Truck purchase, What rearend gears?

[Motorhead]

A friend of mine is ordering a new '02,2500,Cummins of course!,4X4, Quad cab, auto, long bed. He ask me what my suggestions were on dif. gear ratios. He currently owns a '97 equiped as above with 3:54's. He wants to tow some,(up to 27 ft 5ver) but not alot. I figured with the extra weight,4X4 vs 2WD, He might want the 4:10's. At 2000RPM my 2wd with 3:54's is turning about 74 mph. How much slower is the 4:10 at 2k revs. He does long road trips(not towing)and the old boy likes to pour on the coal. What do all you experts out there think?? Chris

 

[LSMITH]

There is only one ratio as far as I am concerned with an automatic transmission, and that is 4. 10!!!! I have an auto with 3. 5 gears and it is miserable, the 4. 10 would help a lot. Then again I would never buy another auto, tell him that the HO/6 speed combo is the same money as a standard engine with an automatic. If he is set on the auto tell him to get the 4. 10.



My honest opinion after 90K miles on this truck.

 

[NVR FNSH]

My truck is running 66mph (per gps) at 2000 rpm with 315s & 4. 10s. The auto might be a mph faster at 2k since it has a slightly taller overdrive. I am seriously considering a Gear Vendors OD for those long non-towing trips.



Brian

 

[kchristopher]

This is what I wrote on a similar thread:



I think almost everyone will agree to go with 4. 10s if you have an auto, expecially if you want to go with bigger tires.



The disagreement comes into play with the manual transmission.



If you tow more than half your time and have a 5 speed, you may want to consider the 4. 10s. It would make the 3-4 split easier.



If you tow more than half your time and have a 6 speed, I wouldn't be so quick to jump on the 4. 10s because the gear splits are pretty good.



If you tow infrequently and have a manual transmission I wouldn't consider the 4. 10s, even if you were considerend a swap to the common 285 or 315 tires.



Look at my truck specs in the sig. For those who aren't familiar, the 255/85 tire is the same height as the 285/75 that alot of people are switching to (but don't really fit well on my puny 6. 5" wheels), they're just narrower. That means I can drive 60mph in 4th gear at about 2100-2200 rpm. Or I can drive 70mph in 5th at 2000 rpm. Since I don't tow that often, I don't want to give up reduced revs at highway speed (see the NVR FNSH post). Intead, if I'm not on the interstate, I can simply drive in 4th gear. If I'm on the interstate, I'll probably tow at a speed that will allow me to use 5th gear. If I were to tow in mountainous terrain (east coast style) and had trouble using 5th, I would pay the $300 to get a new camplate before I would go with the 4. 10. I understand that the 24v people can also upgrade at similar, but maybe slightly higher prices. This may or may not work on west coast style mountains, as I've never driven out there.



Key point - I think that some people forget that just because you have 5 or 6 gears doesn't mean you have to use all of them all the time. If you can't tow in OD, drop to direct. Yes, the split in the 5 speed isn't the greatest, but everybody I talk to how has upgraded power says it makes it a breeze. The 6 speed split seemed great to me as is.



My ultimate combo - my truck with #11 plate and USGear OD. Then I could tow in 4th over, which is just slightly lower than 5th and not worry as much with lugging it. 5th over would be a good highway gear when empty - that would put me at about 1600 rpm @ 70mph, right about torque peak in a 12v.

 

[Snow man]

The 4. 10's will put him at 64 mph@2000,RPM's with 265 tires. I run at 68 mph at 2000 with my 285 tires. I'd say the 4. 10 is the way to go,it also ups towing capacity by 2K lbs,and the transmission will be happier.

 

[klenger]

I think the TDR needs a separate topic for "Gear Ratios" and for "Auto or Manual". It seem like the gear ratio debate would be over if DC offered a 3. 72 or 3. 92.



How about a 7 speed manual transmission, or a two-speed transfere case that would yeild a 3. 54 or 4. 10 final drive ratio at the shift of the lever. Don't need 4Low anyway.

 

[Jumbo Jet]

I have the Auto, 4. 10 gears, and the GearVendors OD.



Folks, for an Auto, it just don't get much better.



Pull a 30' 5th wheel TT a few trips a year.

 

[JTeague]

Better get the 4:10s if he wants it to tow anything like the old 97 12 valve.

 

[jkern]

just my opinion... auto=4. 10's manual=3. 54's



jkern

 

[Motorhead]

What a help all you guys are. So what is the top cruise speed that you 4:10 guys feel comfortable with and what is top governed speed in OD? I feel very comfortable at 75 to 80 with my 3:54's. Also, is there any MPG loss or gain with the 4:10's? Thanks for the info guys! Chris

 

[chuck3]

3. 54 .

 

[K_Arts]

I currently own a 2000 Auto Shortbox and a 2001 Auto Longbox both equipped with the 3. 54.



My overall impression..... the 3. 54 tow's just fine. I have a couple of buddies here in town that do a lot of towing, whether it be for a business or towning 5vers and all of them also have the 3. 54's. None of us have had any problems towing around town nor up in the mountains.



Do the 4. 10's help... probably but I think some of it is personally opinion. I personally like having the lower RPM's with the 3. 54's so that I have extra cushion for passing people on the highway.



JMHO



Kev

 

[chuck3]

3. 54 = better mpg's.

 

[Snow man]

Motorhead,I regualrly cruise at 75-90,the trucl/engien sounds fine until about 2700-thats over 90. My truck will do 110,but thats at about 3200,so it wont go much faster,not thta id want to. K-arts,extra cushion for passing,again,my truck pulls hard to 110,how fast do you need to go,to pass?85 mph is around 2500,wo drives over 85?My 96 12v TST kitted,3. 54 truck definetely got better mpg,but this truck with 4. 10's is so much more responsive ,and quicker,its not fair to even compare them.

 

[SEmerson]

I would think in southern cal 3. 55 would be good. That is what I have and I drive 80 + alot of the time. 4. 10 would be too low for me for sure. I added a ez and injectors and I pull fine. And can still drive 115mphOo. You know you have to stay with southern cal traffic.

 

[K_Arts]

Originally posted by Snow man

K-arts,extra cushion for passing,again,my truck pulls hard to 110,how fast do you need to go,to pass?85 mph is around 2500,wo drives over 85?

Snowman... . taken in account that my shoes are full of concrete. LMAO... Being that I live in farm country and the speed limit around here is 75mph, it is rare that you see anyone doing it. Normally traffic flows at about 90-95. So having the lower rpms really helps me out when I need to pass people that are doing 90+. Though normally it is rare to see me cruising on they highway under 100mph. As it stands, I can do 100mph at on about 2500-2700 rpms, pending on the headwind.



Gotta love them 3. 54's!!!!



Kev

 

[jimnance]

I think with the auto transmission it comes down to where you drive, how much and how often you tow, and your concern for fuel economy.



I have done the math and can see where 4. 10's will put me in the power "sweet spot" of 2,000 - 2200 RPM at 62 MPH. Out of O/D, I will be in the sweet spot at around 50 MPH. We have some pretty tall hills around here, and getting up the grades at a reasonable speed is important to me.



Also, my GCVW is 19,900 lbs and the 3. 54's are only supposed to be for 16,000 lbs. With 4. 10's at least I'm closer as they rate the truck for 18,000 GCVWR.



I'm sure acceleration with a load will be better too. The downside is that unladen cruising down the road will be noisier (more RPM's) and fuel economy will suffer. There is no free ride.



Yes, if I want to pony up $3,500 for a gear vendor O/D I could have my cake and eat it too, but I can buy a lot of diesel fuel with $3,500. 00.



If I were East of the Mississippi I would stick with the 3. 54's.