How to pull front hub?

alvocado · April 25, 2014

Is there enough clearance to pull the sensor wire out without removing the dust shield? It appears to pass through a gap in the shield so disconnect from the truck wiring and pull it through while removing the hub.

lunytnz · July 13, 2014

Is there enough clearance to pull the sensor wire out without removing the dust shield?

I thought about that, too, but then figured I'd have no way of getting the new one back in, where it belongs.

I talked to the local parts store (not a big chain store) and they suggested using MAP gas (saying it gets things quite a bit hotter than propane). So, I tried the MAP gas with the torch and hit it with a regular hammer (and a 3-lb sledge, as best I could--there's limited space) but it STILL would not budge with the impact wrench.

I think that means I'm done. I'm not up for drilling out the bolt or cutting it off with a torch. I think my next step is to see what a shop says and find out how lucky they are with whatever tricks they have up their sleeve. I'm afraid it might mean I have to replace the hub, as well as the sensor... we'll see.

06pirate · July 13, 2014

Do I understand you are heating the bolt? If so, that's the opposite of what you need. You need to heat the part that the bolt threads into, to expand that so it will help separate from the bolt threads. MAPP gas is better than propane because it will heat faster. Oxy-acetylene is best, but not everyone has that.

lunytnz · July 14, 2014

Good point, 06pirate, but, yes I was heating around the bolt (I believe that's the hub). This truck spent it's early years in Canada, where I think they used a lot more salt on the roads at the time. Maybe it just resulted in too much rust and corrosion. It will be at least a week before I can get it into the shop...we'll see what happens.

royesses · July 14, 2014

A striking wrench and 3-5 lb. sledge hammer will do the job.

lunytnz · July 14, 2014

A striking wrench and 3-5 lb. sledge hammer will do the job.

Is a striking wrench something like a big chisel with a flat nose?

royesses · July 14, 2014

Is a striking wrench something like a big chisel with a flat nose?

Think of a box wrench on one end and a large striking anvil on the other. Sort of a manual impact. You can google striking wrench for a photo and availability.

Justinlw · July 15, 2014

I'd guess an oxy/acetylene heat and beat is going to be your best bet. You can get a small plumbers set from harbor freight, or used from craigslist. If you learn to use one, you'll find tons of projects are easier with it.

Mossyoakglock · July 15, 2014

Did you hit the bolts with PB Blaster, WD40 etc?

lunytnz · October 3, 2014

Did you hit the bolts with PB Blaster, WD40 etc?

Ohhh... yeah. I finally gave up and took it to a local mechanic who does work on the side. He said it took all his impact wrench could give it, but the bolts finally broke loose. It was worth it, to me, to just get it done (at a reasonable price). He mentioned that he sprayed the PB stuff from the back side of the bolts, too (I hadn't thought of that).

BTW, I ordered a Timken hub off Amazon. The first one (SP500300) didn't fit my 99 Yukon. After plenty of research, I discovered that the SP550307 *does* fit the 99, but there is a left and right side version (the only real difference, I think, are the clips for the wheel speed sensor... so we were able to bend them and make them work). Apparently, the SP550307 is supposed to fit the Denali. The difference between the two hubs is the bolts go *through* the hub, from the outside, and thread into the control arm on my truck. The SP500300, the bolts go through the arm and thread into the hub, from behind, I think. Hope that helps someone else!

lunytnz · May 7, 2015

Just in case this helps someone else dealing with the same kind of problem… the ABS was still kicking on during sharp turns, so I decided to replace the other hub. Since the mechanic had been successful using just his impact wrench, I thought "I can do this!"… Wrong! I soaked it with PB Blaster (front and back), applied high heat using the MAP gas, and hit it (as best I could) with a hammer (though I did not go buy a striking wrench) and gave it all the impact wrench could give (highest setting and applied 150 PSI of air pressure). I couldn't get any of the three bolts to budge, so off to the local mechanic I went, again.

He said he had a special high torque impact wrench that could apply 1,000 foot-pounds of torque, but that still wasn't enough. So, he ended up using a 3-foot-long breaker bar and managed to get the bolts loose without breaking any of them off. So, it's do-able, but it definitely takes the right tools and know-how when things are rusted this much!

BTW, when I took the wheel speed sensor out of the old hub, I didn't see anything visibly wrong with it (I kind of expected it to be rusted, or something).

Cheers to lessons learned!

Nanotech Environmental · May 8, 2015

Just in case this helps someone else dealing with the same kind of problem the ABS was still kicking on during sharp turns, so I decided to replace the other hub. Since the mechanic had been successful using just his impact wrench, I thought "I can do this!" Wrong! I soaked it with PB Blaster (front and back), applied high heat using the MAP gas, and hit it (as best I could) with a hammer (though I did not go buy a striking wrench) and gave it all the impact wrench could give (highest setting and applied 150 PSI of air pressure). I couldn't get any of the three bolts to budge, so off to the local mechanic I went, again.

He said he had a special high torque impact wrench that could apply 1,000 foot-pounds of torque, but that still wasn't enough. So, he ended up using a 3-foot-long breaker bar and managed to get the bolts loose without breaking any of them off. So, it's do-able, but it definitely takes the right tools and know-how when things are rusted this much!

BTW, when I took the wheel speed sensor out of the old hub, I didn't see anything visibly wrong with it (I kind of expected it to be rusted, or something).

Cheers to lessons learned!

1000 ft lbs should have twisted the heads off those bolts, or broke them free. I'm pretty sure his impact wasn't putting out as much as he thought. Those bolts are only about 5/8" or so in diameter. Even at the highest grades, bolts that size won't withstand 1000 ft lbs.

He probably only put about 400-500 ft lbs max on them with the 3' breaker bar. (Say 150 lbs of arm strength x 3 feet) I had to do that on mine the first time I did them. They are put on tight at the factory.

1000 ft lbs is a LOT of torque. I've only torqued bolts to that degree once in my life and that was on 2" or 2.5" dia bolts used to assemble a big clutch used on a big stamping press. I think we had to go to 1200 ft lbs or something like that. It took several guys with torque multipliers, leverage bars and big torque wrenches. And a lot of time, as there were something like 20 bolts to do.

Mapp gas isn't usually hot enough to loosen rusted bolts. An acetylene torch is better as it gets about 2-3 times as hot as Mapp gas.

The key when replacing these hubs is to clean all the mating surfaces and give those surfaces a liberal coating of anti seize before reinstalling the new hub. Otherwise the damn hub rusts to the hub mount and you need an air chisel to separate them.

Also, the 3 bolts that hold the hub on, need red loctite when reassembling and torqued to something like 180ft lbs. (IIRC) The red loctite will keep the threads from rusting. You need to ensure it seals both the top and the bottom of the bolt that sticks thru the hole.

Do that, and they come off easy next time, with just a burp of a 1/2" impact.

This is why I don't take my truck to a shop, as they can't be bothered to properly reassemble stuff.