Lifted what gear ratio??

Hpstang said:

I wish I had 3.92 over the 3.21 with the 8 speed. I can deal with the 3.21 as long as it doesn't put a lot of strain on my tranny and motor over time and make them fail early. I still have to get use to the low of a gear. It seems from what I read that as long as I have the 8 speed tranny the 3.21 are perfect for 35" tires and 6" lift. Hopefully it holds true

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yillbs said:

You're fine. When your cruising down the highway at 1700 RPM.. it's 1700RPM regardless what's behind you. It woudln't matter if you're towing 10k pounds, your engine RPM is what the " load is ". If the high RPM's are constant in order to keep the truck moving, then you're likely going to have a fault earlier than if you didn't. That's actually a benefit to the 3.21 gear ratio. In 8th gear, at 75MPH, you're sitting at about 1550 - 1600 RPMS.. the 3.92 can't do that Granted... that's about the only " benefit " you get, but you're certainly not losing, the 8 speed makes up for ANY difference you could possibly come up with.

That's why it's so hard to use 8th gear with 3.21 gears. The torque at 1700RPM is so small, going up even the slightest hill requires you to downshift. Hence why a few people don't like the 3.21's. It's all about perception, 1st gear is geared so low, it's honestly a moot point, you'll take off at the line just as fast as any other chevy

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yillbs said:

You're fine. When your cruising down the highway at 1700 RPM.. it's 1700RPM regardless what's behind you. It woudln't matter if you're towing 10k pounds, your engine RPM is what the " load is ". If the high RPM's are constant in order to keep the truck moving, then you're likely going to have a fault earlier than if you didn't. That's actually a benefit to the 3.21 gear ratio. In 8th gear, at 75MPH, you're sitting at about 1550 - 1600 RPMS.. the 3.92 can't do that Granted... that's about the only " benefit " you get, but you're certainly not losing, the 8 speed makes up for ANY difference you could possibly come up with.

That's why it's so hard to use 8th gear with 3.21 gears. The torque at 1700RPM is so small, going up even the slightest hill requires you to downshift. Hence why a few people don't like the 3.21's. It's all about perception, 1st gear is geared so low, it's honestly a moot point, you'll take off at the line just as fast as any other chevy

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smiley said:

The issue comes you are not at all in the sweet spot at that low of RPM unless you solely want MPG. As you stated there is not a lot going on at 1700 so you always have to down shift. A transmission hunting is a worn out transmission. That is why I regeared my 5/6 speed to 4.56 when it was 3.55 it liked to downshift all the time. Annoying and recipe for a dead transmission. With the 4.56 I don't get as good of mileage but power is right there all the time. If I recall the ratio on the 8 speed is the same in 8 as a 5/6 would be in 5 or "6" therefore the 8 speed doesn't help ok highway as much as it helps in takeoff from a ratio perspective. I would think an 8 speed truck with 4.56 would be an animal with so much torque it would be hard to contain no matter the tire size. Anyone out there have that setup?

I personally would enjoy the 3.92 or 3.55 with 8 speed more than the 3.21 as I just think that ratio is not for the folks towing at max or even over like so many people do out there.

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Graygoose said:

4.5", 35's and 3.21/8 speed.

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greatwhitegoat said:

The gear ratios recently came to my radar. I also have the 3.21 and will be installing 35s with 17" (stock 33s with 20"). It sounds like the 3.21 is an issue if I am towing heavy loads or close to max towing capacity.

Does going on a steep inclined affect the performance? Does the "lighter" wheels help?

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Graygoose said:

No sir, I had the wheels almost before I got the truck. I new I was lifting no matter what. I don't drive a ton.

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smiley said:

The issue I ran into with the relatively small rear end is it couldn’t handle the bigger gears and towing as well as I thought it would.

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BWL said:

I run 34s on both my trucks. 6spd and 3.92 and 8spd and 3.92. My trucks spend a lot of time off road so I prefer a little less stress on the driveline with the extra mechanical advantage. I have driven a couple with 35s and 3.21. The difference is pretty noticeable to me.

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greatwhitegoat said:

Do you consider the noticeable differences to be a problem? A problem that should be addressed asap? I guess what I'm really trying to say is, can I re-gear say, 6 months from now and in the meantime still get into light offroading? Should I expect problems with it?

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greatwhitegoat said:

What did you mean by "bigger gears"?

Most of the examples I'm reading on this topic significantly increase in tire size (29s to 35s). I'm wondering if 33s to 35s is THAT much different that the 3.21 will have an issue (this is what Im trying to confirm).

I also found the formula to calculate the ideal gear ratio. It came out to be 3.41. I'm wondering if that warrants it for me to at least re-gear to 3.55???

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BWL said:

It didn't give me the impression it was any kind of problem. Just didn't respond as quickly as the 3.92 getting going. If you're not towing often or off road a lot I don't think there's a reason to change them at all. If it was me I'd have bought the 3.92 off the lot, which I did. In your shoes I'd probably leave it and either re gear if I need a rebuild down the road and I planned to keep it a long time or get a 3.92 the next truck if you change trucks every few years like some guys and enjoy what you have for now.

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