4wd Hub Replacement

[Schurkey]

I realize this is a super old question, but it's a sticky and I needed to know this info too. So here is the GM part number for the bolts. The were $7/ea at my local Chevy dealer, which is cheaper than any website I could find (with shipping).

GM Part no. 15995614

Works for 6-lug hubs. Not correct for 8-lug hubs as far as I can tell.

I don't have a GM part number for 8-lug hub bolts (yet) but the Dorman number is 917-508, and they come as a 4-pack for one price.

www.amazon.com/Dorman-917-508-Bearing-Mounting-Bolts/dp/B01ID3U2W6/ref=sr_1_1?dchild=1&keywords=917-508+Dorman&qid=1635008045&sr=8-1

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As you might guess, I'm doing hub work on my 8-lug truck...harsh language ensues soon, photos and description later.

 

[Schurkey]

1997 K2500 8-Lug Hub--Remove, Repair, Replace
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Vehicle: 1997 K2500 8600 GVW
Other K-series 8-lugs similar, I guess. Verify with the service manual for your vehicle.

My goal for this procedure was to replace the LF wheel speed sensor. Replacing either the brake rotor or the hub (which involves splitting the rotor from the hub by pressing out the wheel studs (Probably Dorman 610-332, but verify 'cause I haven't pulled mine apart yet) would have been additional work.

Photo 1. Wheel removed, brake caliper and hose bracket removed, (temporarily parked on top of upper control arm.) Upper control arm with bushings and ball joint replaced a year ago. Outer CV joint retaining nut removed (36mm deep impact socket, not shown.) I generally try to wire-brush the loose rust off the end of the CV joint before removing the nut; but it'll come off even without.

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Initial intention is to remove the four bolts (15mm hex heads) retaining hub to steering knuckle. These bolts are known to be difficult to remove. Using a 1/2” impact wrench, 1/2” drive universal joint for clearance to the outer CV joint, and a quality 6-point impact socket resulted in no movement. I tried a 3/4” impact wrench, 3/4-to-1/2 inch adapter, the U-joint and socket...and began rounding the corners of the bolt heads. This was obviously not going to suffice. I made the decision to pop the three tapered-studs (lower ball joint, upper ball joint, and tie rod end) free, remove the cable guides for the wheel speed sensor, disconnect the sensor at the frame, and just drop the steering knuckle with hub and rotor on the floor where I could access the bolts easier.

This also meant removing the six bolts holding the CV shaft to the output flange on the front differential, and then wiggling the CV shaft out-of-the-way. The upper ball joint stud has to be popped free of the steering knuckle to get the CV shaft out of the hub, before the knuckle can be released from the lower ball joint stud. CV shaft ends up "trapped" between sway bar end-link and shock absorber--but it's out of the way enough to finish this task.

Photo 2. Suspension minus steering knuckle.

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Photo 3. Hub with rotor and dust shield, removed from suspension. Four "difficult" bolt heads plainly visible.

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Photos 4 and 5. Hub bolt head damage. Two bolts unthreaded with impact wrench and six-point impact socket, although the heads were damaged in the process. They won't be re-used. Two more bolts needed “special attention”.

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At the limit for photos. Continued below.

 

[Schurkey]

Photo 6. My hero. Sort of. I could heat the threaded hub flange around one bolt hole, but the other hub flange bolt hole was not accessible with the torch. God bless Oxy-Acetylene.

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Photo 7. Since the proper, 15mm impact socket would no longer grip the two remaining bolt heads, I abused a 9/16 six-point impact socket by pounding it over the damaged heads with a big hammer and harsh language. Again, I needed the 3/4” impact, adapter, and that pounded-on socket to remove the last two bolts. If this hadn't worked, I was considering welding 1/2” nuts (3/4” socket size) to those two bolt heads, then using a 3/4” impact socket.

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The first bolt had to be pounded back out of the 9/16 socket. The second one wouldn't pound out, I had to use a bearing separator, a punch through the square-drive end of the socket, and a hydraulic press to push the bolt out.

Photo 8. Having removed the four bolts, I then found that the hub was rusted-stuck in the knuckle. I applied anti-seize to the old bolts, put them back in leaving a little clearance between the bottom of the head, and the knuckle. Then I beat the bolts inward with that big hammer. As the bolts were pounded in, the hub was pushed out. I'd back-off the bolts to regain some clearance, and beat them some more. This eventually pushed the hub far enough out of the knuckle that I could remove the bolts and wiggle the hub free.

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Photo 9. Rusted hub, and the speed sensor that is the cause of this disassembly.

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Photo 10. Damaged speed sensor harness—worn through by rubbing on dust shield.

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At the limit for photos, continued below.

 

[Schurkey]

Photo 11. The speed sensor can be removed and replaced without splitting the rotor from the hub. This saves time, money, effort, and enthusiasm. This is my big “short cut”. Splitting the rotor from the hub involves pressing the lug-studs out; the lug studs “rivet” the rotor to the hub. I think this design is insane. Ideally, new lug studs are installed rather than the originals. Sensor bolt uses 5mm Allen wrench, then “wiggles” out of the hub. Grease the new sensor and O-ring before reinstalling. The bolt is anti-seized to prevent future problems. Spec is 13 ft/lbs, but a) that's without anti-seize on the threads (which would lower the torque required), and b) there's no room for a torque wrench anyway. Get it snug, and don't obsess.

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Photo 12. Knuckle has had a solvent bath. Emery cloth removed most of the rust in the hub-hole. The seal could be replaced, I did not. I inspected the seal, it seems OK, so I cleaned it up, re-greased it with ordinary chassis grease, then put a thin film of grease on the hub hole.

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Photo 13. Hub polished with emery cloth and wire brush to remove rust. Lightly greased where it slides into knuckle. Hub now slides into knuckle easily. Get the dust shield and the sensor harness in proper position before sliding the bolts down the holes. Dorman 924-374 is the number for replacement dust shields. Mine was "OK" but not great.

I apply anti-seize to the threads of the new bolts (Dorman 917-508) and reduce the “official” torque spec to 80% due to the lube on the bolt threads. Spec is 133 ft/lbs, I use 107 (80%) with anti-seize.

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Clean up the part of the outer CV joint where it goes into the grease seal and hub. Degrease the ball joint and tie rod end studs, and clean the tapered holes they go into. Upper ball joint stud nut torques to 74 ft/lbs DRY. Lower ball joint stud nut torques to 94 ft/lbs DRY. Insert cotter pin. If cotter pin notches don't align, tighten additional to align for cotter pin (Not more than 1/6 turn.) Tie rod end stud nut torques to 46 ft/lbs DRY. Caliper bolt torque is 38 ft/lbs. 6 bolts on inner CV joint at 58 ft/lbs, big nut on outer CV joint at 165 ft/lbs.

But wait! There's MORE!

 

[Schurkey]

Photos 14 and 15. As long as I have the knuckle off anyway, I might as well pop in a lower ball joint. It's not totally wiped-out, like the uppers were—but it's at the end of it's service life; looser than it should be. It's never going to get any easier.

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Photo 16 and 17. I used a “Powerbuilt” 23-piece ball joint press. This was a “Loaner Tool” set at Autozone. There are many other brands and styles of ball joint presses, with fewer or more included accessories.

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Adapter used is 3rd from left, top row.

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GREASE the pressure screw, and for FiretrUCK's sake, use an impact wrench on the press, not a ratchet. Folks ruin these BJ presses because they use a ratchet and cheater-pipe, which turns the screw but also puts enough side-force on the C-clamp to bend it. The impact wrench turns the screw with no side-force to tweak the C-clamp.

And that's as far as this project has progressed. Give me a few days to get the new BJ installed, and to see if the ABS works for the first time since I've owned the truck (almost 3 years, but probably ~500 miles.)

 

[Schurkey]

I cleaned-up the hole in the control arm with emery cloth. There's "green goo"; some sort of anaerobic press-fit locking chemical that's applied to the new ball joint housing before it's pressed into the hole in the control arm.

Photo 18. Anaerobic compound applied to ball joint housing.

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The instruction sheet provides some conflicting information about the BJ alignment. On the one hand, the grease zerk needs to be aligned with the recess provided in the control arm. On the other hand, the new-style rubber boot for the ball joint has an arrow on it saying to "Install Inboard"; that's the vent that allows excess grease to escape rather than rip the boot--and they want it away from the brake rotor. Aligning the grease vent inboard made the zerk inaccessible. I guess I'll just be careful when pumping the silly thing with fresh grease...

Pressing the BJ into the control arm is a two-stage process. The ball joint press is not big enough to do it in one "squeeze". I used a very thin adapter on the pressure-screw side to get it started, then switched to a taller adapter so I was assured that the ball joint housing wouldn't interfere with the first, thin adapter as it was pushed through the control arm. The lower adapter is the same throughout the installation process.

Photos 19 and 20. The different adapters used with the ball joint press, as the BJ is crammed into the control arm. (First photo posed while I was still assessing which adapters to use, I haven't gooped-up the ball joint with the anaerobic locking compound yet.)

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With the ball joint shoved in, I needed to install the grease zerk, and align the cotter-pin hole so that it's easily accessible. An awl shoved into the hole allows rotating the stud so that the cotter pin is easy to get to.

Photo 21. Still need to tighten the grease zerk, cotter pin hole moved for better access.

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Once all that is done, it's just a matter of pumping grease in, and reassembling "everything". Some folks are insistent on performing an "alignment"; but I figure that if everything up front is in good condition--new ball joints, serviceable control arm bushings, untouched but decent tie rod ends, etc. the alignment is going to be just as the factory built it--unless the vehicle's got collision damage. If anything is worn-out, various alignment angles could be "off"; and if there's bent parts--frame, control arm, etc--the alignment could be "off".

In my case, I still have to pop in the other lower ball joint (next-summer project) and I'll replace all four tie rod ends at that time. Maybe the idler arm. So the alignment is going to wait awhile.

I expect to put ~200 miles or less on this truck over the winter. It's main purpose is to push the snow-plow around my driveway. My goal for this project has been achieved--the ABS light is out, and the ABS seems to work. I made a hard stop with the left wheels on pavement, and the right wheels on the gravel shoulder. ABS rattled, I could feel vibration in the pedal. But that doesn't mean all three channels of the ABS module are working. Time will tell--I'll find out when the roads get icy.

Next big project: Inspect rear brakes, install TrueTrack differential carrier.

 

[454cid]

Wow, Shurkey, that fought you all the way. The first time I pulled my hubs I deformed several of the 8 bolts, but I didn't have that much trouble. I tapped the 15mm socket on with a brass hammer before cranking on them. I think I replaced at least 6 of them, maybe all 8. I got new bolts from the dealer, but this was 2007... at that time they were not expensive at all. I tried removing one of the sensors and broke it, though.

 

[Schurkey]

Those four bolts fought me, and I had some trouble getting the CV axle free of the flange on the front differential. The hub was stuck in the knuckle more than I expected. Everything else went pretty good.

I broke a wheel speed sensor on my Trailblazer trying to get it removed. They may be plastic, but they still "seize" in the hole. The O-rings should be higher up on the sensor to keep the top part of the hole from rusting.

This truck needed the wheel speed sensor on the LF. The RF really ought to get a fresh brake rotor, and also a lower ball joint. So--someday, perhaps next spring--there'll be photos of me pounding-out the wheel studs to free-up the rotor. And then popping the new studs back in. I already own the wheel studs, and ordered the four hub bolts earlier today.

I should replace the sway bar bushings while I'm in there...and the idler arm...and...

 

[454cid]

Those four bolts fought me, and I had some trouble getting the CV axle free of the flange on the front differential. The hub was stuck in the knuckle more than I expected. Everything else went pretty good.

I said I deformed them, but now that I think about it, I think a few of them had thread issues...rust maybe?

This truck needed the wheel speed sensor on the LF. The RF really ought to get a fresh brake rotor, and also a lower ball joint. So--someday, perhaps next spring--t

Yes, getting wet and cold now.... that's no time to be working on vehicles unless you've got a nice heated garage! I'm usually in the driveway.

 

[Supercharged111]

Alrighty, you've confirmed that my laziness thus far on the dually is justified. I had the LCAs out last fall to do bushings, ball joints were still good and tight, but my LF wheel speed sensor is also junk. While the rotors aren't warped, I would prefer to replace them as they have 16X,*** on them and I'm about due for pads again. While I won't (*shouldn't) fight as hard as you did it's still a PITA. I'm really surprised there wasn't even more brown in there.