Looking for a Web site as to Why Wheels may fall off

[Petersubaru]

I have found sites that mention cleaning the mateing surfaces of the hub/rotor/wheel, but no real reason is given as to "why" this must be done...my son-law is being a bit of an a** and insists that I am being overly cautious and thinks that tightening the wheel nut "tighter" is an easier solution then removing the corossion...now every 200miles there is one nut that seems to loosen up..

[CNY_Dave]

I have found sites that mention the cleaning the mateing surfaces of the hub/rotor/wheel, but no real reason is given as to "why" this must be done...my son-law is being a bit of an a** and insists that I am being overly cautious ..

 

 

I keeps the wheel from wobbling from rust or crud buildup.

 

I have to imagine the buildup would have to be pretty insanely thick for there to be risk of losing a wheel.

 

 

Dave

[CNY_Dave]

I have found sites that mention cleaning the mateing surfaces of the hub/rotor/wheel, but no real reason is given as to "why" this must be done...my son-law is being a bit of an a** and insists that I am being overly cautious and thinks that tightening the wheel nut "tighter" is an easier solution to removing the corossion...now every 200miles there is one nut that seems to loosen up..

 

 

Now I see your newer reply (we were both typing at once) and yeah, clean that sucker!

 

Tightening the lug nuts won't help, and if you have a loosening lug nut because the wheel won't sit straight, or the corrosion is collapsing with the pressure, you must clean it.

 

I've worked as a mechanic, and as a licensed NYS car inspector, so now you can tell the little whipper-snapper you are backed by a professional opinion.

 

 

Just how thick *is* this corrosion?

 

 

Dave

[Rooster2]

When I remove a road wheel, I clean up the surface of where the road wheel bolts to the hub. I smear antisieze on the hub, where the back of the road wheel facing meets up, as well as on the threads of the lug bolts.

 

I don't use a torque wrench as the tire stores do, but I do make it a point of retightening the lug bolts a couple of days after driving. Seems like there is always just a tiny bit of looseness that needs to be tightened up. This is especailly true when tightening bolts when using alloy wheels.

[Petersubaru]

Now I see your newer reply (we were both typing at once) and yeah, clean that sucker!

 

Tightening the lug nuts won't help, and if you have a loosening lug nut because the wheel won't sit straight, or the corrosion is collapsing with the pressure, you must clean it.

 

I've worked as a mechanic, and as a licensed NYS car inspector, so now you can tell the little whipper-snapper you are backed by a professional opinion.

 

 

Just how thick *is* this corrosion?

 

 

Dave

how thick, I don't know, but it is more then oxydation on metal and I can feel it with my nail plus the wheel itself has crud build up...the problem of crud build up increases rapidly when changing wheels between summer and winter and back to summer wheels

[aircraft engineer]

The stuff you feel is thin. When the wheel goes onto the hub, the shearing will make the surface mate quite well. IF you clean your wheel lugs, the nuts will spin right on if lubed a bit (if acorn nuts the studs shouldn't corrode anyway since they are behind a "cap")

 

I spray the studs and the insides of the nuts with WD-40 anyway and then use a torque wrench to get the final tightness (75 IIRC).

 

IF you have crud on the studs, take a wire brush to them. Clean the hub flange if you want and the inside of the wheel flange, too with the brush if you wish (but taking off the paint tends to make them rust a bit)

 

There was a discussion about "hub centric (where the hub carries the wheel load) versus "lug centric" (where the lugs carry the wheel load) From a practical standpoint, it doesn't make that much difference except for mounting the wheels - easier to mount hub centric because the nuts can be spun down without needing to re-position the wheel to seat all of the cones.

 

If you have that much crud, I'd wonder what ELSE had a lot of rust, too. It sounds like you don't have the same wheels for summer/winter tires. Like mine - a mix of alloy and steel (1 set of each)

[forester2002s]

I spray the studs and the insides of the nuts with WD-40 anyway ...

Be aware that if you lubricate the threads, you may end up with a much higher stud tension than is intended. This is because lubricated threads make it easier to turn the nut, given a specific torque.

Or to put it another way, you may be applying the correct torque, but might be overstressing the studs.

 

In the absence of any instructions to the contrary, it is always best to apply a specified torque to CLEAN and DRY threads.

 

My Subaru Factory Service Manual says:

- "Fasteners must be tightened to the specified torque.

Do not apply paint, lubricant, rust retardant, or other substances to the surface around bolts, fasteners, etc.

Doing so will make it difficult to obtain the correct torque and result in looseness and other problems."

[aircraft engineer]

not really - torques are developed with lubricated bolts/nuts. (At least that's the way WE do it)

 

Actually, torque is a sideways indicator of "bolt stretch" which is based on the "turn of the nut" (and the ramp angle of the thread calculated to provide the stress on the bolt.)

 

Wheel lugs won't have that overstress problem as long as you use a torque wrench

[forester2002s]

not really - torques are developed with lubricated bolts/nuts. (At least that's the way WE do it)

 

Actually, torque is a sideways indicator of "bolt stretch" which is based on the "turn of the nut" (and the ramp angle of the thread calculated to provide the stress on the bolt.)

 

Wheel lugs won't have that overstress problem as long as you use a torque wrench

Are you suggesting that WE (who?) should do it differently than Subaru recommends?

[Petersubaru]

The stuff you feel is thin. When the wheel goes onto the hub, the shearing will make the surface mate quite well. IF you clean your wheel lugs, the nuts will spin right on if lubed a bit (if acorn nuts the studs shouldn't corrode anyway since they are behind a "cap")

 

I spray the studs and the insides of the nuts with WD-40 anyway and then use a torque wrench to get the final tightness (75 IIRC).

 

IF you have crud on the studs, take a wire brush to them. Clean the hub flange if you want and the inside of the wheel flange, too with the brush if you wish (but taking off the paint tends to make them rust a bit)

 

There was a discussion about "hub centric (where the hub carries the wheel load) versus "lug centric" (where the lugs carry the wheel load) From a practical standpoint, it doesn't make that much difference except for mounting the wheels - easier to mount hub centric because the nuts can be spun down without needing to re-position the wheel to seat all of the cones.

 

If you have that much crud, I'd wonder what ELSE had a lot of rust, too. It sounds like you don't have the same wheels for summer/winter tires. Like mine - a mix of alloy and steel (1 set of each)

summer and winter wheels are both alloy..you wonder what else has rust on it??....well, you can see the rust oozing out thru the caliper stud holes, and I suppose this is to be expected since the car sat outside for a year or so in very damp weather... also I think there is rust behind the rotors thus pushing it out and creating a feel at the pedal of warped rotors ...according to the mechanic (dealership) he said all 4 rotors are warped and is more like a nuisance then a safety issue, ...one wheel/rotor has no free play(spin) at all...I wonder what would happen if a panic stop would occur at 75mph

[jamal]

warped rotors come from unevenly torquing the lug nuts, which it sounds like has been happening with your car. It's also probably the reason some of the nuts come loose. Clean the studs off with a wire brush, torque to 65-80lb-ft, and you won't have to worry about anything.

 

warped rotor tech paper:

 

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml