Could someone explain the diffrence in traction between the two and which a locker would help best.This is on a 79 F-150 4x4.


Much Appreciated Chris

 

First you need to know the need for a differential. The diff is there because when you take a trun in the road, the tires on the inside of the truck have to go slower then the tires on the outside of the truck. To achieve this there is the differential, which has a set of spider gears to allow the tires to rotate at different speeds. The problem with this is that it depends on traction. As long as both tires have the same traction, the diff works flawlessly. If one tire loses traction, all the power goes to that tire. This is the case of the open diff or as some like to call it the "one wheel wonder".

Limited slip is one of the cheaper ways to fix this. I've gotten this confused with Posi-track that gm uses, so I'm gonna let somebody else tell you about it. Basically what I can tell you is that it has a more heavily frictioned set of gears, and dosen't slip like an open diff. It still does not lock the wheels together, but it's better than the open.

Posi-track is what gm did to fix the problem, they use a set of clutches that wear out to lock the wheels together. The clutches slip when going around corners, not so much in a straight line. This works out pretty well, but it does wear out, and then you have open diff.

A Detroit locker uses teeth to lock the sides together, it has a set of teeth that hold both wheels together. There are several types of these. The downside of a detroit is that when you go around a turn, the teeth have to slip past each other, and you hear it knocking. There are selectible lockers, that allow open diff for on road use, and lock up detroit style when off roading, or in bad weather, but they're expensive. There are also carrier lockers, which are the cheapest, and replace your spider gears with detroit teeth. They don't handle a lot of power, but they are the cheapest locker you can get. The Plain detroit replaces the entire carrier gearset with a detroit setup, can handle the power, and is middle of the road in price, but it is really noisy when going around turns, and if the truck is short enough and the turn tight enough, it can actually lock to the point that one of your tires will break loose.

A locker is best to replace an open diff. It helps out to use it to replace a limited clip as well, but not as much as the wheels are already resisting that open diff slip.

Hope this helps.

 

If you are not abusing a limited slip you will never need to replace the clutches. My dad has had limited slip diff's last 300-500K no problems. If you service the diffs at 30k regularly and dont get them full of water you will be fine.

 

so is limited slip the same as posi traction?

 

In the way most people use the words, yes limited slip and posi are the same. There are other differentials inbetween limited slip and a locker, such as a detroit tru trac that uses gears instead of clutchs, and tons of other things all over the range....


Lockers come in two forms: The always-on, or full time locker, and the selectable locker, like ARB, Eaton, etc... When you turn on a selectable, it is locked, when off, it performs like an open differential, giving all power to the tire with the least traction.

For a daily driver, you would want a selectable locker if you choose the locker route, IMHO. For a trail-only rig, save the extra $200.00 and get a regular, non-selectable locker.

I don't want to promote people, but I think when someone does a good job and treats me right, others should know about it. I have had great luck with Randy's Ring and Pinion for parts and helping me make the choice on what equipment I want. www.ringpinion.com

Hope this all helps!

 

I have ordered the factory limited slip 3.73 rear end for my new f250 6.0 4x4. My 94 f150 had "issues" with the open rear end. I got stuck in some embarrasing wet grass areas. I was hoping the limited slip would give me better traction without having to go with something more agressive like lockers. Is there a down side to getting factory installed limited slip?

Thanks in advance.


tedbiv