How to: K2500 front rotor / disc replacement - 8 lug, 4x4

[WarWagon]

Here is what I found when I did mine.

The torque for the axle shaft to hub nut has been revised several times over the years. For an 8 lug 4x4, it's 177 lb/ft. About double that of the average 1/2" impact wrench. The nut, according to the manual, should NOT be reused (although I have on several necessary occasions). The hub on a 4x4 MUST be torqued before bearing the full vehicle weight. The nut supports the bearing. A 2wd can be torqued after the weight of the vehicle is on the bearing, as it is fully supported with or without the nut.

I use the 1/2" impact wrench to sock it down, install the wheel/tire, then lower the tire to the ground enough to prevent turning. Then, put the full torque on it.

If you replaced the hub, the hub to knuckle bolts are torqued to 133 lb/ft, the sensor mounting bolt is 13 ft/lb, and the caliper mounting bracket to knuckle is 221 ft/lb.

Drop the rig into 4x4 with the parking brake on. Or put the caliper on and have a friend stand on the brakes. Do not put any vehicle weight on a 'loose' bearing to tighten it.

It is difficult to wrap your head around this, but, the 4x4 hub is two separate parts The half shaft spindle nut is on one side while the shoulder on other side of the splines are holding the back of the bearing in. Think of the standard 2WD tapered bearings with the nut setting the 'clearance'. (And do you know anyone that sets wheel bearing clearance with an impact?) Any load on the bearing spreads the bearing apart and loosens it up. You can have a new bearing that feels sloppy and it tightens up when you put the nut on the half shaft. Because it is a critical part of the bearing the TQ used on the half shaft nut is Critical!.

Do not run the bearing without the half shaft in. In an emergency just put the splined part in and TQ that down. (I have seen this done.) Otherwise the bearing is sloppy and ruins the bearing and other things.

Impacts like the 3/4 drive one uses to take the nut off could overtighten and destroy the bearing.

 

[GM Guy]

Excellent writeup WW, will be referring to this when I do the front bearings.

 

[jrsavoie]

find the other threads on upgrading to the newer style steering knuckle and hub. So you do not have to pull the bearing to change the rotors. I wish I had done that to mine as I went.

 

[WarWagon]

How to: K2500 lug replacement - 8 lug, 4x4

Yes, you can replace a stud without pulling the spindle. PO had a wheel come loose ruining the lugs and the rim. I used the big impact to snap one locked up lug nut off.

Anyway it's only required to remove the brake caliper to access the lugs. (Yes there is a jack stand under the truck in addition to the jack.)



Note the nut used as a spacer to tighten the lugs in and two left in at all times to keep things together.

 

[jrsavoie]

So instead of a bigger hammer, Snap-On make this cool little air hammer thing. Knocks out 8 lugs in about 16 seconds.

View attachment 34777

I have one of those, but all I have left is the long skinny chisel.

Where can a guy get tools for it?

Do other brands interchange?

https://store.snapon.com/Air-Hammer-Bits-and-Accessories-C629266.aspx

 

[Will L.]

Yes all brands interchange. Harbor freight ones don't hold an edge long, but for blunt driving like this work great. Just be sure to remove "mushroom head" from the end as they wear just like you would a hand chisel.

I learned long ago, invest in a really strong air hammer that is not too bulky. all the attachments for them, you will use it frequently. straight hammering, metal cutting, pickle fork attachment, fanclutch bolt, etc.