Hey Gang,

Have any of you heard about the new 3.42 gears recently announced by AAM for the 9.25 front and 11.5 rear axles? These gears are in AAM's PowerDense line of gear sets and are designed for improved fuel economy under normal driving conditions.

Just wonder if any of you have seen them and if you can guestimate what improvement is reasonable to expect?

AAM does state that the gear set is not intended for conditions such as regular hauling, climbing grades or pulling.

Just like some thoughts as you are all smarter than I!

 

[QUOTE=J2Waite;1867064]...AAM does state that the gear set is not intended for conditions such as regular hauling, climbing grades or pulling./QUOTE]

Can't you just down shift if you need more power for the hills? Or are the gears themselves not strong enough for the extra loads? Better MPG would be really nice.

 

Or oversize tires.

 

Do a search there's a megacab member here who swapped to 3:42's. I'd stick with the 3:73's and jump up in tire size.

 

A 1 to 2 mpg increase is what I read.For that a the loss of towing any kind of weight etc.is not worth it to me.Truck pushes air like a brick and the fasfter you go the harder it works.

 

All great points, Thanks!

I recently read somewhere that as much as 70% of fuel is consumed (expended) in an attempt to overcome the wind resistance....great big brick is right!

 

Depending on how much it cost for labor, I would think you'd need to drive the truck for a lot of miles before you hit the break-even point in fuel savings. A rough estimate (assuming 2 mpg savings) would be you could save about $500 in fuel per 30,000 miles.

 

I don't get it either. The higher gears will ruin what it was built for. They are trucks and meant to work hard with the gears that are in them. I buy cars for mpg and trucks to work. Craig

 

I would only buy those gears if both my front and rear diff blew at the same time- pretty slim chance...

 

But it sure would be nice! Then I would add 285's and roll down the highway in 5th, knowing I had more gear if I needed it!

 

IMO you would spend your money better on a gear vendros OD... better rpms when cruising and more gears when towing... At 75 the 3.42s only drop the rpms by 187, the gear vendors drops it 493...

 

I definitely agree about the gear vendors. Keep the touque offered by the current gear set and have an impressive overdrive (and extra gears) when needed.
I checked into getting one and was told it is kinda tricky with the 2wd tranny and that it would be cheaper to get a 4wd case then add the gear vendors OD.
Does that make any sense?

 

Sounds pretty close. They put one in Greg Hogue's QC 2wd project X truck you can read about it here: http://www.dieselpowermag.com/tech/d...ive/index.html

 

DieselJunky, thanks for the link. They too, switched to a 4wd tranny in order to bolt the gear vendors O/D directly to the tranny.

All in all, I think I would rather keep the gear set and add the gear vendors and end up ahead all the way!

 

The gear vendors is a great option......as long as your not planning on doing any heavy towing (see gear vendors website). I did the 3.42 Swap see mega 3.42 gears in forum. I have over 25,000 on the gears since the swap, and have pulled 90% of those miles loaded. I notice about a 200 rpm difference at 75mph and a mpg increase of 2-3 mpg.

A taller tire would accomplish the same thing, or combined with a swap make it "better".

Good Luck.