I have been reading a lot about the gearing on these. I have the 4.10 in my truck and my fuel economy is 14-15mpg. I run 285/70 17s. I try to keep my speed around 65mph or below. I do tow heavy every once in a while(10k plus), but just in town. Most of the miles are going to WV with a 5k load. Would it be worth it to put the 3.54s in?

 

I think so 14-15 to 18-20 adds up at the pump $1000 bucks to do a ring and pinon or $500 from a junk yard you install

 

I have a set of front gears I'm looking to get rid of. let me know if you are interested.

 

I did the about front and rear about 6 months ago, well I had someone do it for me.
Breakdown of cost:
$200 for gear sets front and rear (got them from the classifieds here on DTR)
$300 for the rear carrier (redlinear on ebay)
$180 for rear bearings (ebay)
$120 for front bearings (ebay)
$50 for fluids
$250 for labor on rear
$350 for labor on front
Total cost: $1450 roughly.
Knowing I've got the gears I want and the benefits to go along with them....priceless.

Thats a breakdown on price, but having lower RPMs at highways speeds, getting 21 MPG finally. Definitely worth it IMO.

 

Purplezr2, How much? I could do the labor myself. Where the ebay bearings any good?

 

Good so far, have about 10,000 miles on them so far. Ha, they better keep lasting.

 

Bearing store can frequently match with a good quality brand name bearing for less than the parts store but you'll be down longer waiting on shipping.

 

I would not mess with cheap parts.
I got a quote for same job.... all Dana parts from HERE.
Nice guy and quality company.... have dealt with him before. Talk to Dan, the owner.
Rear End - $419.00
Front End - $439.00
Included everything!

Worth it - I'd say yes! You presently have a net gear ratio of 3.98 (285's and 4.10 axle)
With 3.55's and 285 tires you net 3.44. That's 15% taller and should net you at least 17 mpg. You won't see 20 mpg w/ an Automatic.
I average 17.2 with 70% hwy and a lot of heavy hauling, up to 10,000 lbs GVW.... but little towing. 18.5 mpg, empty, on long trip.
I would not call it heavy towing till you get over 15,000 lbs.
For what you do, the 3.55's would make sense and, IMO, be more driver friendly.

RJ

 

I have 285's and 3.54s in my truck and get 22-23 doing 55-62, but I drive like a grandpa, got to make the truck last, I hope to have it for another 20 years, and it only has 200k on it.

 

What makes you say that?

My last truck (see sig) 1997 Dodge. I got 22 in that thing on the highway all the time. It had 3.54 gears and 305 tires.

 

You don't have an automatic!!

12v makes a difference. 'JMARX82' has a 24v. My statement was addressed to him.

I don't want to start a war here, but, IMHO, anyone getting 20 mpg or better in a 24v, automatic, QCLB is either coming downhill out of the Rockies...... has a 20 kt tailwind for a whole tank of fuel, or is mis-calculating!
Just my, very firm, opinion!


RJ

 

Thanks for the link and prices. I looked at ringpinion.com too. They have Yukon gear. I defiantly would not mess with cheap parts, I have learned the hard way to many times. I won't even mess with cheap parts anymore on people that bring there junk to me to work on. Its just not worth it.

After hearing everyone's opinion on this, I think the switch is worth it, although a 02 quad cab w/6speed and 3.54s just showed up on craigslist in my area.

Thanks again for everyone's posts.

 

I have an 01.5 QCLB with a 6 speed, and the best I've ever done was 19.8 MPG. I've got the stock 265-16's on it too.

 

With Brownie ( Automatic ) I got 21.76 once, 21.5X many times on Hwy. trips, stock 97 with 3.54's and 235-85-16 tires.

 

I've got 315/70R17s and wish I had 4.10s. I can't get into the power band in OD until I'm going 80mph. If I drove 55 I would get 20mpg, but I don't/can't. I believe tire size is HUGE for fuel mileage. Stay with tires under 285/75/16 and I think you can get near 20mpg driving sanely. With bigger tires (cuz they look cool) and perf mods I get 16-17 driving INsanely. Still better than my neighbor's Avalanche POS. If I wanted better fuel mileage, a Toyota Tacoma would work. It's only money, and my wife spends most of that....