4:10 vs 3:55

[Deezul1]

I am looking at a Dually w 4:10 axle. How do you guys that have them like them, anybody had both for a comparison? my last truck 3:55 and that was great, how much to change them out?
TIA
John

------------------
96 SLT Laramie CC 5spd, 3. 54, no muff, no cat, 5"turn down tip. (its sold)looking for another. Member NRA/USPSA

 

[Charley]

John:

My last ride was a 97 CTD 5 spd with a 3:54 axle and 245/75 tires. I bombed it slightly to pull my 15,000# fifth wheel and it did the job really well even if I did kill lots of mosquitos with the smoke. I wanted an automagic transmission so I called the expert Bill K. He advised to go with a 4:10 and somewhat larger tires to come up with an axle ratio of around 3:9 to 3:70. I have almost 1,000 miles on the replacemnt 01 with the 4:10 axle and 265/75 tires. The tires are enough higher that my rpm seems to be about the same as the old truck at the same speed. If you do go to the 4:10 and find it's geared a little too low for you change tire sizes to lower engine speed.

Hope that helps. I won't bomb or fool with the transmission till I get some miles on. I'll tow the big five at least once on a long trip to see how it performs before deciding what and how much. One thing I have decided is to let Bill K do the trans. mods. Reputation means a lot.

Charley

 

[MikeR]

I've mentioned it before in my comaprison tests. The newer 4. 10 trucks with their bigger factory tires run almost the same RPM as the old 3. 54 trucks do with their factory donut tires.

-Mike

 

[John Berger]

Originally posted by MikeR:
I've mentioned it before in my comaprison tests. The newer 4. 10 trucks with their bigger factory tires run almost the same RPM as the old 3. 54 trucks do with their factory donut tires.

-Mike

How are the fuel numbers? What about towing a load. Do you lose anything going into a strong wind or up a good sized grade? I've got the 4. 10's and like the umph they give me on big grades.




------------------
1999 Dodge Ram 3500 Quad Cab 2wd; 5 spd; 4:10 LSD rear; Mag-Hytec differential cover; US Gear EGT and Boost gauges. Stewart Warner Fuel Pressure Gauge with dual senders, Westach Oil Temp Gauge for differential. Rancho 9000's on order, EZ Box, Amsoil foam air filter and synthetics in the motor and differential. Cummins Power, don't leave home without it

 

[Archive]

I have the 4. 10s... and I love them. When I tow, I can run 60-65mph up any hill... I usually go a bit slower downhill.

I am of the opinion that towing any faster is dangerous to all of us. I cringe when I hear of people towing a huge trailer at 75mph or greater. With 4. 10s, towing at my speeds puts me right in the middle of the "power band", according to Cummins.
They say for mileage, run 1800-2000rpms, and for power, run 2000-2200rpms. I got that from a Power Booster's newsletter several years ago.

 

[Alan Reagan]

I don't have the dually but I do have the 4. 10. I get good fuel economy and this truck will pull a hill and accelerate.

------------------
2001 HO 6 spd 2500, 4. 10 LSD, Towing Package, Electric Brakes, SPA EGT/Boost Gauges, Fog Lights, Real Backup Lights, Molded Running Boards

 

[mikepvg]

My motor is still stock. My experience in the mtns around here I feel the 4. 10's are absolutely necessary & w/o the splitter it would suck. Will that change w/ a bombed motor? I'll find out later this summer.
My mpg is consistantly 19-19. 8 Thats a mix of around town & some hwy. Of course w/ the splitter I do have the best of both worlds. I have a feeling that no amt of power could make up for proper gearing.
Mike
#ad


------------------
94 2500HD 5sp 4. 10LSD 4X4 RWAL w/GearVendor OD, K&N Oval w/ Pre-Filter, Straight Exhaust, Geno's Fumotovalve, AW-Direct Idle Controller, DiPricol Boost/Pyro/Fuel w/ Kevlar BSS line, Mag-Hytec Rear, 126K miles. Halon Protected, NRA Member. V1.

 

[brobeson]

IMHO, 4. 10's are for towing, 3. 55's are for Fuel Mileage when empty.

4. 10's also allow you the option of using over sized tires and still staying within stock Dodge perimeters.

If it is an automatic trany, you will keep the pump pressure up, and the loads lower on the trany, you may get better trany life or clutch life with the 4. 10's.

Stock 4. 10 on a 3500, 2000 RPM = 60 MPH
Stock 3. 55 on a 3500, 2000 RPM = 70 MPH

A stock 2500 has larger tires than a stock 3500 so its speeds are just a little higher.

Stock 4. 10 on a 2500 with 245, 2000 RPM = 62. 5 MPH. with 265, 65 MPH.
Stock 3. 55 on a 2500 with 245, 2000 RPM = 73 MPH. with 265 about 75 MPH.

The meat of your towing power is going to be from about 1800 - 2700 RPM. I do not cruise over 2500 PRM.

My currant truck is a stock auto with 4. 10's and 285/75 tires. Because of the over size tires, my ratio equals 3. 70. I am doing 68MPH at 2000 RPM. I would go to 265 tires for better towing as it towed better with the stock 245.

My new truck will be used for towing most of the time, I want 4. 10's.

If you use your truck empty or little towing you will get better MPG with the 3. 55.

Hope this helps

Bob


------------------
1998. 5, 2500, SLT, Red over Driftwood, 24V, 4X4, Auto, 4. 10, Light Group, Camper Special group, Convenience Group, Travel Group, Trailer Group, Keyless entry, 5 band EQ and 6 disk changer. (ruck is 4-Sale) towing a 35ft. Travel EZE 5er.

It in, due to pick up May 9 or 10, a 2001 3500, SLT+, Green, Tan leather, Duel Power Seats, HO, 6 speed, 4X4, 4. 10, Towing Package, Trailer Tow Mirrors, Camper Package, Sliding rear Window, Jacob’s E-brakes (Dodge), Electric Steps (Dodge), Mud Flaps on all 4s (Dodge). It has every option offered by dodge except the snowplow, including the front Air Dam. Line-X over the rail bed liner, 20K Reese 5th wheel Hitch with Gooseneck, 30” toolbox.

 

[John Berger]

What is the equation for determining gear ratio with different size tires. I've seen this in the TDR and on this website, but it was quite a long time ago. Thanks for the help.

John

------------------
1999 Dodge Ram 3500 Quad Cab 2wd; 5 spd; 4:10 LSD rear; Mag-Hytec differential cover; US Gear EGT and Boost gauges. Stewart Warner Fuel Pressure Gauge with dual senders, Westach Oil Temp Gauge for differential. Rancho 9000's on order, PowerEdge EZ Box, Amsoil foam air filter and synthetics in the motor and differential. Cummins Power, don't leave home without it

 

[pcorssmit]

How much weight are you towing? 2 or 4 wd? 12 or 24V? Auto or 5/6 spd?

If the speed limit in Texas is 75 (like here in CO), I'd go with the 3. 54s unless you tow a heavy trailer often. The 12 vs 24V is also a major factor when choosing gears. One of my buddies has essentially the same truck as mine but with 4. 10s, I've driven his truck a bit and didn't like the gears, plus he's really wrapped out running down the highway.

I recently towed my Blazer on a Flatbed to Utah, total weight around 8000 lbs, and had no complaints about the 3. 54s or the 255/85R16s (~33" tall, same as a 285/75R16).

Pete

------------------
'97 2500 CC 4X4 5spd Sport
'83 K5 Blazer 350 TBI (ex 6. 2), 39. 5 TSLs, 3" lift, Dana 60/GM 14 blt, Detroits

 

[Turbo Thom]

With respect to everyone,
The 3. 55 does just fine. At 2000 rpm in mine I'm running 68 mph in fifth. In fifth-over 2000 is 80. when I'm towing I stay in fifth except for long, flat runs. My timing is set at 17 with 220 cc of fuel being pumped with 300 injectors. I have no trouble at all ,anywhere.
I drove a new 2001 6 speed with 4. 10 in the back and at 2000 I was at 60 mph. That I don't like. The dodge mech. rode with me and when we got back his eyes looked like 2 cups, without the handles. He said "this thing will fly". You don't need a new truck. I just replaced he transmission at 198,468 miles and I still putt-un along.
.
Preston

------------------
96 3500, Black SLT, 5 speed, turbo diesel, , with US Gear overdrive, Rhino liner, Reese 15,000 lb. fifth wheel hitch, US Gear de-celarator exhaust brake, muffler elimination kit, Amsoil lub. , Mag-hytec rear cover, dual-remote by-pass filters, and Roadmaster Active system, AutoMeter Pyro & boost, Primeloc

 

[Wiredawg]

Well Gents, it's time to add my two cents. I have a 2000 6 spd with 3. 54s and I pull a 15K lb 5th wheel. Absolutely pulls great. Runs super empty. Clutch is doing well too. I have no intention of going to any taller tire as I had to flip the axles on my fith wheel to get the proper bed to trailer clearance. On a side note: I was looking for a rig w/ 4. 10s when I found this one used. I'm glad I did.

Wiredawg




------------------
2000 4X4 SLT QC 8' bed; 6 spd, 3. 54 ; BD exhaust brake and 4" exhaust syst; TST PM2; Airlift Super Duty rear air bags; RS 9000 shocks; pyro/boost gauges in 2 gauge a-pillar mount; back preasure gauge mounted under dash; KN air filter; Brown's Welding brush/grill guard, rear bumper & headache rack; nerf bars and aluminum roll top rear cover, Warn front receiver and Hadley air horns, 20K Reese hitch,Mag-Hytec dif cover,Psycotty Air.

 

[CCahill]

Before I got on the hubt for a truck, I read every post I could about the 3. 54/4. 10 debate. I live in the foothills @ 1500 ft. elevation, and work @ 1500-6500 ft. I do tow, on occasion from 4K to 12K, I decided to go with the 4. 10's.
But heres something I've noticed.
With a stock engine/trans, this is a way great gear... . With a modified trans,and a bombed engine you have much more torque, and you are able to pull a taller gear... I guess it just depends what you want to have in the end..... For me I love the 4. 10's, although on the hiway sometimes I wouldn't mind a shorter gear... . a tire change can fix that pretty easy... If you go the 3. 54's, your pretty much stuck... Now I feel like I'm ramblin... .
so like she says in "The Weakest Link"... ... GOO-BY!!!!!
Colin

------------------
2001 Quad,4x4,AT,4. 10LS,LB,Loaded enough,stock,mostly... . 65 Chevelle sedan, Hella nice driver, 53 Nash Rambler Convt,1 of 653 built,[not a Metro], GM drivetrain, injection, and auto/od
Specialized FSR PRO Stumpjumper,Cannondale F2000, Loaded
MTD Lawn tractor with flames
12' fishin' boat, loaded. .

 

[CUMINNTSTRKN]

if you get the six speed get the 3. 54's. when pulling heavy you can drop a gear and it's just like you have 4. 10's. and if you bomb your truck at all you will be able to pull high gear most times.

jim

------------------
if it ain't broke fix it till it is!!
2001 eth, ez box, dd2's,southbendclutch

My Ram Pics

 

[TXRam]

To get the "effective" ratio (if you want to call it that), do the following:

Calculate height of new and stock tires: (Width X Aspect Ratio X 2)/25. 4 + 16

285/75 - Width is 285mm and Aspect Ratio is 75% or 0. 75 times as tall as it is wide.

X 2 because the are two sides of tire in total height.

/25. 4 because there are 25. 4mm in 1inch.

+ 16 for the wheel size (16. 5", 17", etc. )

Divide the height of the stock tire by the height of the new tire. Then multiply by the gear ratio (3. 55 or 4. 10). The result is what gear ratio your truck would have to have to operate at the speed & rpms with stock tires as it will with the new tires.

Example:

(245 X 0. 75 X 2)/25. 4 + 16 = 30. 5" stock tires

(285 X 0. 75 X 2)/25. 4 + 16 = 32. 8" for a 285/75

30. 5/32. 8 X 4. 10 = 3. 80 "effective" gear ratio

This is close, but not perfect. The best way is to look on the tire manufacturer's site and get "rev's per mile" or something similar. divide the old one by the new one and multiply by your gear ratio.

------------------
1999 2500 QC 4X4 LB Auto (DTT Upgraded), 4. 10LS, 275HP Injectors, PowerEdge, PowerEdge EZ, SPA Boost and EGT, K&N Air Filter, Magnaflow straight-thru muffler
NRA Member

 

[SlyBones]

http://www.ring-pinion.com/RPMCalculator.html

I Skipped the main page. It has some graphics that take for ever to download. But these guys have some calulators available on the web. A tire size calculator and an RPM calculator. I used the RPM calculator to reverse engineer effective gear ratio's based on different tire sizes.

 

[Ramafid]

I think the REAL solution to the debate is if DC offered 3. 73's as an option. Ford and Chevy both offer more gear choices and we're stuck with just two. There is just too much difference between the two ratios. I chose the 3. 54's but really wanted 3. 73's like I had in my Chevy. DC WAKE UP!!!

------------------
Y2K 2500 4x4 SLT AUTO 3. 54 LSD HD241 FOREST GREEN/DRIFTWOOD

 

[klenger]

From what I have been able to determine, the 3. 73 gears will fit on the carrier that the 3. 54 use, but not on the carrier for the 4. 10.

------------------
Ken Lenger
2001. 5 2500 QC 4X4 SWB SLT, ETC/DDX 5 Speed, 3. 54 (no LSD), camper group, trailer folding mirrors, RBR CD/Radio, LT265/75R16E AT OWL tires, trailer tow group, Patroit Blue / Agate, Westin CPS Step Bars, Jordan Utlima Brake Controller, Weather_Guard 664 tool box
Trailite 21' Travel Trailer, ~4000 lbs loaded.