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dznf0g · 02-02-2015, 11:37 AM

Steve, it's a NON- MaxTow 6.2L, 8 speed, with 3.23 gears, GMC Sierra. Z71 susp. Double cab, (old Extended size) 6.5 foot bed, SLT with All-Terrain package.

I won't know till I get the trailer out of storage. ( got a foot of snow yesterday!!!!) I know it will be overloading the rear axle with much, if any , of my toys aboard. I should be able to get a feel for the 6.2/8 speed even though rear gear will be a bit higher (lower numerically). I'll get some weights and measures....but it won't be till March or early April...depending when winter departs. I also have an AS parking pad install project awaiting the Village release of concrete flatwork. So spring plans are in flux.

Glenritas · 02-02-2015, 11:50 AM

We had a 2005 Avalanche 1/2 ton 5.3L 4L65E with 4.10 gears. I added a GearVendors OD unit.
This made all the difference with the wide gaps in the 4L65E.
I towed in direct / OD on the hwy and OD/OD when not towing. In the Mountains I spent a lot of time in 2nd / OD.

I was looking at the new GM's but found the trans gearing and axle gearing just not up to the task.

I took a hard look at the other 1/2 tons and found that the Tundra was what I was after.
5.7L , 6 speed and 4.30 axle that puts the others to shame. It's gearing is spot on for towing and cruising. The down side it only has a 27 gal gas tank.

The dark one was on the test drive ,The white one is ours.

white laker · 02-02-2015, 07:58 PM

Rick
thanks for the information on the truck. will be seeing the dealer on the weekend to try to get my head around what he has coming in. The information that he gave me was unclear. Like I said I will wait to see what comes in, check the build sheet and test drive it with the trailer on its back.
Did get a hold of Dexter axles regarding the GM brake controller. They think that the 2015 truck MAY operate their E/H disc brakes so yet again will see it when it comes in. will keep you posted.
thanks again
Pete

KJRitchie · 02-03-2015, 09:48 AM

Glen, what is the yellow payload sticker on the driver's door show for your Tundra's available load just to compare with the Chevy 1500. A hypothetical Tundra 5.7L Double Cab 4x5 with a payload of 1800lbs with a 35 gallon tank would be my ideal tow.

Kelvin

gandttimes · 02-03-2015, 06:30 PM

I'm thinking that the GM with the 6.2 and 8spd is going to be geared a lot better than the Toyota.
1st gear comparison sees the Gm at 15.59 overall in first,
10.15 in second
7.11 in 3rd
5.77 in 4th
The Toyota is
14.32 first
8.4 second
5.8 third
4.3 4th
Toyota only has 2 more gears left at this point while GM with superior HP and Torque has 4 left.
No contest.

George

Glenritas · 02-03-2015, 10:40 PM

Quote:

Originally Posted by KJRitchie

Glen, what is the yellow payload sticker on the driver's door show for your Tundra's available load just to compare with the Chevy 1500. A hypothetical Tundra 5.7L Double Cab 4x5 with a payload of 1800lbs with a 35 gallon tank would be my ideal tow.

Kelvin

We our's is a 2014 2wd dbl cab, the yellow sticker says 1520 # and the gas tank is only 27 Gal. but the aftermarket has a 36 gal replacement tank for a mere $1200. There is talk that Toyota may come up with a 36 gal tank soon.

Our Tradewind weighed 4320# when we dragged it home. By the time I'm done with the rebuild including a washer and a dryer it should come in around 5000# and with our gear around 5500#.

Glenritas · 02-03-2015, 10:59 PM

Quote:

Originally Posted by gandttimes

I'm thinking that the GM with the 6.2 and 8spd is going to be geared a lot better than the Toyota.
1st gear comparison sees the Gm at 15.59 overall in first,
10.15 in second
7.11 in 3rd
5.77 in 4th
The Toyota is
14.32 first
8.4 second
5.8 third
4.3 4th
Toyota only has 2 more gears left at this point while GM with superior HP and Torque has 4 left.
No contest.

George

Our Tundra is a 2014 , at the time we were looking GM didn't have an 8 speed.

But the GM 8 speed doesn't have a direct gear thus it's either under or over drive creating more heat then when the Tundra is in 4th. That said at 60 mph the Tundra likes 5th gear which is overdrive. It pulls our Tradewind happily .

I find the gear spacing on the Tundra just right with no big rpm changes between gears and enough gears for all situations.

phbarnhart · 02-03-2015, 11:33 PM

If I may, I believe what G and T was trying to point out is that the rear differential gearing ratio is only part of the picture in determining how well a vehicle is geared to tow. As manufacturers move towards greater numbers of gears in these automatic transmissions the ability to have a really low overall ratio in first doesn't necessarily depend on having a really low rear differential. It had been argued earlier on in this thread that, on the strength of it's differential gearing, the Tundra is better geared for towing. As George has pointed out, that's only part of the question. And, frankly, this thread was started to discuss an individual who is currently shopping for a TV so, while your point about GM not having an 8 speed transmission when you bought yours may be correct, it's not all that probative for a current buyer.

As for the gear spacing between 6 and 8 speeds, my experience was that 6 speeds was more than enough... until I drove a truck with 8. Ram and GM are already selling them and Ford seems to be planning to skip right to 10 speeds. I imagine diminishing returns kicks in at some point here but I don't really know where. I expect Toyota will follow suit in the near future.

Also, the GM 8L90 does have a direct drive gear, it's 6th. http://www.thetruthaboutcars.com/201...-transmission/

tjdonahoe · 02-04-2015, 04:30 AM

That is basically what we would call a double over transmission,seems like most every one is going to that ,lower rpm's = better fuel mileage! my 6.7 dodge with 6 speed auto and 3.73 gears , goes down the road, with our 31' classic, in 6th at 1525 rpm easy.....

dznf0g · 02-04-2015, 06:59 AM

It doesn't matter whether you are achieving the sweet spot for a particular load with the trans or the diff.....or wheel/tire rolling radius. The performance of a vehicle at a particular load is a function of "effective gearing" which is a function of all three mentioned above.

Unless you have a multi-speed rear axle (big trucks only), more gears in the trans allows for sweet spot achievement over a wider variation of loads and terrain than a single "fixed" gear in the rear end.

The trend for more gears allows a manufacturer to tune the engine to a more narrow RPM band, bringing it closer to the efficiencies of an Atkinson cycle theory of operation.
Combine the theoretical use of an Atkinson, with variable valve timing and multiple gearing and you are getting closer to a practical application for real world vehicles. Next is individual, real time valve regulation, that will not only control the timing of valve opening and closing, but duration and lift as well. That will allow for closer tuning to Atkinson theory and probably will result in MORE gears.

Those who argue a lower rear end gear(numerically higher) aren't wrong....just somewhat outdated in their outlook. I am confident Toyota will follow suit with higher gearing in the rear end and more speeds.....they have to, IMO.....and probably for 2016 model year. BUT, Toy sells more small cars as a ratio to 1/2 ton trucks than GM, F, and R, so they may get past the 2016 CAFE and their shift may come later....but it will come.

J. Morgan · 02-04-2015, 07:35 AM

More than five gears used in a gas engined pickup truck are not there for the sake of performance, but to extract tenths of an MPG.

1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

dznf0g · 02-04-2015, 08:22 AM

Quote:

Originally Posted by J. Morgan

More than five gears used in a gas engined pickup truck are not there for the sake of performance, but to extract tenths of an MPG.

1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

Ummm, It's about both. Volumetric efficiency for the engine, which precludes the need for a narrow RPM band (for street applications) at which fuel efficiency and driveability under a vast number of need sets and loads can be accomplished.

More gears keeps a well designed and tuned engine, to fill those needs, in an RPM band where that volumetric efficiency can result in max power and fuel efficiency for a varied need set.

It's harder in trucks because they are used under a wider range of loads and lifestyles. Some are used as little more than passenger cars with a LARGE trunk....and the same platform may be use by some as a workhorse (most of us here, to some extent)

More gears isn't done as a whim...if all we needed out of a truck was to move a couple of passengers, all we'd need is a 2.5L naturally aspirated 4 cylinder with a powerglide. To heck with driveability, pleasability, and fuel economy.

With all due respect...and I mean that...your comment reflects a very simplistic analysis of the product segment and manufacturer(s) research and offerings. Yes, the Govt. does mandate fuel economy standards, but the mfrs. HAVE TO offer performance, particularly for the truck market.

J. Morgan · 02-04-2015, 09:11 AM

Your view also is simplistic, but in a different way.

The reason the power band on modern gas engines is practically narrowed is not because of the limitations of the technology itself, but because the engineers have taken the path of a narrowed practical powerband to extract every bit of advantage from a narrow range.

1/2 Ton 4WD Truck, 72 Sovereign Hensley Arrow

dznf0g · 02-04-2015, 09:21 AM

Oh, ok, have a nice day.

Glenritas · 02-04-2015, 09:34 AM

Ok now that we've gone deep into transmissions and gearing and given the original poster an education, let's save the discussion on the merits of where the manufactures and government are taking us.

Bottom line will the truck be used primarily for towing or for commuting ? This will make a difference in the selection of the truck specs and the trailer that will be towed.

To the O.P. you now have a wealth of info, use it wisely.

DC Bruce · 02-04-2015, 10:01 AM

Thanks all. The sum of all this appears to be that I can get 1700-1800 lbs cargo capacity in a Ford 1/2 ton right now. . . and nowhere else. If I wait until Chevy accepts orders for the 6.2/max trailer tow combination or I order that with the 5.3 engine, I can get that in a Chevy/GMC too. When Ford starts accepting orders for the max payload package, I can get above 2,000 lbs. cargo.
I'm not happy about waiting another 4+ months and I'm not comfortable about overloading the truck. While I may not exceed GAWR, I have no idea how the truck will handle.
So, I need to have a chat with my wife about 3/4 ton gasoline trucks which don't have these issues. While they don't perform well at their max towing capacity, I would be pulling about 60% of that. So I think the power would be adequate. Certainly they use more fuel empty than 1/2 tons, but fuel consumption towing seems to be about the same.

dznf0g · 02-04-2015, 10:32 AM

Bruce, are you still looking for a trailer, as your status to the left indicates? It is conventional wisdom to find your trailer, then decide on TV. That prevents you from under or over spec'ing your truck...and being wasteful financially or fuel wise.

If you're looking for a 30'er (or even a 25...relatively heavy tongue weight), you're dealing with the same conundrum as I. Whenever I buy my "retirement" truck in the next 3 - 5 years, it will primarily be a dedicated tow vehicle for the duration. That's why I have tried 2500 (gas and diesel), 1500 (5.3L and now a 6.2L), Suburban, Escalade, Yukon XL (all 6 speeds, some 5.3 and some 6.2 old generations)

I am anxious to pull with the 15 Sierra with new gen 6.2 and 8 speed...even though it's a non-MaxTow. I'm still on the fence. I loved the 2500 Duramax I just got out of, but it was sure nice to have the refined feel of the 1500. It feel like a luxury vehicle compared to old body style 2500. HOWEVER, the new 2015 2500 is much quieter (ala the 1500 body refinements), but has the same running gear as the 2014.

I have much weighing and analysis to do.....if you're interested in waiting for that.

lsbrodsky · 02-04-2015, 11:24 AM

Rich,

You seem to be the only voice closing in on an optimal TV, one that tows well and rides/drives well when not towing. Everyone else just seems to proclaim their favorite because it is their favorite. Keep us posted...maybe start another thread when you reach a conclusion.
Larry

Lance M · 02-04-2015, 11:35 AM

No Larry. I have the optimal TV, for me anyway. Don't we all?

dznf0g · 02-04-2015, 11:39 AM

Thanks, Larry,
I will post about it when the time comes. I'll wait until after the snow is gone (over a foot on the ground and still snowing), I get weighings, and probably after I tow to Key West and back in June (with a week's detour throughout the Smokies).

Optimal is different for varying equipment and lifestyles. All we can do is gather from others' lessons and derive our own needs based on that.