in order to get my performance back because of the 33's

1998 F-150
MOD'S
-5.4 LITER
-FLOWMASTER DUAL
-SUPERCHIP
-K&N F.I.P.K
-POWERAID TB SPACER
-3IN BODY LIFT 33.1250 BF MUD TER'S
-3.55'S
-STANDARD CAB SHORT BED
-KATSKIN CUSTOM LEATHER
-TOWING PACKAGE
-CLIFFORD ALRM WITH REMOTE START
-DOUBLE LIMO
-MOONLIGHT BLUE
-ROLL-n-LOCK
-WELD TYPHOON'S 16.5x9.75
-WESTEN NERF'S

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Yes you do...3.73 may be OK, but if that was me I would really be looking at some 4.10's

Gearing is everything when it comes to big tires like that!

Myself....I sure wish that the SuperCrews came with 373's instead of 3.55's

 

yup go for 4.10 gears LS while your at it Oh and since you have the front diff open, put in some lockers

But go with 4.10s

 

Do you need to change the gears in the front end on a 4x4?

Greg

 

GregS
I would change the gears in the front end too. If you don't when you put it in 4wheel drive you would have the smae problem up front that you had in the rear. If your backend gets stuck and you have high gears and big tires you can't turn your front tires well enough. You could definetly get by without doing it, but I would not recommend it.

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1997 F-150 Lariat
Ext Cab Short Box
4x4 Off Road Package
3.55 Gears
265/75 R16 Uniroyal Laredo M/Ts

My 2 cents worth

 

HI Triton Times,

Yes, absolutely, there is no other way around it (except to go back to stock tire size), and 4X4's *have* to have both front & rear differentials done.

What has happened is that you have significantly lowered the number of rpm's your engine can turn for a given speed in any gear, and that is now causing your motor to have to operate well below it's actual power band. That kills performance and gas mileage too!

When you *properly* compensate the gear ratio by doing the calculations to match your engine rpms to the same number it was turning for a given speed in Overdrive that is was with the factory tires, then your speedometer and odometer will automatically be corrected, as will your shift points in the automatic transmission models.

In your case, you are going to need something in the order of 4.20 or so, but do the math to correctly nail the gear ratio exactly. What I mean by doing the math is, calculate the percentage difference between the number of rpms you used to turn at say, 65 mph in Overdrive to what you're now turning at that same speed with the bigger tires, and then apply that percentage to your current gear ratio (3.55) to arrive at what you ideal gear ratio should now be.

If you need any help with this, just give us a call.

------------------
Mike Troyer
Performance Products, Inc.
National Distributor of Superchips
(540) 862-9515
Email: mtroyer@compuserve.com
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