4:10 vs 3:73 gears, 6.0L

[Breadbagel]

I've got a 2008 GMC 2500HD 4X4 with the 6.0l and 3:73 gears. Just wondering if anyone can tell me if there is a huge difference between the two gear ratios, as in towing performance and difference in RPM at cruising speed on the highway. I live in SouthWest British Columbia and anywhere I go camping requires pulling my 5000lb RV and 4 dirtbikes in the back of the truck up steep grades. I got the truck late last year and so far have only used the truck in this scenario (and with the A/C on) once and so far wasn't too impressed. Not sure if my expectations are too high? Would it be worth replacing the gears? what would be a rough estimate as to cost of replacing gears?

 

thanks,

 

Andy

I have owned 2 2015s with the 6.0. One with the 3.73 and one with the 4.10. when I went shopping for the truck initially there was no data for the 3.73 except that you could only get it with the diesel. so when looking at towing numbers I assumed every 6.0 either had the 4.10 or the towing numbers wouldn't be affected as there was some other limiting factor. after I bought the first truck I found in the manual that the 3.73 only tows 9200 lbs. 400 lbs less than the f150 with 3.55 gears that I traded in for it. I was so upset when I discovered that I made complaints to gmc and eventually the dealer swapped for a truck with the 4.10. first off, the 3.73 seemed to be very sluggish by itself and the one time I pulled my 8000 lb trailer around the block it was horrible. the mpgs I got with it weren't any better than my 4.10 either with mixed driving without a trailer. Both were right around 13.5. The 4.10 did much better than the 3.73 by itself and while towing. I think that one is rated for 13000 lbs compared to the 9200 with the crew cab 4x4.

[Jim80]

I pull a 9000 lbs travel trailer with 3.73's......it's a beast! No complaints.

[Jsdirt]

Depends on how many hills you encounter where you live as to how bad, or not-so-bad it's going to tow. I've got 3.73's in my 5.3 Silverado - hasn't been a load I've towed where I've wished for more gear. 91 North around here is all hills - could definitely use 4:11's on that road. MA Pike is fine with 3.73's. Towing 84 Westbound to Scranton, PA, to 81 South, I managed 9.9 MPG towing about 5,800 lbs. - once I got down in NC all the way through GA & AL to FL, I got 12 MPG maintaining the same speed. Lot less hills down there.

 

Maybe unloaded, off the line acceleration could use improvement (that's the nature of the LS engine more than the gears though - my old 350 would stomp this thing stoplight to stoplight, but the LS stomps it everywhere else), but it tows with no complaints from me. Everything from 2k lbs. up to severely overloading the truck, it's pulled it without an issue.

 

Could be due to the Hypertech program, K&N CAI, and Corsa cat back - those add-ons really woke the engine up compared to when it was stock.

[nekkidhillbilly]

im guessing since I have a 3500 its a 4.10 truck mine does great though.

[kstruckcountry]

People assume that the high revs are bad... turbo motors build big boost, and you don't hear people complaining about that. Different motors do different things.

 

Sent from my SM-G920V using Tapatalk

[Jsdirt]

I drove my '72 El Camino back and forth from Phoenix, AZ to Livermore, CA twice, been to the Grand Canyon, and Nogales, MX, then towed a U-Haul trailer with it from Livermore to Central MA - 3,200 miles.

 

On all of these trips, the engine was spinning between 3k - 4k RPM for hours and hours, stopping only for fuel, food, and occasional rest. That old school 350 never missed a beat! The day I sold it, it still left rubber at 1/4 throttle.

[Jsdirt]

im guessing since I have a 3500 its a 4.10 truck mine does great though.

 

In your RPO code list in the glovebox, the "G" code will tell you what gears you have.

 

GU6 = 3.42 (you won't have this), GT4 = 3.73, GT5 & GT8 = 4.10 ...

[Cowpie]

Rear end ratios can be one thing, what gear in the trans is being used and at what RPM the motor is turning is yet another that impacts towing. Actually, a trans in one gear down at 3.73 will tow just fine as top gear with 4.10 for the most part. Not an apples to apples thing, but I have an 18 speed with two overdrives in my semi. Normal setup for that would be 3.55 or 3.73 diffs. I instead have 2.64 diffs. Still pulling same gross weights. But I primarily run at normal highway speeds in 16th which is direct drive with those 2.64's. I have a slightly less parasitic loss, and lower trans operating temperatures, by running in direct 1.00 trans ratio than in overdrive and I can pull the same 80,000 lb gross truck weight right on up and over the hill along side trucks with lower diff ratios running in OD. Many times, I can even outpace them. It is a matching game of diffs, trans ratios, and engine power bands. Unfortunately, the pickup OEM's use a cookie cutter, one size fits all approach. But it can be overcome to some degree. While a taller ratio, say 3.73 over a 4.10, one might suffer a loss in startup capability, at average road speeds, I would bet with the same trailer, one pickup with 3.73 and running 1 gear down would be able to comfortably keep pace with a pickup with 4.10 running in top gear. Now, I haven't actually put it to the test, but based on my experience with dozens of commercial applications, I do not see why the principle would not hold true with pickups.

[nekkidhillbilly]

mine is a 373 I figured it was a 4.10. it moves real well. came from a 04 dmax to this and still haven't had a complaint

[Andrew Wallace]

I was wondering i have a 2004 gmc sierra 2500hd 4x4 with a 4.10 axle ratio and a trans kit how much would i be able to haul now and its a 4speed trans but how much will i be able to haul now with that

[Jsdirt]

With my half ton, the next size lower gearing (numerically higher) only added 500 lbs. to the towing capacity. YMMV on the HD, but it's not much more.