I suspect just a bit of tongue-in-cheek or skepticism in GoFish's comment -- and/but while it may be an oranges-to-tangerines comparison, diesel engine companies have found that foot-to-the-floor acceleration to getting the truck up to speed and in cruise gear actually saves fuel !!!

Believe it or not (and, based on stuff we run at work) I believe it.

When you think about it, it should make sense that you can use many many more engine rpm while slowly accelerating up to speed, when by rapidly getting up to speed, you turn many fewer rpm.

Perhaps you've noticed that jackrabbit starts -- by themself -- are not fuel killers, rather the number of starts and the overall average speed are the fuel killers.

High-mileage runs are done at WOT then coast -- rather than slow cruise. Think about THAT for a bit.

 

Ok lemme see if I can get some feedback here,
I have a reg cab XL, V-6, and 5 speed
I don't tow anything, just me, camper top,
bikes and camping gear ( not too heavy)

Been thinking really hard about some 285's
and Ditching the OEM 255's With my "little" engine (but lighter truck) and with the mods I have , will I be Hating life without the gear change? I would rather do both but can't at same time right now. Am I better off waiting till I can do both ?



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Y2K F150 4x4 XL Med Torredor Red
4.2 5 speed,AIRAID, SuperCHIP,
3.55 LS, Leer camper shell, bedrug,
Ranchhand Rover Brushguard 2X Off road lights
Tint/alarm/ aftermarket keyless entry/locks
2m radio, CB, 3 Scanners
regulator@f150driver.com

 

Regulator:
You will need the new gears. Otherwise you will change gears so much to keep your engine in the powerband, that you will feel like if you was rowing a boat, and you will get "clutch foot disease" HEHEHE.
Seriously now, you can change your tires now and gears later on, but the gear change is really a must.
Roberto

 

Roberto-
The R&P is aftermarket and made by Precision Gear.

I don't think it is so much aftermarket vs OEM but more about the installation. When the pinion is slightly mis-aligned (shimmed, angle, etc.), you get noise. I had the gears installed at a 4x4 shop that does a lot of gear swaps/replacements.

 

If you increase the diameter of the tires, the miles traveled over a measured distance will decrease due to the speedometer only being accurate at the original tire diameter. i.e., if traveling 100 actual miles with 29 inch diameter tires gives an odometer reading of 100 miles, then traveling the same distance with 31 inch tires will read 93.5 miles. Therefore if 10 gallons were used both times, the actual gas mileage would be 10 mpg, BUT the apparent gas mileage would be 9.35 mpg with the larger tires. If tire size increases, miles traveled decrease,fuel consumption "appears" to decrease even if it's the same. If you then increase the rear end ratio without changing the speedometer gearing you reverse the process and the gas mileage seems to increase back up to 10 mpg. This is how increasing the rear end ratio, (ex./ 3.55 to 4.10) will appear to increase gas mileage. To find out if gas mileage really changes, drive 100 miles between fillups using mile markers with both setups or change the speedometer gearing when changing gear ratios or tire sizes.


[This message has been edited by tto (edited 09-02-2000).]

 

True. But I have always accounted for any errors introduced by tire size. Going from 30" to 33" tires made compensating for that extra 10% easy. After the 4.10 gear install, the correct speedo gear was installed to make the measurements accurate at the guages (speed/odometer).

Getting the engine back into the "sweat spot" is definitely what happened in my case. Downshifts on hills are gone- subsequently removing the 4000+ rpm engine bursts that gobble gas. Net result is a savings in fuel.

 

nomo-

Were did you purchase your gears at? Also did you have the front and rear gears change? How long was the your Expy in the shop? I am really considering this upgrade and am probably going to go with the Ford Motorsport gears.

Thanks!

 

The gears are made by "Precision Gear" and were installed at a local 4x4 shop.

In a 4x4, you have to change both front and rear or you'll have some problems. In all, they had the truck about 1 1/2 days. They did a great job... no noises or binding on turns. They also installed the Auburn limited slip diff in the rear. If you have installed larger tires, new gears are almost a must!


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1997 4x4 Expedition- 4.6L, true dual exhaust w/glass-packs, K&N air filter, SuperChip, airbox mods, Edelbrock shocks, 285/75R16 BFG ATs, 2000 "XLT" wheels, 4.10 gears, Auburn LS, Clarion In-dash CD player, Smitty Bilt push bars and nerf bars.

2000 4x2 F150 XLT Reg. Cab LWB- 5.4L, Tow Pkg, 3.55LS, CD player,Remote Keyless Entry, Sliding back glass, Special Appearance Pkg., tinted windows, Line-X bedliner, K&N air filter, SuperChip, airbox mods, 285/60R16 Goodyear Eagle GT IIs and Prime #155 wheels.

http://members.visualcities.com/NoMo

 

Nomo-

Thanks for your feedback! Why did you go with the Auburn limited slip diff? I have a LS with my 3.73's. What does this improve? Also, would you have gone to 4.10's if you had already the 3.73's on your truck. I call Steeda and Kenny Brown today and they both reccommended that I leave it be. What are your thoughts? I believe that I have 9.75 rear and 8.8 in front. Steeda said that they do not make 4.10's for the rears. I'm confused!

------------------
'98 EB Expy 4x4
5.4L 3.73 LS
Trail.Tow & Skidplate Pkg.

DA MODS....

** Pro-M 80mm MAF w/Filter & SC cal.
** WMS Velocity Tube
** 75mm Edelbrock/BBK TB
** Magnason/Eaton M90 Supercharger
** Autometer Boost Gauge w/ A-pillar mounted pod
** Cust. Prog. Superchip
** JBA Jet Black Ceramic Coated Headers
** Stage 8 Locking Header Bolts
** Gibson Sweptside Catback
** IPD Rear Anti-Swaybar
** Bilstein Shocks
** Manik Grill/Brush and Rear Taillight Guards
** PIAA 520 Foglights
** Clear Corner Lens
** Stull Billet Grill and Bumper Insert
** Ford Molded Mud Guards
** Ford Hood Guard
** "EXPEDITION" Receiver Cover

COMING UP NEXT, IN THE FUTURE....

** 4.10 gears
** Brembo Crossed Drilled Brake Kit
** 18" Wheels, due to Brembos
** F1 Cobra style hood

"Its Sooo Big...Its Gotta to be Blown!"

 

I'll try this again... bombed out the first time!

The Auburn LS was chosen by the 4x4 shop that did the install (they also chose the gears). The "X" had no LS at all before.

There is another Expedition owner who has your setup ('98/5.4L/3.73LS) and 33" tires who has not changed his gears and says he sees no need to do so. I would tend to agree IF you don't mind the small performance hit. With an extra $1100 laying around, I'd do the gear swap.

Steeda is confused. Neal (the HP freak), as well as others here, have installed 4.10's in the 9.75" rear-end. At this time, only Ford seems to be offering a LS diff for that size. Maybe that's what Steeda is talking about. Two different subjects, though.

You should come join the e-mail list at www.xpedition.net We need more "mod-minded" people and it's a good compliment to this site.

 

Check this out.

I've just returned from a trip to Georgia. Running mostly 70-75 and at times 80 mph with the family and A/C on. The worst milage I got was 15.1 mpg. The best was 16.9 mpg. With an average of 15.9 mpg. I looked through my records and the best the truck has ever gotten is 17.4 mpg. I don't think that's too bad considering the Magnacharger and 4.10's. The engine turns about 2100 rpm at 70 mph and 2275 rpm at 75 mph. It never once shifted down into drive. Before, it did it enough to be aggravating. The bottom line is, I'll GLADLY eat the small difference in milage to have the power my truck has now. I just regret not doing the gear change first.

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98 F-150 XLT 4X4 ORP Super Cab Short Bed, 4.6, Auto, 4.10's, Magnacharger supercharger, Superchip, Gibson single cat-back, 80/100w German head lamps, Warn HS9500i winch with semi hidden mount, Wrangler dual battery kit with red & yellow top Optima batteries, Torsion bars cranked up 2.5 turns. Needs one more door.

 

I have also decided to go to 4:10 gears! Thanks for all the info from everyone.

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98 White 4.6 Triton STX (It's not an STX anymore) Flairside,Class III hitch, Blue Cobra Stripes, Euro Lid by Astro, Bed Rug, Fiero Wing, Air Dam,Westin Step Bars, Ground Force 2-4 Drop,Custom MB Phantom Wheels,Custom Programmed Super Chip,Pillar Pod w/ boost and trans temp,Jacobs DIS Ignition,New transmission on the way, K&N, Jet coated JBA stainless headers, Magna Flow Muffler with Stainless Duals and of course fully Blown by Magnacharger!