It's true. When it comes to gears I'm clueless. Please check out my sig below. With the mods I've made should I be thinking about 3.73's or 4.10's? I felt high end increases with the exaust and Velocity Tube but I know I lost low end power after I installed the 305's. What am I looking at in terms of dollars for a gear switch? And what about the LS? Will it work with new gears? Sorry about all the questions but like I said, I'm clueless!

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Stock Stuff:
Y2K SCab 4X4, Chesnut Metallic, 5.4L, 3.55 Limited Slip, Skid Plates, Factory AM/FM/CD, 40/60 Split Bench, Sliding Rear Window, Towing Package and Keyless Entry.

Extras so far:

• GY 305/70X16 Wrangler ATS Tires
• American Eagle Series 146 Chrome Wheels
• Ravin Z-55 3" Single In/Out Exaust System
• WMS Velocity Tube
• K&N Filter
• Blaupunkt Houston CD Player
• Blaupunkt PCxt573 Speakers
• PIAA Super White Bulbs
• Catch-All Floor Mats
• Tinted Windows
• Bull Ring Retractable Tie-Downs
• www.f150online.com Sticker (below center brake light)
• University of Georgia Hitch Cover "GO DAWGS!"

Coming Soon:

• Clear Corner Lights (ordered 10/11/00)
• Clear Tail Lights
• PIAA Air Dam #30530
• PIAA 520 Series Fog Lights
• Spray-in Liner (or Herculiner haven't decided)
• Stainless Step Bars
• Hood and Window Deflectors

Pictures:
http://albums.photopoint.com/j/Album...3401&a=8556922



[This message has been edited by onemilmhz (edited 10-23-2000).]

 

You are probably looking at around $1100-1200 for gears since you have a 4 X 4 and would have to change both front and rear. You also need to get your speedo corrected. I would go with 4.10s. Yes, LS works with new gears but you want that on the rear only.

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97 F-150, 2WD, Reg Cab,Flareside,Dk Toreador Red, Windsor 4.6, Magnecor 8.5mm wires, Bosch Plat +4s, 3.55 LS, EGR Bug Deflector, ******* Bed Cover, Bed Liner, XL Full Length Running Boards, Air Aid Kit, Gibson Single Out Cat Back, Superchips, TransGo Shift Kit, Hellwig Rear Sway Bar, Hellwig 2500# Overload Springs,Energy Suspension Polyurethane Front Sway Bar Bushings, 265 70 16 tires, Rancho RS9000 shocks

 

You better start saving your pennies, and dollars, and 5 dollars, and

With the 4x4 you have to change both the front and the back differentials in a gear swap. It's a times two deal.

That being said, 3.73s will get you close to the ratio you had with the stock tires. (Assuming you had the 255/75/16s) Your running about 3.36 effective ratio with your bigger tires. The 3.73s will put you back to about 3.53. The 4.10s will give you an effective ratio of about 3.88 which would probably work good for you.

The Stangers swear by tall gears. Some guys are running 4.30s and 4.66s in their street Stangs, but thats getting pretty tall for a daily driver truck, IMHO.

I'm not sure if your LS will work with the new gears, or if you'll need a different one, but you can, and will want to, run a LS with the taller gears.

Do a search on gear swaps. It has been done, and seems to runs $300-500 installed per differential.

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2000 F150 XLT 4X4 Off Road 5.4L Reg. Cab 3.55

Performance Enhancemets:
K&N, WMS Velocity Tube, and Gibson Sweptside...

Audio Enhancements:
All of the above, plus
Sony C7000X HU, Cerwin-Vega SS2502 components(Front), and Blaupunkt PCst573s(Rear)

(For now)

 

The gears will get your low end back. With taller tires, I'd skip the 3's and get into the 4's. Your LS will work fine. $500 per axle, including gears, is a good reference point.

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2000 F-150 XL,RC,LB,5.4,4R70W,3.55LS,
Class III tow/Payload #3/Convenience pkgs.,
4-wheel disc/ABS,Chestnut/Parchment 40/60,
Ford bedliner & gas/wheel/spare locks,
3" cold air box modification, Superchip,
Dynomax ultra-flow welded 3" cat-back,
3" exit Y-pipe, Hellwig rear anti-sway bar,
Rancho RS9000s.

 

I to have limited knowledge on rear ends. I plan on changing my gears to. (3.08 just don't cut it). do I need to get gears with a 31 spline, or does spline not matter for the gears them self?

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99 F150 ext.cab 4door 4.6,auto, 3.08, no mods.

 

The spines are on the axles and in the diff; they meet here. The gears have teeth. Since the diff has to be removed for a gear change, it is a good time to get a LS if you don't have one. If you replace the diff, you need the correct # of spines (31).

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2000 F-150 XL,RC,LB,5.4,4R70W,3.55LS,
Class III tow/Payload #3/Convenience pkgs.,
4-wheel disc/ABS,Chestnut/Parchment 40/60,
Ford bedliner & gas/wheel/spare locks,
3" cold air box modification, Superchip,
Dynomax ultra-flow welded 3" cat-back,
3" exit Y-pipe, Hellwig rear anti-sway bar,
Rancho RS9000s.

 

Okay that's settled, I want new gears. In the meantime am I doing any harm to my truck with the lower ones? Any undo stress on the rear end or tranny while towing? I don't do a lot of towing but occasionally my buddies Chevy breaks down and he needs a lift!

 

Really the only con to a gear swap is that your engine will run at higher rpms. At highway speeds instead of running 2000rpm at 75mph, you may be running 2300rpm at the same speed. For you the 3.73s will put you at about the same rpm you were at with the stock tires. The 4.10s will put you at a higher rpm. I think for your truck, the lower gears would actualy benifit you. They will put you higher in the power band at crusing speeds which equals less downshift. The gears are also good for towing.

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2000 F150 XLT 4X4 Off Road 5.4L Reg. Cab 3.55

Performance Enhancemets:
K&N, WMS Velocity Tube, and Gibson Sweptside...

Audio Enhancements:
All of the above, plus
Sony C7000X HU, Cerwin-Vega SS2502 components(Front), and Blaupunkt PCst573s(Rear)

(For now)

 

onemilmhz- the lower gears (higher number) make your engine work easier, and can reduce stress. In your situation, you are not changing the ratio enough with the tires to overstress anything. You are still in the range of what Ford uses for gears. You will not have the towing efficiency or quickness that a change in the other direction would have.