Rear diff problems

[gmcman]

So one day going into work I'm sitting at a red light I do pretty much every morning, uphill and already turned to the left. When I go, I hear and feel this long-forgotten sound.....thump, and a minor tremor at the same time. I thought I slipped on something until it happened the next day.

I had some remaining Amsoil Severe Gear oil so I picked up a tube of modifier and figured I would check things out.

I had the fill plug out not terribly long ago but this time there's some animosity towards someone, and I didn't do anything.




Let me assure you of something, when I get you out, you're mine. I will wait you out.

With that being said, even my squared-off short extension and squared-off breaker bar end, still boogered up the square hole. May need to weld a bolt or something so I opted for the vent tube for the refill. I needed to do this today since something is not right.

The bottom drain opened easily, and was greeted with an unwelcome sight.

First glance was a short sigh of relief.

Then I spun the carrier to find not 1 or 2, but all the spider tips chewed off.

The gears on the sides are fine. Am I really lucky or is this the norm? With what a G80 goes for should I opt for a junker 8.6 or 9.5?

The truck rolls nice and smooth, even turns are fine.

I'm sure the inevietable is near but how long? She has 174K on those sweet legs.

 

[Wooluf1952]

You can probably get the entire stronger 8.6" for less than the G80 alone. Also, if your looking for the 9.5" from an SS, they only came with the 4.10 ratio.

 

[gmac310]

I had to replace mine oer July 4th weekend because of this same problem. Seems to be a weak point in the G80s. The other gears will eventually get chewed up also since the other spider gears mesh with them. I hate to say it but it looks like it's time for a replacement.

 

[gmcman]

Also, if your looking for the 9.5" from an SS, they only came with the 4.10 ratio.

Luckily if I choose that route I already have the 4:10. I know Hardtrailz did this but needed a locker.

On the cheap, can all 4 of the spiders be replaced without pulling the carrier?

 

[NJTB]

Yes they can. YOu need 2 side gears and 2 spiders. I don't know if they come matched to the rear (read:lapped together).
I did lots of rears years ago, and the tough part is getting the bolt out that holds the shaft that pushes the axles outboard to hold them in place. It's just a shit bolt and breaks. If it breaks, get a left turning drill bit and drill it out. They require some patience but will come out.
Remove the bolt that holds the shaft, slide the shaft out. Push the axles inboard and slide out the 2 clips that hold the side gears in place. Pull the axles out of the car (don't let them rest on the seal).
Then you can wiggle the side and spider gears out.

 

[gmcman]

Yes they can. YOu need 2 side gears and 2 spiders. I don't know if they come matched to the rear (read:lapped together).
I did lots of rears years ago, and the tough part is getting the bolt out that holds the shaft that pushes the axles outboard to hold them in place. It's just a shit bolt and breaks. If it breaks, get a left turning drill bit and drill it out. They require some patience but will come out.
Remove the bolt that holds the shaft, slide the shaft out. Push the axles inboard and slide out the 2 clips that hold the side gears in place. Pull the axles out of the car (don't let them rest on the seal).
Then you can wiggle the side and spider gears out.

Thanks, I may opt for that swap.

I did find a low-mileage SS rear (37K) and not sure on a good price. I can pick it up but it's a drive.....prob 6-7 hrs round trip. Not terrible but I may get it for $380-400. Includes rotors and calipers, 2007 model.

What do you think?

 

[gmcman]

Something I did notice in comparison to Hardtrailz' swap, there are gussets on my 8.0 and his was smooth, curious as to why that is.

Are there any clearances issues with a non-lifted envoy using the SS rear?

 

[HARDTRAILZ]

Rotors and calipers are the same on both.

Driveshaft will likely need shortened.

The SS only came with the g86 limited slip and 4.10s.

 

[HARDTRAILZ]

Not sure what gussets you are referring to but I had ground off some of the lower diff on rocks.

The 07 rear will have sensors on tubes near the ends that you dont need. Either figure on plugging them or get the sensors left in and cut wires off.

 

[gmcman]

Driveshaft will likely need shortened.

You stated your driveshaft was possibly too long, do you know how much shorter it needs to be? The 447 U-Joint from NAPA I assume it fits the stock shaft?

The SS only came with the g86 limited slip and 4.10s.

I thought so, he listed it as a locker but wanted to be sure.

 

[gmcman]

Not sure what gussets you are referring to but I had ground off some of the lower diff on rocks.

This is the pic I borrowed from your post.

 

[HARDTRAILZ]

That pic is the g86 carrier i believe. I replaced it w an open carrier...that was gusseted and more heavy duty...and a locker. I never opened up the 8.0 when i removed it.

I went 1.5 inches shorter based on driveline techs recommendation. Works great.

The 447 worked perfect w my stock steel driveshaft. I believe the earlier aluminum ones are the same.

 

[gmcman]

That pic is the g86 carrier i believe. I never opened up the 8.0 when i removed it.

Ok, I thought it was from the 8.0

A buddy of mine brought up another good point. How much lower does the 9.5 sit than the 8.0?

I already have stock ground clearance and not sure how much this will take away.

 

[HARDTRAILZ]

Not much. If you still have the swaybar back there you wont lose any cause its under the diff.

 

[NJTB]

Thanks, I may opt for that swap.

I did find a low-mileage SS rear (37K) and not sure on a good price. I can pick it up but it's a drive.....prob 6-7 hrs round trip. Not terrible but I may get it for $380-400. Includes rotors and calipers, 2007 model.

What do you think?

If you can get the side and spider gears, I would take a chance and put them in. Clean everything out real well and install them. At least it will buy you the time ro find a rear closer to home.

 

[gmcman]

If you can get the side and spider gears, I would take a chance and put them in. Clean everything out real well and install them. At least it will buy you the time ro find a rear closer to home.

I offered $350 so if he accepts then I will only be out $400 given fuel costs. If that does not work out then I will try the spider change.

 

[gmcman]

Not much. If you still have the swaybar back there you wont lose any cause its under the diff.

OK, I thought it may be significant, like maybe 3".

 

[HARDTRAILZ]

8.0 Mr. Roadie's Pic

8.6 Alek's Pic

9.5 My Pic

Maybe an inch at the most. The strength is more than worth it for me.

 

[gmcman]

Maybe an inch at the most. The strength is more than worth it for me.

Sweet, thanks.

Well, it's a done deal. TBSS rear for $350 and it has 37K miles, caliper to caliper :wootwoot:.....he even left the HD Bilsteins attached.

Dealer price on the 4 spiders was $440 and that was discounted. Granted I could have picked them up aftermarket but this is just one more area I don't need to beef up now unless the factory limited-slip is rather weak.

Which leads me to another question....how solid or "locked" for lack of better terms is the SS rear? Reason I ask is I have been spoiled with the G80 in snow and when I need both rears to grab or when pulling a trailer over uneven terrain, that extra grip is welcome.

 

[The_Roadie]

The SS has a (standard equip?) limited slip. Not a full locker. I think it has 3 or 4-to-1 torque bias. Better than nothing on snow for sure.

 

[HARDTRAILZ]

G86 limited slip standard.

If you keep your tires on the ground you may very well like it more than the g80 esp in snow.

 

[gmcman]

The last real limited-slip I have spent time with is what's in my 78' T/A.....so it has been awhile, maybe 10 years. I like it since it's very predictable when the surface gets slippery. I don't know how the newer crop compares but I'm sure it's similiar. I'm fairly certain the limited-slip in this SS rear will work fine but before I install it, I have been pondering also the Eaton Truetrac.

Does the Truetrac have more of a torque-bias than the G86, or how similiar or disimiliar are they? I can't imagine I will be unhappy with either I'm just doing alot of homework first. This definately won't be a crawler so I don't need a locked rear, much easier to swap with the axle out for sure.

 

[HARDTRAILZ]

I had to get new bearings...an open carrier...and a shim kit to do a locker. You may need that as well if swapping to a different limited slip

 

[Decembersend]

I don't know if I miss read this thread but I wanted to make sure you are aware that the SS has 4:10 gear ratio as Hardtrails said. Being that you have a 4x4 you'll have to change the front gear as well.

 

[Wooluf1952]

I don't know if I miss read this thread but I wanted to make sure you are aware that the SS has 4:10 gear ratio as Hardtrails said. Being that you have a 4x4 you'll have to change the front gear as well.

Post #4, he already has 4.10.

 

[Decembersend]

Post #4, he already has 4.10.

I did miss read lol