3.55 to 3.73 LSD swap compatibility. | Ford Explorer Forums - Serious Explorations

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3.55 to 3.73 LSD swap compatibility.

CallMeSyd

Elite Explorer
Joined
March 31, 2021
Messages
301
Reaction score
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City, State
Hattiesburg, Mississippi
Year, Model & Trim Level
2004 Explorer NBX 4.6 4x4
I have a 2004 NBX 4x4 with open 3.55 diffs and AdvanceTrac. I also have a 2002 Limited 4x4 with the full tow package including 3.73s with LS in the rear. Is it possible to swap the differentials between them? I read somewhere that the AdvanceTrac equipped models have a sensor and tone ring in the differential. Is this true? If so, will it cause issues if I put the diff without it into the AdvTrac? Or is there a way to swap the tone ring and sensor over? Also, will the wheel speed difference from the 3.73s cause issues with the ABS, PCM, or traction control? If so, can it be programmed to accept the 3.73s? Will the LSD fight against the traction control? Any issues with the 3.55s going into the 02? A lot of questions here I know but any help would be greatly appreciated.
 



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The 8.8 differentials will swap, and the ring gears will all have or take the speed sensor ring. The front diffs, those will only swap if the whole front assembly housing is the same(I think those two are identical). The LS won't affect the traction control etc.
 






The 8.8 differentials will swap, and the ring gears will all have or take the speed sensor ring. The front diffs, those will only swap if the whole front assembly housing is the same(I think those two are identical). The LS won't affect the traction control etc.

How far into it would I need to go to swap the tone ring?
 






The tone ring is pressed onto the ring gear, so the whole differential has to come out to get at the ring gear. If the two trucks are both 3rd gen Explorers(2002-2005), then the tone gear is in there and you can swap the whole diff. That swap is a big job though, I'd have someone else do that if your not familiar with it.
 






The tone ring is pressed onto the ring gear, so the whole differential has to come out to get at the ring gear. If the two trucks are both 3rd gen Explorers(2002-2005), then the tone gear is in there and you can swap the whole diff. That swap is a big job though, I'd have someone else do that if your not familiar with it.
I can handle swapping them. I just don't know about the tone ring and sensor I've never had to deal with that or know how it would effect it not to have it.
 






I can handle swapping them. I just don't know about the tone ring and sensor I've never had to deal with that or know how it would effect it not to have it.

ABS and traction control won't function without it.
 












I can handle swapping them. I just don't know about the tone ring and sensor I've never had to deal with that or know how it would effect it not to have it.
I did this on my 96(would be the carrier same part). The tone ring comes off with tapping, its pressed on. They say not to reuse it, but I am sure its ok. I found a new one on ebay for under $10 when I did it. I put the part in the oven for an hour at 250 and the diff in the freezer and it went on with very little effort. On some trucks that tone ring may supply the speedo output so I would preserve it. And as said before, certainly needed for any ABS. Since you don't have sensors on each wheel and just one tone ring, unlikely you have traction control
 






From what I understand, the AdvanceTrac vehicles have tone rings on the outer cv axle joint. With the pickup sensor on the back of the wheel hub. In other words, 4 wheel abs sensors. That older diff from the 2002 will have the tone ring inside. 3-sensor abs. It won’t hurt anything to leave it in there, and swap the axles over from the newer 2004 vehicle to keep your AdvanceTrac systems operating.

The trouble you may have is with the LSD from the 2002 differential. I think that is going to not work well with the AdvanceTrac system.

Y’all feel free to correct me, if I’m wrong here.
 






From what I understand, the AdvanceTrac vehicles have tone rings on the outer cv axle joint. With the pickup sensor on the back of the wheel hub. In other words, 4 wheel abs sensors. That older diff from the 2002 will have the tone ring inside. 3-sensor abs. It won’t hurt anything to leave it in there, and swap the axles over from the newer 2004 vehicle to keep your AdvanceTrac systems operating.

The trouble you may have is with the LSD from the 2002 differential. I think that is going to not work well with the AdvanceTrac system.

Y’all feel free to correct me, if I’m wrong here.
My F150 has Trac Lok and AdvanceTrac. All Trac lock will do is stop some wheel spin if the conditions are right. I think the advance trac compliments it because it can apply some bias with the brakes.
 






My F150 has Trac Lok and AdvanceTrac. All Trac lock will do is stop some wheel spin if the conditions are right. I think the advance trac compliments it because it can apply some bias with the brakes.
trac loc is a limited slip, which has clutches that will try to keep the two wheels spinning at the same rate, until the force is enough to make the clutches slip. advancetrac will ad brake to try to keep slip less. they can compliment each other, as its an old trick to use some brake with an LS/open to try to equalize the forces. however, soemtimes advancetrac can only do so much, as different levels of brake, etc are sued on different terrains (consider how some have mud/ruts mode, snow, etc) i do imagine that advancetrac is made for street/rain so sometimes it can be too restrictive. some newer systems cut fuel etc do keep revs low and limit slip. not sure what these have as far as the advancedness of advancetrac.
 






I can confirm on mine with advtrac and tc that the tc/advtrac will cut the throttle in certain situations. The only reason I know this is because I had a left front wheel speed sensor sending a weak signal and every time I would make a right hand turn it would cut out the throttle as if I was letting off of the pedal. Changed the sensor and it stopped.
 






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