A Limited Slip Question

[jtb1689]

Some background: So I was lucky enough to acquire my '93 Sport Eddie Bauer a few years back and always just assumed it was a normal ol' explorer 4x4. Driving in the snow, in the mud, off road, in the rain, I have always been convinced it has an open diff as friends (that know nothing about vehicles) have enlightened me to the fact that when stuck sometimes one wheel spins and the other doesn't. So, needless to say I was a little irked today when I checked the codes for the first time and found that lovely D4 under "Axle." My original thought was sweet, I've got a limited slip and 3.73's, I might not need new gears for 33's after all when I get there. Then I remembered it has never been there to help me when I needed it most.

Actual Question: Why? I am new to diff's (spend most of my time in the lifting, off-road accessories sections of the forum) so I don't know much about them yet, do the limited slips wear out over time? Because I will swear by it one rear wheel will spin when another does nothing if I get stuck. Do the clutches go bad? By the way I am sure there has been very little, probably no maitenance at all, on the limited slip (should have checked to see if it had one sooner I guess...).

 

[JDraper]

The clutches are probably worn out. You can buy a re-build kit and do it yourself if you are decent with hand tools. You can get the re-build kits from many places. Ford, Summit Racing, Jegs, etc. Do an on-line search for Trac-loc rebuild kit.

 

[FROADER]

The stock Trac Lock L/S could be worn out as they tend to do. Especially on a truck that is 15-16 years old.

My original thought was sweet, I've got a limited slip and 3.73's, I might not need new gears for 33's after all when I get there.

Just because you have L/S in the differential doesn't mean you don't need to regear when you get 33s. 3.73s with 33s sucks and will wear out other parts of the driveline quicker.

 

[jtb1689]

Just because you have L/S in the differential doesn't mean you don't need to regear when you get 33s. 3.73s with 33s sucks and will wear out other parts of the driveline quicker.

That's exactly what I wanted to hear actually. You people need to keep me in line. I knew you had to regear with 3.27s but wasn't sure on 3.73s. Little off topic but would you recommend 4.10s then?

Back to point, you're saying the whole thing is worn out then? As in I should probably look into a new one, or just the rebuild kit like JDraper said? Keep in mind a regearing as mentioned above is a ways away and it would be to my benefit to just rebuild what's in there if it's under $100 for now.

 

[FROADER]

I would recommend 4.56s for 33s but 4.10s will put you closest to the stock ratio.

Just rebuild like Draper said if you want the stock L/S back. If not, then this is the time to get a locker or a better quality L/S.

 

[JDraper]

Re-Gearing for 33's is recommended, but it's also significantly more money. If you go that route, I'd also recommend 4.56's. I had 33's with 4.56's on my '94 Sport and I was quite happy with it.

You can re-build your trac-loc for under $100. Here's the Summit Racing kit: Trac-Loc Rebuild Kit . If your bearings and gears are fine (no leaking out the axle ends, no grinding or clunking from the rear), and just the LS is not working, this will repair it.

 

[jtb1689]

That pretty much settles it. Thanks guys. I would love to put a locker back there but as a college student and just one car doubling as the daily driver and off-road vehicle I don't have the money or inclination right now to turn her into a real mean off-roader. Just would like to have what I am supposed to have, it would have been nice in the almost 2 feet of snow seattle was hit with a couple weeks ago. Warn manual hub conversion and fixing the l/s next weekend, I'll have to try it all out off the road sometime soon. Thanks again.

 

[htrdlncn]

look on ebay,you can find carbon fiber trac loc kits from Ford
originally meant for the Supercharged Cobra Mustang "Terminators"
for the almost same price as the normal rebuild kits,
it uses carbon fiber clutches and a heavier spring ,
put that in and your trac loc will
work very well in most cases though it will never be a locker.
Thats what I just put in mine when i rebuilt it.
look here:
http://cgi.ebay.com/ebaymotors/1986...ryZ33731QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[FROADER]

Also, before you do buy the rebuild kit, make sure that the L/S is actually worn. When you have been stuck, were both back tires off the ground. I ask because if there isn't enough drag on the tire that is "on the ground" it won't transfer the power to the tire that isn't. Did that make sense?

 

[JDraper]

look on ebay,you can find carbon fiber trac loc kits from Ford
originally meant for the Supercharged Cobra Mustang "Terminators"
for the almost same price as the normal rebuild kits,
it uses carbon fiber clutches and a heavier spring ,
put that in and your trac loc will
work very well in most cases though it will never be a locker.
Thats what I just put in mine when i rebuilt it.
look here:
http://cgi.ebay.com/ebaymotors/1986...ryZ33731QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

You can get the same kit from Summit Racing for $104. http://store.summitracing.com/partd...+4294925134+4294839047+4294848426+4294901314+

 

[jtb1689]

Also, before you do buy the rebuild kit, make sure that the L/S is actually worn. When you have been stuck, were both back tires off the ground. I ask because if there isn't enough drag on the tire that is "on the ground" it won't transfer the power to the tire that isn't. Did that make sense?

I will check to make sure before I do order (your probably right though, 15 years and 120,000, probably worn). And when I've been stuck I don't necassarily mean high centered as much as I just simply mean the wheel just spun in the mud or snow. I know on the snow last time it happened a couple weeks ago both tires were on the ground, but one decided to just spin and have the all-terrain tire dig through the 8 in. of packed snow base and put another few inches deep hole in the dirt, while the other wheel just sat there.

On the subject, there is no l/s in front with the 4x4 right? Because what happened in this particular incident actually was both my passenger side tires spun while I looked out my window to see both driver side tires sitting still.

 

[FROADER]

Nope, no L/S in the stock front end.

 

[Albino 94LTD]

A rebuild is about 2 hours (45 minutes of that is getting the damn S spring back in). I just rebuilt mine last fall, replaced 1 spacer with one of the old clutch plates. Now that thing is tight

 

[carlson1038]

You can check your ls without taking it apart. Jack up one side of your rear axle, put the trans in nuetral, release the e-brake and try to turn the rear wheel. It should be very hard or impossible to turn by hand (there should be specs for just how much torque this takes in the manual). Aternative method would be to jack up the entire rear axle, release the e-brake, put it in park and try the same thing. An open diff the oposite wheel will turn in the oposite direction as the one you are turning. A worn out ls will do the same thing.

On another note. Your 3.73s are perfect for 31s. You would only be gaining 3/4 inch of ground clearance by going with 33s. No re-gearing and you can use the stock wheels.

 

[jtb1689]

So, to recap: Turn the car on with engine running, get one rear wheel off the ground. It shouldn't turn, if it does the ls needs a rebuild. This is done with the car in neutral. Or, jack up the whole back end and put the engine in park. (Shouldn't that basically stop the rear wheels from turning at all?) Turn one wheel, and if the other one turns the other way, ls needs a rebuild, and if the ls is fine, the wheels won't move at all or they will move together?

And about the tires: I feel like 31's might look a little small if I did a 3-4 in. lift. I've considered 32's but since people say you HAVE to regear at 33's I figure it might be a good idea to do it with 32's? Anyway, maybe some of those questions should be moved to my registry, don't want to take away from the Limited Slip title

 

[carlson1038]

Make sure the engine is NOT running and block the front tires.

 

[JDraper]

So, to recap: Turn the car on with engine running, get one rear wheel off the ground. It shouldn't turn, if it does the ls needs a rebuild. This is done with the car in neutral. Or, jack up the whole back end and put the engine in park. (Shouldn't that basically stop the rear wheels from turning at all?) Turn one wheel, and if the other one turns the other way, ls needs a rebuild, and if the ls is fine, the wheels won't move at all or they will move together?

And about the tires: I feel like 31's might look a little small if I did a 3-4 in. lift. I've considered 32's but since people say you HAVE to regear at 33's I figure it might be a good idea to do it with 32's? Anyway, maybe some of those questions should be moved to my registry, don't want to take away from the Limited Slip title

Nope..Here's the proper way to test it so you don't get killed.

First, block the front wheels. Second, with the vehicle in neutral, lift both rear tires off the ground and support the axle with jackstands. Spin one wheel by hand. The opposite wheel should go in the same direction. If it spins the opposite way, your ls is toasted.

If it passes the first test, put the truck in park or in gear (if a manual) and try and turn one wheel. It should not turn, or it should be VERY hard to turn.

If the rear has never been serviced, and you're over 75k miles, there is a very good chance the clutches are shot. As with any friction surface, they will wear out over time.

As for tires, you won't want to go above 31's on your truck without regearing if you want to keep your performance and keep the transmission intact. It will work on larger tires, but it will be a dog, and it will burn the transmission up much faster.

 

[jtb1689]

Well I don't have the jack or jackstands up here to support the entire rear end. But I did jack the one side up with the mini jack that comes with the car. Put it in neutral (engine was off though) and the one rear wheel turned as easy as the front wheels normally do, with the opposite wheel on the pavement. So does this say anything? Or should I still jack the entire rear end up (when I am at home with the shop and the tools) and try your ways JDraper?

Second, if what I did was sufficient and the ls is clearly not working, is the only possible reason bad clutches? Or is there a possibility at low gear oil or fluid (if there is any of that in an ls, again I'm new to this ls business)? I am wondering if I should just order the rebuild kit now and hope I can have it by the weekend when I plan on doing my hubs also, or wait till I go home and investigate more and then fix the ls on another weekend in the near future. Again, '93 with 120k, as far as I know, no service on the rear end. I know I haven't touched it in the last 3 1/2 years I've had it.

 

[JDraper]

If it spun freely the way you did it, it's toast. There should be resistance. If the rear is operating properly as an open, and it's supposed to be a ls, then yes, the only thing that would cause that is a worn/damaged/missing ls component.

If I remember correctly, a Ford Trac-Loc limited slip rear of your vintage usually uses 80W90 gear fluid with a friction modifier additive.

You are doing no more damage driving it as an open, so you don't have to fix to make the truck safe to drive.

 

[jtb1689]

Yea I know I'm doing no more damage. It's just winter is here and though I faired ok in our recent "seattle snow storm," an ls would have been pretty helpful at times. So then, should I even waste my time checking the gear oil in hopes that all I need to do is add some or should I just go ahead and buy myself a rebuild kit?