I was having some pulsating when braking on my 1997 GMC K2500 Suburban (6.5L turbo diesel, 3/4 ton, 4×4). I hadn’t seen the brakes on this truck yet, so I put it up on four jackstands and pulled the wheels. The drums, rotors, shoes and pads all looked good. I was pleasantly surprised to see that the brake pads on the rear matched an extra set that I had ended up with that were too large for my other Suburban, a 1993 K2500 Chevrolet (5.7L gasoline, 3/4 ton, 4×4). To investigate further, I decided to pull the rotors.
As I would later learn, not only is this really hard on the 8 lug 8600GVW GM trucks, but I had already learned this lesson from the other Suburban, but had forgotten.
- Loosen lugs
- Loosen axle nut
- Jack vehicle and secure with stands
- Remove lugs and axle nut
- Remove four 15mm bolts that hold the hub to steering knuckle *** READ BELOW ***
- Pull hub off axle
- Remove ABS sensor from hub, or disconnect from frame rail, if attached
- Knock out lug studs from plate, being very careful not to damage the threads
- Separate plate, disc rotor and hub
- Installation is reverse of removal
Be extremely careful remove the four 15mm bolts. These are special bolts and cost five to seven dollars at a dealership each. They are torqued very high. I would strongly recommend dousing them in PB Blaster at least 24 hours in advance. Removal will require a long cheater bar. Use only high quality six point sockets. Take the time to either turn the steering wheel for each pair of bolts, or remove the tie rod ends.
I had three that would not budge. Heat did not help. A mild impact wrench did not help. Soon enough the bolt heads started to round off. “Bolt extractors” were laughably useless. In the end, I used special left-handed cobalt drill bits to drill the heads off the bolts. I started small and worked up to the size of the bolt just beyond the head, which is a little larger than at the threads. Thus I was careful to check my depth. I used progressively larger drill bits until I was able to remove the remains of the heads using an extractor.
Once the hubs was separated and I was able to remove it from the vehicle, I applied additional penetrating lubricant overnight. The next day I was able to break two of the bolts using a vise on the hub and a vise grip on the bolt. The remaining bolt wouldn’t budge. I went to my metal shop and tig welded a piece of angle iron to bolt remnants, headed the bolt and tried to use the leverage, but only ended up bending the angle iron. Then I cut the bolt off and drilled it out, but still could not get the bolt threads outs. I kept adding heat until I started to damage the hub. Lacking the correct size tap, and having damaged the hub, I replaced this hub altogether.
I happened to have a spare ABS sensor for this truck, due to getting the wrong one when working on the aforementioned previous truck. This was good, because when I had remove the sensor from this hub, the plastic around the pickup coil broke off. Ultimately, I suspect this sensor was all I had to replace to resolve my symptoms. However, due to the design I had to remove the rotors to get to it, so I put on new rotors and pads while I was able to.
This is to the person who did the 8600GVW disc rotor replacement.
OMG that’s a ton of work. I have a 97 3/4 ton Suburban with 123k. ABS sensor causing anti-lock brake dash light to come on once rolling. This may become an inspection sticker issue, necessitating a similar task. I’m a machinist, so I have good metallurgy understanding. The last guy who I paid to replace the rotors a few years back, put the same 15mm bolts back in that he butchered taking out, leaving me with a problem now. I tested the integrity of the bolt heads, sprayed w/PB 24hrs before & shocked the bolt head tops with a ball peen hammer. Used 6 point socket & 22″ break bar, no dice, heads started to roll over, so I’m thinking junk yard. Perhaps I can ask them to torch off two decent whole assembles. I could take a chance on the ABS sensor & bearing, saving some cash, if the donor truck mileage is low. I’d do the bench work, pressing out studs, new rotors & ABS wheel bearing/sensor assemblies, if necessary. Then pay labor to someone better equipped to swap them. I’m thinking about $800 in parts (maybe less)and $400-$500 labor. Calipers and pads are new, so they can hang during the swap. May not even need front end alignment if the mechanic is sharp. What do you think? This way may be a bit more costly then your route. However, my back never hits the ground.
Thanks for any advice you may have.
When the four steering knuckle to hub bolts come out, it is a pretty easy job provided you know the steps. That is, as long as you know that you have to remove the entire hub via those four bolts, it looks less like a solid unit with irremovable disc rotors.
Part of me was tempted to make it someone else’s problem. But if they knew what they were doing and weren’t going to trash the front end, I’m sure they’d charge both a high, albeit fair, price.
If I had to do it again, I’d find out the bolt sizes and get a tap beforehand. It isn’t too hard to drill the heads off the bolts to remove the assembly from the truck, just time consuming. I used special left-handed cobalt drill bits, but I imagine you could use regular bits but take it really slow to avoid breaking off a bit in the bolt. If had the tools to drill and tap the holes and knew I might have to do that beforehand, I probably could have saved the hub.
Other than getting the bolts out, there isn’t a lot of work. If you pay someone get the bolts out, might as well have them slap it back together when they’re done. The hardest part is that you’ll need between zero and eight of the expensive bolts and you won’t know until they get to it. Most mechanics are used to working that out with the dealers though.
Good to hear you finally got it done Bryan. Did you solve the problem of a pulsating pedal and did you replace the front discs?
I did replace the front rotors + pads. The pulsating pedal is gone, but I’m pretty sure the drivers side front ABS sensor was bad and thus the cause.