I think that both the F350 DRW and F450 have the same 11.8" ring gear. [Coming from a classic high-horsepower Camaro where I upgraded my 10-bolt 8.2" ring gear rear to a bullet-proof 12-bolt rear with a 8.875" ring gear, 11.8" is gigantic.]

Your right about the non-F450 variants having the same rotor size as last year. It is interesting that the 2017 has a smaller brake pad on those trucks.
Front inboard 14.92 sq inches --> 11.95 sq inches
Front outboard 14.92 --> 13.5
Rear 11.45 --> 9.89

The F450 got much bigger pads for 2017
Front 14.92 --> 17.21
Rear 11.45 --> 16.21

Man, I'm spending too much time pouring over the spec sheets - I've already ordered the F450, I guess I just need to chill out and wait now.

 

Haha yeah but it's fun going over the specs. Unfortunately I don't have my computer in front of me with all the details but I really like to see the differences.

The 450 is the Ultimate Beast, you will love it.

 

You can cheat...go to a smaller diameter tire.

You can do the same thing to improve your MPG. Just go to a smaller front tire than rear tire and you truck is now driving downhill all the time. What that mpg go up like a rocket.

A word of caution, don't go to small on the front tire as you will save so much fuel that it starts to run out of the filler pipe. I hate that when it happens, ruins my life time wax job.

 

You can swap in a 4.10 Ring and Pinion ( Gears in the Differential, not the entire axle assembly) for the front Dana Super 60 axle pretty easily by purchasing the 4.10 gear set and an install kit from many gear vendors like "Randy's Ring and Pinion", "Yukon Gear", etc. The gear sets for the Dana Super 60 are not particularly expensive, unless you buy from a Ford Dealer (the most expensive option you could choose..!) You would then have to have a reputable shop like a "4 Wheel Parts" of other shop that specializes in Ring and Pinion Gear installs (again, Ford Dealer likely most expensive option here). The Dana Super 60 has a 4:10/4.56 carrier break. To run 4.30 and lower gears (4.30, 4.10, 3.73, 3.55, 3.31), you will need a 4.10 and down differential carrier (your stock carrier). To run 4.56 and higher gears, you would need a 4.56 differential carrier.

As far as your rear axle, which is the new Dana M300, while the 4.10 Ring and Pinion sets ARE available, they are at the moment very hard to find as the axle is so new... Also, the R & P Install kits may be difficult to find... Aftermarket manufacturers should start making R&P's for these axles but R&D takes time and then there ahs to be a market... Dana is prolly your best bet right now to get the R&P for the rear axle... I can't seem to find any info on the Dana M300 axle carrier breaks, but the Dana website prolly lists it somewhere...
I'm assuming you know YOU CANNOT RUN MIXED R&P RATIOS IN THE AXLES, SO DON'T EVEN CONSIDER SWAPPING THE FRONT UNTIL YOU CAN ALSO SWAP THE REARS AT THE SAME TIME...

 

That will depend on where the carrier break is. And it will be different front to rear.
Sometimes you will need a new carrier to fit a really deep gear set. 4.10's are right on the edge of some of the older carriers.

 

You are correct.

There are generally 2 sizes of carriers and this holds the ring gear and is driven by the number of teeth on that ring gear. I will dig back into my memory banks hazard a guess that the break on the 60's stingray corvette for example came at 30. Options were 4.10, 4.56, 4.88, 5.13 and 6.14 I also think there was another 5.xx in there but not sure. IIRC later on when they dropped the 5's and 6 ratios the break came at 3.73.

My guess is the 3.55 in most of our trucks is the smaller carrier and the 3.73 is the larger allowing 4.10's.

The question comes up as much today as when I got into 4x4 transportation: can you run mixed AXEL ratios f/r?

The answer is yes. 2 things come into play to allow this. First the final ratio much be the same. The final ratio does not stop with the axle ratio. The axle ratio is just one of several inputs to arrive at the final ratio. Transmission gear(S) and tire diameter.

Secondly the driveshaft and or the axle shafts must spin free, point being don't try on full time 4x4 setups unless you compensate for the difference in axle ratios with different f/r tire diameter in order to achieve the same final drive ratios which much me the same f/r or a catastrophic event will occur.

The next question to be asked is: SHOULD YOU? NO! I cannot and will not recommend it. That said I wheeled with a guy who did it, he had 3.55 in the front and installed 4.10's in the rear, he compensated with tire diameter and when it had saved up enough money he bought a new carrier and 4.10 gear set. His axles freewheeled unless he manually locked them.

I have spoken with some of the 'mudders' and have been told they some of them run different ratios and do so because that want the f/r wheels spinning at different rates for better traction....dunno, not a mudder, but I can see their logic on that. Supposedly if the front wheels spin faster say a 4.10 ratio and the rear is a 4.88, the faster spinning fronts will clear a path, dig deeper and the 4.88 will be able to gain traction better????? I have seen stranger things in my over 50 years of 4x4 playing.






Look close at these lower control arms




Note the nylon ties holding on the lower leaf spring

 

Yeah, and I could always sell the extra fuel I'd be saving...

 

With part-time 4x4, you can run any axle ratio you want in the front vs rear, but as soon as your engage 4x4, you have a problem: whichever end has the numerically lower axle ratio is going to cause extreme wear on the transfer case. Yes, *it* will be spinning at the same rate as the rear, but the effort to "force" the mis-matched axle to turn faster will probably break something inside the t-case.

Front axles don't have to be as strong as rears on part-time 4x4 rigs because the front will never see more than 50% of the torque of the engine, nor typically have to move more than 50% of the weight of the vehicle. Likewise, the front output shaft of transfer cases is typically not designed to withstand full force.

I guess if you had a 3.55 front and a 4.10 rear, you could try to compensate by putting small tires on the front, but that would be pure retardation and not create any benefit off-road at all.

As for the carrier size, remember that the 350 duallys run 3.55 or 4.10 - I'd bet its the same carrier, at least within the M300 axle.

The 350 dually at 4.10 is effectively the same as the 450 at 4.30 with its slightly taller tires...probably a slight pulling advantage to the 450.

 

From my off road jeep building day. You can use any index you want and apply this to any situation on or off roadIf you want to play with data inputs and see how they will affect, I use the RCI:

RCI (Rock Crawling Index) to see what affect changes will make. This gives a realitive score based upon a known performance index and it factors in tire size.

TM = TransMission (driven gear ratio, 1, 2, 3, etc)

TC = Transfer Case Ratio

AR = Axle Ratio

CR = Crawl Ratio

TD = Tire Diameter in inches

TM (transmission ratio) = 4.01 < enter data

TC (transfercase ratio) = 4.00 < enter data

AR (axle ratio) = 4.10 < enter data

CR (crawl ratio) = 65.76 TM x TC x AR

TD (tire diameter, inches) = 31.00 < enter data

CR divided by TD = RI (Rubicon Index or any index you chose from a dually to a motorscooter)

4:1 TM x 4:1 TC x 4.1 AR = 66 CR/31 TD = 2.12 = OEM Jeep Rubicon

RCI = 2.12 (rock crawling index FOR the '03-'06 TJ Jeep Rubicon), now enter your data from your rig and compare with the Rubicon or ???? what ever you chose.

NOTE: as you go up in tire size you need to increase the index slightly to compensate for the added mass the larger tires bring. Start adding extra weight, wider tires (increased CoF), trail tools etc etc and the OEM Rubicon 2.12 will not cut it so the RCI has to continually drift upward.

Data does no good unless you have something to compare with.

 

As I recall some Dodge Power Wagons in the 70's had a 4.10 in the front and 4.11 in the rear, the effect was to get improved longitudinal stability in very slippery instances. Not enough binding that a tiny bit of scrubbing couldn't cure.

 

doubt it . stick with ford gear . I have 4.30s. the 37s , bring the ratio down to roughly 3.80s . this truck still pulls like a freight train . extreamly . happy with the power and tranny gearing . yet to pull any of the big stuff but quite frankly not too worried lol...

 

The Super Duty's have the same issue. It's not an engineering strategy. It's due to Dana Spicer using a slightly different gear ratio list than Ford. I encountered the same when switching my 06 from 3.73s to 4.10/4.11

 

So the 2016 f450 rear axle had a 16k rating from dana and what rating did ford put on it? And whats the 2017 f450 rear axle ratings both from dana and ford? I know this is an old topic but I have never seen the numbers.