urban4x4

I'm changing my differentials oils today, do i need to add a additive, I read something about a additive is needed if i have limited slip differential (I don't know if I do or not).

Thanks



Work with mE, Im nEw @ tHis...

rrich

If you have a limited slip - you need the additive - a little tube of it. Some lubes claim they already have t in - but it's usually not enough.

Even if ykou don't have limit slip - it cannot hurt.

Symptoms of not enough - clunking, strange noises, cold or hot. Sometimes it can make it handle funny when turning.

djb383

Won't hurt a thing in a open diff.....just makes the clutches slip even more in a limited slip. If the clutch type lsd is not noisy/chatters in a tight turn, it doesn't need additive.

rrich

Symptoms of not enough also includes funny noises when backing up at slow speeds. That was the problem with mine. One little tube almost instantly cured it.

Noises, locking when it shouldn't, locking or unlocking, staying locked during turns, even locking and unlocking unexpectedly while driving straight are symptoms.
Often diagnosed as other troubles - front end, alignment, bad bushings etc.

It's not just on tight turns.

It's just extra slippery stuff, haven't seen any research on it, but I'd bet it would also run cooler.

Caution - never in a manual transmission! It's so slippery the synchros won't be able to grab properly. Synchros are a friction device.

A friend tried it in his trans, then he could hardly shift it. I drained and flushed it with kerosene twice - it worked.

A tube is about $10 - far cheaper than a diff rebuild. But use it properly. Some diff lubes say they already have it in their mix - but it's seldom enough.

Interesting to note - Currie makes great diffs - but they will not warranty a diff that had synthetic lube in it. Their research found the syn's make it run hotter. They say to use regular old dino lube.

Apparently the syns don't carry away the heat as well. All the advertising hype (lies) doesn't tell you that.

djb383

The only time a diff is needed is in a turn. Clutch type lsd don't lock/unlock, they slip when the wheels need to differentiate (in a turn).

rrich

Even backing up straight there's a slight difference in rotation the diff has to compensate for - terrain, tire diameter., inflation, etc. If the clutches can't slip when they need to, then finally do slip suddenly - clunk!

It doesn't have to be a radical or hard turn.

I suggest you learn how they work.

Like I said - it made a world of difference on mine. I just bought it.
The PO said he's had all the fluids changed. It had a quickie oil change sticker on the windshield. Who knows what they put in. I simply added a tube of the additive - it no longer clunks.

I've seen it before several times.

It's a cheap fix easily worth the try. Most shops or "pseudo mechanics" will deny it - they'd rather you spend 500 to 1000 bucks "rebuilding" it. But since the economy is bad and business is slow, if you can afford it - believe them.

$10 For a tube of it.

I believe on doing things the cheapest and easiest, and most effective way when possible. That's what made my shops so successful.

djb383

U sir, have some learning to do about clutch type lsd and diffs in general.

austinjoe13

Pull the plug out of the rear end and stick your finger in it . Feel the carrier. If it feels rounded towards the bearing caps then it is open and you can run regular gear lube. If it feels can shaped then it is an LSD and you need to use synthetic oil with the additive. Hope this helps!

rrich

Ha He - then you are saying it did not make mine stop clunking? Then what did - your good thoughts?

What do you think the LSD does? Do you think it only releases on a hard turn?

Sorry, but I won't argue with someone without actual experience.

djb383

Have no idea why your clunking stopped, glad it did.....but the fact that it stopped clunking doesn't explain how a clutch type lsd works and what the additive does. Using the word lock or locked in the same sentence with clutch type lsd is a good indication of not understanding how a lsd works. Put both palms together, push hard together, turn hands in opposite direction. They slip, right? That's a very simplified explanation of how a lsd differentiates in a turn. Do the same thing except turn both hands the same direction and u have a clutch type lsd going straight. Now, interlock your fingers together, that's a autolocking diff going straight.....separate your fingers and that's a autolocking diff unlocking or mechanically separating in a turn. A clutch type lsd doesn't unlock or mechanically separate in a turn.....the clutches slip, but don't separate.....like your palms. The additive makes your palms (clutches) slip easier. Your palms (clutches) don't clunk together or apart. Let's hear your explanation.....but keep it simple, it's late, I'm old and tired.

rrich

Your explanation of the palms together is correct. Now put glue on your palms. When you put enough force you can break the glue. Your palms finally slip suddenly. Put oil instead of glue - now they can slip properly. The additive is just more "slippery" than gear lube. It lets them slip when needed better.

Without the additive the clutches don't slip so easy, when enough force is applied they suddenly release - clunk/jerk - as the built up pressure releases.

Same thing happens during a hard turn, clunk.
For some reason mine rarely clunked on turns, but it was very noticeable backing up - slow or fast. it may have been I just didn't hear it as well.

It's not unlike a lunchbox locker the way it acts on turns without the additive. Just the LSD is supposed to be smoother - unfortunately it doesn't actually lock tight.

It's better than an open dif, but not near as good as a real locker.

I run some lunchbox lockers on some, but on most of my rigs I have selectables. ARB and the stock selectables on my Rubicon.

He Ha - The good thing about a selectable - when you've had enough, you can turn it off. Just like the ideal wife with a switch on her neck!

Yes - I've done quite a few.

austinjoe13

My shop teacher test drove a mountaineer we had just took the rear end out of. After the owner got it back the LSD was locking up. I heard the tire dragging from a pretty good distance. So LSDs CAN lock up it's just a problem . BTW we used synthetic oil and a proper additive. I forget what the problem ended up being.

rrich

When defective they can lock up - unintentionally.

No additive or anything else will help broken parts. Even killing a sheep at midnight, wearing a pyramid hat, or throwing $100 bills in a fountain doesn't help.

djb383

Clutch type lsd clutch chatter is multiple/rapid sounds/pulsations when in a turn. It's not a single clunk. The additive usually cures chatter by making the traction enhanced lsd "less traction enhanced". The additive will not fix something that is broken.

djb383

Didn't think we talking about a BROKEN lsd. Lock/unlock is not a normal function of a clutch type lsd......lock/unlock is the normal function of a locking type diff.