I'm about to go thru and swap in a full-floating diff form a 1 ton into my C2500, and am curious what a good fluid spec should be for one of these.
Diff Fluid for 14 Bolt Full-Floater
- Thread starter KenO
- Start date
- Status
GM's Dexron LS (75W90). One of the better gear lubes out there. I use it in the my TrailBlazer SS' 14 bolt.
Mobil 1 in the right viscosity.
Originally Posted By: NHGUY
Is the gear ratio the same? Your speedo may be off.
Speedo is driven off the trans, so no it won't. But, I'm going from a 3.73 to a 4.10. Spoke to my tuner (truck has an 0411 PCM swap and custom tune) and he said the shift points should be the same between both gears, so he said I should be a-ok to just swap.
Is the gear ratio the same? Your speedo may be off.
Speedo is driven off the trans, so no it won't. But, I'm going from a 3.73 to a 4.10. Spoke to my tuner (truck has an 0411 PCM swap and custom tune) and he said the shift points should be the same between both gears, so he said I should be a-ok to just swap.
Any quality synthetic 75W90 will get the job done.
synpower 75w90? its relatively cheap too, im running it in my car now and it seems great.
Originally Posted By: KenO
Originally Posted By: NHGUY
Is the gear ratio the same? Your speedo may be off.
Speedo is driven off the trans, so no it won't. But, I'm going from a 3.73 to a 4.10. Spoke to my tuner (truck has an 0411 PCM swap and custom tune) and he said the shift points should be the same between both gears, so he said I should be a-ok to just swap.
IF the speedo is driven from a VSS on a FRONT wheel, the rear end ratio doesn't matter, but if from the transmission it does.
Originally Posted By: NHGUY
Is the gear ratio the same? Your speedo may be off.
Speedo is driven off the trans, so no it won't. But, I'm going from a 3.73 to a 4.10. Spoke to my tuner (truck has an 0411 PCM swap and custom tune) and he said the shift points should be the same between both gears, so he said I should be a-ok to just swap.
IF the speedo is driven from a VSS on a FRONT wheel, the rear end ratio doesn't matter, but if from the transmission it does.
Amsoil 75w110 is one of the best out there.
The speedo would need a calibration to compensate for the new axle ratio.
Any old 80W90 would suffice for lubrication. 14 bolts are stout and not picky.
Any old 80W90 would suffice for lubrication. 14 bolts are stout and not picky.
Originally Posted By: HerrStig
Originally Posted By: KenO
Originally Posted By: NHGUY
Is the gear ratio the same? Your speedo may be off.
Speedo is driven off the trans, so no it won't. But, I'm going from a 3.73 to a 4.10. Spoke to my tuner (truck has an 0411 PCM swap and custom tune) and he said the shift points should be the same between both gears, so he said I should be a-ok to just swap.
IF the speedo is driven from a VSS on a FRONT wheel, the rear end ratio doesn't matter, but if from the transmission it does.
Good point. I'll double check with him on this. Thanks!
Originally Posted By: KenO
Originally Posted By: NHGUY
Is the gear ratio the same? Your speedo may be off.
Speedo is driven off the trans, so no it won't. But, I'm going from a 3.73 to a 4.10. Spoke to my tuner (truck has an 0411 PCM swap and custom tune) and he said the shift points should be the same between both gears, so he said I should be a-ok to just swap.
IF the speedo is driven from a VSS on a FRONT wheel, the rear end ratio doesn't matter, but if from the transmission it does.
Good point. I'll double check with him on this. Thanks!
MolaKule
Staff member
As I sated in another thread, an E-P additive is needed to prevent galling and wear of the drive pinion, ring gear, and axle bearings.
What you need in a hypoid differential is a lubricant that has a protection level of GL-5 with a PI package that has an Extreme Pressure (E-P) additive.
As others have recommended, you need to use a 75W90 or 75W110 lube such as a Lubricant Engineer's or Amsoil gear lube.
What you need in a hypoid differential is a lubricant that has a protection level of GL-5 with a PI package that has an Extreme Pressure (E-P) additive.
As others have recommended, you need to use a 75W90 or 75W110 lube such as a Lubricant Engineer's or Amsoil gear lube.
Last edited:
The speedo is driven from the VSS in the tranny.
It will need the speedo recalibrated. It will read slow by about 10%.
But, thats besides the point.
Honestly, the abuse those things survive is amazing. And gear oil will work. Just make sure that if it has a G80 you don't use limited slip friction modifiers because the clutches are designed to work without it, and will actually slip with it. For this reason I avoid vavoline full synthetic since it includes limited slip formula.
I had my yukon apart the other night and autozone had mobil 1 85w90 for $10/quart. Not too expensive when the cheapest was still $7/quart.
But, thats besides the point.
Honestly, the abuse those things survive is amazing. And gear oil will work. Just make sure that if it has a G80 you don't use limited slip friction modifiers because the clutches are designed to work without it, and will actually slip with it. For this reason I avoid vavoline full synthetic since it includes limited slip formula.
I had my yukon apart the other night and autozone had mobil 1 85w90 for $10/quart. Not too expensive when the cheapest was still $7/quart.
Last edited:
Originally Posted By: chevy_man
It will need the speedo recalibrated. It will read slow by about 10%.
But, thats besides the point.
Honestly, the abuse those things survive is amazing. And gear oil will work. Just make sure that if it has a G80 you don't use limited slip friction modifiers because the clutches are designed to work without it, and will actually slip with it. For this reason I avoid vavoline full synthetic since it includes limited slip formula.
I had my yukon apart the other night and autozone had mobil 1 85w90 for $10/quart. Not too expensive when the cheapest was still $7/quart.
Ya, Walmart has gallons of Supertech gear oil for like $12. Do we think thats adequate??
It will need the speedo recalibrated. It will read slow by about 10%.
But, thats besides the point.
Honestly, the abuse those things survive is amazing. And gear oil will work. Just make sure that if it has a G80 you don't use limited slip friction modifiers because the clutches are designed to work without it, and will actually slip with it. For this reason I avoid vavoline full synthetic since it includes limited slip formula.
I had my yukon apart the other night and autozone had mobil 1 85w90 for $10/quart. Not too expensive when the cheapest was still $7/quart.
Ya, Walmart has gallons of Supertech gear oil for like $12. Do we think thats adequate??
Originally Posted By: KenO
Ya, Walmart has gallons of Supertech gear oil for like $12. Do we think thats adequate??
I use it in everything. Has always served me well, even in racing applications.
Ya, Walmart has gallons of Supertech gear oil for like $12. Do we think thats adequate??
I use it in everything. Has always served me well, even in racing applications.
dnewton3
Staff member
Originally Posted By: Zaedock
14 bolts are stout and not picky.
Correct.
Any GL-5 rated hypoid gear oil will suffice just fine.
Use syn's if you expect greatly extended OCIs.
Any grade from 75-90 up to 80-140 and any reasonable option in between.
14 bolts are stout and not picky.
Correct.
Any GL-5 rated hypoid gear oil will suffice just fine.
Use syn's if you expect greatly extended OCIs.
Any grade from 75-90 up to 80-140 and any reasonable option in between.
Fantastic, thanks everybody!
- Status
