auto with 4.10s. This is only true through first and second gear. In 1 to 1 direct drive, (3rd on a 4 speed and 4th or 5th on a 6 speed - I'm not sure which) the 4.10s will smoke the 3.43s. Also in OD the 4.10s will have much more (19.5% more) power. Once again, it's in the math.