GM 14-bolt FF Rear End with 149k miles
Hi to all, Our TV is a GMT400 1997 GMC K2500 7.4L Burb with 149k miles. It is 8-lug, 3.73, GVWR 8,600, with GAWR RR of 6,000 lbs for the full floater rear axle. We believe the rear end also has 149...
Forum Discussion
An update after taking the '97 K2500 burb to our local chevy dealership for rear end service.
They were happy to do a differential service but they would not add synthetic fluid. They said the synthetic fluid would cause the sealer to leak as the stock setup has no gasket. I mentioned installing a gasket, lube locker or felpro, but they would not install a gasket. They said that even with a main gasket installed the pinion gasket could leak. I can't be sure exactly why they wouldn't add the gasket, but it may be just because it wasn't gm standard service for my model year, and this dealership guarantees their work. I'll try to find out more in the next week or so.
My friend who is a tech there said that he can't put synthetic in his truck for the same reason and he pulls a 11,000 lb 5er with his truck. He said he has the same 14-bolt rear with G80 locker and his truck is either a 2005 or 2006. This surprised me since BurbMan's 2001 came with the synthetic. I wonder if the 2001 synthetic rear situation may be similar to the brakes on a 2000 K2500 we had for a while that had 4-wheel disc brakes that were only installed by gm for a few model years.
So now our burb 14-bolt has regular differential oil with no additive, and they concurred that no additive should be used on this differential since it has the mechanical locker. And when asked about the 2000 Astro, they said that the Astro has the smaller ring gear differential that has a clutch pack instead of the mechanical type, so it needs the additive.
For those of you who have installed a rear differential gasket to allow usage of the full synthetic, was anything done with either the pinion seal or the axle end seals?
Thanks,
Marty
They were happy to do a differential service but they would not add synthetic fluid. They said the synthetic fluid would cause the sealer to leak as the stock setup has no gasket. I mentioned installing a gasket, lube locker or felpro, but they would not install a gasket. They said that even with a main gasket installed the pinion gasket could leak. I can't be sure exactly why they wouldn't add the gasket, but it may be just because it wasn't gm standard service for my model year, and this dealership guarantees their work. I'll try to find out more in the next week or so.
My friend who is a tech there said that he can't put synthetic in his truck for the same reason and he pulls a 11,000 lb 5er with his truck. He said he has the same 14-bolt rear with G80 locker and his truck is either a 2005 or 2006. This surprised me since BurbMan's 2001 came with the synthetic. I wonder if the 2001 synthetic rear situation may be similar to the brakes on a 2000 K2500 we had for a while that had 4-wheel disc brakes that were only installed by gm for a few model years.
So now our burb 14-bolt has regular differential oil with no additive, and they concurred that no additive should be used on this differential since it has the mechanical locker. And when asked about the 2000 Astro, they said that the Astro has the smaller ring gear differential that has a clutch pack instead of the mechanical type, so it needs the additive.
For those of you who have installed a rear differential gasket to allow usage of the full synthetic, was anything done with either the pinion seal or the axle end seals?
Thanks,
Marty
