GKN Visco Lok LSD - Disc Pump Seals

[SirPancake]

I'm in the middle of rebuilding the OE GKN LSD. Unfortunately some of the seals within the viscous pump are damaged, but they don't seem to be of any standard I've seen before. Has anyone ever sourced/replaced these?

[bigjae46]

Nope. If you’re using the racing diffs kit it supposedly doesn’t rely on the viscous unit since it has a large Belleville spring. I’d verify that.

not sure if a compromised seal in the unit would cause other issues

[sapote]

Nope. If you’re using the racing diffs kit it supposedly doesn’t rely on the viscous unit since it has a large Belleville spring. I’d verify that.

Does this mean the large spring shim locking up the clutch stack all the time, including when turning? I think the spring shim is not so strong and allows the clutch slipping when turning, and this means the LSD still needs the pump piston to press down the clutch when one wheel spinning.

[sapote]

I'm in the middle of rebuilding the OE GKN LSD. Unfortunately some of the seals within the viscous pump are damaged, but they don't seem to be of any standard I've seen before. Has anyone ever sourced/replaced these?

Do you find out why the pump splined center is hard to rotate relative to the housing? How much torque needed to turn the pump?

[maupineda]

Nope. If you’re using the racing diffs kit it supposedly doesn’t rely on the viscous unit since it has a large Belleville spring. I’d verify that.

not sure if a compromised seal in the unit would cause other issues

How could this be, the viscous coupling unit is what locks the clutches. The shim just preloads the system, but speed differential is what makes the pump to work and provide the locking function.

my logic is that a bad seal would empty the viscous unit and then is just an open diff.

i maybe wrong though, but that is my understanding.

[bigjae46]

How could this be, the viscous coupling unit is what locks the clutches. The shim just preloads the system, but speed differential is what makes the pump to work and provide the locking function.

my logic is that a bad seal would empty the viscous unit and then is just an open diff.

i maybe wrong though, but that is my understanding.

Racing Diffs mentions this in the DIY video. Maybe I misunderstood what they were saying…

[sapote]

Racing Diffs spring shim is for taking out the spider gears backlash to avoid the clunk, but it can't take the place of the shear pump which compresses and locks the clutch together when the wheel's spinning.