Posi?

[bolsen]

Posi - dangerous or better?

Discuss...

[SpartaPerformance]

Dangerous?? How?

[SC Cheesehead]

Dangerous?? How?

That's what I'm wondering.

I've always preferred posi over an open rear end.

[EMAS]

I'll tell you how it's "dangerous". If you are on a crowned road, like most are, and you hit 2nd or 3rd gear at WOT and it's cold and/or wet the car gets sideways. With an open rear end only the one tire spins and the car doesn't get sideways. So yes with someone who is inexperienced/not prepared it can be dangerous. Still I prefer having a traction enhancing diff and most of my vehicles are so equipped. But I prefer my vehicles to have "4 wheel steering".

[SC Cheesehead]

I'll tell you how it's "dangerous". If you are on a crowned road, like most are, and you hit 2nd or 3rd gear at WOT and it's cold and/or wet the car gets sideways. With an open rear end only the one tire spins and the car doesn't get sideways. So yes with someone who is inexperienced/not prepared it can be dangerous. Still I prefer having a traction enhancing diff and most of my vehicles are so equipped. But I prefer my vehicles to have "4 wheel steering".

Sounds like hitting WOT on cold and/or wet roads may be a little dangerous in and of itself... ;)

[EMAS]

Sounds like hitting WOT on cold and/or wet roads may be a little dangerous in and of itself... ;)

Yea but it's fun. :D

[Mr. Man]

True posi isn't good for anything except drag racing and turning around at the end is an experience. Most cars with "posi" are limited slip which allows the car to negotiate corners. Try driving a true posi car on the street. It's not fun

[bolsen]

exactly. when both spin the same, you run the risk of losing around corners. independant spin helps the car maintain an even ride around corners and while turning.

so, it is not a good mod for a DD?

[Mr. Man]

Modding a car to a limited slip is fine for a DD. I wouldn't want a true posi for anything but drag racing. Posi is just the name General Motors coined for thier limited slip.

[RF Overlord]

I'll tell you how it's "dangerous". If you are on a crowned road, like most are, and you hit 2nd or 3rd gear at WOT and it's cold and/or wet the car gets sideways. That's more of an example of "driver stupidity". (not referring to you, EMAS)

[EMAS]

That's more of an example of "driver stupidity". (not referring to you, EMAS)

Not necessarily stupidity, more likely inexperience and/or lack of knowledge of the specific vehicle and it's attributes.

[EMAS]

Ok lets get some terms cleared up and a 101 class on differentials.

The term "Posi" came from shortening posi-traction the GM brand name for their clutch type limited slip traction enhancing differential. However it has become the common generic term many people use for any sort of Traction Enhancing Diff.

There are many different types of TEDs and a full or mini "spool"

A spool or what many off-roaders do a "lincoln-locker" (welding the spider gears to the side gears) locks both axle shafts together permanently. This is really only suitable for drag racing and off-road use because at least one tire needs to slip to be able to do anything other than go in a straight line.

A true "Locker". Some of the common ones are the ARB, ECTED and Gov-lock. The ARB and ECTED are manually engaged either by air or electrically and lock the two shafts together like a spool when engaged. The Gov-lock is automatically engaged when the difference in speed of the two shafts is too large.

Also referred to as lockers are the Lock-right and the Detroit locker. These use "teeth" to engage the axle shafts and will allow different shaft speeds, usually accompanied by a "ratcheting" sound, if you can hear it over the stereo or exhaust.

Here is a link to show how and explain how the ARB, Detriot, and Lock-right work. http://www.fourwheeler.com/techarticles/128_9702_locking_differentials/index.html

The most common type of TED, including what is used in our Marauders, is a clutch type limited slip. There are dozens of brand names for these so I won't attempt to list them all. Ford's name is Traction-lok. Here clutches or friction plates are used to limit the side gear motion relative to the case. When the difference in torque on each shaft is large enough they will allow differential action because of the clutches slipping. IF the proper fluid or additive isn't used you can sometimes hear that ratcheting sound. These can be set up to have different thresholds of when they will allow slip. IE put more plates or use a stronger spring and it will take more torque for differential action to occur. These will all eventually wear out with use. Here is a link showing some cross sections of a clutch type unit and how a open diff works. http://auto.howstuffworks.com/differential.htm

A special type of clutch style TED is Dana's Power-Lock. By the use of "ramps" on the side gear shafts the higher the input torque the greater the torque difference at the axle shafts will be required to induce differential action. This one can be "dangerous" if you aren't aware because it can "lock" when accelerating in a corner.

An unusual TED is the Torsen or Torque sensing unit. It uses a system of worm gears to apply torque to the axle shaft that is providing the most resistance so it will shift the torque away from the tire that doesn't have traction. The problem with these is they actually provide a multiple of the wheel with low traction to the wheel that has more traction. So with one wheel on ice or off the ground in the case of a 4x4 it will not provide any torque to the wheel that does have traction. A light application of the brake will provide torque to the wheel with traction.

The most unique TED is Warn's short lived Positrac (note no hyphen to avoid copyright issues with GM's Posi-trac) it used a system of overrunning roller clutches to allow the outside wheel to spin faster than the inside wheel.

Billions of vehicles have been factory equipped with one or another type of TED for decades and are still available in some vehicles to this day. If they were that dangerous they wouldn't still be available factory installed. Ralph Nader would have got them off the OEM market long ago like he did the Corvair.

[ctrlraven]

exactly. when both spin the same, you run the risk of losing around corners. independant spin helps the car maintain an even ride around corners and while turning.

so, it is not a good mod for a DD?
Limited Slip yes, posi no.

[SC Cheesehead]

Yea but it's fun. :D

True, that! :D I had a '65 GTO back in the day that used to be subjected to that exercise on a routine basis... ;)


True posi isn't good for anything except drag racing and turning around at the end is an experience. Most cars with "posi" are limited slip which allows the car to negotiate corners. Try driving a true posi car on the street. It's not fun


Good point. I was thinking of limited slip in the context of the "posi-traction" brand name. Agreed on the issues with true "posi," not really street-friendly.

[yjmud]

[QUOTE=RF Overlord;1096354]That's more of an example of "driver stupidity".
++++++++1
we don't need smarter cars just smarter drivers

[RF Overlord]

Agreed, but this is America...we are incapable of doing anything for ourselves and need gov't supervision to accomplish the simplest tasks, so smarter drivers will never happen.

[SC Cheesehead]

Agreed, but this is America...we are incapable of doing anything for ourselves and need gov't supervision to accomplish the simplest tasks, so smarter drivers will never happen.

Ooooooh, do not get me started....:mad2:

[DOOM]

I'll tell you how it's "dangerous". If you are on a crowned road, like most are, and you hit 2nd or 3rd gear at WOT and it's cold and/or wet the car gets sideways.

Who would go "WOT" on a CROWDED WET ROAD??? :loco:

[EMAS]

Who would go "WOT" on a CROWDED WET ROAD??? :loco:

CROWNED not crowded.

[Vortech347]

Who would go "WOT" on a CROWDED WET ROAD??? :loco:

Who in the hell would be happy with an open dif?!

If you can't skid control just about any situation at full throttle you shouldn't put the pedal down period.

[DOOM]

CROWNED not crowded.

My bad.... :D

[jstevens]

I love going sideways, maybe not at WOT. The real trick with wet or cold roads is knowing how much tq is being produced.

[bolsen]

So what do the 03s come stock with? I turned it around hard, in a parking lot, and it was a one tire fire.

[guspech750]

So what do the 03s come stock with? .

Two seats up front. One bench seat in the back. A trunk lid. Engine and drivetrain. 5 tires. As a bonus the tires come with air in them. Lights front, rear and sides. Windows for you protection from outside elements. 4 colors to choose from. Wires, fuses and such. Radio and speakers. And other stuff :lol: :D


---
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Eaton Swap = Wreeeeeeeeeedom!!

[CBT]

we don't need smarter cars just smarter drivers

That is true, man that's almost quote worthy. :beer:

[jstevens]

So what do the 03s come stock with? I turned it around hard, in a parking lot, and it was a one tire fire.

Correct me if I'm wrong but you should've been sideways with both of them lighting up.

[EMAS]

So what do the 03s come stock with? I turned it around hard, in a parking lot, and it was a one tire fire.

From everything I've seen ALL Marauders were equipped with Ford's version of the clutch type limited slip diff known as Traction-Lok

Because it is a clutch type unit it will eventually wear out and function as a standard open type differential in all but the most slippery conditions.

The one in my Marauder is still working strong at 110K. The one in my Mountaineer was getting weak as early as 70K and is pretty much shot at 120K. So how long they last seems to vary pretty significantly. Since I didn't buy my Marauder new it is possible that it has had it's clutches replaced, while the Mountaineer was purchased new so I know they are the originals.

The plus side is that the Traction-Lok is pretty much the easiest one to replace the clutches in and the upgraded OE Ford stuff is commonly available for reasonable a price.

Back in the day many manuals listed the minimum "acceptable" torque required to cause differential action to occur. You jack the vehicle up and replace one of the wheels with the special tool which was nothing more than a chunk of metal with the bolt pattern and a 1/2" square hole in the middle to connect your torque wrench to. But you can get a good idea by jacking up the car leaving it in park, parking brake off and trying to turn one of the wheels by hand. If you can make it spin by hand the clutches are shot. Or if you didn't buy the vehicle new maybe somewhere along the line someone had the Trac-lok removed and replaced with an open unit. Possibly because they thought it was "dangerous"?

[babbage]

Posi - dangerous or better?

Discuss...


Marauders came from the factory with a limited slip differential. You have one already.

[massacre]

I have always found that Posi does awesome work for great prices.....

http://www.posiperformance.com/

[Vortech347]

^haha wrong posi