how to lower RPM

[hemijustin]

WOW, thats the first I heard of a GV blowing up. Did yo use the clutch when shifting in and out of overdrive? So far mine is doing good, I changed the fluid when i did my clutch and it looked god. I don't imagine it gave you much warning when it blew, did it? I kept my original tail shaft and drive shaft so I could switch back easily if I need to. If it breaks that willbe my back up plan.



On another note, took a road trip to Nashville this week (still here) and the truck did great. Filled up North of Findlay Ohio and drove to Nashville, around 470 miles. I have since drove 118 miles around Nashville and when I filled up today my overall mileage was exactly 21. I should have topped off after the highway part to see what it was. !!

nope no warning. . i was just crusing up a hill and bam. i started down shifting becaus of a similer feeling i once had while driving a nv 4500 truck but to my suprise hit 1st gear while going 55 mph. but i also had an exhuast brake... i hear that those are hard on them. theres a guy that lives near me that blown a couple of them up with a 1st gen automatic truck. oh yea... i dont use the clutch for regular shiftiong but i did use it for the od... of course there were a couple of times i accedently hit the swich.....

justin

 

[bpenrod]

I know GV specifically will not allow the use of an exhaust brake with the OD unit engaged. I understand the US gear one will. I'm going to put my brake and OD on a switch so only one or the other can be selected. I have the safety feature installed but when the brake comes on and the OD kicks off with no clutch it is quite a BANG!

 

[hemijustin]

my bother in law has the us gear. . IMO its alot nicer... i like the 2speed reverse and 4x4 ... ...

 

[ilovetrains]

new ratios would be best

I would be happy to just change gear ratios, that is the best solution, I think.



Does anyone have any info on the US gear unit? Is it any cheaper than the GV unit?

 

[JayB]

I have a GV unit on my 2000 ford, its nice cruising the highway at 75mph and 1875rpm. I gain about 1. 5-2mpg but if I could do it over I'd go with the US Gear unit so that I could use an exhaust brake. I'd like to put one on my new dodge but they don't list anything for the G56.

 

[DPKetchum]

The US gear unit works best with a manual trans. The gear vendors with a auto. I'm surprized someone broke a gear Vendor unit. I've watched HOTROD T. V. and they have installed them behind built 440s etc. The torque rating on the Gear Vendor is extremly high if I recall. But least let me say these trucks are built to haul and TOW a load. That is D. C. main interest and the reason I for one bought one. I have 4. 10s in mine and perfectly happy with what its designed to do.

 

[67guzzler]

But least let me say these trucks are built to haul and TOW a load. That is D. C. main interest and the reason I for one bought one. I have 4. 10s in mine and perfectly happy with what its designed to do.

You're right. Point taken. I just think that if you get a 3. 73 rear with the G56, you should get what the 3. 73 ratio represents, not what the 4. 10 with the NV5600 represents. All I'd ask is to offer a 3. 55 or 3. 27 with the G56 as an option to the 3. 73. It's about choices and when they went away from the NV5600 they took away a more economical choice for those of us diesel enthusiasts who don't always tow.

 

[DPKetchum]

I don't always tow. I drive a 1500 slt then. Gets same mileage just at 80. No pun intended I've ALWAYS kept another car(first time truck on truck)for most of my everday driving or back and forth to work. Had a 85 Chevy Caprice Classis for YEARS. Put 250k on her. Before that a 1984Nissan Maxima. Put 265k on her. My trucks get used to haul and tow period. I like to get them paid for and have low miles. I keep a BG truck 10/12 years. My 03 has 19k on it. Owe less then 9k last time I checked. Wife drives a 2000 Merc. Marquis Liminted v8,leather etc. It gets a 100 miles on it. Never drive it but RARELY on weekends.

 

[67guzzler]

I don't always tow. I drive a 1500 slt then. Gets same mileage just at 80. No pun intended I've ALWAYS kept another car(first time truck on truck)for most of my everday driving or back and forth to work. Had a 85 Chevy Caprice Classis for YEARS. Put 250k on her. Before that a 1984Nissan Maxima. Put 265k on her. My trucks get used to haul and tow period. I like to get them paid for and have low miles. I keep a BG truck 10/12 years. My 03 has 19k on it. Owe less then 9k last time I checked. Wife drives a 2000 Merc. Marquis Liminted v8,leather etc. It gets a 100 miles on it. Never drive it but RARELY on weekends.

Dewd. I didn't say you did tow all the time. I did say that DC took away a choice that folks who got the NV5600 w/3. 73 rear got to make when they came out with the G56. People who don't tow tow all the time may appreciate not turning 2200 rpm's at 70 mph by default when their buddy, who ordered his truck 2 months earlier and got the NV5600 turns 2000 rpm's at the same speed. That's all. Can't you sympathize with that? We're all friends here. Peace.

 

[DPKetchum]

The other fact is the majority of the trucks are auto's. Maybe D. C. will offer another ratio in the 6 speed and maybe not. They don't care if it gets better mileage or lower rpm's at 80 mph. They designed it to pull.

 

[bpenrod]

my bother in law has the us gear. . IMO its alot nicer... i like the 2speed reverse and 4x4 ... ...

I liked those idea's as well but was nervous lengthening the front drive shaft as well as the ease of going back to stock if need be. It would be nice to use it in 4x4 and with the exhaust brake!!

 

[67guzzler]

I liked those idea's as well but was nervous lengthening the front drive shaft as well as the ease of going back to stock if need be. It would be nice to use it in 4x4 and with the exhaust brake!!

Yup -- Me too. The "reverse-ability" of the Gear Vendors has an appeal. But after thinking long and hard about it, the US Gear would be the better choice for me as it's a true 2 speed solution at all times / scenarios. You could basically run it in the overdrive all the time if you had the 6 speed. You could even make use of the L (first) gear that way... ... The exhaust brake and the 4wd modes are additional pluses.



The negatives are if you go with the US Gear you're pretty much married to it. The only way out would be an expensive divorce -- 2 new drive shafts. Also -- Short Bed folks have to get their gas tanks modified



Regardless -- If my truck came with the US Gear setup, I'd be thrilled. I just don't know if I can go through the mods.

 

[bpenrod]

I also heard about the fuel tank issues since mine is a SWB. Everything is a matter of compromises!

 

[ilovetrains]

Any further response from AAM?



Anyone want to post the price of the US Gear unit? The GV looks like 3600 off their website.



Does the fuel tank problem on the US Gear with a short bed apply to QC models as well?

 

[RMalone]

I feel for you guys with g56 if it's a daily driver not a tow mobile. D. C. should offer an "option" from the factory especially since more and more CTD drivers are using them as primary transportation with only sporadic towing.



Oh yeah I'd rather drive my Cummins on 3 cylinders than drive a gasser.

 

[hemijustin]

my GV would not allow me to use it untill i was already going 45mph. and would automaticly disingage if i went below 25mph with it on. and if u were to turn that off. and run it all the time u would risk using it in reverse. i dont know what would happen but im gessing it would not be good



Justin

 

[Mrudolph]

Whats the tallest tire available for a dually?

 

[CJ Lagos]

These are 3/4 and 1ton pickup trucks with a powerful diesel engine and great payload/towing capacity. They ride rough and make a lot of noise, get used to it. To me, 3. 73s are already pretty high. Lots of 4x4 vehicles with . 79 overdrives use those gears(wranglers, cherokees, etc).



The difference between NV5600 . 79 and the new . 73 is less than 200rpm. I bet many would have a hard time noticing a difference on the tachometer. :{



I would like to get a US Gear unit to use while cruising empty. There are three things that will kill an engine. Idling, turning it off and high rpm.

 

[ilovetrains]

These are 3/4 and 1ton pickup trucks with a powerful diesel engine and great payload/towing capacity. They ride rough and make a lot of noise, get used to it. To me, 3. 73s are already pretty high. Lots of 4x4 vehicles with . 79 overdrives use those gears(wranglers, cherokees, etc).



The difference between NV5600 . 79 and the new . 73 is less than 200rpm. I bet many would have a hard time noticing a difference on the tachometer. :{



I would like to get a US Gear unit to use while cruising empty. There are three things that will kill an engine. Idling, turning it off and high rpm.

When looking for mine I drove the 5600 and G56 back to back. It is a huge difference above 70. You will swear you missed a gear and hit fourth. When that 200 RPM is the difference between 2400 and 2600, it seems like a whole lot more. Keep in mind that every 100 RPM in 6th gear is almost 5 MPH. Think of your 5600 truck running 90, all the time. Get the idea?

 

[CJ Lagos]

When looking for mine I drove the 5600 and G56 back to back. It is a huge difference above 70. You will swear you missed a gear and hit fourth. When that 200 RPM is the difference between 2400 and 2600, it seems like a whole lot more. Keep in mind that every 100 RPM in 6th gear is almost 5 MPH. Think of your 5600 truck running 90, all the time. Get the idea?

This is not like my NV5600 @ 90mph(~2800 rpm).



G56, 3. 73 gears, . 79od, 75mph = 2320rpm

NV5600, 4. 10 gears, . 73od, 75mph = 2356rpm (2%more)

NV5600, 3. 55 gears, . 73od, 75mph = 2040rpm (12% less)



5mph increase = ~155rpm increase.



I see your point though. With the 2nd gen trucks you could pick 3. 55 for highway gears or 4. 10 if you wanted to tow.



With the new trans and lower OD, you don't have the choice and they set the truck up like it was meant to tow 10,000-15,000lbs.



Assuming taller gears were available for these axles, it is expensive and can be difficult to find someone to do a good job with the gears. I think I would invest in the overdrive unit instead.