Gear ratio

[Redemption]

Have really enjoyed this thread! Lots of information...and lots of opinions! I guess for my driving/towing, I can't see when I would ever use 6th gear with the 3.42's. I agree that wt. being the only consideration the 3.42 would pull just fine especially with the Aisin. But driving at 65 mph would be at very low rpms...way below torque curve....so I would basically never use 6th gear? Seems like a wasted gear for my driving style. I believe it really all comes down to how fast or slow you drive. In my mind, driving at 65 with 4.10's gives me a bit more rpms than I want to cruise at all day....my 3.73's are just almost perfect around 1700 and I do think the 3.42's would be way too low....if I could throw in something like a 3.9 I think it would be perfect-for me! It's not a matter of weight....it's a matter of speed. I would like to see a high mileage test comparing a one ton DRW with the three gear ratios...would be interesting to see actual mileage....but bottom line for me is that I bought to tow at my speeds...

 

[RVTRKN]

It’s hard to convince the 3:42 crowd, and I gave up awhile back trying to convince otherwise. But the sweet spot for a 6.7/5.9 is between @1800 - 2100 RPM and the 4:10 will allow that towing Heavy. My only experience was with a 2500 3:42 68rfe CTD and had to constantly manual shift it to keep RPM’s up while cursing slow. Good luck with your choice, whatever that might be.

 

[SnoKing]

We started out today with EVIC showing 18.4 MPG and drove(65MPH) up to Fountain Hills and then around and back down the Bush highway to Gold Canyon. Mileage climbed to 19.4, which would be 18.4 or above hand cal'd. Not in TH and let the Aisin do its own thing. We climbed Usery Mountain pass in 6th at 1200-1300 RPM in 6th smoothly. No bucking or stuttering. 4 adults, stuff in both bed boxes, and most likely over 8300 to 8500 pounds.

Don't tell me we would be better off with low gears.

 

[Cummins12V98]

Like I said before I had ZERO issues towing 29K combined with my 11 HO Dually with 3.42's in 6th at 62 on flat ground and even rolling hills. But I decided overall it was better to just lock out 6th because the mileage was slightly better and did not have it up and down shifting on larger hills. It towed just as well as my 15 with 4.10's in 6th.

 

[Cummins12V98]

"Quote Originally Posted by RVTRKN View Post
What RPM when empty, as an example 50MPH T/H off and Aisin in Drive cruising on level ground?"

Here ya go! First pic is no TH or EB Second is with both.

 

[kthaxton]

Sheesh.......3.73's are a good compromise.

If I found myself needing to always, or at least very frequently, lockout 6th, it would mean that I didn't choose the best gear ratio for my purposes.

With that said....for the 3.42 detractors....I have 3.42's and for what I tow (usually 22k combined), and the speed I tow (up to 70-73 where allowable, and safe) they work great.
If I towed considerably more, and/or towed slower than I do, I would benefit from lower gears....and I'm betting 3.73's would suit me well....since I doubt I'll ever tow a monster trailer.

 

[SnoKing]

Sheesh.......3.73's are a good compromise.

If I found myself needing to always, or at least very frequently, lockout 6th, it would mean that I didn't choose the best gear ratio for my purposes.

With that said....for the 3.42 detractors....I have 3.42's and for what I tow (usually 22k combined), and the speed I tow (up to 70-73 where allowable, and safe) they work great.
If I towed considerably more, and/or towed slower than I do, I would benefit from lower gears....and I'm betting 3.73's would suit me well....since I doubt I'll ever tow a monster trailer.

Again, with 3.42 gears in tow haul it will not shift to 6th until 65 MPH. I only lock out TH because of down hill and EB performance. It has nothing to going forward up to 65 MPH.

 

[Learjet]

Even with the 3.73 and my 12,000 lbs. tall 5'ver I sometimes lock out 6th in the hills because I prefer it not to shift constantly between 5-6. 5th pulls like a freight train at 65-70 mph in hills or very strong headwinds and rpms are @ 2,200 IIRC.

 

[CUMMINZ]

After towing at 27-28k for 14k all the way around these United States of America last summer I have come to the realization that there are many more roads with inclines than roads that are flat. All I am saying with 19.5s & 4.30s.

 

[kthaxton]

After towing at 27-28k for 14k all the way around these United States of America last summer I have come to the realization that there are many more roads with inclines than roads that are flat. All I am saying with 19.5s & 4.30s.

View attachment 101550

Stating the actual tire diameter would more useful info than the wheel size.

 

[CUMMINZ]

Stating the actual tire diameter would more useful info than the wheel size.

Left my factory 17" Right my 19.5" 33.5" Goodyears

 

[CUMMINZ]

KT I am running Firestone's now and they are 33.5"