Hitchhiker

I'm looking at a 04 3500 HO, six shooter to pull my 14,000# fiver. I find that a Ram with 3.73 rear end is rated for 21k GCWR and with a 4.10 is rated at 23k GCWR. It doesn't matter if it's SRW or DRW.

Why the difference and what would you exprienced operaters recommend.

I owned a 98 12 V CTD and traded for a new 01 F350. I can't wait to get back to a Commins.

DF5152

If your gonna tow it alot get the 4.10s If only once in a while the 3.73s will work. running 4.10 is just like using a bigger leaver to move a heavy stone you dont have to work as hard

Nevada

I wouldn't give it a second thought with a six-shooter, with a slushbox I would hold out for the 4.10's.

Hitchhiker

Thanks for your replys. I understand the principle of power through the gear ratios. I just don't understand why the GCWR would change 10%.

Is the 4.10 a heavier rear end, bigger axle or bigger Ring gear?

Mopar_Mudder

This will confuse you even more : the 3.73 is actually a stronger gear then a 4.10 is. As gear ratios get lower the pinion get smaller and has less teath, making it weaker.

The only thing I have been able to come up with is that with the lower gears you can pull the extra weight and keep your speed up versus being slow on every hill and a road hazard with the the 3.73's

Here is a picture I took awhile back, the pinions are out of a Dana 60. From left to right they are 4.10 - 4.88 - 5.86 you can see how as the gear gets lower the pinion gets smaller. But 3.73 - 4.10 is a pretty small amount and not enough to worry about.

Crabjoe

[quote author=Hitchhiker link=board=11;threadid=20953;start=0#msg196608 date=1066138778]
Thanks for your replys. I understand the principle of power through the gear ratios. I just don't understand why the GCWR would change 10%.
[/quote]

In this case, I'd say it's not that one is stronger then the other as both are sufficiant to do the job. The difference is that there's a 10% difference in RMPS, 10% in fuel usage, 10% easier on the drive train so it makes since there would be a 10% increase in the tow capacity. That's my edjamacated guess.

BoldtsWagon

I think that some of the tow ratings also involve how much GCWR you can move up a 20 percent grade starting from a dead stop. The higher gear ratios will put more torque on the wheels.

Hitchhiker

Nobody really can figure this out. I've asked my salesman, his service manager and seniur tech and all they can come up with is what you folks have said. The 4.10 has more power to pull a heavy load. Seems like a lousy reason to restrict GCWR.

I talked to a dealer in Omaha, NE today that deals very heavy in 1 ton Dodge trucks. He said they never stock a 4.10, only 3.73's Go figure.

Thanks for your thoughts and experiences

Paul

Hitchhiker

Hey bolts: I thank you have a point in general and I think it's a lousy reason to limit the GCWR. It's just too important a number in terms of legal issues after an accident. Also, I'm not worried about a 20% grade. I think 8-10 is my limit.

Wilber1

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Nobody really can figure this out. I've asked my salesman, his service manager and seniur tech and all they can come up with is what you folks have said. The 4.10 has more power to pull a heavy load. Seems like a lousy reason to restrict GCWR.

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4.10's are are also going to make life easier for the clutch, transmission and U joints. Perhaps this could have something to do with it.

P Kennedy

The lower gear ratio allows one to "lift" the load easier when starting to move the load and will require to drop out of overdrive sooner when pulling utilizing direct gearing producing less stress on the tranny. By running in direct or below the tranny will run cooler and last longer than continous overdrive operation, however running 3.73's allows rearend to run slower and run cooler with better fuel milage under lighter loads. The GCVW difference is directly related to the lifting ability of the gears reducing stress and wear on the clutch and driveline. Mopar the smaller the pinion the stronger it is because the load on the gears is closer to the pinion shaft radius which is where most break. Also the pitch on the gear is way higher allowing more gear to gear surface contact distributing the force farther around the pinion gear it self. Remember a larger wheel takes more force to turn than a smaller one and the mass of the pinion gear itself is to compensate for this. PK

2manydogs

Wow, Mr. Kennedy, I always believed that the lower the ratio, numerically, the stronger the gear set was. But, you have put up a good argument for the opposite. Is just the pinion stronger or is the ring gear also stronger? I have 3.07's and a five speed. Is this not as strong as say, a 4.10? I would be curious as to what the max torque rating would be for these ratios. Jim, weirding out about weird things!

Mopar_Mudder

I have to disagree, the pinion shaft itself has less stress on it yes. But with the smaller pinion you have less teeth, this means that their is less tooth contact at any time. The problem is not in the streght of the pinion shaft, it is in the fact the you strip off the teeth. Being in off-road/mud bog seen you see lots of deep gears and the problems that come with them.

Patrick Campbell

The fact that you could tow X more pounds with a lower gear (higher numerically) is a little ridiculous. You could just put it in 5th gear instead of 6th, or 4th instead of 5th. As someone else stated, the 3.73 R&P itself is actually STRONGER than the 4.10, naturally because it has fewer teeth, each tooth is physically larger. The idea that you can tow more is just saying that it'll be easier to get pulling and continue pulling but it's not going to be any sort of necessity.

Haulin_in_Dixie

[quote author=d-train link=board=11;threadid=20953;start=0#msg208426 date=1068562611]
If your load is so heavy that you need the bigger rear and it's associated higher tow rating to be within ratings, I'd go for it, but if not, I'd base the decision on how well the rear puts the engine in a sweet spot for the truck's nominal mode (55-65 mph on the highway in direct drive (5th on the NV5600), as a guess with that trailer).



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As I think PK was saying the ratio only has to do with the starting up, once moving you put it in the proper gear. I run 3.55 with my loads, no problem.