I have a question......WHAT IS LIMITED SLIP differential..do I need it for 5% towing?????????????I have to decide tonight,please help.

joe

 

It simply means that power is transmitted to both rear wheels instead of only to the one with the least traction.

I would think that you would want it for towing. Slippery wet boat ramp?

I made sure that my truck had limited slip with 3.73 gears

 

Thanks bamenard,
no, I'd only tow ATV trailer/2800lb total/ , I am gonna use the truck for highway travel,95%....towing once a year for about 3500 miles/. Gas mileage is important/ 30000 a year/.
Joe

 

Somebody correct me if I am worng but L/S does not have any effect on your gas mileage. Just limits the ammount of wheel spin you have on slippery surfaces.

 

Gas milage is an interesting subject. I had an 01 Scab 3.55 gear and an 03 Screw with 3.73 limited slip and the 03 Screw got better milage, and was easier to drive. Much less downshifting and turning off overdrive. Does any one else have any experience with both rear ends? My dealer told me that 3.55 gears got better milage.


Your correct L/S has no milage effect.

 

The gear ration determines your mileage on simalarly equipped vehicles. An F150 with a 3.55 will get better mileage than a 3.73. The motor has to spin more to make the truck go the same speed on taller diffs. So the lower the number, the better the mileage.

For a 3.55 diff, the driveshaft has to spin 3.55 times for every 1 time the tires turn. and 3.73 times for a 3.73 and so on.

Limited slip only means that it's harder for 1 tire on the smae axle to turn more than the other. This has no effect on mileage.

 

Thanks, I will correct my earlier post now. Both of those trucks had L/S. The only dif was gear ratio and the 3.73 got better milage

 

If you were going to be doing any driving off-road, on wet grass, or in snow it would be advantageous to have a limited slip rear end for traction purposes.
Regards
Gary

 

The only things I can think of that would make your Screw(3.73) get better mileage than the Scab(3.55) is aerodynamics. Maybe you had a shorter bed on the Screw, which wouldn't give the wind enough chance to wrap around the cab and get caught up in the tailgate/bed.

Was the motor the same? Maybe in 2 years Ford made some advances in power/mileage on the motors.

Just speculating...

 

Both trucks had same engine, 5.4 Scab had 6.5 box. I even got better gas mileage in city driving. I think that 3.73 gears is a better match to that truck.

 

The truck with the 3.73 didn't have to work quiet as hard to accelerate. If you do a lot of city driving, stop and go, or towing, I could see how a 3.73 would get better milage. At long distnace highway speeds, the 3.42 would show better. Keep in mind that we are talking about only a few precent difference in ratio between the two axels, so differences may be slight.

Back to the question.
Since the limited slip will not affect milage, and has some definite advantages, I would order it. I had a truck with out it, and it could be real handful on a wet or icy road with the back end empty. The limited slip helps a bit, at least in my experience. I would never order another truck with out it.

 

If you ever drive off-road in muddy conditions (like a muddy pasture) limited slip is HUGE improvement. It really helps on slick boat ramps also.

Grim

 

Limited slip should be standard equipment on the 4X4 trucks in my opinion. Makes a huge difference if you really use the truck in tricky 4x4 situations. As far as 2WD - guess if you only want one out of four tires doing all the work, don't worry about it. Otherwise, adding a $300 or less option is a no-brainer to me.