this is a aweosme truck but the price would kill me

towcat

Supporting Member
Supporting Member
Joined
Jun 24, 2004
Posts
18,196
Reaction score
1,437
Location
SantaClara,Ca/Hamilton,TX
now in a idi ford would it be able to as you say overcome the gearing?
different motors. different powerbands. bottom line is you need to drive it to understand.
IH v-8's like to rev. the powerband for them is higher and spread out farther.
while a 3.55 behind a IH will allow it to make good fuel economy, the gearing does not allow the motor to rev easily. with 4.10's the truck can climb up the side of a building, but fuel economy suffers a little.
A Cummins 6bt makes it's power from 1800-2200 rpm with a stock governor of 2800. you can move the upper limit a little by installing a 3200rpm governor. Still, a Cummins powered truck will bennefit from 3.55's due to where the powerband is at.
 

icanfixall

Official GMM hand model
Joined
Apr 10, 2005
Posts
25,858
Reaction score
672
Location
West coast
The lower the number the faster the truck can go but.... It makes it really tuff to haul heavy. Balance is what you want. That means balance what you plan on hauling with the speeds and gears you want. I tun a 3.55 gear and feel its just a bit to high or as some call it tall of a gear. Empty running I can do 85 mph in double overdrive with my gearvendors turning only 1850 rpm. And getting 18.9 mpg....:sly I do have more available horse power than most others have. I run very easy crusing at these speeds. No real strain on the motor. I may just change the rear gears to something closer to 4.10 but I'm thinking hard about that. I know if I did go that direction I could probably pull the paint off anything on the road but... I wouldn't want the motor spinning up around 3000 rpm all the time. Thats where the gv will help out. Just something I'm looking at. I know if I make my rig a dually I would have the 4.10 gears with just the differantial changeout thats needed to do this srw to dually change... Then if the 4.10 are not "nice" I could have a set of 3.73 installed.... Or just go back to a set of 3.55 gears....:dunno All good thing in time.....
 

GWDriver

Registered User
Joined
Aug 25, 2010
Posts
34
Reaction score
0
Location
San Antonio, TX
Real simple: take 3.54 gears. What this means is a ratio that for every 3.54 turns of the drive shaft the tire turns 1 time. So lower the number, the higher the gear is.
If you have a Cummins, which has alot of torque and a low RPM power range, you can handle going from 4.10 to 3.54 or higher like 3.08. In the end, going with higher gears drops your rpm which increases fuel economy, as long as your engine has the torque to overcome the gearing.

Not to hijack the thread, but my '03 Dodge 3rd Gen. has 4.10 gears with the 48RE tranny. I've seen 18.5 mpg on the overhead console. Is that the best I can hope for at about 65 mph?
 

towcat

Supporting Member
Supporting Member
Joined
Jun 24, 2004
Posts
18,196
Reaction score
1,437
Location
SantaClara,Ca/Hamilton,TX
Not to hijack the thread, but my '03 Dodge 3rd Gen. has 4.10 gears with the 48RE tranny. I've seen 18.5 mpg on the overhead console. Is that the best I can hope for at about 65 mph?
that mpg computer in the overhead is affectionately known as the lie-o-meter. never trust it. take your truck on a long distance run and do the calcs by hand.
 

Forum statistics

Threads
91,217
Posts
1,128,517
Members
24,045
Latest member
Ramtough01

Members online

Top