Limited Slip Differential?
03-03-2009, 06:45 PM
#11
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I seem to stay out of trouble with owning a 2wd. Last time I owned a 4wd I kept breaking parts. Not because the truck was junk but because I would offroad it like I stole it. 2wd keeps me from getting myself into one of those "hey can you give me a ride to work? I broke my truck" situations lol.
03-04-2009, 02:12 AM
#12
Senior Member
I would make the comparison that a 4.6 liter 3 valve with the 3.73 gears would be kinda close to the 5.4 liter with 3.55 gears. The bigger engine will be torquier (if that's a word). What I'm saying is, don't necessarily be turned off by the 4.6 Particularly in a 2wd. Gearing is very important to pay attention to. If you were to look at the towing ratings of the 2009 F150's, you'll see that properly gearing a 4.6 puts the towing rating far beyond that of a 5.4 with higher gearing.
Unless you'll be towing ALOT of heavy stuff frequently, You won't hurt the 4.6 at all. It's a great motor.
As far as which one is better... Both motors are pretty much identical except for the bore/stroke. Even the V-10 in the big trucks is the same (+2 cylinders).
Bottom line, don't pass up a truck you like just because it has the 4.6, but try for one with 3.73 gears. It'll do anything you want it to do.
Unless you'll be towing ALOT of heavy stuff frequently, You won't hurt the 4.6 at all. It's a great motor.
As far as which one is better... Both motors are pretty much identical except for the bore/stroke. Even the V-10 in the big trucks is the same (+2 cylinders).
Bottom line, don't pass up a truck you like just because it has the 4.6, but try for one with 3.73 gears. It'll do anything you want it to do.
Last edited by driver444; 03-04-2009 at 02:20 AM. Reason: more info
03-04-2009, 08:00 PM
#13
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i heard putting in bigger gears will distort/mess with the speedometer, any truth to that??? Also I drive my truc pretty hard(93 dodge ram d150, 167k on it) and I am wanting to upgrade because i have enough money for a new truck.
I really like the way stepside looks, and i want my truck to be reg cab because im a college guy with nobody else to drive and it just adds about 400lbs, i want it to be red, but thats not really a big issue. I also want the bigger engine too, but again if i can meet my other requirements, I will be ok with a 4.6. I am just pretty picky, make that ultra-choosey
haha Thanks for the info and replies, keep them coming. . .
I really like the way stepside looks, and i want my truck to be reg cab because im a college guy with nobody else to drive and it just adds about 400lbs, i want it to be red, but thats not really a big issue. I also want the bigger engine too, but again if i can meet my other requirements, I will be ok with a 4.6. I am just pretty picky, make that ultra-choosey
haha Thanks for the info and replies, keep them coming. . .
03-04-2009, 10:28 PM
#14
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get the 4wd man... i thought i would never need it but i have needed it in numerous situations. although you can get through a good bit of stuff in a 2wd with a limited slip and good tires. i personally have only gotten my 2wd stuck once but there were many times where i would have felt better with 4wd. just go for it. better safe than sorry
03-06-2009, 08:42 AM
#16
Senior Member
Yes, bigger (lower) gears and tire size affect the speedometer.
If you lower the gearing, your engine and transmission will turn faster than before to achieve the same road speed, so your speedometer will read FASTER than you're really going.
If you increase the tire size, The opposite happens. The drivetrain will turn slower to achieve the same road speed, and your speedometer will read SLOWER than you are really going.
If you do both, (bigger tires and lower gears) you'll probably be pretty close to actual speed, and won't need to change anything. The increased diameter of the tires will cancel out the lower gearing (to some extent, but not completely). Powerwise, it's the same. The increased power from the gearing will be soaked up by turning the bigger diameter tires.
Having said all this, changing tires from say a 275-70-17 to a 285-70-17 (any difference less than 3%) really won't make any noticeable difference.
And as far as gearing goes, just find the "percent" difference in the gear ratio, and the percent difference in your actual speed and speedo reading will be the same.
Yes, these can be adjusted. Most tuners/programmers allow you to adjust for tire and gear changes.
Summary... Small changes need not be adjusted for
If you lower the gearing, your engine and transmission will turn faster than before to achieve the same road speed, so your speedometer will read FASTER than you're really going.
If you increase the tire size, The opposite happens. The drivetrain will turn slower to achieve the same road speed, and your speedometer will read SLOWER than you are really going.
If you do both, (bigger tires and lower gears) you'll probably be pretty close to actual speed, and won't need to change anything. The increased diameter of the tires will cancel out the lower gearing (to some extent, but not completely). Powerwise, it's the same. The increased power from the gearing will be soaked up by turning the bigger diameter tires.
Having said all this, changing tires from say a 275-70-17 to a 285-70-17 (any difference less than 3%) really won't make any noticeable difference.
And as far as gearing goes, just find the "percent" difference in the gear ratio, and the percent difference in your actual speed and speedo reading will be the same.
Yes, these can be adjusted. Most tuners/programmers allow you to adjust for tire and gear changes.
Summary... Small changes need not be adjusted for
Last edited by driver444; 03-06-2009 at 08:44 AM. Reason: mistake
11-13-2018, 08:06 PM
#17
Limited Slip clutch!
First, for future reference, All FX4 trucks are limited slip.
There's a few ways to check what you have.
1. Look at the small metal tag attached to one of the rear differential cover bolts, (passenger side of differential). It will have your gear ratio stamped on it. If it has an "L" between the numbers, (example 3 L 73), you have limited slip. If it's just the numbers, (example 3 73), you don't.
2. Look at the axle code on the manufacturer sticker in the door jamb. Then look in your owners manual to find out which axle it is.
3. If you can jack up the back of the truck (both tires off the ground), put it in park and turn one rear tire. If the other rear tire spins the opposite direction, you DO NOT have limited slip. If you can't turn the tire at all, you do.
Having said this, with 100K miles, your limited slip clutches are probably pretty close to shot. Factory limited slip differentials aren't exactly famous for lasting a long time. The good news is that even if it is shot, it's still perfectly driveable, and you won't hurt anything. As the limited slip differentials wear out, they just become regular differentials. At that point you can either replace the clutches, replace the differential, or not do anything and live with it!
There's a few ways to check what you have.
1. Look at the small metal tag attached to one of the rear differential cover bolts, (passenger side of differential). It will have your gear ratio stamped on it. If it has an "L" between the numbers, (example 3 L 73), you have limited slip. If it's just the numbers, (example 3 73), you don't.
2. Look at the axle code on the manufacturer sticker in the door jamb. Then look in your owners manual to find out which axle it is.
3. If you can jack up the back of the truck (both tires off the ground), put it in park and turn one rear tire. If the other rear tire spins the opposite direction, you DO NOT have limited slip. If you can't turn the tire at all, you do.
Having said this, with 100K miles, your limited slip clutches are probably pretty close to shot. Factory limited slip differentials aren't exactly famous for lasting a long time. The good news is that even if it is shot, it's still perfectly driveable, and you won't hurt anything. As the limited slip differentials wear out, they just become regular differentials. At that point you can either replace the clutches, replace the differential, or not do anything and live with it!
Last edited by ZegaPrime; 11-13-2018 at 11:01 PM. Reason: need to add more
11-13-2018, 11:11 PM
#18
I shifted in 4wd and passed them up, then pulled in front of them . I was able to due to 4wd, when they tried to speed up to match me and keep me from passing they just spun tires. For very brief instant i considered running them off road into ditch.....
11-13-2018, 11:33 PM
#19
Senior Member
