Hi, first time poster so go easy on me.

I just purchased a '94 F150 2WD extendend cab, long bed with the 5.8L EFI engine, E4OD tranny & 3.08 gears. As far as I know it's an open type differenial.

Problem is, I have no clue what that all means !

Is there an online resource that explains gear ratios, the difference between limited slip, no slip, posi track and lockers? 8" rear end vs 9" rear end, etc ?? Also what about the impact on vehicle peformance and MPG when you change something in the drive train?

I have some ideas & questions about changing the current setup to help improve my odds of NOT getting stuck heading out to the duck blind in it this fall but I need to educate myself first so I can ask intelligent questions. I don't plan on "extreme" offroading with it, I just don't want to get stuck in a shallow mud puddle!

Thanks,
dSmith

 

There isn't any site that I know about. But I'll try to give you some basic info.

First: Gear ratio. The rear end gear ratio is the number of turns of the drive shaft to the number of turns of the wheels. So a 3.5 rear end means that 3 and 1/2 turns of the drive shaft are required to turn the wheels once.

Next: Limited slip, posi, lockers, etc. On a turn the inside and outside tires travel a different distance. The differential (commonly called the rear end) is what allows this to happen without causing a lot of tire wear. However when one tire is on a slippery surface such as ice this tire will spin and no power will go to the tire not on ice, ie, the tire that has traction. (It is hard to expalin exactly how this happens; but it is true, trust me on this.) These normal rear ends are called "open" opposed to the "locked" type. Lockers, posi and limited slip are basically the same thing. They allow the differential action to occurr but when one tire is on a slippery surface they lock the two axles (tires) together so neither spins at a different speed and usually the vehicle can move off the slippery surface.

Next: 8", 9", Dana 44, etc. This is the size of the rear end. The number "9" for example refers to the size of the ring gear. "44" is a type ot rear end manufactured by Dana Corparation. Basically bigger is stronger and has more load carrying capacity. Stronger rear ends are heavier, sometimes much heavier.

Last: What about the impact on vehicle peformance and MPG when you change something in the drive train? Well changing the rear end gear ratio directly effects gas mileage and ability to move a heavy load from a dead stop. Low numbers 2.75 and 3.00 are good for gas mileage but not for pulling or carrying heavy loads; high numbers like 4.11 or even 6.20 are great for pulling a heavy trailer but give poor gas mileage.

And by the way, every rear end ratio is a compromise between getting the most mileage and the necessary power for the load.

I had to simplify this but I hope it helps.

Bob
'66 7 Litre, top loader, 3.25 Traction-lock, Sidewinder Intake, SCJ Exhaust
'88 F150 LWB 4x2, XLT Lariat, 302, 5 speed, 3.08
'99 Ranger, 4x2, 3.0, 5 speed, 3.73 posi

 

Thanks for the info, Bob.

dSmith

 

Helpful information.

Now if you want to see pictures with it, go to howstuffworks.com and look up differentials.

Raul
w/ 81 F-100, I6, SROD, Carter 1V non-feedback carb, no A/C, no PS, no PB, but it gets me where I need to go