5.3 3.42 gears vs 3.73

mookdoc6 · September 6, 2016

The 3.42's are going to work just fine....make sure you have the 8speed and forget about the 3.73's

The trucks 8speed actually blows me away on grades! I have always hated that 6speed!

Deadeye · September 6, 2016

I have a 2016 5.3 6 speed with 3.42 gears the puts my 2009 5.3 4 speed 3.73's to shame. Hard to believe the extra torque and 2 gears in the trans make pulling my #6000 camper so much better.

SouthernSilveradoGuy85 · September 6, 2016

The old 4.8 and old 5.3 were not that much different in the power department but still never could figure out why they even made the 4.8. I have owned both a ext cab 4.8 with a 4.10 rear and a 5.3 with the 3.73 rear and IMO my 4.8 with the 4.10 gear towed as well if not better than my 5.3 with the 3.73 and was more "enjoyable" for daily driving. To the OP, I would think the 5.3 with the 3.42 would do as much and more than your old truck so you shouldn't have any problems.

Well he was comparing an '03 4.8 and a '15 5.3 so there's a big difference there. I compared an '11 48 and my '14 5.3 which isn't as big of a difference, it's still a pretty good difference since I've read that you can feel a big difference between the current Ecotec 5.3 and the previous 5.3. My buddy's 4.8 3.42 feels identical to my 5.3 and 3.08 so I can only imagine if I had 3.42s or even 3.73s.

siskiyou · September 6, 2016

The problem with the 8 speed is that it is not an option on the LT just the LTZ.

Mike

tnchevy · September 7, 2016

Well he was comparing an '03 4.8 and a '15 5.3 so there's a big difference there. I compared an '11 48 and my '14 5.3 which isn't as big of a difference, it's still a pretty good difference since I've read that you can feel a big difference between the current Ecotec 5.3 and the previous 5.3. My buddy's 4.8 3.42 feels identical to my 5.3 and 3.08 so I can only imagine if I had 3.42s or even 3.73s.

I was a little unclear on my original post. I had both the 4.8 and the old 5.3 (2003 model) and there was not much of a difference in those two engines. The new 5.3 has way more power and way better braking than my older trucks had. The biggest thing I miss with my 02 model is that I really enjoyed driving that truck. That 4 speed may be outdated but it shifted flawlessly and when it should while my 2014 sometimes hesitates and then all of a sudden sends out gobs of power. I have gotten used to is and know how to handle the gas pedal in my 2014 but I still don't like how GM set up the computer in these newer trucks.

WilliamBos · September 7, 2016

The problem with the 8 speed is that it is not an option on the LT just the LTZ.

Mike

Another idiotic move by GM. Don't bundle interior options with mechanical options.

brians09 · September 7, 2016

I have the 3.42 gears and 6speed. I towed my toy hauler dry weight 6200# plus two quads and gear, total a bit over 8k# up 6% grades for about 6-8 miles and truck didn't keep up with the speed limit. Maybe you like to push the rpms a bit more but I didn't want to drive in 2nd gear, if I needed to pass a semi I could slowly at over 4,000rpm... Watch the temps and you'll be fine. http://uploads.tapatalk-cdn.com/20160907/adb23851b6429549c175bc9a1339

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siskiyou · September 7, 2016

Thanks for the info, you are definitely towing more than I am, mine is right at 6500# fully loaded with water. I think I am going to see if I can order the max tow and I shouldn't have any problems but I know they used to be hard to get.

Mike

2004lebanshee · September 8, 2016

I have 15 5.3 with 3.42 6 speed. I spend a lot of time towing my 6,500 lb boat over an hour a pop and it tows effortlessly. On the free way I constantly catch my self hitting 75-80mph with no struggle and have to get out of it. I never use tow haul. The only complaint is when I make a slow 90 degree turn and it shifts from 1st to 2nd too soon sometimes and it kinda boggs. It's the only shift that does it. In tow haul it doesn't have this problem.

peejaykay · September 8, 2016

I have the 3.42 gears and 6speed. I towed my toy hauler dry weight 6200# plus two quads and gear, total a bit over 8k# up 6% grades for about 6-8 miles and truck didn't keep up with the speed limit. Maybe you like to push the rpms a bit more but I didn't want to drive in 2nd gear, if I needed to pass a semi I could slowly at over 4,000rpm... Watch the temps and you'll be fine. http://uploads.tapatalk-cdn.com/20160907/adb23851b6429549c175bc9a1339

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2nd gear probably would've brought your trans temp down 5-10 degrees and you may have been able to hold 50mph. My trailer is 10,600 and I climbed up to Eisenhower tunnel from the west, held 50mph the whole way only slowing for traffic. But then, got it back to 50 no problem. I also have 3.73s, that may have helped.

Cowpie · September 8, 2016

The 3.42's are going to work just fine....make sure you have the 8speed and forget about the 3.73's

The trucks 8speed actually blows me away on grades! I have always hated that 6speed!

You do know that the 6 speed and the 8 speed have almost the very same top gear ratio don't you? .667 for the 6 speed and .65 for the 8 speed. Hardly a noticeable difference. It is only the spreads between gears that make a difference, keeping the engine in a slightly tighter RPM band between shifts. So, depending on the situation, you could be right, but in most cases for the general user, it won't make a bit of difference.

But rear end ratio can indeed make a major difference in how the power gets to the ground. Some things can be overcome to some degree, like keeping the trans in Manual mode and controlling the shift points and limiting the use of top gears. And depending on how fast one drives and the roads they are on, and what they are hauling/towing, staying out of top gear or even top 2 can be of benefit. Overdrive gears, by their very nature, are parasitic in regards to power. But then, one loses some of the advantage of having 8 speeds. I have been personally fond of 4.10 rear ratios for a long, long time. Since about 1970. 3.73 would be the tallest ratio I would consider in anything. But then, I am not trying to get pole position at Daytona every time I drive down the highway. It is one thing to have narrow spreads between gear shifts, it is another to be able to actually use all those gears effectively.

mookdoc6 · September 8, 2016

You do know that the 6 speed and the 8 speed have almost the very same top gear ratio don't you? .667 for the 6 speed and .65 for the 8 speed. Hardly a noticeable difference. It is only the spreads between gears that make a difference, keeping the engine in a slightly tighter RPM band between shifts. So, depending on the situation, you could be right, but in most cases for the general user, it won't make a bit of difference.

But rear end ratio can indeed make a major difference in how the power gets to the ground. Some things can be overcome to some degree, like keeping the trans in Manual mode and controlling the shift points and limiting the use of top gears. And depending on how fast one drives and the roads they are on, and what they are hauling/towing, staying out of top gear or even top 2 can be of benefit. Overdrive gears, by their very nature, are parasitic in regards to power. But then, one loses some of the advantage of having 8 speeds. I have been personally fond of 4.10 rear ratios for a long, long time. Since about 1970. 3.73 would be the tallest ratio I would consider in anything. But then, I am not trying to get pole position at Daytona every time I drive down the highway. It is one thing to have narrow spreads between gear shifts, it is another to be able to actually use all those gears effectively.

Fully aware of the Spread on 8speed vs 6speed! Or the the ratio as it's like to be called which is why it's been lowered for mpg's vs the 6speed.

Now...Since we both understand that? Why does this transmission not exhibit any of the known problems the speed has? The difference is quite noticeable meaning: When you drive these trucks apples to apples up a healthy grade one has 6 and other has 8 it's Rather apparent which one is better.

Now same trucks driving in large headwind the 6speed will constantly shift at the hwy speed in/out of 5th,6th gear has with traffic and headwind!

I have put probably 250,000 miles plus on the 6speed so I can say I am versed with it. Now, the 8speed knowing that I am buying the truck for personal reasons and the spread ends up being almost identical to the 6speed I am thinking what the hell is GM doing?

10,000 miles later I can say my 8speed acts nothing like the 6speed at all even though they are almost the same albeit the other 2 gears. Many of you are far more TRUCK guys than myself. But, as this truck is concerned it's behavior is nothing like the 6speed when climbing grades or the dreaded 5/6th gear shifting at hwy speeds this transmission is night and day better than 6speed.

Note: I do get the pedal feel of the 1-2 shift and it's slightly noticeable when cold other than that it's a freaking beast and loves to climb!

For the guy talking about pulling 6500lbs that's the sweet spot and would not even think about the 6speed!

Jon A · September 8, 2016

You do know that the 6 speed and the 8 speed have almost the very same top gear ratio don't you? .667 for the 6 speed and .65 for the 8 speed. Hardly a noticeable difference. It is only the spreads between gears that make a difference, keeping the engine in a slightly tighter RPM band between shifts. So, depending on the situation, you could be right, but in most cases for the general user, it won't make a bit of difference.

But rear end ratio can indeed make a major difference.....

It does make a huge difference and that's largely caused by the rear end ratios the 1500s are stuck with. The problem is towing a heavy trailer up a steep grade, at some point the truck won't be able to pull 3rd gear and maintain speed (will happen more often with the 5.3 than the 6.2). 2nd gear is "overkill" as the gap between them is huge. So you either slow down in 3rd or rev the engine unnecessarily in 2nd to maintain speed.

With the 8 speed you have another gear between the two so you always have the right gear to find that sweet spot. I think it's a bigger advantage with the 5.3 which needs that extra gear more often than the 6.2, but even the 6.2 will need it if the load is heavy enough and the hill steep enough.

Of course with a set of 4.10 gears so the 6-speeds could stay in 3rd gear--especially the 6.2's--much of the advantage goes away. Unfortunately swapping gears on these trucks isn't cheap, and 4.10's aren't yet available for the 6.2's/MaxTow rear. So getting that 8-speed from the factory really is a big benefit for those who tow heavy much.

cmysstailights · September 8, 2016

My brain hurts reading all of this lol. Biggest problem is that technology can be great or hinder what you wanna do. Me i would love to swap my 6sp in my 14 for a 8spd. Bet that is impossible to do because of the technology in the truck.

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Cowpie · September 8, 2016

One of the many reasons I got a 6.0 2500. I get the 4.10 standard and I am not locked in to limited fuel choice like the 6.2.. More reasons than just that, along with being cheaper than equivalent 6.2 1500.