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

[scouthead]

So my blazer has been pulling to the right for a while. It pulled just a little, but all the time.
Then my brakes started to squeel a bit and it would pull harder while braking. So i took a look at the brakes, everything looked O.K. until I stuck a dial indicator on the rotor and turned it. Off by 6 or 7 thousandths of an inch. So my rotor is warped, right?
Bought a new rotor, and it's off by 13 thousandths??! Crappy rotor?

So I took the rotor back off, wire wheeled the back of the hub, cleaned the rotor and reassembled. Still of by 11 thousandths.
Then I match marked the rotor and hub, took the rotor off, and spun it 180 degrees on the hub.
THe high spot is following the same spot on the hub - ?? The rotor appears to have nothing to do with it.

Can the backside of the hub warp?

I pulled off the driver's side wheel just to stick the dial indicator on that rotor for comparison... within 1 thousandth of an inch.
So it is possible for the rotor to spin true to the spindle...
I have a couple extra hubs laying around so I mounted one up with a different (used) set of wheel bearings. It did not have a rotor on it, so I measured the back of the hub, on the rotor mounting surface. This one was off by 2 or 3 thousandths on the hub...
What's going on here?

I want my hub and rotor to spin straight and true so I can be sure nothing is dragging and causing/ contributing to the pull to the right side...

Any thoughts here?

 

[4X4HIGH]

You need to mount the new rotor to the hub THEN have it machined true. There are going to be people that will argue this point with me but as you can see the rotor is crooked and needs to be machined while it is attached to the hub which is the new center that is perpendicular to the spindle. I have been machining brake rotors for 22 years and anyone that says or thinks differently is crazy.

 

[la-zdunck]

for the $25, i'd put on a new caliper to be sure that isn't your problem.?.

 

[RudyO]

Just as a point- I always have new rotors machined before installation. Just because they are new does not mean they are true.

 

[scrappyk5]

for the $25, i'd put on a new caliper to be sure that isn't your problem.?.

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.

 

[Stomis]

Sound like you have a bent spindle to me.

 

[jtrapani]

your flux capacitor may have defecated on your scuzzy input. If you have twice pipes it can get hot and warp stuff. This is easily remedied by a double dipstick. If you don't fix it you could blow your kenetic thruster.

 

[scouthead]

your flux capacitor may have defecated on your scuzzy input. If you have twice pipes it can get hot and warp stuff. This is easily remedied by a double dipstick. If you don't fix it you could blow your kenetic thruster.

Oh well, my truck can sit in my driveway laid up all weekend, but at least I got a good laugh out of it now.

 

[scouthead]

You need to mount the new rotor to the hub THEN have it machined true. the rotor is crooked and needs to be machined while it is attached to the hub which is the new center that is perpendicular to the spindle. .

Ah HA! This is what I have been thinking... My 90 Burb is a 3/4 ton and the hub and rotor is one piece cast together. So the hub and rotor have to be machined together. Unfortunately nobody nearby can cut a rotor like this...

Another question -
How do they "chuck up" a rotor and hub together to cut the rotor? Is it usually by the lug studs? or through the spindle axis somehow? Reason I ask is because if it's by the studs, then I want to assemble everything on whichever hub has the straightest wheel mount surface... Right?

 

[4X4HIGH]

Brake rotors that aren't a "drop off" style are set up on the bearing races so that they are machined perpendicular to the spindle centerline.

Where and what is H. B. (Humboldt) California?

 

[scouthead]

Brake rotors that aren't a "drop off" style are set up on the bearing races so that they are machined perpendicular to the spindle centerline.

Where and what is H. B. (Humboldt) California?

O.K. Being set up on the bearing races seems to be the way it SHOULD be done... I'll have to make a few calls.

And H.B. is Huntington Beach (Surf City USA - and no, I don't surf)

 

[4X4HIGH]

O.K. Being set up on the bearing races seems to be the way it SHOULD be done... I'll have to make a few calls.

And H.B. is Huntington Beach (Surf City USA - and no, I don't surf)

Huntington Beach, makes sense now.

Just take a short vacation and drive north about 6.5 hours and i'll take care of it for you.

 

[scouthead]

Huntington Beach, makes sense now.

Just take a short vacation and drive north about 6.5 hours and i'll take care of it for you.

Boy I wish I had done that! It would have saved me time and money!

Just had my rotors turned and... They're worse!
they were turned while attached to the hub, took 'em home, slapped 'em on...
The one that was 6 thousandths off is now 13 off, and the one the one that was 11 thousandths off is still 11-13 thousandths off. What the **** happened here?! I have swapped between several sets of wheel bearings on each hub/rotor assembly and it doesn't change anything. It is definately the way the rotor is mounted in relationship to the spindle axis.

At least I didn't pay too much for the rotor cutting, but now I have 2 new rotors that are both missing a decent amount of metal, and nowhere near as straight as the ancient one still mounted on the driver's side of my axle!

I am actually looking forward to going to work tomorrow...


A litter of puppies and Mary Poppins herself couldn't put me in a better mood right now.

 

[4X4HIGH]

The offer still stands when you're tired of goofing around with shops in your area.

Obviously the shop did not use the proper set-up or make sure the rotor/hub assembly was running true before they machined it.

 

[cybrfire]

What method did you use to apply the studs? BFH or press?

 

[scouthead]

The offer still stands when you're tired of goofing around with shops in your area.

Ha. Sweet - Roadtrip!

Obviously the shop did not use the proper set-up or make sure the rotor/hub assembly was running true before they machined it.

Yeah... I'll try somebody else tomorrow or tues. There's enough meat on the rotors to try again (but not too many times more!)

 

[scouthead]

What method did you use to apply the studs? BFH or press?

first BFH and then some extra lug nuts drenched in oil tightened against a spare wheel - aka "GHETTO PRESS"


Those things are really on there, and both mating surfaces are spotless, but I'll tell my local guy to hit them with the press before he turns them just in case. (he wasn't open today or yesterday)

 

[scouthead]

A litter of puppies and Mary Poppins herself couldn't put me in a better mood right now.

well, ttrhree glasses of firestone are doing a pretty good job

 

[CHEVYDADDY]

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.

for the $25, i'd put on a new caliper to be sure that isn't your problem.?.

2X this!

 

[dyeager535]

May or may not be applicable, but without a GOOD attachment method of measuring, and the front end sitting on jackstands, it's impossible from what I've found to get a valid reading. If I had a base that would actually clamp physically to the axle/backing plate, etc., instead of using a not strong enough magnetic base, I might give it another try.

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.

I said forget it, and will either throw on a set of hubs/rotors that are on the other truck that are a known commodity, or simply buy new hubs/rotors, assembled, probably OEM at rockauto.com.