Engine/Transmission (1994 - 1998) gear change or bigger tires

[cahammer]

hey yall i have a 98 3500 quad cab 12v with 4. 10 gears nv4500 limited slip rear and diesel prices suck so i was wondering witch is better differnt gear ratio like 3. 55 or taller tires (thinking about 19. 5's) and where can i get the best prices i drive 300 miles 5 nights a week for my job and yes it is a dually thanks for the responses

 

[tp0d]

ouch 4. 10 gears are the worst for mileage. . 19. 5's would give you a bit better mileage, but you gotta figure in the cost of new rims, etc. . specially with 6 tires heh. .



As for the best prices, if you have a Flying J around, they move a lot of diesel and seem to have good prices for the area. their website is http://www.flyingj.com/fuel/diesel_CF.cfm , you can check prices from a range of stations.



I`ve had good luck with adding a cetane booster to my fuel, particularlly in the winter months. Gotta watch the overall cost of that also, adding more booster doesnt give you better mileage. Once you reach a certain cetane level, there is no more efficiency.



Then there's drugs. . Propane. . Someone here said they knew a friend getting 26-28mpg with 20% LP fumigation. . Sounds real interesting, expensive, and kinda risky if the system would ever fock up. (ie toasty motor)... I work with natural and LP systems all the time, and I`m wary of attempting that one (other than buying a kit that is)



hmm... thats about all on my mind. . good luck



ohya, and welcome to the TDR (yay another virgin)



-jerry

 

[Joseph Donnelly]

It takes a long time for tires/wheels to pay for themselves, same for gear sets and installation (obviously easier on you if a 4x2 than 4x4). Also you can't go much taller on tires as they tend to get wider and then the sidewalls rub on a dually. look into Cooper 255-85-16 as they are about the narrowest in that size, pretty clsoe to stock total width.

I suggest taking your timing from 13. 5 deg stock to 15. 5 deg. That gave my 2500 club cab 4x4 about 2 mpg on the highway.

 

[WaynesWorld]

Joe,

While you are talking timing, I want to move my timing up a little more. Its now at 15 3/4. Should I ? If so how far ?



Thank You,

WAYNES WORLD

 

[KLockliear]

If that's a 4x4, you could also consider an overdrive unit. Cost wise, it will be a little more than swapping gears in both axles, but now you can select which ratio you want to run.



You could also consider finding used complete axles from a wreck to swap in. That will probably be the cheapest. We got a posi 3. 55 D80 for my '94 for $200.

 

[cahammer]

If that's a 4x4, you could also consider an overdrive unit. Cost wise, it will be a little more than swapping gears in both axles, but now you can select which ratio you want to run



do you know of any one who has done the overdrive unit in their rigs and have they had any poblems with them

 

[KLockliear]

Yes, lots have. We even sold a few. The US Gear overdrives work quite well.

 

[JGheen]

If you want I will trade you straight up my stock 3. 54s for your 4. 10s? I am running 37" tires and my truck is lifted and I have been in the hunt for 4. 10 sets for a long time but can't afford the price for a new set of gears. I know we might be out of a running vehicle for a while, while the gears are removed and sent to each other but just a thought.



Let me know,



Joe

 

[cahammer]

cahammer's dad . what kind of mpg might a guy get with a gearvendor ( preferred ? )/ us gear set up. I have a 05 3500 4x4 ctd 6 speed 373. I'm pulling rv's in the winter months and need return trip mpg increase badly.