5.3 3.42 gears vs 3.73

[siskiyou]

I tow a travel trailer that weighs about 6500# and go up grades of up to 6 - 7% that will last for 20 to 30 miles. I am looking at getting the 5.3 which I have now in an 02 Silverado with the 3.73 gears. I know max tow was hard to get so if I end up without it, do any of you tow about that much weight in the mountains with the 3.42 gears, and if so, can you maintain highway speeds or even accelerate if you get slowed down?

Thanks

Mike

[WilliamBos]

Get the 3:73, they make a huge difference.

[clloyd069]

I have the 5.3 with 3.42 gears. I sold my camper so I haven't been able to pull a lot. I have pulled several times with 3,000 lbs up Mountains with similar grades as you are describing. No issue at all. With that weight I accelerate up the grades. I am interested to see how it does with 7,000 lbs or so. I think it will handle it well. If you are currently pulling that same load with your old 5.3 with 3.73 the new truck will out tow it easily...even with 3.42 gears.

[Bigmac]

I'm in the middle of a 3 month cross country trip around the US. Pulling my 6900 + rv trailer with my 2015 5.3 with 3:42 gears. It has pulled the passes at 10k feet better than I thought. Pulling 12.5 mpg average. Very happy with the towing ability. Your results may vary .

[JerryCanada]

I have both a '15 with 5.3/3.42 and a '03 with 4.8/3.73. We just purchased a 6000# travel trailer last week and the '15 towed uphill without an issue. Wouldn't even consider using the '03 to tow this big of a load.

[smrr1]

You have to remember more than just the rear gear ratios. Trans makes a huge difference too. Pretty sure todays 6 speed has more aggressive gears than the old 4 speed. Also if you are looking at the 8 speed those gears are much much more aggressive and make up for that rear end ratio. Might not get to keep it in OD but the lower gears will be better than yesterdays 373 i bet.

[siskiyou]

Thanks for the replies and keep them coming, the reason I ask is because of the transmission switch from 4 to 6 sp. and also I know the engine now is putting out more power than my old one. I just don't want to stay the same or lose power, I would get the 6.2 but I don't want to have to use premium.

Mike

[siskiyou]

I'm in the middle of a 3 month cross country trip around the US. Pulling my 6900 + rv trailer with my 2015 5.3 with 3:42 gears. It has pulled the passes at 10k feet better than I thought. Pulling 12.5 mpg average. Very happy with the towing ability. Your results may vary .

When you say better than you thought do you mean you can pull those hills at freeway speeds?

Mike

[Bigmac]

When you say better than you thought do you mean you can pull those hills at freeway speeds?

Mike

The only pass I had to really push was the Powder River pass ( if I remember correctly). It is almost 9k in elevation and worked the truck hard . I kept up with my 2 other friends diesel trucks but they were towing larger rv's than mine. Most I have had no problem with. Camper is an ultralight and tows great.

[bboyce536]

The 3.42 in a 6 speed is equivalent to the 3.73 on the old 4 speed. Yet you still have a mechanical advantage. The 3.73 on a 6 speed is similar to the 4 speeds 4.10. It's a lot more then that, but you get the idea.

[siskiyou]

When I am towing up into the mountains if my speed drops down to about 55 I drop down from 3rd to 2nd gear which puts my engine at between 3500 and 4000 rpm which is right in its power band. I tried to figure out where that would be with the 6 sp. and it looks like it puts it between 2nd and 3rd with 3.42 when I figure the trans gear ratio, differential and my tire size of 245/75 R16. I just wanted to hear in the real world what happens because although I don't always push it up to highway speed if I am the only one around, I do if I would be holding up traffic.

Mike

[smrr1]

Did not tow a travel trailer but a 6x12 enclosed loaded around 6-6500 lbs up to 9500 ft with no issues at all. 5.3 342 6spd Z71 2015 silverado. It would hold gears ok but had no issue holding speed on inclines by down shifting a couple.

[SouthernSilveradoGuy85]

I have both a '15 with 5.3/3.42 and a '03 with 4.8/3.73. We just purchased a 6000# travel trailer last week and the '15 towed uphill without an issue. Wouldn't even consider using the '03 to tow this big of a load.

 

Well it's hard to compare gear ratios when you have 2 different engines, not only with size but different design. Most of that issue is the older 4.8 and also the trans. I'm assuming the '03 just has the 4 speed while the '15 is a 6 speed like my '14. A buddy just recently bought a '11 Sierra with the 4.8 and 3.42s. It actually has a lower tow rating than my '14 with a 5.3 and 3.08s by about 1,000 lbs.

[tnchevy]

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.

[JerryCanada]

 

Well it's hard to compare gear ratios when you have 2 different engines, not only with size but different design. Most of that issue is the older 4.8 and also the trans. I'm assuming the '03 just has the 4 speed while the '15 is a 6 speed like my '14. A buddy just recently bought a '11 Sierra with the 4.8 and 3.42s. It actually has a lower tow rating than my '14 with a 5.3 and 3.08s by about 1,000 lbs.

 

Just giving the info to the OP. My '03 4.8 and his '02 5.3 are fairly close in specs when compared to the '14+. Towing capacity on my '03 is 6800# and my '15 is 9200#. Having more power, a better 6 speed transmission, better brakes and other things that changed since those trucks were released in '99 will make it better for towing even with a faster diff gearing.