WTF? thought I had a warped rotor. Replaced it, but not the rotor? WTF?

[scouthead]

I was getting measurements all over the place, ended up with the drivers side of the axle sitting on a block on the concrete floor (so the backing plate wasn't ruined, as I don't have jackstands yet, never had a level hard surface to work on lol), with the dial indicator base sitting on the concrete, or even anchored to a 20 pound chunk of steel. Not only would the runout of the rotor move the indicator assembly enough to mess up the reading, but pushing up on the truck even with a finger was enough to induce thousandth's of "runout", as also was rotating the hub by hand.

.

Yeah the way I had things set up it was easy to push/pull and induce a false reading... like when a freind leaned on the truck and my dial inicator jumping around - "hey get off of there!"

Anyways, got one of the assemblies returned at a different shop, and it went from 13 thousandths out to 4-5 thousandths out. that is at least 1 thousandth better than the old rotor I took off... I'm giving up for the time being and installed everything. I'll check everything in a few thousand miles and see if it gets better or worse with use...
unless it doesn't work right at all, and then to hell with this P.O.S.

 

[dyeager535]

I feel your pain, although my problem is a bit different. Replaced spindles/ball joints/steering arm on one side, pulsing so bad when braking thought the lug nuts had come loose. Replaced the (leaking) steering stabilizer, and problem is minimal now, however I can feel it's still there as the brakes heat up.

With the tolerances that the rotors are supposed to be at, not sure measuring them on the vehicle is accurate enough, unless they are really bad, which I suspect mine are. No replacement in the 10 years I've had the axles, and they are probably original with the axle.

What REALLY doesn't make sense to me, is that the GM manual lists the runout of the wheel bearings...how can you accurately measure the rotor runout if there is runout from the bearings in the first place?

 

[4X4HIGH]

What REALLY doesn't make sense to me, is that the GM manual lists the runout of the wheel bearings...how can you accurately measure the rotor runout if there is runout from the bearings in the first place?

Remove all runout from the bearings then measure the rotor runout.

 

[dyeager535]

Makes sense. Then again, when adjusted to the specs given, they are already hard to rotate, can you even turn a rotor with all bearing play removed?

If the entire replacement of both rotors/hubs/bearings wasn't $300+, the work would probably be better spent simply replacing them all. I can see where testing this stuff can be cost effective.

 

[BAJA_BLAZER]

dont forget also , as time goes by brakelines can weaken and start collapsing inside so when you hit your brakes, they wont fully release. I have had two lines on different trucks do this.

You are being too annal, the run out isn't causing your brakes to pull (could cause pulsations in the peddle though) it is the hydrolic system that is causing the problem. $10 says it is old brake hoses, but I wouldn't rule out hanging Calipers.

 

[Greg72]

Holy Cow......! Ramsey, good to see you here!

It's been a while.