Engine/Transmission (1998.5 - 2002) 2001.5, 4.10's, disk brakes, wanna trade your 3.55?

[Piston Slapper]

Just bought a new to me used truck with 85,000. It has 4. 10 gears in it, that I do not care for in this truck. It is going to be primarily a commuter vehicle and I am seeking mileage gains. Was wondering if anybody w/ disk brakes, 4x4 and 3. 55 would want to have an axle swapping party?



Was thinking just swapping complete axles around as to not have to setup the differentials by just swapping gears.



2500 rpm at 80mph is killing my mileage! Use to 2100 rpm in my old truck with 3. 55 and 2wd running 20mpg. I am not expecting to run that with this 4x4, but it has to be better than 15-16mpg I am running now.



Anybody?

 

[gottorq33]

hey piston slapper PM me I may be intrested in this I have all the above

 

[JamesSimpson]

Not to bust up any plans but I have an 02 QC4x4 with 3. 55's and i only get about 17mpg

 

[Dieselnutz]

You big wus! :{ Slap some big o'l meats on that thing and roll with it. Seriously put something like 295/75/16's BFG's or Toyo's and I think you would be Happy. That size is about 33. 7" tall and should lower your RPM quite a bit. What are your bombing plans? Do you still have your comp?

 

[Piston Slapper]

It has some pretty good meats on it now. 305/70/16's. the Calcs say I ought to be doing 2200 rpm w/4. 10's at 75 mph on the 33 inch tires. My speedo is pretty close. Truck will run 17mpg (barely) if I keep it 65 or below. Most of my driving is on the interstate at 76-78mph and runs about 15mph. I think I'd be able to run 18mpg w/ the 3. 55's cause I commute with it 40 mile interstate one way. I miss that extra 90 miles per tank or so I used to get out of my 99 2wd auto with 3. 55's.

 

[Jrowe]

I've got what you're looking for, but don't think I want to swap. Just lift the front end and run 35's. That will lower you rpms.

 

[Dieselnutz]

I get 18mpg on a good day. 16 if I drive it hard. I think the wind resistance is your worst enemy at 75 mph and up. After a ticket 2 weeks ago my mileage has improved> The 2wd sits lower therefore has less wind resistance. The t-case does not help either.



I not sure lowering rpm's will help fuel mileage much. If your running 75 mph, the fuel rate will be close to the same but at a lower rpm. I sure the noise would decrease with lower rpm's.

 

[Piston Slapper]

One more tidbit, I found a guy I work with that has 01 with rear drums and wants to swap. I have heard you can just unbolt the brake housings from the axle housing so I can keep my rear disc. Basically we can just swap axle housings. I also read that the axle housing might be different for disc vs drum brakes.



Can we just swap brake housings? Are the bolts holes the same for disc and drum?

Are the axle housings the same?



Neither of us have had a chance yet to compare our two trucks side by side yet.



Thanks,

Gap



Dieselnutz,

Lower RPM will consume less fuel at the same MPH. Read that somewhere on here too, but couldn't scientifically explain why. The post did, but I couldn't reiterate it to ya

 

[JKuehl78]

Piston Slapper,



If the brake housings are interchangeable I'm interested. My front end is completely new and the LSD in the rear has spanking new clutches in it. I'm in Louisville, KY, just 3 hrs north of you. I'm running 315 BFG's with 3. 54 and would LOVE 4. 10's.



If the offer is still on the table let me know



Jeff Oo.

 

[WTBurke]

I lifted my truck and suffered with 3:55's turning 315's for a year. Going to 4:10's brought the RPMs back into the sweet spot and my fuel milage improved. I also think being in overdrive below 1500 RPMs is hard on the auto trannies.



William

 

[Mactruck]

I lifted my truck and suffered with 3:55's turning 315's for a year. Going to 4:10's brought the RPMs back into the sweet spot and my fuel milage improved. I also think being in overdrive below 1500 RPMs is hard on the auto trannies.



William

William



What is your RPM's at around 65 mph. I'm debating between 3. 73's or 4. 10's.

I have 315's as well and don't know what the RPM's will be with 4. 10's.

It will help my decision.

Thanks in advance!

Kevin

 

[WTBurke]

Kevin,

At 70mph I'm @ 2k rpm's perhaps 2050 , @ 65 I think it's about 1875 to 1900 maybe a smidge lower.

I have the Dana 60 upfront of course however; the Dana 70 rear in the sport trucks did not allow me the choice of 3:73's... . ( I have the 2001. 5 and the boys at 4 Wheel Parts told me this... . the gear suppliers don't grind many options for the Dana 70's. I also found that any thing beyond 4:10's required a carrier change and added to the over all cost.

I can say the 315 Goodyears feel very fine with the 4:10's and the rig acts like it did before when it had the wimpy factory tires on it. It was very lame before the gear change.



William

 

[Mactruck]

Thanks a bunch.

Is that where you got your gears? 4 wheel parts?

Also I thought you had to change the carrier if you went to 4. 10's.

Did you keep your stock LSD or go aftermarket?

I'm debating a locker (detroit)

Thanks again

Kevin

 

[WTBurke]

Hey Kevin

Yes I had 4 Wheel Parts in Sacramento do my lift and gears. They used US Gear and no you won't need a carrier change unless you go beyond 4:10's.

I stayed with the factory locker it works well as long as we keep fluid changed and proper chemistry for the clutch pack. I thought I'd save the money for an ARB on the front axle. If I were to have to replace the rear I'm with you... . I'd go detroit too.

If you do the 4:10's with your 315's I'm sure you'll enjoy it. It's as it should be.



William

 

[Chipstien]

Yep, love my 4. 10's with the 35's. The people that are running 35's with the 3. 55 and say that it is great have obviously never been in a truck with 4. 10's. Can you say Doooooogggg!

 

[Snow man]

4. 10's with 315's, absolutely perfect gearing. 2000RPM puts me about 70 mph. Speedo is showing 64-65mph at 2000,its off about 5 mph at 70.