What are the dots on spider gears for - 1999 Chevrolet Silverado 1500

Hey Jim, pick out the one that is like yours..

BLACK SHELLED SPIDER WHITE DOTS ON THE SHELL Google Search

Fully rebuild, or partial rebuild? Pinion, ring, spider gears, pumpkin, bearings? Rebuilding it FULLY and PROPERLY is a big story, one too big to relate here, and it takes quite a lot of special tooling (differential spreader, dial indicators, etc). Please don't attempt this unless you have a well equipped shop.

If you just need to replace the spider gears, that's easy. Drain the oil, remove the cover, rotate the pumpkin until you can unbolt the crosspin. Push/pull the crosspin out, rotate the spider gears until they come out. Remove the side gears. Remove all four thrust washers.

Replace all four thrust washers, then the new side gears, then mesh the new spider gears with the side gears & rotate them into place. If the crosspin hole won't line up, rotate one axle shaft until it does. Install the new crosspin and bolt it in. Replace the cover gasket and cover, refill.

Going further requires a LOT more work, but you'll need to remove the spider & side gears first anyway. If you're replacing bearings or the pumpkin or the ring & pinion, you'll need a bunch of new shims to work with until you can get the ring-pinion clearance exactly right. You'll also need a differential spreader to get enough space to remove/install the pumpkin with its bearings in place. If you're replacing the pinion gear, you'll need to take some painfully exact measurements or you'll NEVER get the ring/pinion clearances correct.

The differential pin may be worn due to possibly getting stuck and excessive spinning has caused the spider to route out the pin, the excessive play could be caused from the slack between the worn pin and the spider gear. Take the differential cover off and observe this as you play with the slack.

new spider gears or possibly u-joints in your rear drive shaft. Or it could just be a cheap rear i have a jeep and its done it since i first bought it.

What is the problem?

The side gears can only go one place,
they have the axle splines

The spider gears get retained by the pin

Drop them in & rotate the side gears

spider gears are in the rear differential on this car. there is a gear on each axle and two other gears between them. This allows the wheels to rotate at different speeds, as what happens when you take a turn. If you didn't have this the wheels would bounce or chuck going around turns

I accidentally rotated the spider gears out when putting a new axle seal on a 04' F-150. I didn't have the tool to compress the clutch packs so I removed the differential carrier and took it and the spider gears down to the local Ford dealership and they put them back in for $20.

I am asuming that you mean the crown and pinion gear in the rear differential?

There is no "Spider Indicator", but the fuel injection system is sometimes referred to as a spider assy because it has a central unit with individual legs (hoses) going to each cylinder. There are also gears in the differential housing that are reffered to as side or spider gears.

It's not easy to put them back, but if you get the side gears in position with the axles bumped out as far as you can, the smaller spider gears can be "walked" into place. Try having your buddy rotate one of the wheels slowly until each one fits in. It's tricky but you'll get it.