SOLVED! 97x 8.6 LSD Is my Rear End Toast?

Pygot

Silver Supporter
Recently bought a 2008 Saab 9-7x with 142k. I was doing the rear diffential service (10 bolt 8.6 w/LSD) and noticed when on the lift the LSD was failed ( both wheels spun opposite directions) probably due to the terrible maintenance by the previous owners. The rear diff fluid was black, foamy and aerated and gave every impression of never having been changed in its whole life. Lots of terrible noises when putting the car into reverse on the lift, although this could be due to the transmission I fear. I guess my question is should I wait to see if the LSD will function as normal with new fluid as my mechanic seems to think it OR look to replace the rear end or what specific parts I could buy to rebuild it. Note: I will be pulling it apart again soon this week (2/18/2020) as I need to replace the pinion seal on the rear diff as well, and my parts guy screwed me and got the wrong gasket so I had to use the old one for a couple days until the new one comes in tomorrow (2/19/2020)
Thanks!
 

Maverick6587

Silver Supporter
Is there any play in the ring gear? I JUST did my rear diff fluid change twice because mine was as bad as yours seems to be, completely black. I changed the fluid two weeks ago and got the diff as clean as I could. Changed the fluid again Saturday (along with the seals and bearings) and it was still completely black!

Did you also put the limited slip fluid additive in the rear diff along with a quality 75W-90 oil? Do you have any pics of the gears? I attached a pic of how mine looked during the cleaning two weeks ago.
IMG_20200201_201245.jpg

If you're replacing the pinion seal you might as well do the bearing seals (maybe the bearings with it?). AWD is tricky when it's not actually moving on the ground. When I have mine on the hoist it does NOT like front or rear wheel drive with the wheels off of the ground. IRC, I think my wheels spun in opposite directions as well. I'm sure someone else can better explain the AWD functionality. If there's very little to no play in the ring gear, I think you're ok. I beat on mine pretty hard and it has 230k miles on it and there is almost zero play in that ring gear.

That transfer case is known to go bad so, make sure you change that fluid soon as well. Only use ACDelco/GM Auto Trak II fluid.
 

TollKeeper

Well-Known Member
Have to confirm he has a G86 LSD. I know 90% of the Saabs got them. But I have run into 2 of them at the salvage yard that DID NOT.

Check your RPO sheet and verify it has the G86. I have never seen it on a Saab, but see if it even has a G80 RPO code too.
 

Maverick6587

Silver Supporter
@TollKeeper Good call. Both of mine are G86 with an 8" diff. From his post he has the 8.6" diff, he is probably in that 10%.
 

Mooseman

Moderator
And who knows if it may have been replaced with a G80 because the original G86 got blown. Check the glove box and then open the diff to visually confirm. If it's a G80 that's there, it may be OK as it's normal to act like it is now. It can be tested.

 

TollKeeper

Well-Known Member
@TollKeeper Good call. Both of mine are G86 with an 8" diff. From his post he has the 8.6" diff, he is probably in that 10%.
The 8.6 should mean he has the V8. Which to me, one would think it was an "upscale" model, and should have the G86. But GM being GM, who knows! LOL
 

Maverick6587

Silver Supporter
@TollKeeper I actually just learned my lesson on that! My 06' has the 4.2i and the 07' has the 5.3. Without looking, I went and bought the 8.6" gasket. Quickly found out I was wrong. The 5.3 at least in my 9-7x still has the 8" rear diff and is also the G86.
 

waSAABi

Member
My 06 97x has the G86. When I bought this vehicle it had a number of issues with the AWD binding. The front and rear were both binding in tight turns with some moaning coming from the diff. Did a quick search here and found a TSB for this condition and the G86. Here ->Forum page

I opened up the diff and like yours was black! I cleaned everything up, reused the fancy gasket and filled with the DEXRON® LS gear oil, P/N 88862624 and ran it through as per the TSB. I am happy to report that it has been smooth as silk since the fluid change without any leaks, so yes this gasket is reusable.

Yes, my G86 will turn both wheels in the same direction when off the ground and in neutral. Just another note, these AWD systems don't like to be off of the ground and ran, I did it and it lit the cluster up like a xmass tree.
 

TollKeeper

Well-Known Member
Well back to the OP @Pygot , I would do exactly as your mechanic suggested, but take it a step further. You have changed the fluid once, drive it for 500-1000 miles, and change the fluid again. This way you can get all the gunky buildup that may be in there out.

Some oils DO NOT have the LSD Friction Modifier additive for the LSD. Im hoping you checked the label for it, or added it as well.
 

HARDTRAILZ

Moderator
@TollKeeper I actually just learned my lesson on that! My 06' has the 4.2i and the 07' has the 5.3. Without looking, I went and bought the 8.6" gasket. Quickly found out I was wrong. The 5.3 at least in my 9-7x still has the 8" rear diff and is also the G86.
That would be the first stock V8 to have an 8.0.
 

Maverick6587

Silver Supporter
Great! Well, there's an excuse for an "upgrade".
 

HARDTRAILZ

Moderator
True!

Are you sure it is factory and not a rear stick under it later?
 

Maverick6587

Silver Supporter
I have no idea at all. I bought it a month ago at 228k miles. Someone could have changed it at some point from a junkyard. It's not a huge deal though. Glad to know that I can put a bigger diff on it (that's supposed to be there anyway).

I assume there is no relearn needed for the pcm/tcm with the gear size change, since it's only reading wheel speed?

:hijack: (still related though)
 

Mooseman

Moderator
I assume there is no relearn needed for the pcm/tcm with the gear size change, since it's only reading wheel speed?
If it's an 06 or later. Before that, the single rear speed sensor was at the tranny or transfer case tail shaft. May affect AWD function in any case.
 

Maverick6587

Silver Supporter
@Pygot Were you able to replace the pinion seal and take it for a test drive?
 
OP
OP
Pygot

Pygot

Silver Supporter
Have to confirm he has a G86 LSD. I know 90% of the Saabs got them. But I have run into 2 of them at the salvage yard that DID NOT.

Check your RPO sheet and verify it has the G86. I have never seen it on a Saab, but see if it even has a G80 RPO code too.
It says 8.6 on the rear end I have pu
True!

Are you sure it is factory and not a rear stick under it later?
No
 
OP
OP
Pygot

Pygot

Silver Supporter
So I replaced the pinion seal today and part guys screwed me again. He got me a pinion seal that was 74mm instead 70 mm.... needless to say today was long. Rear differential fluid was black after ~600 miles of driving (7 days) since I pulled it apart. Fortunately the LSD has started working again, the rear wheels both spun the same direction on the lift which did not happen previously. I believe the lack of fluid may have caused the failure? I will be pulling it apart for round 3 in april to replace both the pinon seal and the diff cover gasket, as I got screwed on both parts and want to replace them with new parts (although miraculously neither are leaking right now).
@Pygot Were you able to replace the pinion seal and take it for a test drive?
Is there any play in the ring gear? I JUST did my rear diff fluid change twice because mine was as bad as yours seems to be, completely black. I changed the fluid two weeks ago and got the diff as clean as I could. Changed the fluid again Saturday (along with the seals and bearings) and it was still completely black!

Did you also put the limited slip fluid additive in the rear diff along with a quality 75W-90 oil? Do you have any pics of the gears? I attached a pic of how mine looked during the cleaning two weeks ago.
View attachment 93219

If you're replacing the pinion seal you might as well do the bearing seals (maybe the bearings with it?). AWD is tricky when it's not actually moving on the ground. When I have mine on the hoist it does NOT like front or rear wheel drive with the wheels off of the ground. IRC, I think my wheels spun in opposite directions as well. I'm sure someone else can better explain the AWD functionality. If there's very little to no play in the ring gear, I think you're ok. I beat on mine pretty hard and it has 230k miles on it and there is almost zero play in that ring gear.

That transfer case is known to go bad so, make sure you change that fluid soon as well. Only use ACDelco/GM Auto Trak II fluid.
So the wheels actually started working today which was interesting (they spun the same direction on the rear end) so maybe fixed for now? Also for the transfer case it also had every impression of no maintenance ever and has about 1000 miles on it wth theac delco autotrak and liqui moli ceratech additive. The fluid looked really good no filling needed.

@Pygot Were you able to replace the pinion seal and take it for a test drive?
Yes! So far no leaks but parts guy got wrong size seal so I will be pulling it apart again in april!

Well back to the OP @Pygot , I would do exactly as your mechanic suggested, but take it a step further. You have changed the fluid once, drive it for 500-1000 miles, and change the fluid again. This way you can get all the gunky buildup that may be in there out.

Some oils DO NOT have the LSD Friction Modifier additive for the LSD. Im hoping you checked the label for it, or added it as well.
I use Redline 75w-90 and it comes with the friction modifier also Liqui Moly Ceratech. LSD is now functioning normally on the lift. In april I will be pulling it apart to do it all over again bc parts guy got me the wrong size stuff

Have to confirm he has a G86 LSD. I know 90% of the Saabs got them. But I have run into 2 of them at the salvage yard that DID NOT.

Check your RPO sheet and verify it has the G86. I have never seen it on a Saab, but see if it even has a G80 RPO code too.
The rear differential cover says that 8.6, idk if that is correct but can confirm the LSD on the rear has started working.

If it's an 06 or later. Before that, the single rear speed sensor was at the tranny or transfer case tail shaft. May affect AWD function in any case.
This was something I was considering if the LSD didnt start working after replacing the fluid which, fortunately, it has !

And who knows if it may have been replaced with a G80 because the original G86 got blown. Check the glove box and then open the diff to visually confirm. If it's a G80 that's there, it may be OK as it's normal to act like it is now. It can be tested.

I have opened the differential and it has LSD springs, and functions as a locking diff while moving like in the video above after replacing the fluid. I should've taken pictures of how low the fluid was before changing.. probabky 1/4 of what it shouldve had black and foamy.

The 8.6 should mean he has the V8. Which to me, one would think it was an "upscale" model, and should have the G86. But GM being GM, who knows! LOL
I believe most saabs came with the 8.6 even models with the 4.2L like mine. Can confirm the LSD is now working
 
OP
OP
Pygot

Pygot

Silver Supporter
So I replaced the pinion seal today and part guys screwed me again. He got me a pinion seal that was 74mm instead 70 mm.... needless to say today was long. Rear differential fluid was black after ~600 miles of driving (7 days) since I pulled it apart. Fortunately the LSD has started working again, the rear wheels both spun the same direction on the lift which did not happen previously. I believe the lack of fluid may have caused the failure? I will be pulling it apart for round 3 in april to replace both the pinon seal and the diff cover gasket, as I got screwed on both parts and want to replace them with new parts (although miraculously neither are leaking right now).



So the wheels actually started working today which was interesting (they spun the same direction on the rear end) so maybe fixed for now? Also for the transfer case it also had every impression of no maintenance ever and has about 1000 miles on it wth theac delco autotrak and liqui moli ceratech additive. The fluid looked really good no filling needed.


Yes! So far no leaks but parts guy got wrong size seal so I will be pulling it apart again in april!


I use Redline 75w-90 and it comes with the friction modifier also Liqui Moly Ceratech. LSD is now functioning normally on the lift. In april I will be pulling it apart to do it all over again bc parts guy got me the wrong size stuff


The rear differential cover says that 8.6, idk if that is correct but can confirm the LSD on the rear has started working.


This was something I was considering if the LSD didnt start working after replacing the fluid which, fortunately, it has !


I have opened the differential and it has LSD springs, and functions as a locking diff while moving like in the video above after replacing the fluid. I should've taken pictures of how low the fluid was before changing.. probabky 1/4 of what it shouldve had black and foamy.


I believe most saabs came with the 8.6 even models with the 4.2L like mine. Can confirm the LSD is now working
Now I am not sure bc the pinions seal my guy ordered is for the 8.6 so maybe I do have the 8.0?
 

Maverick6587

Silver Supporter
Do you have your rear differential cover off? If so, can you attach of picture of the gasket?
 
OP
OP
Pygot

Pygot

Silver Supporter
Do you have your rear differential cover off? If so, can you attach of picture of the gasket?
I do not have it apart rn but will takes pics next time I take it apart in april. Rn nothing is leaking after resealing the pinions seal and diff cover gasket so I am leaving it for about a month
 

Maverick6587

Silver Supporter
The 8.6 in diff has a circle gasket (the blue gasket) while the 8 in has an out of round shape (the black gasket).

61dWYqoWfrL._AC_SL1500_.jpg41I+23eGelL._AC_.jpg
 
OP
OP
Pygot

Pygot

Silver Supporter
I have the 8 inch then for sure that is the gasket I pulled off... anything to know about this vs the 8.6? I believe mine has an LSD
 

Maverick6587

Silver Supporter
The gearing is not my forte. Just make sure there is very little to no play when attempting to move the ring gear.

Maybe someone else has information on the gearing or LSDb side of things.
 

Reprise

Lifetime VIP Supporter
Here's a site with a little bit of info on the GM 8 in. differential:

I don't agree with the images they post of it, but the written info / specs look correct.
Was surprised to find that there was some aftermarket support for it (thx to the Hummer products that got it, according to the site)
 

HARDTRAILZ

Moderator
I did not think the 8.0 got a G86 LS, but got the G80 locker. The G86 was 8.6 and 9.5 I thought.


I can only imagine what someone will think when they look in my glovebox at codes then find a 9.5 with an open carrier and lunchbox locker and a 4.10 front diff under it since it says it is an 8.0 w G80 and 3.73.
 
OP
OP
Pygot

Pygot

Silver Supporter
So they rear end does say g86 on the cover and I can take a pic. The gasket matches the g80 with the 3.73 tho (after ordering wrong gasket see above).
 

Maverick6587

Silver Supporter
I'm thinking all gmt360 AWDs are G86 and 8in?
 
OP
OP
Pygot

Pygot

Silver Supporter
I'm 99.5% sure my Olds Bravada (AWD) is G80 in 3.73. Full locker.
Does it say g80 or g86 on the rear diff cover? Bc mine SAYS g86 but is definitely an 8in bc it uses that gasket.
Update: After 2 weeks of driving the pinion seal and gasket are not leaking amazingly. I had used the old gasket and seal (big no no but had wrong parts). Will be pulling apart in 3 weeks to update and change these out
 

Mooseman

Moderator
It might be saying 8.0. I know that the replacement diff I got for my Saab with the V8 said 8.6 on the cover. The cover was rust free enough to read it clearly as 8.6.
 
OP
OP
Pygot

Pygot

Silver Supporter
It might be saying 8.0. I know that the replacement diff I got for my Saab with the V8 said 8.6 on the cover. The cover was rust free enough to read it clearly as 8.6.
I honestly would not be suprised if my car had a replacement rear end considering the maintenance history
 

HARDTRAILZ

Moderator
I would like to see the G86 on the cover.

The gasket has nothing to do with G80/G86/or fully open. The gasket is affected by the ring and pinion size, not the slip options.
 
OP
OP
Pygot

Pygot

Silver Supporter
I would like to see the G86 on the cover.

The gasket has nothing to do with G80/G86/or fully open. The gasket is affected by the ring and pinion size, not the slip options.
I can tell you for a fact that I have a 70mm pinion seal bc I pulled it out and measured it w/ a caliper. Also I got parts for an 8.6 which was 74mm. Very hard to tell apart. No pics of ring sorry april will have some when I do service.
EDIT: Outer diameter of the pinions seal* =70mm
 

HARDTRAILZ

Moderator
Cool. You said you could take pics of the G86 on the cover...
So they rear end does say g86 on the cover and I can take a pic. The gasket matches the g80 with the 3.73 tho (after ordering wrong gasket see above).
None of that has anything to do with a quick pic of cover.
 

TequilaWarrior

Well-Known Member
I'm just going to put this out there because I think there's some confusion regarding the difference between G80 and G86:
From the RPO Compendium:
G86 - Limited Slip Rear-Axle
G80 - Locking Differential Rear-Axle
If I read this correctly, G80 and G86 have absolutely no relation to the ring gear diameter but are options for the differential STYLE (locking vs limit slip). An extension to this would be that the STYLE has nothing to do with the seal diameter or the cover gasket shape/size.

Does anyone know if G80 and G86 are BOTH available in 8.0 and 8.6?
 
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HARDTRAILZ

Moderator
No one knows according to what is posted with the obvious confusion of what is what...I still think the G86 was not offered in an 8.0 Still have never seen proof in over a decade of this platform.

They were both available in the 8.6 for sure.

The G86 was a far less common option across the platform.

The discussion really needs cleaned up due to the ross-contamination of terminology and options.

8.0 8.6 9.5 are independent of the G80 or G86 or Open internals.

Pinions/gaskets/ring gears/lug pattern/gaskets(which should just be RTV) sure as hell do not determine the open or slip options.
 

Maverick6587

Silver Supporter
Here are my RPO codes from my 06' and 07' 97x's. As well as a pic of the diff from the 07' 97x. I do not have a picture of the covers. I might be able to grab one after work though.

Both the 06' and 07' have limited slip with 8 inch differentials (they both used the 8 inch gasket).
Just trying to help with any confusion I may have caused. Let me know if any other information is needed from the limited slip side of things.

2006 9-7x RPO Codes.jpg 2007 9-7x RPO Codes.jpg 2007 9-7x Rear Diff.jpg

EDIT: Found a pic of the 06' rear diff and cover.
2006 9-7x Rear Diff.jpg 2006 9-7x Rear Diff Cover.jpg
 
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