If anyone paid attention to the photo posts from the recent Centralia/St. Clair mini-meet, you might have heard me mention my locker was having problems.

Basically, it would load up with torque and then slip -- suddenly and violently making a nasty sound. Some people thought I'd broken my differential, it was that obnoxious sounding.

However, it soon became clear that the differential was okay, but it was the locker slipping.

The problem was "too much of a good thing". Here's what happened:

1) After I first built the new axle, I filled it with a Quaker State gear oil that had the limited slip additive already in it and it worked fine.

2) After 1000 miles or so I took the cover of and retorqued all the bolts. I refilled the diff with Amsoil "Severe Gear" gear oil. It reputedly does not need friction modifer in most limited slips.

3) I noticed a tiny amount of chattering from the limited slip with the synthetic alone.

4) I added the friction modifier (the whole bottle) that came with the ECTED.

5) Chatter went away.

6) Solid locking ALSO went away, lol. You could even make the slipping happen taking a turn on asphalt with the locker engaged.

Apparently the combination of the synthetic AND all the friction modifier allowed the clutches to slip even when pressured by the locking mechanism.

Using my Explorer aluminum cover, I drained an refilled the oil -- man what a joy that is: it's SO easy with the drain plug on the back. This time I used the non-synthetic oil again.

Drove it for a day, then tested the locker -- whoo-hoo!!! It works fine again. When I lock it and take turns the tires scrub and it does NOT slip.

Note: The Auburn documentation EXPLICITLY TELLS YOU TO NOT USE SYNTHETIC!!! I'm an idiot, yes...

Anyway, problem solved -- just in case you happen to be an idiot also.

 

way to go john, i will keep this in mind for when i do this in the future

 

cool John glad it was nothing serious

 

Gnaryo brohan!

 

so what type of fluid did u end up using? did u add a friction mod? i need to know for when i get mine :D

 

Sweet John.

 

I talked to a guy at work who's a mechanic there and he suggested I use conventional oil WITHOUT the limited slip additive at first. His reasoning was like this:

1) You're leaving quite a bit of oil behind in the axles and all, even when you drain it -- so there will still be some synthetic and limited slip additive in there.

2) The clutches need to get clear of the stuff soaked into them, so give them an oil without the additive that will help that along.

3) Don't know how much is "too much", so start with very little (just the residue)

4) The additive can always be added later if needed.

So, I took his advice and so far I just put in regular old 80W90 conventional gear oil -- no limited slip additive yet.

Right now, no chatter, and good locking. If the chatter comes back I'll add the additive, and ounce or less at a time, and give it a few days to soak the clutches before deciding if it's enough.

That's how I'm proceeding.

 

glad you got it fixed john

 

gotcha 8090 .... sweet .... i have 75140 in front and rear diffs right now ....

 

Well the rear for sure. The Torsen limited slip you have in the rear requires the heavier lubricant. I didn't know they spec'd it for the front as well.

If you replace the Torsen with an ECTED, you'll want to use the recommeded 80W90 oil and not the heavier 75W140 probably. My experience now suggests that you use the CORRECT oil in the ECTED, lol!

 

So the Ected is not a mechanical locker? It uses the clutch packs to "lock" the rear? I guess that good nad bad in a way...good b/c you may not break something, bad b/c it's not a true mechanical locker.

 

Exactly. It works really well unless you "sabotage" it. With enough friction, you're basically "locked". The breakaway torgue when the thing is at spec is very, very high.

So, as long as you keep it up, it's good. I'll change the oil regularly, and just do the maintenance. I like the limited/slip locker function and there are no pins to jam or break or whatever and no pneumatics to get wierd.

 

I've always wondered (and am sure you have already covered it, so pardon me) how is it wired. It's electro-magnetically triggered right? So you have a switch in the cab.. It's just a simple toggle, right.. or is it a rheostat?

 

No, it's a toggle. You can, in fact, drive it with different amounts of current and either add to the bias on the limited slip, all the way up to a full locker.

It's not "triggered" per-se: the current is continuous the whole time you have it locked.

 

Bad choice of words.. electromagnetically driven is probably more accurate, no? So w/ no current you've effectively got a clutch type L/S..

Have you experimented w/ variable amounts of current? Maybe seperate dry-weather, rain, snow, and all-out mud positions? I seem to remember you were thinking in those terms at one point.

 

I was -- but it works so well on the street as it is (it's a pretty "aggressive" LS) that adding anything to it might not be all that helpful. I think the place it could be is in a traction control system where the current is modulated by the control system dynamically and I know such systems exist -- but I'm not designing one, lol.

Basically, the LS is just great and (when working, lol) the locker is too so I've had no real motivation to make the variable bias system. I did buy a high current PWM board kit to do it with -- I just might use that now for my electric fan to get variable speed. Turns out the locker doesn't pull much current anyway.

 

Hey John weren't you thinking about coming up with an adjustable current thing to adjust for different degrees of locking ? Have you put any more thought into that ?

 

Ha ha! Read the post above yours. I was just talking to Colin about that.

 

Sweet!