G80 staying locked after new spider install

[phatz_hatz]

Ok, so i have just swapped out my old shredded spiders with new ones, the rack and pinion are fine, no wear on them, the clutches seemed a lil burnt up but not anything to crazy .

I put full syn 75w90 with the LS additive, everything i read is either thats the problem or it doesnt eefect it all. with that being said ive driven it 60 mph put it in reverse and cut the wheel did same thing in drive and it just will not unlock im gonna change it at 500 miles to ac delco gear fluid and hopefully that fixes it but its driving me nuts that i know i put everything tg correctly and i just spent 600 dollars on the spider kit from a chevy dealer, if anyone could have any other diagnosis it would be much appreciated.

I have 08 Tahoe with 112000 on it with the 5.3 in it. im just scratching my head at this point and have no idea what to do. is there any way maybe i put the block in the wrong way that goes in between spiders to keep it locked ?

 

[exp500]

Likely you aren't the first one inside it. Probably why spiders broke. Find the Overhaul Manual Might be Unit Parts service Manual too.

 

[phatz_hatz]

Likely you aren't the first one inside it. Probably why spiders broke. Find the Overhaul Manual Might be Unit Parts service Manual too.

so i should most likely start looking for a new carrier with a 3.73 gear ratio, or just go to junk yard and get a whole new rear axle.

 

[OR VietVet]

If you are looking for an easy way to get back on the road just get a diff from a salvage yard and bolt it in and go.

 

[phatz_hatz]

yea i figure this would be the easiest and most likely most effective way to fix it, i have no idea how many miles i am going to get out of this and hoping it does not grenade on me for a couple thousand before i can find one

 

[OR VietVet]

Make sure that you get a copy in writing of the warranty that the salvage yard gives you.

 

[exp500]

And don't use the additive this time!

 

[swathdiver]

Ok, so i have just swapped out my old shredded spiders with new ones, the rack and pinion are fine, no wear on them, the clutches seemed a lil burnt up but not anything to crazy. i put full syn 75w90 with the LS additive, evverything i read is either thats the problem or it doesnt eefect it all. with that being said ive driven it 60 mph put it in reverse and cut the wheel did same thing in drive and it just will not unlock im gonna change it at 500 miles to ac delco gear fluid and hopefully that fixes it but its driving me nuts that i know i put everything tg correctly and i just spent 600 dollars on the spider kit from a chevy dealer, if anyone could have any other diagnosis it would be much appreciated. i have 08 tahoe with 112000 on it with the 5.3 in it. im just scratching my head at this point and have no idea what to do. is there any way maybe i put the block in the wrong way that goes in between spiders to keep it locked ?

I suspect its the limited slip additive, get rid of that, our trucks don't need it.

 

[phatz_hatz]

im hoping that changing the fluid will fix the problem but if it doesnt, it would just make more sense to buy a brand new one for 1400 compared to one with 115 on it for 1100 at this point

 

[exp500]

Buy the Scrap yard/Upullit, It's complete so you don't have to learn how to setup a rear end. Save your money for fixing next find until you know overall condition of truck.

 

[wsteele]

I think @exp500 and @swathdiver are right.

I was just reading about the G80 on another forum. There was a post that had an excerpt from a GM bulletin that specifically calls out limited slip additive as the culprit in bad acting Eaton Locking diffs. The bulletin recommends a complete flush and replacement only with the recommended synthetic gear lube.

 

[phatz_hatz]

I think @exp500 and @swathdiver are right.

I was just reading about the G80 on another forum. There was a post that had an excerpt from a GM bulletin that specifically calls out limited slip additive as the culprit in bad acting Eaton Locking diffs. The bulletin recommends a complete flush and replacement only with the recommended synthetic gear lube.

now should i just use 75w90 acdelco synthetic and just open up the diff cover to flush it out

 

[OR VietVet]

Use a degreaser or brake clean to clean it all out. Hell even carb cleaner will work. Clean it all out and blow it all dry. No additive.

 

[wsteele]

now should i just use 75w90 acdelco synthetic and just open up the diff cover to flush it out

I agree with Ron. In that piece, they said Eaton and GM recommended a complete flush and cleaning to remove any traces of the LS additive and then just the Delco Synthetic lube. They didn't specify weight as some call for the 80W90 and others 75W90. I suspect either would be fine. Your owners manual will call it out though.

 

[exp500]

Usually the additive makes chatter, rather than fully not unlocking. As I stated before, I think someone else was in it and may have shimmed it for more offroad lock. Something that shouldn't be done to G80. Hard to tell what some folks are thinking while they turn wrenches.
I've said many times before-"Some Poeple Shouldn't Have Tools".
My guess is about 350-450 at the yard for replacement. Hub to hub.

 

[phatz_hatz]

Usually the additive makes chatter, rather than fully not unlocking. As I stated before, I think someone else was in it and may have shimmed it for more offroad lock. Something that shouldn't be done to G80. Hard to tell what some folks are thinking while they turn wrenches.
I've said many times before-"Some Poeple Shouldn't Have Tools".
My guess is about 350-450 at the yard for replacement. Hub to hub.

no one Deff didn’t shim it for off road use it was fine before and just bombed on me so i figure I’d just do it myself considering i looked up enough on it before i took it apart put everything back together properly. I’m an ASE very mechanic just don’t get it might be the mechanism it self still yet to change the fluid and just drivin her diligently

 

[exp500]

Glad to hear It's in good hands. Keep us updated on findings.

 

[thompsoj22]

Your govlock is engaged somehow, pull the cover and spin the diff and see what is going wrong, Youll be on the road in a couple hours for the cost of some gear oil. The additive is a "friction modifier" not a locking mechanism and my opinion the additve is not the problem> so you have the EATON M locker?

 

[phatz_hatz]

well its been raining cats and dogs for past couple days havent had the oppurntunity to open the plate up been driving her easy, hopefully weather clears up so i can get in there

 

[phatz_hatz]

Your govlock is engaged somehow, pull the cover and spin the diff and see what is going wrong, Youll be on the road in a couple hours for the cost of some gear oil. The additive is a "friction modifier" not a locking mechanism and my opinion the additve is not the problem> so you have the EATON M locker?

im not sure if its the eaton but it is the G80 M locker which im sure is made by eaton i also suspect that the fluid is not the culprit and it is soemthing more i just need to open it up and see what it is