I look at it this way. The 4.30 gears give my 6.2 about a 15% advantage. Would you really gain much going from a 6.2 with 4.30's to a 7.3 with 3.73's? Yeah, I know the 10 speed helps some. But . . . . I'd definitely go with 4.30's. IMO, there is no downside.

 

Some quick math actually shows the 6.2L w /4.30 gears would have a slight pulling advantage over the 7.3L with 3.73 gears, assuming the tranny is the same in both trucks (example 2020 F-350 with 10spd). Regardless of the tranny gear, the 4.30 diff adds 15% torque multiplication over the 3.73 diff. If the 6.2L makes 430 ft-lb max, then add the 15% "gain" of 65 ft-lb, you'd be at 495 ft-lb of effective torque (discounting the tranny gear; we'll assume the same for both trucks). The 7.3L makes 475 ft-lb max, but has no "gain" because we use the 3.73 as the baseline of comparison, so it's still making 475 ft-lb effectively, again ignoring the tranny gears. Now, if you add the 4.30 gears to the gasser 7.3L, then you get an effective value of around 545 ft-lb (which is more than what the old venerable 7.3L PSD made with it's 3.73 gears at only 525 ft-lb!).

Honestly +/- 25 ft-lb isn't really that much from one to another, especially when you're in the higher gears of the transmission. In the lower gears, every ft-lb counts, but ONLY if you're in a condition that calls for a maximum thrust force generation. Given the new 10spd has DEEP gearing in the three lower gears, any truck is going to pull hard! Regardless if you choose the 6.2L or 7.3L gas motor, when you pair them with 4.30 gears and the deep gearing of the 10-spd, you're going to be equipped to pull quite a load. Those who loved the old 7.3L PSD would be similarly impressed with these new combinations.

 

For me, I would always choose the deepest gears I could get from the factory, particularity with a gas engine. I will say though, that having 10 gears makes the rear axle ratio less important to me now then when I had only 4 or even 6 gears. For towing performance, the rear axle ratio difference makes the biggest impact in first and last gear. That's because for a given speed the trans can select a higher or lower gear as needed to compensate for the rear axle ratio difference as needed. For example a 3.73 geared truck may pull a grade in 3rd while the 4.30 geared truck pulls in 4th. Works great for many conditions as long as you have plenty (10) gears at your disposal. When I order my F350 7.3 I'll probably consider 3.73 gears for a few seconds before I choose the 4.30s, lol.

As a point of comparison to the old days, I'm currently towing a 7000lb travel trailer with a Suburban 2500 8.1 (340hp, 455 tq) 4-speed with 4.10 axle. I previously had the same truck with 3.73s. Big difference! The 4.10 Suburban tows well in overdrive (.75) and drops to 3rd (1.0) to pull grades, rarely needs 2nd and only when accelerating up the steepest grades. So for highway towing, I can tow 85% percent of the time in overdrive with 3 usable gears available to me.

With the 3.73 Suburban I could only tow in overdrive on the flats, so I end up mostly towing in 3rd, which was really too low of a gear for cruising, but still not low enough to pull steep grades without the noisy drop to 2nd gear. So really only 2 gears available for highway towing. Obviously a 6 speed or 10 speed transmission would have closed the performance gap between the differently geared trucks by giving me more gears to work with.

Another interesting point is that the horsepower and torque curve of the 8.1 Chevy and new 7.3 Ford are very similar from idle to 4400rpm at which point the Chevy really drops off and the 7.3 keeps pulling.

 

What it will come down to is fuel economy. The 7.3 with 4.30’s will pull the 20k, but if your going to be pulling 10 tons or close to it a lot, you’d be better off getting the diesel.

the 4.30’s will obviously pull better, but if your not pulling a heavy trailer a lot, it may be worth getting the 3.73’s if the 3.73’s get 2 more mpg.

I know people don’t buy these trucks or buy the 7.3 for fuel economy, but mpg does it come into okay for some people.

personally I’d pair the 7.3 with the 4.30’s.

 

I agree with you, but with a big caveat ... This depends upon how you define "better off". Sure, higher MPG is nice. But if you only drive a vehicle 5k miles a year, that better diesel MPG is killed by the $10,000 price tag; it would take a couple DECADES just to break even, and that does not include the other operational costs of regens, maintenance fluids and filters, etc.

I used to have a 2006 Dmax; great engine and decent MPG. But I only drove it 52k miles in 12 years! I only used it for pulling the RV; it was a part-time-use truck. And so the diesel engine cost didn't pay for itself in the long term. When I went truck shopping last year, the only "can't have" was a diesel engine. Simply cannot justify the cost for my use and loads. Now, if you need to pull a big load AND you're going to do it 5 days a week, all year long, then the diesel option may be "best", if the math works out in your favor.

This has all been covered a bazillion times in many threads. How one person defines "better" is not the same for the next guy. The reality is that there is no perfect truck; there are always compromises to make. Most people will be happy if they are honest with themselves and truly seek a vehicle that has the most pros and least cons for their type of expected use for the majority of the time, knowing that there is nothing that will ever be a perfect fit for all conditions.

 

Always go with the lowest gears available. Like my dad taught me, always get the biggest engine option and the lowest gears. You will never say "what if", or "I wish I had the ____ engine, or gears"

Gear ratio was a bigger decision back in the days of 3 and 4 speed transmissions without overdrive. 3K RPM on the highway wasn't pleasant. Today's transmissions with 2, 3, or 4 OD gears?....low gear ratios are less of a concern.

 

For me, it is about pulling power.

 

Totally agree with several of the above posters that axle ratio was a HUGE thing when we all had 4-speed transmissions, and really, that wasn't that long ago, so it's where a lot of the "conventional" wisdom comes from. Much smaller deal on trucks with the 10-speed transmission, but also, for all the same reasons, less risky if you get "the wrong" gearing.

That's a long way of saying that you probably won't notice much difference either way, so don't overthink it too much if you are having a hard time deciding, you'll be fine.

 

I'm looking at the tow guide for F350 4x4 7.3 and 5th wheel CC SRW.
GEAR GVW Trailer
3.73 23,750 16,200
4.30 27,500 20,200

4k is quite a bit of difference, I'm glad I ordered 4.30

 

If it dosen't make any difference why is it that a F350 CCLB 4x4 DRW with 3.73 gears is rated for a for a 16000 lbs trailer and with 4.30 gears it's rated for 20000 lbs.

Denny

 

Maybe a clearer thing to say would be that if you know what you want, get that, and if you are confused, or feel like you are torn between two options, relax, because the "real-world" difference will be small.

I always buy deepest gears just like many of you, and I'd probably do that with this 7.3/10-speed combination too if I was shopping for one. I do think most of us are guilty of overthinking things here.

 

I think that there would be a difference between the gearsets in terms of getting off the line. Once moving at highway speeds, probably less benefit to deeper gears with the new 10 speed.

 

Yes they will come off the line easier and there will be less stress on the whole driveline all the way through the gears and with 3 OD gears it will eliminate the down side of having deeper gears.

Denny

 

Are the gear ratios published for the new superduty10 speed Trans?

 

Duplicate post

Denny