3.42 gears for TC

[LL8]

Hello,

Just looking for some thoughts on pulling hills with 3.42 gears.

I'm going back to a pop-up TC @ 1800 lbs dry weight.

The trucks I'm looking at are the Chevy and GMC 3500's SRW 4x4, standard bed, crew cab, with the 6.6L diesel.

Their payload rating in 4185 lbs

They only come with a 3.42 gear option but have a 10 speed Allison transmission.

And I like the 20" wheels just for the looks.

Do you think this will be an issue hauling up mountain roads and interstates (East Coast) at closer to 3000 lbs fully loaded? Or should I look at the other competitors with a 3.73 option?
TRANSMISSION & AXLE

Thanks for the advice

Type: Hydra-Matic 6L90 six-speed automatic (6.6L gas)
Allison® 10L1000 10-speed automatic (6.6L diesel)

Gear Ratios (:1): 6L90 10L1000

First 4.03 4.54
Second 2.36 2.87
Third 1.53 2.06
Fourth 1.15 1.72
Fifth 0.85 1.48
Sixth 0.67 1.26
Seventh -- 1.00
Eighth -- 0.85
Ninth -- 0.69
Tenth -- 0.63
Reverse 3.06 4.54

Final Drive Ratio:
3.73 (6.6L gas)
3.42 (6.6L diesel)

[3_tons]

Well, I’m happy to leave ‘comprehension’ to the perfumed Experts (lol), but would only note that what I had previously offered was a non-theoretical, actual real-world scenario with an ‘actual diesel’ intended for what might possibly be a larger (uninitiated) viewer audience…. I don’t recall hearing disclosures of other’s ‘actual experience’ (or *rigs?), but admittedly, my situation with 5k camper, while occasional towing 5k enclosed double axle trailer might not be as applicable for some others (I donno?)…FWIW, here’s what I’d previously stated (in the interest of clarity…), but as is always the case when reading differing opinions, discernment is a welcome asset…

* (I was not aware that GM and Ford stopped offering 4:10’s?)

3 tons wrote:

….However, much of this depends on where and if something is being towed - for a flatlander grocery-getter I’d easily go with the 3:42, but this is a slide-in camper forum and some campers (loaded…) are nearing 5k#, and some folks tow in the mountains…When crossing the Sierra’s on hwy 80 (not towing, but 5k Camper), even with a Dsl (800lb torque) I find myself occasionally downshifting from 6th to 5th overdrive - but that’s just me and I feel it’s negligent to make an engine lug…

3 tons

3 tons

[Grit_dog]

valhalla360 wrote:


Might want to work on the reading comprehension.

Already covered it. If you are pushing the truck to the upper limits beyond the max allowed for the taller rear end, yes it gets you some advantage but that's about the only time it's an advantage.

If you are just carrying a 5k truck camper, there is zero advantage because the 10speed can handle it easy by selecting the appropriate gear

Easily being an understatement! Someone, not you, took the thread off the rails a ways back, but yeah, brand new Dirtymax is about 300% more than what will move that camper down the highway competently.
Heck, my old '86 K20 (with 4.10s, lol) with a 3 speed trans will haul any TC that doesn't break the truck frame or axle, down the highway easily in top gear at 70-75mph.

[valhalla360]

3 tons wrote:
Ok, I get it - there’s no way to justify a 4:10 rear end (even with 2-3 OD tranny ratios…), and no reason for a manufacture to offer one on their order list - I truly had no idea that increasing the GVWR and the towing capacity was just a marketing thingy (heck, who knew!!), obviously I blew it (dummy me - lol), ‘one ratio for all’ is now starting to make more sense than ever, and who knows, maybe even the manufactures might read this, recognize their goof and rethink the ‘perceived magic’ of costly 10 speed trannys with OD??

3 tons -

Might want to work on the reading comprehension.

Already covered it. If you are pushing the truck to the upper limits beyond the max allowed for the taller rear end, yes it gets you some advantage but that's about the only time it's an advantage.

If you are just carrying a 5k truck camper, there is zero advantage because the 10speed can handle it easy by selecting the appropriate gear and when you aren't carrying the camper, you get better freeway efficiency because it can pull the engine RPM down into a more efficient range.

[Grit_dog]

3 tons wrote:
Ok, I get it - there’s no way to justify a 4:10 rear end (even with 2-3 OD tranny ratios…), and no reason for a manufacture to offer one on their order list - I truly had no idea that increasing the GVWR and the towing capacity was just a marketing thingy (heck, who knew!!), obviously I blew it (dummy me - lol), ‘one ratio for all’ is now starting to make more sense than ever, and who knows, maybe even the manufactures might read this, recognize their goof and rethink the ‘perceived magic’ of costly 10 speed trannys with OD??

3 tons -

Sarcasm indeed! Marketing? Well aren’t most new things marketed? That’s just business.
I know you’re not accepting of this and consider it to be some charade. But that’s ok. Maybe it will spur you (without admitting it of course) to be more well read….Or maybe it’s easier to just keep talking about how back in your day you had to walk 5 miles uphill to school both ways, in the snow, and if only the bus had 4.10 gears, life would have been different! Lol

On a serious note, it’s a balance between available power, available trans gearing, and strength of components.
I mean, why does GM only offer 3.42s with their diesels and now only 3.73s with their Hd gassers ( which is a mistake. They didn’t take a step forward in the gasser market at all with the new 6.6…dunno why) when Ram offers 4.10s in both and I think ford goes up to 3.90s but a standard 3.31 behind the diesel?
1. Ram is still using old outdated transmissions. A signature move for …ever now. Not sure why.
2. Ford, idk, maybe they figure their trucks are strong enough to handle the power, 10 speed deep gearing and deeper rear gears.
3. GM, idk, they’ve always only offered 1 ratio behind a Dmax. Simplicity in mfg? No need for deeper gears? Who knows and who cares?
It’s the principles in design here that are being discussed. Take the names out of it. But until you understand the engineering principles, you’ll continue to show your butt while defending your position, which happens to be with your pants down….figuratively speaking of course…I hope!

[mkirsch]

3 tons wrote:
Ok, I get it - there’s no way to justify a 4:10 rear end (even with 2-3 OD tranny ratios…), and no reason for a manufacture to offer one on their order list - I truly had no idea that increasing the GVWR and the towing capacity was just a marketing thingy (heck, who knew!!), obviously I blew it (dummy me - lol), ‘one ratio for all’ is now starting to make more sense than ever, and who knows, maybe even the manufactures might read this, recognize their goof and rethink the ‘perceived magic’ of costly 10 speed trannys with OD??

3 tons -

While I recognize your sarcasm here, let me add some food for thought:

It's stronger and easier to gear down than gear up. That's why the 10 speed offers 7 underdrive gears and only 3 overdrives, instead of 3 underdrive and 7 overdrives.

The 3.42 gearset in the axle is also stronger than the 4.10 by virtue of the larger, deeper teeth of the gears.

What I love about this conversation is how many "converts" there are now to the new way of thinking. For YEARS, I tried to get people to abandon the church of "Our Lady of the 4.10 Gearset" by virtue of the then-common 6-speed transmission and was called all kinds of names for it.

[3_tons]

Ok, I get it - there’s no way to justify a 4:10 rear end (even with 2-3 OD tranny ratios…), and no reason for a manufacture to offer one on their order list - I truly had no idea that increasing the GVWR and the towing capacity was just a marketing thingy (heck, who knew!!), obviously I blew it (dummy me - lol), ‘one ratio for all’ is now starting to make more sense than ever, and who knows, maybe even the manufactures might read this, recognize their goof and rethink the ‘perceived magic’ of costly 10 speed trannys with OD??

3 tons -

[valhalla360]

3 tons wrote:
“There's nothing magical about overdrive. It's just another gear ratio.”

Except, fact is that it reduces engine speed which helps compensate for numerically high rear axle - No magic is involved, just engineering and this is why overdrive exist, ‘nowadays’ there’s multiple overdrive ratios…

However, much of this depends on where and if something is being towed - for a flatlander grocery-getter I’d easily go with the 3:42, but this is a slide-in camper forum and some campers (loaded…) are nearing 5k#, and some folks tow in the mountains…When crossing the Sierra’s on hwy 80 (not towing, but 5k Camper), even with a Dsl (800lb torque) I find myself occasionally downshifting from 6th to 5th overdrive - but that’s just me and I feel it’s negligent to make an engine lug…

3 tons

Yes, there is engineering behind it but nothing magical. Overdrive is just another gear ratio. The engine doesn't know if it's overdrive with a 4.x rear end or a drive with a 3.X rear end if the overall gear ratio from crank shaft to wheels is the same.

Marketing more than anything for the average owner. "Overdrive" sounded more cool than "4th gear" when they switched from 3 speed to 4 speed transmissions.

As far as choosing a rear-end ratio, the modern trucks with 8/10speed transmissions they simply pick a gear that gets the correct overall gear ratio.

Maybe it's an old timer thing where you felt the truck was less capable if it had to downshift. Odds are towing or carrying a large truck camper you will rarely be running in top gear with the new transmissions...and it's designed to be that way.

[JRscooby]

3 tons wrote:

Well I offered what’s just my alternative view, but much of this is purely subjective, so will stop short of talking anyone off their religion…

For a manufacture to decide to offer only 1 ratio, and somebody to declare that ratio will not work with recommended loads, comes pretty close to alternative facts. The cost savings of only 1 ratio compared to the cost of a large percentage of buyers just don't work.

[3_tons]

JRscooby wrote:

3 tons wrote:
“There's nothing magical about overdrive. It's just another gear ratio.”

Except, fact is that it reduces engine speed which helps compensate for numerically high rear axle - No magic is involved, just engineering and this is why overdrive exist, ‘nowadays’ there’s multiple overdrive ratios…

Can you explain how much different that is from shifting from 4th to 5th with the old 5 speed manual in the old F-5? Watching the dash, takes a big drop in RPM to make the shift.

However, much of this depends on where and if something is being towed - for a flatlander grocery-getter I’d easily go with the 3:42, but this is a slide-in camper forum and some campers (loaded…) are nearing 5k#, and some folks tow in the mountains…When crossing the Sierra’s on hwy 80 (not towing, but 5k Camper), even with a Dsl (800lb torque) I find myself occasionally downshifting from 6th to 5th overdrive - but that’s just me and I feel it’s negligent to make an engine lug…

3 tons

If the only RA ratio offered is 3:42 I would bet you will have no issue moving max GCVWR. Now if you are over the combination rating without a trailer, you might be disappointed.
You complain your snot downshifts on a hill? Why put transmission in there?
It takes a certain HP to move load a given speed. As grade increases, more HP is needed to hold the speed. Engine spinning faster makes more HP

Well I offered what’s just my alternative view, but much of this is purely subjective, so will stop short of talking anyone off their religion…

[JRscooby]

3 tons wrote:
“There's nothing magical about overdrive. It's just another gear ratio.”

Except, fact is that it reduces engine speed which helps compensate for numerically high rear axle - No magic is involved, just engineering and this is why overdrive exist, ‘nowadays’ there’s multiple overdrive ratios…

Can you explain how much different that is from shifting from 4th to 5th with the old 5 speed manual in the old F-5? Watching the dash, takes a big drop in RPM to make the shift.

However, much of this depends on where and if something is being towed - for a flatlander grocery-getter I’d easily go with the 3:42, but this is a slide-in camper forum and some campers (loaded…) are nearing 5k#, and some folks tow in the mountains…When crossing the Sierra’s on hwy 80 (not towing, but 5k Camper), even with a Dsl (800lb torque) I find myself occasionally downshifting from 6th to 5th overdrive - but that’s just me and I feel it’s negligent to make an engine lug…

3 tons

If the only RA ratio offered is 3:42 I would bet you will have no issue moving max GCVWR. Now if you are over the combination rating without a trailer, you might be disappointed.
You complain your snot downshifts on a hill? Why put transmission in there?
It takes a certain HP to move load a given speed. As grade increases, more HP is needed to hold the speed. Engine spinning faster makes more HP

[Grit_dog]

3 tons wrote:
“There's nothing magical about overdrive. It's just another gear ratio.”

Except, fact is that it reduces engine speed which helps compensate for numerically high rear axle - No magic is involved, just engineering and this is why overdrive exist, ‘nowadays’ there’s multiple overdrive ratios…

The other "magic" is that this thread was about a 10 speed Alli with 3.42 gears, which if you actually understood the differences, you'd know that the 10sp with the tall gears starts out deeper than your Dodge with 4.10s and either trans they offer. And the Alli has 3 ODs, which IMO are not needed with the tall gears but could be handy IF it came with lower gears (Which is to your point)

PS, I can run in 5th gear all day, doing a lot more than hauling a TC WITH the lesser of the Ram 6 speeds and 3.42s and turning 37s.
Youd have to be drivin miss daisy pertty hard, on stock size wheels to need to drop to 5th with 4.10s in your truck.

You have missed the point you were somehow trying to prove.

[3_tons]

“There's nothing magical about overdrive. It's just another gear ratio.”

Except, fact is that it reduces engine speed which helps compensate for numerically high rear axle - No magic is involved, just engineering and this is why overdrive exist, ‘nowadays’ there’s multiple overdrive ratios…

However, much of this depends on where and if something is being towed - for a flatlander grocery-getter I’d easily go with the 3:42, but this is a slide-in camper forum and some campers (loaded…) are nearing 5k#, and some folks tow in the mountains…When crossing the Sierra’s on hwy 80 (not towing, but 5k Camper), even with a Dsl (800lb torque) I find myself occasionally downshifting from 6th to 5th overdrive - but that’s just me and I feel it’s negligent to make an engine lug…

3 tons

[mkirsch]

3 tons wrote:
Huh?? Time now to recognize the ‘new reality’ - Nowadays (21st century…) with the final three gears ‘as overdrives’ how is it that a 4:10 any kind of obstacle!!

3 tons - with a DRW 4:10, 6 speed, two final gears are both overdrives, purrs at 70 mph

Three words: Fuel economy standards.

You're still >2000RPMs at 70MPH in OD with your 4.10s. I know I'm at 2500RPM with mine, but it's a gasser. With 800HP and 1000TQ or whatever these latest diesels are pushing out, you should be able to run 70 empty loping along at 1200RPM.

[valhalla360]

3 tons wrote:
Huh?? Time now to recognize the ‘new reality’ - Nowadays (21st century…) with the final three gears ‘as overdrives’ how is it that a 4:10 any kind of obstacle!!

3 tons - with a DRW 4:10, 6 speed, two final gears are both overdrives, purrs at 70 mph

There's nothing magical about overdrive. It's just another gear ratio.

With moderate towing or city driving, not much difference. It will pick the gears that match the RPM the truck decides the engine should run at. Very rarely will it get into top gear and it won't really need 1st gear hardly at all.

It's at the far ends of the operational regime where it makes a difference:
- When towing really heavy in mountainous conditions, you might exceed the tow ratings with the 3.42. Then the 4.10 might get you the maximum towing capability for the truck..
- When not towing and cruising at high speed on the freeway, the 4.10 may get the RPM higher than ideal even in top gear. The 3.42 will allow the engine to stay in the optimal RPM range.

Given the tremendous towing capability of modern trucks, the 2nd situation is likely to be beneficial far more often.