Drivetrain Tech General discussion of drivetrain for the Ford Ranger.

FX4 rear end questions

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Old 10-30-2006
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FX4 rear end questions

Level II.
I know it has the stronger axles and supposedly some sort of locking or limited slip rear.
Correct?

I took off kind of fast in the rain and it seemed to spin 1 wheel.

How can I tell if it is working correctly?

What does it take to repair if it isn't?

Is it worth it?
 
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Old 10-30-2006
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Level 2's are equipped with a 8.8 31 spline axle with Torsen LS.

A cheap way to find out if it's working is go spin out in some grass or something. If there's only one tread mark, you may have a problem
 
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5SPD LII had some problems and there was a 'soft' recall
yours might not have been serviced
I would check FORD records for your vin # and see if it had a retrofit
 
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Old 10-30-2006
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The Level II uses a rear Torsen limited slip differental. It is gear driven and does not suffer from the decrease in performance like the cluch pack / stock l/s does. It is still posible to spin one wheel with a limited slip.

Reading

http://www.torsen.com/products/products.htm

http://www.sonic.net/garyg/zonc/Tech...ferential.html
 
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Old 10-30-2006
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Or you can jack up the rear and spin the tire and see if the other one spins
 
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Old 10-30-2006
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Originally Posted by Roach2004
Or you can jack up the rear and spin the tire and see if the other one spins
Spins the same direction. An open diff will spin opposite
 
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Old 10-30-2006
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Originally Posted by LILBLUE04FX4L2
5SPD LII had some problems and there was a 'soft' recall
yours might not have been serviced
I would check FORD records for your vin # and see if it had a retrofit
There was a stop sales/stop production/recall for the Torsens in the first half of 2002 FX4 Off Road manual production. The Torsens were not recalled on any of the 2003 FX4 Level II's.

It is possible to spin one tire with a Torsen. It is a limited slip, not a locker.
 
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Old 10-30-2006
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correct what bob sayed i might not have a torsion i have the reguilar LS and everyonce and a while it will just spin one but a few min later grabs both...
 
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Old 10-30-2006
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For a limited slip, one wheel has to start slipping before the L/S will engage and transfer torque. This is especially apparent in the Torsen unit because it multiplies torque. If, for example, one of your wheels were in the air, you'd have 0 torque there and no torque could be transferred to the other wheel, because anything times 0 is still 0. That's about the only situation where some of the other l/s units are better.

Check out www.howstuffworks.com and find their article on differentials. They have a VERY thorough explanation of how all different kinds of diffs work. Very cool stuff.
 
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Old 10-30-2006
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does just the fx4 level II have the 31 spline axles or does the reg. fx4 have it also?
 
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Old 10-30-2006
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Originally Posted by justistep
does just the fx4 level II have the 31 spline axles or does the reg. fx4 have it also?
'02 FX4 and '03+ Level 2
 
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Old 10-30-2006
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Originally Posted by fx4me
'02 FX4 and '03+ Level 2
'01 FX4 as well
 
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Originally Posted by gopher18
'01 FX4 as well
There's no such thing.
 
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Originally Posted by gopher18
'01 FX4 as well
um Sean there is no such thing as a 2001 FX4
 
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Old 10-30-2006
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oh i so beat you Zach!
 
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that you did...
 
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Old 10-31-2006
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I stand corrected... i thought for sure there was and they were the same as the '02 FX4's... man am I out of the loop on this crap...
 
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Old 11-01-2006
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OK, so now I'm confused.
Some say to see if 1 tire spins and others say that it could even if it's working?
Maybe I'm just stupid. . .

How can I tell if it is working correctly?
 
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Old 11-02-2006
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Originally Posted by Dadinator
How can I tell if it is working correctly?
Put the tranny in neutral and make sure the parking brake is off. (front wheels chocked)

Jack up the left rear tire so that it's off the ground.

Take a torque wrench and measure what torque it takes to turn the raised wheel by using one of the lugs nuts. (make sure your not torqing accross the axle center line. Put the wrench on the furthest most rearward nut and push down)

This is the method to properly inspect a LS diff. Once you have that torque reading go compair it to what the spec should be and you'll know if it's still good or not. (not sure where to get the spec for a ranger.. but someone around here has to have a Ford manual)

For reference a 9.75 ford diff measures between 25ft lbs and 35ft lbs.

Rich
 
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Old 11-03-2006
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Or you can do what someone else already said thats MUCH easier than any other method but will give you decidely UN-scientific results.

Park your vehicle in some relatively loose material, grass, dirt, stones, whatever. Hammer the gas for just a few seconds and then STOP, see you left TWO nice tire/burnout marks.

If you DIDN'T then yes, your L/S is not functioning as it should. It will however not always engage on slippery surfaces, especially if your turning because the WHOLE point of an L/S is drivability as opposed to TOTAL traction.
 
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Old 11-04-2006
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Not a valid test, unfortunately. Even an open rear can spin both tires in that situation. You can't tell from that UNLESS you leave a single "dig".

In other words, it may prove you have an open, but it does NOT prove you have a limited slip, or that you don't have an open. It's not a definitive test.
 
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Old 11-06-2006
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Originally Posted by n3elz
Not a valid test, unfortunately. Even an open rear can spin both tires in that situation. You can't tell from that UNLESS you leave a single "dig".

In other words, it may prove you have an open, but it does NOT prove you have a limited slip, or that you don't have an open. It's not a definitive test.
So what is?
 
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Old 11-06-2006
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Jacking up the rear end after blocking the front wheels, putting the vehicle in neutral, and rotating the tires as indicated previously. A totally open rear will allow you to FREELY rotate a tire and you will observer the tire on the other end spinning in the opposite direction. The driveshaft, interestingly enough, may not turn at all.

On a limited slip vehicle where there is always some bias, the tire will be harder to turn (typically) and the other tire will spin in the same direction, and the driveshaft will move.

That's about all you can do. An open differential provides a "zero sum" division of torque to the two wheels. That is, the driveshaft total input is split between the two wheels such that the sum equals the input power (minus friction and other losses).

This means that they can have equal torque, or any split from one wheel getting it all to anything in between. This is why the "slippery ground" test doesn't tell the story necessarily. Many people think an open diff always means only one wheel gets the power, but it simply is not the case.

What's the BEST test: taking the diff cover off and looking at what's in there, lol...
 
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Old 11-06-2006
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Originally Posted by n3elz
What's the BEST test: taking the diff cover off and looking at what's in there, lol...
That still won't tell if it's working properly though

My suggestion would be to do the test John just elaborated. Jack up the rear wheels and spin them to see what happens.
 
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Old 11-06-2006
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thanks, gentlemen!
I'll give it a whirl.
 


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