2020 F250 7.3 10 spd rear diff order question

yfarm

Observer
About to order 2020 F250 XL Supercab short bed 7.3 10 spd. Standard package is 3.55 gears with 31.7 tires, plan to do either 35s or 37s probably former. With the 3.55 and 35-37 engine will be running around 2100 rpm. Thinking about ordering with 4.30 which with the taller tires will move my effective ratio to around 3.73. With the 10 spd does it matter, could just not use the top 2 or 3 gears? Buying primarily as a long distance highway vehicle and hunting vehicle, will occasionally pull 29 and 33 Freeman cats, 10-13k shorter distances. May add FWC as well. Do not want diesel.
 

IdaSHO

IDACAMPER
With 35's, I say dont bother.
Bigger than that, go for deeper gears.


We roll on 35's with our 3:55 geared 6-speed 6.2

While deeper gears might FEEL better, the truck does great as is.
Even in North Idaho where we rarely exceed even 60MPH and where nothing is flat, we use all but 6th gear.

Anywhere else, Nevada, CA, UT trips, 6th gear is used on the highway at 60+ MPH

It has the torque, and delivers. Your 7.3 with the 10-speed should only be better.

North Idaho travel we see 8-10MPG
Flatlands, its 10-12MPG

50199183173_455b5d5077_b.jpg
 

MTVR

Well-known member
About to order 2020 F250 XL Supercab short bed 7.3 10 spd. Standard package is 3.55 gears with 31.7 tires, plan to do either 35s or 37s probably former. With the 3.55 and 35-37 engine will be running around 2100 rpm.

Is that a typo, or is your intended cruise speed 105 mph?

With 37" tall tires, a 3.55 final drive, a .63 10th gear, and the torque converter clutch locked up, your engine will be running at about 1,200 rpm at 60 mph.
 

MTVR

Well-known member
Thinking sbout ordering with 4.30 which with the taller tires will move my effective ratio to around 3.73.

Forget "effective ratio" and just do the math- a 4.30 final drive in conjunction with a .63 10th gear, is 2.71 overall.

With 4.30 final drive and 37" tires, your engine would be running at about 1,500 rpm at 60 mph in 10th gear.
 
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coastalcop

Active member
I have the 2020 supercab shortbed 7.3 (going to do a writeup on it shortly when i get most of the pieces installed). I have the 3.55 (it had every option I wanted BUT the 4.30) it was the only supercab I could find on the lot that ticked almost all the boxes for 1000 miles. Get the 4.30 gears. The 3.55 is ok (im running yoko 35" tires) but the 4.30 will do better with the 10 speed (and increase your towing capacity to boot) .

Waiting on my 5star tunes to get in, that will wake things up a bit, lots of torque but the 10 speed likes to skip gears (to maximize fuel economy) sometimes when Im trying to merge on the highway.

As an aside, goose gear is about to release an insert for the 60% portion of the rear seat (like they did for their 50Ten build) according to John at goose gear (spoke with him on the phone about it yesterday). Rear 60% takes about 10 minutes to remove if you dont need the space for kiddos and would easily fit a fridge (also has both dc and ac power at the back of the center console if you go with that versus a bench type front seat.

go ahead and add the dual alternators ( 115 dollar option for 397 amps) and batteries (210 dollar option) and the locker for the 4.30 (390 dollar option)when your there as well. These are much less expensive from the manufacturer than doing aftermarket. Second battery already comes with several spaced power points on the positive side, prefused at 125A , 100A, 25A (as I recall so dont quote me on the amp rating but its pretty close) . Tons of room under the hood, even with the "big" 7.3.
 
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MTVR

Well-known member
OP, I think I may have figured out where you came up with the incorrect 2100 cruise rpm- I think you may have not been taking into account the top three gears in the transmission or the torque converter clutch. You would be doing about 2,100 rpm at 60 mph if you had an old C6 3-speed non lock up transmission from the 1960s, but with the 10R80, your cruise rpm on the highway will be MUCH lower, because of those three overdrive gears (8th, 9th, and 10th) and lockup torque converter clutch.
 

MTVR

Well-known member
...and regarding towing with oversized tires and/or lift kits, keep in mind that the factory-specified GVWR, GCWR, and trailer tow weight ratings, are for STOCK vehicles. Modifying the vehicle with oversized tires and/or lift kits, will REDUCE the amount of weight that your truck can safely handle.

This is important, because 13,000 pounds is already kissing close to the 14,000 pound maximum trailer tow weight rating for a STOCK F250 4x4. Putting tires on that are 5" taller, a lift kit to clear them, and/or aftermarket wheels with non-factory offsets, would put you and everyone who shares the public roads with you, into a dangerous situation.
 
D

Deleted member 9101

Guest
I'd definitely go with the 4.30 gears too. The 10 speed will make sure your engine is happily lugging along while your on the HW.

The tune should wake up the 7.3. From what I have read the stock tune is pretty conservative.

Also, I would just level it and run 35s. Towing a 13k trailer with a lift kit and that much TQ can be nasty for drive line components.
 

MTVR

Well-known member
If he wants to tow 13,000 pounds with a lifted Ford truck on oversized tires, he should be looking at the F350, F450, F550, F650, or F750.
 

MTVR

Well-known member
Towing a 13k trailer with a lift kit and that much TQ can be nasty for drive line components.

...and raising the center of gravity and reducing the braking capabilities of a light-duty truck towing that much weight, is not a good idea either.

Not to mention the fact that if he smokes a transmission because of towing with oversized tires and/or an aftermarket tune, Ford isn't going to be buying him a new 10R80 transmission under warranty- he'll be paying for his own transmission out of his own pocket. The warranty only covers defects, not things that owners do to their own vehicles.
 

phsycle

Adventurer
Agreed on towing but I don’t know what his definition of “shorter distances” means. Down the road to the job site every now and then, I don’t think it’s a problem. 50 miles away over a mountain pass......wouldn’t advise it.
 

coastalcop

Active member
...and raising the center of gravity and reducing the braking capabilities of a light-duty truck towing that much weight, is not a good idea either.

Not to mention the fact that if he smokes a transmission because of towing with oversized tires and/or an aftermarket tune, Ford isn't going to be buying him a new 10R80 transmission under warranty- he'll be paying for his own transmission out of his own pocket. The warranty only covers defects, not things that owners do to their own vehicles.


He could probably make the warranty stick with 35" tires and as Ford does that with the Tremor package, the tune would be the real issue (and something I considered when I ordered my tunes) considering the ability to check codes by the dealer. Lift and tires would make it more difficult on the waranty
 
D

Deleted member 9101

Guest
Not to mention the fact that if he smokes a transmission because of towing with oversized tires and/or an aftermarket tune, Ford isn't going to be buying him a new 10R80 transmission under warranty- he'll be paying for his own transmission out of his own pocket. The warranty only covers defects, not things that owners do to their own vehicles.

I wouldn't worry about the tranny...the 10R140 Torqshift in the F250 is the same one in the F550. It's in the F350 thats rated to tow something obnoxious like 35k....soooo...13k with bigger tires probably won't bother it...lol.
 

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