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 > Why 4.1 axle?

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Sport45

Not far enough from Houston, TX

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Posted: 06/14/19 10:13am Link  |  Quote  |  Print  |  Notify Moderator

Personally, I think the 4.10 ratio is perfect for you. When I had my V-10 F-250 it had 3.73 gears and I always wished it had 4.30 when towing. Ford didn’t offer a 4.10 ratio which I always thought would be a perfect compromise between towing and not.


’19 F350 SRW CCLB PSD Fx4
'00 F250, CC SWB 4x2, V-10 3.73LS. (sold)
'83 F100 SWB 4x2, 302 AOD 3.55. (parked)
'05 GMC Envoy 4x2 4.2 3.73L.
'12 Edge 2.0 Ecoboost
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Grit dog

Black Diamond, WA

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Posted: 06/14/19 10:35am Link  |  Quote  |  Print  |  Notify Moderator

6.0 is not a powerhouse. If towing, get all the gear you can find.
FWIW higher gears than 4.10s aren’t even an option on the newer models I believe.


"Yes Sir, Oct 10 1888, Those poor school children froze to death in their tracks. They did not even find them until Spring. Especially hard hit were the ones who had to trek uphill to school both ways, with no shoes." -Bert A.

blt2ski

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Posted: 06/14/19 11:19am Link  |  Quote  |  Print  |  Notify Moderator

rjstractor wrote:

Lantley wrote:

If your talking 4 speed transmissions the gear ratio can be critical and make a significant difference but with the newer multi speed 8-10 gear trannies the ratio is less of a factor


Winner winner chicken dinner! Towing 8K with a 6.0 and a 4L80E you want 4.10s for sure. The 3.73 would do fine on gentle hills but if you find yourself stopped on time2rolls aforementioned 26% grade you'll be sweating bullets since
the 4L80E doesn't exactly have a great 1st gear ratio for launching on hills.


Actually, with a 4 sp 4.10 gear ratio, said truck would literally NOT be going up said hill. At 20K lbs, you have a max gradability of around 16-20%. The 6 sp with the higher torque, you have over 30% gradability. meanwhile, my old 05 dmax had 26% at 20K lbs..........this is grade in first gear, no 4lo, just regular old rwd!

I would get the 4.10, or 4.33 if available with the new 6sp, then my final tall gear would be equal to a 4 sp with 4.1's. I usually only drive a max 60 mph, 70 is less than 5% of my driving, so I setup up for a 60-62 mph in high gear. Then I usually have ALL the low gear I need for said STEEP grades to launch on. I've never been worried about the 6% freeway grades, if I can not pull one of them in 1st gear, you are in a BIG world of hurt!

Marty


92 Navistar dump truck, 7.3L 7 sp, 4.33 gears with a Detroit no spin
00 Chev C2500, V5700, 4L80E, 4.10, base truck, no options!
92 Red-e-haul 12K equipment trailer

Check RV.Net Blogs at: blog.rv.net

BenK

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Posted: 06/14/19 11:43am Link  |  Quote  |  Print  |  Notify Moderator

Am planning the update of my 1996 K3500, 7.4L Suburban

Ordered it with 4.1's and will change them to 5.38's or higher numeric

Plus a GearVendors 0.7 gear splitter, that will provide 8 speeds (16 icluding the transfer case's compound low) for a final gear ratio of approx 2.6 to the axles

Haven't decided if G80 or Detroit yet...want to fill with tungsten or molyb diasulfide rich synthetic lube

The new close ratio trannies w double OD are great, IMHO, still desire higher numeric diff ratos


-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

valhalla360

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Posted: 06/14/19 01:13pm Link  |  Quote  |  Print  |  Notify Moderator

twodownzero wrote:

It is a myth that more RPM = lower fuel economy. You can "overshoot" the ideal cruise rpm by several hundred rpm without any realistic difference in fuel economy.

My older truck used to cruise in the 2,400 rpm range at 65 mph and now cruises over 3,000 RPM. There has been zero change in fuel mileage, city or highway. If it had overdrive, it would have probably seen a significant increase in mpg by going from the 4.10s it had to the 4.88s it has now.

If the myth that rpm=lower mpg would die, more people would be driving vehicles geared more appropriately. No gas 3/4 ton or bigger should have anything less than 4.10s these days. 30+ years ago, even without overdrive, 4.10 and 4.56 would have been much more common than 3.73s. With the .6x:1 overdrives that are common now, 4.88s or deeper would make for a better towing truck even with the 32-33" tires that come on these trucks from the factory. with the overdrive ratios they have, they would probably still get better mileage than the old 4 speed autos with .7x:1 overdrive ratios and 3.73/4.10 gears. With 6, 8, or 10 gears, there's simply no reason to undergear.

Somehow we've ended up in a situation where we have better control over air fuel ratio and higher ratio overdrives, and we decided to gear the trucks the same. That makes no sense to me. I imagine that it's because they're trying to squeeze every imaginable bit of empty fuel mileage out of these trucks but they're doing a disservice to those of us who work our trucks every day. Trucks have way more power than they had 30 years ago, so we can get away with it, but we'd be in a much better position to use that power with lower gears.


You should go tell the manufactures about this because they've spent a ton of money putting in overdrive gears to improve MPG over the last 30-40yrs. Obviously, they haven't got a clue and I'm sure they will be happy they can cut costs by going back to simple 3 speed transmissions.


Tammy & Mike
Ford F250 V10
2008 Copper Canyon 5er
Catalac Catamaran 34'
Full Time spliting time between boat and 5er


RoyJ

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Posted: 06/14/19 01:51pm Link  |  Quote  |  Print  |  Notify Moderator

valhalla360 wrote:

twodownzero wrote:

It is a myth that more RPM = lower fuel economy. You can "overshoot" the ideal cruise rpm by several hundred rpm without any realistic difference in fuel economy.

My older truck used to cruise in the 2,400 rpm range at 65 mph and now cruises over 3,000 RPM. There has been zero change in fuel mileage, city or highway. If it had overdrive, it would have probably seen a significant increase in mpg by going from the 4.10s it had to the 4.88s it has now.

If the myth that rpm=lower mpg would die, more people would be driving vehicles geared more appropriately. No gas 3/4 ton or bigger should have anything less than 4.10s these days. 30+ years ago, even without overdrive, 4.10 and 4.56 would have been much more common than 3.73s. With the .6x:1 overdrives that are common now, 4.88s or deeper would make for a better towing truck even with the 32-33" tires that come on these trucks from the factory. with the overdrive ratios they have, they would probably still get better mileage than the old 4 speed autos with .7x:1 overdrive ratios and 3.73/4.10 gears. With 6, 8, or 10 gears, there's simply no reason to undergear.

Somehow we've ended up in a situation where we have better control over air fuel ratio and higher ratio overdrives, and we decided to gear the trucks the same. That makes no sense to me. I imagine that it's because they're trying to squeeze every imaginable bit of empty fuel mileage out of these trucks but they're doing a disservice to those of us who work our trucks every day. Trucks have way more power than they had 30 years ago, so we can get away with it, but we'd be in a much better position to use that power with lower gears.


You should go tell the manufactures about this because they've spent a ton of money putting in overdrive gears to improve MPG over the last 30-40yrs. Obviously, they haven't got a clue and I'm sure they will be happy they can cut costs by going back to simple 3 speed transmissions.


Agree, lower rpm almost always = better rpm. You have lower pumping losses period. Modern semi tractors are designed to lug down to 1000 rpm under full throttle, full torque.

The only time this is not true, is if you're using so much throttle in a taller gear that the engine enter open loop (rich mixture).

FishOnOne

The Great State of Texas

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Posted: 06/14/19 06:02pm Link  |  Quote  |  Print  |  Notify Moderator

Flashman wrote:

My Ram 3500 SRW only came with a 3.4 rear end. I was worried but it tows great. Buzz up every hill in the western US without breaking a sweat - with a 12,000 lb toy hauler.


Sure it does [emoticon]....I'm sure it pulls great if you drive it like an old man... LOL


'12 Ford Super Duty FX4 ELD CC 6.7 PSD 400HP 800ft/lbs
"Built Ford Proud"
'16 Sprinter 319MKS "Wide Body"


ib516

Canada - soon to be Costa Rica

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Posted: 06/15/19 06:04am Link  |  Quote  |  Print  |  Notify Moderator

Most people think the gear ratio matters a whole lot more than it does for mpg. Going from a 3.42 to a 4.10 will cause a much smaller increase (~0.5 mpg) than driving style can (30%). Slowing down on the highway by 1 or 2 mph will have the same effect, and there's no compromise in pulling power.

I always suggest the highest number (lowest ratio available) for the axle, then just don't drive like a dummy.


Prev: 2010 Cougar 322QBS (junk)
02 Dodge 2500 4x4 5.9L CTD 3.55
07 Dodge 3500 4x4 SRW Mega 5.9L CTD 3.73
14 Ram 2500 4x4 Crew 6.4L Hemi 4.10
06 Chevy 1500 4x4 E-Cab 3.73 5.3L
All above are sold
Current: 07 Dodge 1500 5.7L Hemi 3.55 / 2010 Jayco 17z


JRscooby

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Posted: 06/15/19 07:14am Link  |  Quote  |  Print  |  Notify Moderator

Gear ratio is always a compromise. For best mileage you want the overall ratio (Trans, rearend and tire diameter) to keep engine RPM at most efficient point at the normal road speed. And because you loose more to friction when you turn the output faster than input, ideally if the rear ratio did all the reduction and top gear was direct you should be best. But that high speed rearend would strain the housing, driveshaft, transmission, clutch, motor-mounts, frame when starting the load. Remember, at take off, peak HP, peak torque don't matter, it is the torque just above idle that matters.
To gain the extra strength the rest of the vehicle would need to be built heavier, need more fuel to move the extra weight.

Back about '75 my parents bought a new TT. After the first trip Mother called me crying, the I6 in the '69 Econoline would not pull it, they could not buy a new TV. I don't remember what the original ratio was, (near 4:1) but I changed the ring and pinion to a 4.88s. (And replaced the clutch that had smoked) That was enough of a change to let them camp for a few years. Dad said he lost some mileage on the highway but it did not change in town.

valhalla360

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Posted: 06/17/19 06:09am Link  |  Quote  |  Print  |  Notify Moderator

JRscooby wrote:

Gear ratio is always a compromise. For best mileage you want the overall ratio (Trans, rearend and tire diameter) to keep engine RPM at most efficient point at the normal road speed. And because you loose more to friction when you turn the output faster than input, ideally if the rear ratio did all the reduction and top gear was direct you should be best. But that high speed rearend would strain the housing, driveshaft, transmission, clutch, motor-mounts, frame when starting the load. Remember, at take off, peak HP, peak torque don't matter, it is the torque just above idle that matters.
To gain the extra strength the rest of the vehicle would need to be built heavier, need more fuel to move the extra weight.

Back about '75 my parents bought a new TT. After the first trip Mother called me crying, the I6 in the '69 Econoline would not pull it, they could not buy a new TV. I don't remember what the original ratio was, (near 4:1) but I changed the ring and pinion to a 4.88s. (And replaced the clutch that had smoked) That was enough of a change to let them camp for a few years. Dad said he lost some mileage on the highway but it did not change in town.


If you tow within the manufacturer's ratings, you shouldn't have an issue blowing apart the diff due to overloading.

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