anyone have the 342 gears?

[KHauglie]

soon to be ordering 2500,6 spd auto,4x4 crew with 8' box. Looking for input on usability with that set-up. 90% will be without load or pulling. Thought that with 2011 power level combined with 6spd auto will be good combo. Replacing a 98 quadcab,auto 4x4 with 8'box and 354 gears and am happy with drivability and towing a 6k -8k trailer.



Any input?



Khauglie

 

[KLauber]

I have 3. 42 rears with the 6-spd manual. I think the auto trans requires a higher rear end ratio to get the same final drive ratios. Have had no problems pulling a 14-15K trailer in very hilly terrain here in Upstate South Carolina.

Ken

 

[Simplysmn]

I believe with the auto you can get 373's or 410's I have a 08 and love the 410's run's right at 2000 rpm's at 70-75

 

[JHumphries]

The auto has a double overdrive.
6th = 0. 63
70 mph with 3. 42s = 1604 rpm
70 mph with 3. 73s = 1750 rpm
70 mph with 4. 10s = 1923 rpm
If you only do 60 on local highways, you will be lugging at 1375 rpm.

That is really low for these engines.
If you lock out 6th and only use 5th, 60 mph is 1790 rpm with the 3. 42s.

 

[KHauglie]

thanks for the input. so sweet spot-torque/HP is about 1700-1800? have not seen charts on new motor transmission combo. I am used to my 98 w/354 gears and had no issues-automatic 4x4-quadcab 8'bed.

 

[KHauglie]

Thanks-empty or towing at highway-60-70+mph? What kind of mileage are you getting?

 

[rscurtis]

Keep in mind your '98 had 16" wheels. 3. 54 with 16" wheels is about the same revolutions per mile as 3. 73 with 17" wheels.

 

[RustyJC]

Even if they were available, the 3. 42 gears would be pretty useless with the 68RFE's double overdrive gear ratios. With the 4. 10s, my truck is only turning 1612 RPM @ 60 mph versus my previous 2002 that had 4. 10s with the NV5600 6 speed and was spinning at 2000 RPM @ 60 mph. We needed the additional GCWR that the 4. 10s offered for towing our 16,000 lb 5th wheel, but the 68RFE makes these gears much easier to live with.



With 3. 42s, the 68RFE would be spending a lot of time in 4th or 5th gear when towing, I suspect.



Rusty

 

[KHauglie]

2012--8 spd trany--anyone know anything

 

[HBarlow]

2012--8 spd trany--anyone know anything

Extremely unlikely to be offered in our trucks anytime soon in my opinion. Truck sales are soft and Dodge has recently invested big bucks in developing the 68RFE for pickups and the Aisin for cab and chassis trucks.

I agree completely with comments made above by several members regarding 3. 42 gears. You don't want 3. 42 gears with a six speed automatic.

I don't think I've seen published specs for the ISB6. 7 but Cummins website used to state the most efficient operating rpm for the late 5. 9HPCR engines was 1950 rpm. I would guess the 6. 7 is similar.

I ordered 4. 10 gears for my '08 C&C. It works great for empty highway cruise or towing my heavy fiver.

 

[RDHamill]

I currently have the 6spd manual with 3. 42:1, I find it great for towing. I used to have the auto with 3. 73:1, which was also great. I think if you had the 6spd auto and 3. 42:1, the truck would be geared very tall. Might make 6th gear almost useless except when empty and at fairly high speed. I'd only want that combination if I knew I was not towing anything heavy and doing allot of highway travel, which was going to be at least 75mph.
stick with the 3. 73:1 with the 68RFE, you'll be happy.
Check the towing guide that Dodge puts out, it will show how the effects of ratios effect the trucks GCWR.
good luck

 

[AEdelheit]

Keep in mind your '98 had 16" wheels. 3. 54 with 16" wheels is about the same revolutions per mile as 3. 73 with 17" wheels.

The wheel size does not matter, the overall tire diameter is what effects gearing ratios.