So what are some symptoms of the clutch packs in a LS diff headed south?? I've got a clicking sound from underneath the truck and it seriously sounds like it's coming from the axle. I've pulled the wheels and have found zero problems with the brakes or anything else. No clicking sounds when you turn the wheels by hand. Just can't pin it down or find any broken parts.

Symptoms: The clicking sound occurs mostly in left hand turns, but occasionally happens during braking when going straight. Clicking only happens when it (the truck/axle) is warm. Never happens when things are cold. Also, when making a right hand turn (and only a right hand turn) off a side street or some other full stop-start, it takes literally no throttle at all to spin the right rear tire on a wet road. This is a new development, so I'm considering it a symptom.

Anyways, wasn't sure if there were any tale tell signs of those clutches in the LS pack going bad or not. Is there anything I can to do definitively test out the LS to see what shape it's in??

Truck drives great and otherwise you'd never know anything was going on.

 

Put it in Park, take the e-brake off, and jack one rear wheel up and try to turn it. It shouldn't turn easily, if at all.

 

When the clutch packs were bad in my '04 F150 the rear end would shudder on right hand turns from a stop. The whole rear end would shake and it was very noticeable.

 

I had a 87 Bronco with / 8.8 ring gear - 3.55 LS. It went south at around 70 or 80 thousand miles.

A test you could try: Jack up one side of axle with bottle jack, put right under the axle. Lift tire just enough to clear the ground. Put e- brake on, put in drive; you should be able to drive it off the jack.

Another way is a torque wrench check on one of the lugs with one wheel up.

I don't know the "break away" torque here, but the test is around 25 ft lbs. with the tool to rebuild this on a bench. On a lug you'd be off center, this would give a lower foot pound # due to the leverage.

 

ALSO CHECK THE FLUID?????? maybe

 

OK...jacked up one wheel and left truck in Park with parking brake released. I physically cannot turn the wheel either direction. Put truck in neutral (one wheel still off the ground/other wheel on the ground) and I can turn the wheel but with quite a bit of resistance. I can turn it relatively easy; takes some effort, but I can't send the wheel spinnin by no means.

I repeated the same procedure on both wheels and all results from side to side match. There's no noise or clunking/ticking in the rear end while one wheel is spinning.

The search continues...


Ahhhh, the simple stuff. Always a good tip. Will check tomorrow.

 

Have you checked/changed the rear u-joints recently? When they start to go bad it will make a ticking sound that sounds like a can dragging behind you, and it normally gets faster as you accelerate. To check for it you can crawl under the truck and try to turn the driveshaft by hand and it shouldn't have much, if any, play in it.

 

My noise does not get worse with acceleration. As stated, no noise at all during acceleration or driving. Only left hand turns and sometimes approaching a stop. My noise is NOT speed dependant.

 

Hmmmmm.... that clicking noise .....I have a good hunch it's the clutches in there. Try draining it and a refill.

Put in 4 oz of Ford limited slip modifier with new fluid.. assuming you don't use LS gear lube in conjunction with the 4 oz. If possible, try to get straight up synthetic lube without "LS" and put in their modifier.

Also when you pull diff. cover, look for obvious signs of broken parts. I found broken bearing( preload) shims in my mine, they were broken making a half mooned appearance. Ultimately need a complete overhaul.

Likely you'll be fine.

I had a "clunk" that developed, and hence the needed overhaul.

 

I did a major "duh" there........

Yep, that's exactly how it should be. However, I don't know exactly how much drag (clutch slip) you should be getting when turning the wheel in Neutral.

 

Well, I currently have Amsoil Severe Gear in there and have a Mag Hytec cover. I actually have two bottles (8 oz) of friction modifier in there because of the quantity. It's not old either, by gear oil/Amsoil standards. Probably 60K or so.

I'l pull the dipstick to see if there's anything stuck to it and then decide to pull the cover if I find anything significant.


Yea, me neither. Might try to find a buddy with a newer one and compare. It's got drag though; like I said, you certainly can't send the wheel spinning, but it will turn. It takes two hands to turn it. Same amount of drag both directions on a given wheel and equal drag from one wheel to the other.

 

Not to interrupt here, but maybe you're fine with that drag. The preload spring is working the clutches. But how do the clutches perform under real-time conditions?

Say, will it hook up with E brake on, with only one wheel in a mud hole?

By putting the E brake on, as when you have a large difference from side to side traction; you create a force on the clutches from the drive shaft end. This side loads the two side gears, essentially squeezing or locking out the spider gears.

It's safe to use the E brake in these scenarios.

One check as I mentioned in upper thread, was safely testing this with a jack.

My dad's '94 F150 will drive it off as we recently tested this last year. My 4x4 Bronco would click as mentioned, and one day I drove it into a sugar sand trail and the one 32 inch tire dug a hole straight down. Put on E brake and nothing.Toast.

Later, and unrelated, the diff needed an overhaul by probably a bad factory gear set install--IDK here, but it prematurely failed with those broken shims--( at the time I had the extended warranty-- it was covered.)

If this passes then I'd take it to a gear shop.

A safe bet that lube is just fine-- being Amsoil with those miles.

I'm not an expert but I have a little experience in this I've done a complete rebuild last year with new gear set and a new differential--

All I can do. My 2 cents.


Anyone feel free to chime in.

 

Thanks MLD! I must admit though, (and I blame me, not you) I'm not tracking on the whole e-brake thing. Seems to me that equally (assuming the e-brake is adjusted properly) applies the same amount of pressure (braking) to both wheels. How does this force one side to turn? If that's what you're trying to accomplish.

I haven't checked my fluid in 50,000+/probably 2 years for two reasons; A: It has Amsoil. B: No signs of a leak or anything. Thus, not much reason to check it. Upon checking tonight I discovered perfect fluid level, perfect colored fluid (literally looked bran new), and almost zero contaminants on the magnetic dipstick. I was surprised at this as I actually expected some debris at least from normal wear and tear, but there was absolutely nothing to indicate a failure or any type of debris in the fluid.

 

No rear end shop for me! Replacing all the clutches and anything else in there (pretty much a complete rebuild) shouldn't require removing the pinion gear or upsetting the carrier; thus I should be able to do all of it in house.

 

To illustrate:
Say, if you drive off the shoulder of a road and you drop one drive wheel into the mud; most likely the other wheel will not catch or "hook up", because of the large traction difference between the two wheels.(We have all experienced this in some way in an open differential.)

This is why you can spin the tire by hand when one wheel is up as you did. No different if that same tire was planted on an icy surface or in the mud. In fact that same torque you felt as the wheel "dragged" is about all that would applied to the good wheel on the dry ground. Still some torque there, but only at about 25 foot pounds because of the internal springs-- definitely not enough to move the truck, though.

But by applying equal pressure to both wheels by using your parking brake, the clutches are "loaded" and the useless spinning wheel is pinned internally by the 6 clutches inside.

Most factory LS differentials work this way in principle. This allows you to corner normally, like a conventional differential.

The problem though is the differential doesn't "sense" that you dropped your tire in that mud hole--- thus it breaks loose just as it does in that corner.

The brake in this case will coax it into an even equal performance as in driving it straight ahead down the road-- thus two wheels turn together - *evenly* as it does driving down the road.

Interestingly, my wife's newer 4x4 senses wheel spin via sensors and the computer uses the brakes to grab that spinning useless wheel. All in real time to keep you going-- no need for e-brake.

Hope this helps.