2003 F250 limited slip quit working

[joemcmillen]

In addition, I purchased all of my parts from "Just Differentials". Very cordial people. Delivery was very fast.

[triumph406]

Originally Posted by joemcmillen

I disassembled the axle and found that the clutch pack was installed as specified (plate, clutch, plate, clutch, etc). 5 of each plate type on both sides as specified in the manual. I did, however notice that I had 0.060" of wear as compared to a new set. I replaced all of the steel discs, clutch plates, shims and belville washers (Ford OEM part). All is good in the world. I did add another 0.030" of shims (0.015" to each side) as an extra measure. The original shim package was 0.060" per side, so my change took it to 0.075" per side. I tried to pack it to 0.115" on each side. but got bucking and popping in turns, so I went with what I stated above.

Joe,
how long did the installation take? I could see quite a few hours worth of work to do the work.

Have tried it in the rain yet? I could see if you were getting bucking and popping in turns with the .115" shims that cornering in the wet might be fun, how is it with .075"? How it's in the rain on the street is my main concern. I need to do something with the LS as it's not working.

Dave

[joemcmillen]

Dave,

I took quite a while (approx. 3hrs), but I am a fanatic about getting it right. A competent mechanic can do it in an hour and a half. Remember I have a lift, so access was easy.

Be careful about packing too tight, as you will exascerbate the problem and cause premature faliure. Driveability was my main concern, as this is my wifes truck. I also have the full Banks Big Hoss Bundle installed, so I am making more power than stock (I'm guessing about +150hp). the truck is very fast and has lots of torque.

In a nutshell, lift truck, remove diff cover, drain oil, remove hubcaps, remove axle bolts, slide axles out to clear diff inside housing, remove carrier bearings, remove diff, fix diff and reinstall in reverse order.

Make sure you torque to specs. (axle shafts-80lbft, diff bolts-90lbft, carrier bearings-88lbft). I used a long narrow shaft to hold the diff while removing/installing the diff bolts (diff on a work table). Use a caliper to measure all of the plates. Purchase a new rebuild kit first. Not all trucks are the same. If I were you I would go back with what was in there originally plus a few thousandth's for good measure. Soak the new cluth plates for at leat 30 minutes in the friction modifier. If you're running the bejesus out of your truck, I would recommend installing the MagHytek cover. It's expensive, but worth it in the long run.

I have their tranny pan and my tranny runs 15-30 degrees cooler and added 8 quarts to the capacity.


Good Luck!

Joe

[yosh30]

the same thing is happening to mine, i didnt know what the hell was wrong..so what exactly do i need to replace, and how much does it run?

[joemcmillen]

Yosh30,

If you have the same problem as I did, the clutches in the limited slip differential have worn out. If your diff. is the same as mine (Sterling 10.5", w/3 pinion limited slip differential, OEM), the clutches have been worn past the point that they don't have enough preload to handle keeping both axles spinning together under load. The limited slip system consists of two sets each of clutches and discs (in an alternating "pack", disc-clutch-disc-clutch, etc). There are five of each type (clutches & discs) on each side of the carrier housing. That makes a total of 10 clutches and 10 discs in the whole assembly. The balance of "stuff" in the assembly include a belville washer on each side (2-total) and shims (same thickness on each side). All parts are critical; The clutch-disc combinations are what create friction to make the system work (slip or not), the belville washers are what create preload (very imortant) and the shims make up for tollerance differences so the belville washers can do their job. When you buy a rebuild kit, it comes with everything you will need, except a cover gasket, new gear lube and the friction modifier (critical).

You should be able to get all the parts for around $200+. Based on your truck in the picture, you should get a MagHyteck diff cover, which adds 2 quarts to the total capacity and helps keep the fluid cool because it has cooling fins (around $250). If you get the Mag cover, you won't need the cover gasket, because it comes with an integral O-ring seal (very nice unit). Most of us are adding additional power and larger tires, which puts additional stress on the drivetrain.

See my discussion above for how to.

A few extra notes: Get the FORD service manuals, they are cheap compared to what you get from them (around $100). Keep from running your tires on dissimilar surfaces (asphalt and dirt). Namley one tire on the road and one tire in the dirt. One tire on the road and one off will force the differential to handle two completely different surfaces causing the limited slip diff to manage two traction inputs. I believe this is what caused mine to wear prematurely.

When removing the differential, be careful as it is very heavy. Be careful not to damage the trigger wheel (mounted on the differential next to the ring gear). The trigger wheel is part of the speed sensor input for the anti-lock braking system. You don't have to remove it to service the clutches.

Just Differentials has the clutch rebuild kit, friction modifier, and MagHyteck cover. They will be able to help you with getting the right clutch kit.

DON'T get two kits, they won't fit and you will be wasting your money. I don't know who stated that jambing more clutches in the diff will help, but they won't. There isn't enough room. You may be able to jamb one more clutch disc on each side, but you will be overpacking the unit and you won't be able to get any shims in.

When disassembling the differential, use a caliper and measure/record the disc and clutch ticknesses. You will find that the old clutches will be a few thousands thinner than the new ones. All those differences will add up giving too much clearance in the assembly. The metal discs should be about the same thickness between new and old (mine were). Don't use any old parts, install all new and add about 0.015" additional shim to each side (0.030" total). the kit comes with tons of shims, so you will have enough. Make sure you measure the shims that are removed, as that will determine what to go back with. Instructions come with the rebuild kit, but the manual is very helpful.

What you will need:
Clutch rebuild kit
cover gasket (if you don't get the MagHyteck cover)
Gear Oil (Amsoil 95-140 severe gear oil)
Ford friction modifier (one 4oz. bottle w/o the new style cover, two with)
MagHyteck diff. cover (optional)

Tools:
sockets
1/2" breaker bar
long bar (differential housing holder, see above)
Torque wrench
gasket sealant (I use permatex #2, awsome stuff, don't need with MagHyteck)

Good Luck! Let me know how it goes of if you need additional help.

Joe

[triumph406]

Originally Posted by joemcmillen

Dave,

I took quite a while (approx. 3hrs), but I am a fanatic about getting it right. A competent mechanic can do it in an hour and a half. Remember I have a lift, so access was easy.

Be careful about packing too tight, as you will exascerbate the problem and cause premature faliure. Driveability was my main concern, as this is my wifes truck. I also have the full Banks Big Hoss Bundle installed, so I am making more power than stock (I'm guessing about +150hp). the truck is very fast and has lots of torque.

In a nutshell, lift truck, remove diff cover, drain oil, remove hubcaps, remove axle bolts, slide axles out to clear diff inside housing, remove carrier bearings, remove diff, fix diff and reinstall in reverse order.

If you're running the bejesus out of your truck, I would recommend installing the MagHytek cover. It's expensive, but worth it in the long run.

I have their tranny pan and my tranny runs 15-30 degrees cooler and added 8 quarts to the capacity.


Good Luck!

Joe

Joe, 3 hours, that's pretty quick work even with a lift, I figure it will probably take me 6+ hours. Nothing I do seems to go according to plan!!

I have a friend with a lift, I might give him a call, otherwise I'm going to get some heavy duty stands and do it the hard way.

Your advice has been very helpfull, thanks!

Dave