Ok some of you know, some dont. but i have upgraded to some mastercraft MT tires. i am new to all this, and i knew the speedometer would change. i was noticing just now on the freeway was going 50(on speedometer) and when i tryed going faster, i had to push a bit harder to get it to budge more. is it possible to fix that? what programming and all do i need?

 

Ford programming or an in-line speedometer calibrator on 98-00 trucks. Aftermarket programmers WILL NOT fix the speedo on this gen.

 

What you are suffering from is lack of gearing.....your effective ratio had dropped enough to cause adverse effects on the highway because of the addition of the larger than stock tire size. You are out of your target torque curve. Your truck possibly had 3.73s and 28's in stock form...jumping up to a 31 dropped that ratio down to something in the area of 3.30. Only way to cure a sluggish truck after install of larger tires: shift down a gear for more rpms which will get you more torque to keep or gain speed or install a new gearset.


Speedo calibration will do nothing performance wise.

 

well all i have is D, how do i get better than that?

 

Speedo calibration will fix the shift points, doesn't add any performance, but it helps some. But like Fx4wannabe01 said, gearing is probably the most effective way to fix your performance.

EDIT: 'D' as in drive? That has nothing to do with your gear ratio...you have to buy a new set of gears and an install kit...that or find a complete axle with a higher ratio, such as 4.10...What ratio do you have now? You can check on your door tag for the AXLE CODE.

 

my previous tires were 225 70 15, these knew ones are 31x10.50r15, least i think im reading that right

 

To figure out your actual speed: Figure out the percentage difference in tire height from stock to new tires. Them multiply that by a number(in your example, 50).


For example: my truck came stock with 30.5" tires. I now have 34.8" tires. The difference is roughly 10%. Since the addition of larger tires makes your speedo read slower than you really are going, at 50(on the gage) I'm actually going 55.

 

ok so if drive like this, is this bad?what are my risks? and will my gas mileage be effected badly? i get an average 285-300 with a quarter left, never let it get below that

 

More wear on the transmission, but not a huge deal, your tire size isnt too large. But if you can deal with the 'slower' performance, you'll be fine. Alot of people stay like you are. If your speedo bothers you, you can have it recalibrated that or use a gps.

Your mileage will drop a bit, but that comes with larger tires (more weight and such). what engine size do you have? 2.5/3.0/4.0?

 

Did some math....


If a 31 actually measures 31", at 50mph of the gauge, your truck is actually going 56.6 mph.



If your truck has 3.73's, your effective ratio is currently 3.30...so it drive like it has 3.30's. To get your truck to drive just like it was stock on stock tires, you'd need 4.22:1 gears...but since those aren't out there....4.10 or 4.30 are your options for being a 2wd.

 

its a v6 3.0. and these gear ratio things your talking about, is that like programming?or like actual parts i need to buy?

 

gears are located in your rear axle

for example



they provide a certain output to the input from the engine

They are physical parts.

 

gears in your rear axle.....converts the driveshaft power into the two rear wheels. the numbers.... for example: 4.10 turns of the engine = 1 turn of the tire.

they are parts that require a professional install. budget $500 for a gear swap for a rear axle.

 

My truck is close to identical to yours, I have a 3.0 with 3.73 gears. I have 32x11.5 tires, more weight/taller tires than you. I live with it for now. Hope to find a 4.10/4.56 rear end sometime, but its not the most horrible thing. Fix your speedo, and you will feel like your going faster, because the way you are now, you are going faster than you think you are.

 

damn thats alot.....with that, that fix's the sluggish driving for sure? what else is it good for?im so sorry for all this, really appreciating all the help.

also whats a good computer to get that will fix the speedometer? you said somethin about aftermarkets not working.

 

no problem, there comes a price with modification, but in the end you will be happy.

Cyberdyne 9901 <-- CHEAPEST speedo calibrator i have found, wish i would've waited to find this. Your shift points will be fixed, and you will know that you are going the actual speed. Hence, you will not feel like your truck is sluggish.

Gears. Drive it for a while. You can probably live with it. If not, then start saving!

 

Aftermarket Performance Programmers (such as the XCAL) will not fix the speedo your truck...but the CYBERDYNE box will fix it...you have to install it by splicing into the Vehicle Speed Sensor (VSS) wire. Pretty simple install tho.

 

sorry, what exactly is that? it just installs into my truck somewhere?or you plug in, it fixes, and unplug?

EDIT: oh ok i see. ill have to look into it. is this all i need for now? i think i could get use to it if it doesnt feel as sluggish as it does now

 

The reason you feel that it is REAL sluggish know is because your actual speed is not correct, you are going faster than you think you are.

All that unit needs is a power, a ground, and to splice into the VSS. I can help you with all this if you purchase the unit. Then you have to follow the instructions to calibrate the unit correctly.

 

oh ok. wow really appreciate all this help, you guys are my heroes. ill have to look into buying it soon. thing is, getting it without a credit cars :/. it really sucks not being able to have one, and all i got is an atm card with a savings account. thinkin about going checking so i could buy things online besides money order( newegg.com haha, im a nerd :P).
but yeah, really appreciate the help. 1 more question about this, is there maybe a better one out there? im willing to spend up to $80 if its necessary... if not ill go with this one.

 

haha you'd have to spend $88!!!! I have the dakota digital unit currently. It works perfectly for me. and the install is real easy. Its waaaay cheaper than the Superlift Truspeed and the Jet Accuspeed.

Here's the link Universal Speedometer Signal Interface

Here it is for $55!!! cheap! Dakota Digital Universal Speedometer Adapter SGI-5 NEW:eBay Motors (item 310153615010 end time Aug-05-09 1212 PDT)

I paid like 80 for mine... oh well

 

btw is your tranny an auto?

 

its auto

Cyberdyne Speedometer Operating Instructions and is this in the process of programming? or its an install and works like that?

sorry i keep adding questions, just my curiosity and all is rising haha

 

ok, you will benefit the most with an auto trans. as for the cyberdyne unit, i personally have never used it. but im sure that it is simple. If you can get someone to buy you a unit soon, get the dakota one through ebay. It is $55 shipped. I can guarantee that will work, and can walk you through it

EDIT: for the cyberdyne, im sure that all you have to do is install it, and then mess with the little dial that it has. Looks similar to the superlift unit. Regardless of what unit you get, you MUST calibrate it. a GPS is very handy to get it near perfect.

 

Its alright man, im glad i could help. I dont want you ending up like I was, trying to search for answers.