4:10 vs 3:55 rear

[Snow man]

Diesel boy said he's getting an auto,so why argue about whats best for a stick?

 

[NVR FNSH]

Originally posted by Alan Reagan

Check out the article by Jim Anderson (?) in the new issue of TDR. That may help with your decision. I had the 4. 10 in my 98 auto and now in my 01 with a 6 speed. As Mr. Anderson points out, the sweet spot on the 24 valve engine is around 2200 RPMs. That's 70 mph with the 4. 10. I get 21. 5 empty. Towing mileage varies with load and type of trailer (wind resistance). Towing I get as low as 14 and as high as 17. But with the 4. 10, especially on the two lane roads, I don't have to down shift very often. At 55 I tach around 1800. That's a good range to tow on two lanes. Any lower and I would lug when I hit the hills.

Alan - 2wd or 4wd? 21. 5 mpg with 4. 10s turning what rpm?

I agree with Jim Anderson that the sweet spot is 2200rpm but my mileage drops way off if I'm turning over 2000rpm. If I watch the instantaneous MPG on the computer (relative values only) I see ~19mpg @ 1800 & 13mpg @ 2200rpm.



Brian

 

[kchristopher]

Originally posted by Snow man

Diesel boy said he's getting an auto,so why argue about whats best for a stick?

The posted thread subject is fairly generic (4:10 vs 3:55 rear) One day (maybe today) somebody else will read this thread and with an interest in buying a new truck with a stick. My input would help this person. Had it been 4:10 vs 3:55 w/auto, I wouldn't have said a thing.

 

[Alan Reagan]

NVR Finish, The 21. 5 is my highway mileage. Right now, all of my miles are running between Savannah, GA and Warner Robins, GA. It's a 170 mile trip with 30 miles on two lanes. 70 MPH is 2200 RPMs. Now, If I'm fighting a headwind, it drops, of course. The 21. 5 is my good average per trip. Start factoring trips where there is wind, traffic, or whatever and it does go down. Worst case average so far on a trip has been 19. 5. The 10% difference on that was attributed to a fuel stop where I probably didn't get the best fuel. Normally, when I'm not making this ride all the time to serve my country, most of my mileage is on the two lanes. That's why I like the 4. 10. I cruise comfortably in the hills in 6th gear without lugging. That's why I like the 4. 10. When I hook up to the trailer, that's when I love the 4. 10.

 

[jbone]

Owned both--I pull 10,000 lb trailer--98. 5 was 2500 w/3. 55, now have 3500 w/4. 10--both auto's... . IMHO, I like the 3500 w/4. 10's better, but--mileage is not as good about 17 unloaded 10-12 pulling..... It has slowed me down a little on the freeway, probably good for rest of you citizens . . my . 02 worth... . J. B.

 

[John]

Originally posted by MikeR

If you ever ask THE transmission guru, he'll tell you that 4:10's is the better choice in the auto.

HUH? I suppose maybe that's why his Ram (now Stefan's) has the 3. 54:1 axle ratio.

 

[RACE427]

Cruzin

Because I bought my truck strictly for traveling over the road and commuting I will have to cast my vote for the 3. 54 Limited slip rear with the auto trans in my 4X4 Quad Cab. Since the truck had 600 miles on it, empty I am getting 21. 3 mpg on the road without Synthetic lubricants. I am looking forward to Synthetics increasing this mileage to I hope will be about 23 mpg. No way am I looking to install taller tires, what I have works well in stock form.



Loving my Diesel with the tighter rear, I have had 4. 10s in the past, also in my GMC Suburban, engine winds out too much for my liking. Just a thought!! Tony G

 

[pwr2tow]

Fuel mileage might be down 1-2, maybe???



Keep in mind that all these truck vari when it comes to fuel mileage. You can have two trucks of identical configuration and they can vari by as much as 5 MPG.



If you are going to tow anything over say 8,000lb's I would get the 4:10's and be happy with the tow side of things.



If you are going to add transmission upgrades and power enhancements anyhow I would go with the 3:54's and have the best of both worlds and you could blow by the cummins guys on a steep grades with 4:10's by down shifting to 3rd lockup, this will give you more rpm's than them if they have to down shift, hense, more speed.



Ron

 

[klenger]

I was thinking about this topic while I was driving around today. These comments apply to 5 and 6 speeds, and stock condition only. I don't have experience with the auto or bombing, so those may not apply there.



3. 54: You can cruise down the inerstate at 75 MPH empty no problem, but if you are towing, you have to downshift into direct drive gear (4th or 5th) and anything over about 60 MPH and the RPM's are getting too high. 3. 54 Conclusion: Great for driving empty on the interstate, but a little slower towing.



4. 10: Cruising down the interstate empty, you will want to stay around 65 - 68 MPH or the RPMs get too high. Towing, stay in top gear and still run in the 62 - 68 MPH and you are right in the power band. City driving on local roads and city freeways, 65 MPH is as fast as you need to go anyway, and sometimes you can get into top gear where your couldn't with the 3. 54. 4. 10 Conclusion: Great for towing, but you will be driving empty on the open interstate at slower speeds to keep the RPMs down.



Conclusion:

Which is more important? Having the towing gears when you need them, even if you don't tow that often, or cruising at 75 MPH empty?



What do you do the most? Heavy towing or open interstate driving empty? If you use the truck for both heavy towing and high speed interstate driving, either gear ratio will require you to drive slower at some time.



Disclaimer: I am not affliated with any company or any job, but I'm working on it.

 

[Jar Head]

QUOTE]4. 10: Cruising down the interstate empty, you will want to stay around 65 - 68 MPH or the RPMs get too high. Towing, stay in top gear and still run in the 62 - 68 MPH and you are right in the power band. City driving on local roads and city freeways, 65 MPH is as fast as you need to go anyway, and sometimes you can get into top gear where your couldn't with the 3. 54. 4. 10 Conclusion: Great for towing, but you will be driving empty on the open interstate at slower speeds to keep the RPMs down. [/QUOTE]



I don't get the "too high" thing. Every one of us can set the cruise on the edge of red line and run it there all day and night and hurt nothing.



I routinely drive on 75 mph interstates at the speed limit and my truck runs great, sounds great, and is awsome passing and climbing.



I started my turbo diesel backhoe this morning, let it idle for about two minutes then proceeded to run it wide open for about six straight hours with no problems. I'll do the same tomorrow. [

 

[klenger]

I guess I was stating that from an engine noise and fuel economy perspective. I understand that the engine can maintain the high RPM's. Those numbers are just what's comfortable to me.

 

[Snow man]

I cruise at 75-85, 2200-2500 RPM,the engine sounds fine,it dont sound happy above 2700 to me. The mileage is not nearly as good as my 96 3. 54 auto though,it got 20 mpg easy at 70-75,this truck gets 16 in the same conditions.

 

[JJW_ND]

Lots of stock 3.54 miles.

While 3. 54 was and is hand down for even heavy towning with a older 12V it has worked out fine for the 99s, 2000s and 2001s we run. All stock on power (fleet trucks)



Never had a 4:10 to try. Western states allow a little higher road speeds. Higher road speeds make for higher rpms. Our stock 24V 5sp and the few newer 6sp pull our 13K loaded trailers just fine. Infact if you want to keep up (or even out run) a 4:10 (same as you would a big block gasser) just drive it like a modern gasser and down shift at 2200 out of 6th (5th) when approaching a big hill. Lugging it down to 1800 worked on the 12V but these stock 24V don;t climb out of that as easy. I am sure 4:10 climb out of low rpms faster but that is what the shift is for. Even with our wind I have never had a situation where a BROKE IN (not brand new motor) truck would not pull the loads we pull in overdrive. Just got to keep the speed up.



BTW, the newer 6sp all but eliminates the nasty jump from 3nd to 4th that plauged narrow rpm band 12V trucks. Real easy to keep it in the power and increasing speed.



If I lived out east, or anywhere one has to drive 65 or less. Then I agree you would be spending more time in direct. But when you can run with the big dogs you need tall gear to keep up.



jjw

ND

 

[John]

Originally posted by Jar Head

I don't get the "too high" thing. Every one of us can set the cruise on the edge of red line and run it there all day and night and hurt nothing.

Actually, Cummins states that you can run the 24v engine at 250 rpm under rated maximum engine speed (3,250 rpm) for an indefinite period of time (which equals 3,000 rpm).



However,IMPO, I wouldn't want to listen to that much noise for a long duration of time... say over about one minute! I like the sound of the Cummins CTD, but not that much!

 

[rubberneck]

3.54 ROCKS

I have the 3. 54's, and most of the time i wish i had a 7th gear. If i weren't driving this thing so hard all the time, i would put in a US gear overdrive, im just a little worried about the lifespan of one with the kind of torque im putting out. . Heard they dont like it very much.

 

[DEZLPWR]

Hey John,

Off the subject, but I saw you at Tacoma Dyno Days without your truck... I have heard a lot about it and I was looking forward to seeing it. Why didn't you bring it? Is it running ok? Also, what has it dynoed at? I am real curious to see what the #'s would be with your setup... .

 

[me4osu]

3.54:1

I don't tow heavy loads all of the time. However, I once towed roughly 10,000 lb about 100 mi at 75MPH, and the truck had no problem with it.



I read in another post that the ISB is most fuel efficient around 2000 RPM. Thats where my 5sp runs with the 3. 54 ratio at ~ 72 MPH.

 

[Souders]

Originally posted by chuck3

My auto with the 3. 55 gears runs 2000 rpms at 75 mph, I like it because in 3rd lockup I can run 55 mph at about 2100 rpm.

When you say third lockup are refering to running out of overdrive or are you using a lockup switch for the converter ?.

 

[RACE427]

Cummins 24 Valve Sweet Spot

Last summer at a Diesel seminar at Ohio Diesel Tech in Cleveland I had the pleasure of meeting and speaking with a Cummins Rep. He claims the sweet spot for the 24 Valver is around 1800 to 2000 RPM. I would have to agree with him as this is where I obtain my best fuel mileage. Just a thought for whatever it is worth. Hope this helps. I still like my 3. 54 s, and I have had 4. 10s and 4. 56 in the past... . engine screams too much for my liking. If you plan on going oversize on the tires then 4. 10s will work out, just remember, when you change tire size you are messing up the ABS calibrations for the brake system module. Tony G LI, NY

 

[RACE427]

Combination MPG with 3:54

With my 4X4 Quad Cab with auto trans and 3:54 to 1 ratio Dodge I drive 20 miles to and from work doing a combination of local and some highway driving. Filled the tank to the top today and fuel mileage is 17. 3 mpg. This is better than the 2 WD Ford Ranger I owned with the 4. 0 V6 and the 5 spd auto trans. I cannot complain about the 3:54s or the stingynish of the Cummins Diesel. Just letting you guys know. Tony G