I have a 98 F-150 4X4 ORP 4.6L 3.55LS Ext Cab that lacks any, and I mean any acceleration. I have installed the Superchip (helped), K & N filter, and airbox mod. It still leaves a lot to be desired.

I know that it is a big heavy truck, and I do not want to burn the tread off those 17 inch tires, I just want to go.

I have played around with the idea of blower, camshafts, and the like. But I have come to the conclusion that it it not a lack of power, just FMC attempt to eeck out every MPG they could on these trucks.

My latest inspiration came from Tina, after I was complaining about the thing hunting between 3rd and OD while driving down the road. I expermented with leaving the thing out of OD and slowing down a bit. Worked great, but the thing is still anemic from a stop to that point.

The engine seems to pull great from 2,200 to 2,500 RPM. My idea now is to have the engine operate in that range while drivig the highway at the speeds I operate at AND get better acceleratiion and lower speeds.

I figured that the way to get that is to change to a rearend gear to one that will put me in that 2,200 to 2,500 RPM (in OD) while giving better acceleration at lower speeds. Fuel economy is not a factor here, I expect this thing to suck to fuel. I figured that switching from the 3.55 to 4.10 would accomplish this along with a transmission shift kit to stiffen up the shifts a bit.

Any input from anyone would be appreciated. Has anyone done a ring and pinion swap in this thing? I know that a Superchip mod would be in order for the new gears. What about how this would affect the vehicle when in 4WD?

 

I don't know what tires you're running, so I don't know what your speed in gears will be with 4.10s, but you're right in that it will help acceleration a good bit. Remember that Mustangs that use 4.10s as a race gear are running 26" tires and weigh 1000# less than your truck, so you're not looking at as radical a modification as you think. Your fuel mileage may not suffer as much as you expect either.

The real problem is cost. Two R&P sets is pretty big money, especially the installation on the front, which i've been told is a bit of a nightmare. Get a parts and labor estimate from a good shop and compare the cost to simply trading up to a 5.4. You might be money ahead with the trade. Good luck

 

wschubbe,

I assume you have the factory ORP tires (265/70R17) which are 32" in dia. According to the gear ratio chart in the september issue of 4x4 power at 65 mph in 3rd gear:

w/ 3.55 2,423RPM
w/ 3.73 2,546RPM
w/ 4.11 2,805RPM
w/ 4.56 3,112RPM

This does not account for overdrive which would drop RPM's 15 to 20 percent. I have the same setup, 97 ORP 3.55LS and have long felt I could use lower gearing. 4x4 power suggests 4.11 or 4.27 for best all around daily driver performance with 32" tires. I am planning to install 4.56 gears this fall when I add a suspension lift and larger tires (33x12.5's which have an acctual dia. of 32.5") and feel this would work well with overdrive. I have priced the work to replace ring & pinion's front and rear at West Coast Differentials and they qouted me $1,150 parts and labor.

 

Man, I don't have an answer for you but I sure know where you're coming from. I had a 4.6 and went thru the exact same thinking process but ended up trading for the 5.4 which is no rocket but has better "command".

On a more somber note, Why has speed become such an issue with pick ups lately ? Historically nobody ever bought a pick up for speed or even thought about it (well maybe a little) Must be the Craftsman series or something having an effect but it sure is a big deal with the late model P/U's

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99 F150 5.4 4x4 ORP 3.73 styleside deep wedgewood blue ..no mods (yet)




[This message has been edited by Dondo7 (edited 07-26-1999).]

 

I remember one of the members here "NEAL" is either fixing to add, or has added those gears to his truck. Look for some of his most recent post (he likes Victorys & Defeats) He could most likly answer a lot of your questions.

 

Actually you'll be running more like 2100 in OD at 70, still in the torque band of the engine. Fuel economy shouldn't suffer much either. As to gear brand Zoom, Richmond and Ford SVO all make good stuff as do many others. Be SURE you get "street" gears, "race" gears are often intentionally left softer so that they will bend rather than break under impact loading and as a result don't last very long in the real world.

 

Thanks for the info, both of you. I will look up Neal's posts and post my decision(s).

 

Glad to hear that this is not such a stupid idea. I agree with all of you and thank you for the input. Unfortunately, trading is not an option right now (next time I will be more careful with what I buy!). I think that the gear change may be the most economical choice, especially when you look at superchargers and the like. My truck does have the factory ORP 17” tires (32” diameter). I figured that with the 4.11s I would be running about 2,300-2,400 RPM at 70 in OD, which would be perfect. I have checked and found that $1,200 should take care of the problem.

Has anyone done this swap on his or her own? Just wondering if it is worth doing yourself or pay someone the extra $500 and save the aggravation. Who makes the best gearsets (quality and instructions)?

Thanks Again

 

WSCHUBBE:
It is worth the money to have it done right.
The install is simple enough, it's the set-up that is the killer. Takes some time for the pro's to do it right. If not done properly you will have a high pitched whine and premature wear.

 

I have read all of your replys, I'm currently running a hypertech chip,3" stainless steal exhauste with a 3" edelbrock stainless muffler, K&N filter with the air box mods. Lowered the truck with the ford motosport kit. It has the 5.4 with 3.55 gears extended cab short bed. If i could get the wheel hoping to stop the thing will put the tires up in smoke. (got it to do it one time with out wheel hop.) The hyper tech chip made a world of difference,( almost every other chip upgrades are only a piece of wire that changes the fuel and timing for short periods). The truck will chirp the tires just pulling from a stop sign like a normal person. I still average about 16 to 17 miles to the gallon. I drive the thing hard all the time and is a blast.

 

WS
You really need to have the R&P set up by a pro. It has to be perfectly shimmed or you'll be replacing it more often than tires. I assume you realize that both axles must be changed. Good luck in your pursuit!

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99 SC 4X4 5.4 ORP 3.73LS Lariat Black over Gold on Tan.
Mods-K&N FIPK,Superchip,Dual Flowmasters,Westin Nerf Bars, 305/70/16 GY M/T's, Extang Black Max Tonneau

 

BJohnston:

Yes, I am aware of this. I lucked out in that I have a Ford 8.8 in the front also (Richmond said that they could come with a Dana 40). Looks like the front will be easier than the rear due to the fact that the axle can be dropped out of the truck completely without much work.

The installation looks fairly straight forward, no real fancy or expensive tools required. Just time, patience, and good marking compound. As always, open for suggestions, especially to those of you who have accomplished this task.

Also, has anyone gone through a speedometer recalibration? What is involved? I checked with M. Troyer and he said that a Superchip flash is not possible for this.


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98 F-150 4X4 Ext Cab ORP 4.6L Superchip, Gibson Cat Back Single exit exhause, TransGo Performance Shift Kit, K&N w/airbox mod.

[This message has been edited by wschubbe (edited 08-13-1999).]