It’s a German made Getrag G80 3:73 LS. It came in the Solstice, Saturn Sky and many other cars including the Cadillac CTS . It was always a bit noisy and clunky in slow speed turns but has become much noisier especially when decelerating with no load. Under load it wasn’t noticeable at all. I took it to a transmission/differential shop and after a test drive was told it was more than likely the pinion bearing which from my research seems to be a common problem with these diffs. Getrag has since went out of business and the only source for these diffs is from salvage yards. I changed the diff oil last week with Redline 75w90 with the LSD additive already in the oil but with no Change in the noise. I did the figure eight routine in an empty parking lot and drove it about 10 miles with no change. I found a used G80 3:73 LS diff in Indiana from a Solstice/Saturn Sky yard that specializes in these cars for $600 shipped. It’s supposed to be delivered tomorrow by UPS per the tracking number. My question is if there is a procedure for preparing this used diff for the car like flushing it with say Valvoline, Supertech or whatever 75w90 LS after driving the car say, 25 miles or should I just add the Redline 75w90 and change it again after 5,000 miles? My local trusted father/son shop will be doing the work.
2008 Pontiac Solstice 36,000 miles : needs a differential
- Thread starter gman2304
- Start date
Magna PT is what they operate under now, maybe they can help. Canadian company.
If it's a common problem, what makes you think a used one is going to be any better? I would learn to ignore the noise or turn up the stereo until it becomes a real problem.
AZjeff
$50 Site Donor 2023
Good point but it's being delivered tomorrow. Might as well try it. The noise probably takes some of the fun out of a fun car.
I remember I had to replace the pinion seal on my 05 STS and retorque the pinion nut to something like 250 ft lbs.. Make sure yours isn't wet before you install. I also had to replace all the bushings that mounted the diff.. Those caused a good bit of clunking on acceleration/deceleration and when you shifted into drive or reverse.. I assume you've checked the bushings on yours, or maybe your diff was mounted differently? All the bushings also failed in the shift linkage itself and it would clunk and cause it to not be in the indicated gear.. That car was enough to make me not want anything GM for a long. long time.. Hope yours gets sorted.
Here was the part I replaced for the clunk:
https://creative-steel.com/shop/cad...-stsv-rear-polyurethane-differential-bushing/
Here was the part I replaced for the clunk:
https://creative-steel.com/shop/cad...-stsv-rear-polyurethane-differential-bushing/
I explained it in my OP. These diffs are no longer made, and used are about the only options left for these cars unless I have this one rebuilt which the diff shop I contacted said a rebuild would be around $3,000. I’ll take my chances on a used one with a 30 day warranty.
Good looking car! I always like those and the Saturns. Definitely check out the bushings when swapping a quick google implied these had some issues with them as well. I know it was very common on the cts/sts. Mine was bad at 8yo/80k.
AZjeff
$50 Site Donor 2023
Love the satellite dish on your country cabin. 
That is actually just an old house in SW Virginia just off the Blue Ridge Parkway that we stopped at to take the picture. The wife thought of it as being rustic.Love the satellite dish on your country cabin.
