Brake disc / Wheel corrosion

[cmsusllc]

I'm changing tires, cleaning and painting wheels,etc and was wondering what should be done about the corrosion between the steel brake caliper and the cleavland wheel? I've cleaned everything up and sprayed corrosion x on the wheel. What else, if anything should be done? Yes George I've checked the fourms but don't find anything.
Thanks again. Scott.....53B

[hungstart]

Is the corrosion on the wheel or the disk? If it is on the wheel you are going to have to determine if it is within limits after you have removed it. If you don't kill it, remove all of it, it will continue to grow and eventually cause failure of the wheel half. The disk will have limits also, but they are usually more liberal than the wheel is. I will look in the manual and see if I can find some limitations on corrosion. After you are finished you will need to replace the surface finish on the wheel usually a FR primer and a top coat of paint.

Rick

[hungstart]

From the Clevland manual; AWBCMM0001-7.3/USA

Replace any cracked or excessively corroded parts. Small nicks, scratches, or pits may be
blended out and polished with fine sandpaper. Treat and repaint per paragraph 4. Brake and
Wheel Refinishing. Figure 308

For the brake disk:
Inspect brake disc for cracks, excessive wear, or scoring, mounting hole elongation, corrosion,
and warpage. Remove corrosion and blend out small nicks using fine (400 grit) sandpaper.
Replace brake disc if worn below wear limits detailed in Appendix A. Coning of disc in excess
of 0.015 inch (0.381 mm) is cause for replacement. Ref. Figure 309.

Heat created during braking promotes the development of corrosion and pitting at the flange
to cup area. Annually, or on condition, sandblast these areas or use a wire wheel to remove
corrosion and pitting. Treat affected areas with zinc chromate primer and a coat of heat
resistant spray paint. Heat resistant paints may be locally procured from auto parts supply.
NOTE: Corrosion, if left unattended will result in decreased service life of the part.

Wheel refinishing:
C. Surface Pretreatment
All cast products are to be surface pretreated after any nicks, dings, corrosion, or other discontinuities
have been mechanically removed. It is necessary to know the cast alloy material such that the
proper treatment can be performed. Both aluminum and magnesium alloy casting are used in
products at Cleveland. Refer to A3. Brake Assembly Back Plate Tie Bolt Torque and A4. Wheel
Assembly Torque Values table for material identification.
(1) Aluminum parts should have a protective barrier between the topcoat and base material. It is
recommended they be treated with conversion coating per MIL-C-5541, Class 1A (Alodine).
NOTE: Alodine is ineffective on magnesium.
(a) Apply solution liberally and evenly. Allow it to set from 1 to 5 minutes. The solution must
completely wet the surface and overlap onto the adjoining anodize.
(b) Remove excess coating by flushing with clean water.
SAFETY WARNING : RUBBER GLOVES AND EYE PROTECTION SHOULD BE WORN
WHEN MIXING AND APPLYING THIS SOLUTION. CARE SHOULD
BE EXERCISED TO PREVENT SKIN CONTACT. WASH EXPOSED
AREAS IMMEDIATELY WITH COLD WATER AND SOAP.
(2) Magnesium parts may be treated with surface pretreatment per MIL-M-3171, Type VI, Chromic
Acid or Oxsilan®.
NOTE: MIL-M-3171 Type VI is ineffective on aluminum and Oxsilan® is currently not being
used on aluminum specified applications.
MIL-M-3171 Type VI (for use on parts with a dull bronze to bright gold surface treatment
appearance).
(a) Apply mixed solution liberally at room temperature and allow to dry. Parts may be
dipped for 1/2 to 2 minutes in solution at room temperature.
(b) Remove excess coating by flushing with clean, cold water.
(c) Dry in oven or hot air. Never rinse in hot water.
(d) Alternate option would be to re-coat with Oxsilan® (see instructions below).
Oxsilan® (for use on parts with a clear to irridescent surface treatment appearance).
(a) Scrub surface with an abrasive material such as Scotchbrite pad.
(b) Rinse surface with water.
(c) Wipe excess water with clean cloth.
(d) Spray with a liberal amount of Oxsilan® so that the entire scrubbed area is saturated.
(e) Let stand for 5 minutes (to expedite the drying process, a mild airflow source can
be used).
C. Surface Pretreatment
All cast products are to be surface pretreated after any nicks, dings, corrosion, or other discontinuities
have been mechanically removed. It is necessary to know the cast alloy material such that the
proper treatment can be performed. Both aluminum and magnesium alloy casting are used in
products at Cleveland. Refer to A3. Brake Assembly Back Plate Tie Bolt Torque and A4. Wheel
Assembly Torque Values table for material identification.
(1) Aluminum parts should have a protective barrier between the topcoat and base material. It is
recommended they be treated with conversion coating per MIL-C-5541, Class 1A (Alodine).
NOTE: Alodine is ineffective on magnesium.
(a) Apply solution liberally and evenly. Allow it to set from 1 to 5 minutes. The solution must
completely wet the surface and overlap onto the adjoining anodize.
(b) Remove excess coating by flushing with clean water.
SAFETY WARNING : RUBBER GLOVES AND EYE PROTECTION SHOULD BE WORN
WHEN MIXING AND APPLYING THIS SOLUTION. CARE SHOULD
BE EXERCISED TO PREVENT SKIN CONTACT. WASH EXPOSED
AREAS IMMEDIATELY WITH COLD WATER AND SOAP.
(2) Magnesium parts may be treated with surface pretreatment per MIL-M-3171, Type VI, Chromic
Acid or Oxsilan®.
NOTE: MIL-M-3171 Type VI is ineffective on aluminum and Oxsilan® is currently not being
used on aluminum specified applications.
MIL-M-3171 Type VI (for use on parts with a dull bronze to bright gold surface treatment
appearance).
(a) Apply mixed solution liberally at room temperature and allow to dry. Parts may be
dipped for 1/2 to 2 minutes in solution at room temperature.
(b) Remove excess coating by flushing with clean, cold water.
(c) Dry in oven or hot air. Never rinse in hot water.
(d) Alternate option would be to re-coat with Oxsilan® (see instructions below).
Oxsilan® (for use on parts with a clear to irridescent surface treatment appearance).
(a) Scrub surface with an abrasive material such as Scotchbrite pad.
(b) Rinse surface with water.
(c) Wipe excess water with clean cloth.
(d) Spray with a liberal amount of Oxsilan® so that the entire scrubbed area is saturated.
(e) Let stand for 5 minutes (to expedite the drying process, a mild airflow source can
be used).

I'm going to stop here instead of going on as all this info is available online for free. Just google the MM number; AWBCMM0001-7.3/USA

Rick

[cmsusllc]

Almost more info than I can absorb. The problem area is the mating surfaces between the wheel and brake and I have completely cleaned both surfaces. Thanks Rick for the direction.
Scott.....53B

[hungstart]

You will need to refinish them both to keep future corrosion at bay. The cup portion of the brake disk can be primed and painted with some heat resistant paint, the wheel should be alodined with some brush on alodine if you have sanded the surface finish and taken the suface corrosion off and then zinc chromated and finished with the some silver paint to match.

Rick

p.s., in my world (121 airline) when we remove corrosion we do a FPI (flourescent penetrant) inspection to be sure there are no pits left in the part, that lets us know that we got all of the corrosion. If it is aluminum we alodine it and then bring the surface finish back to original. If it is steel we cad plate it and then refinish as required.

Rick

[Zreyn]

All the emphisis on heat resistance must come from jet plane exrerence.28 years of flying a 170 into & out of the shortest & roughest fields outside of Alaska & the great north west & never used enough brake to get anything even close to hot! I use regular rattle can paint to keep the wheels & disc cups in shape & have never had any corrosion between the two because of disimilar metal or salt from landing & taking off on beaches.I used to use zinc chromate primer until EPA or OSHA or whomever decided we cant have it anymore.Now I use whatever the substitute that "Spruce" sells & rustoliem rattle can paint in color of choice.

[hungstart]

That would be the locally procured paint that Clevland talks about.

[GAHorn]

Great response, Hungstart! Just the sort of information needed.

Notice that magnesium wheels must be treated with chromic acid to deter corrosion. This is the same stuff your local mechanic/shop will have on hand to treat Beechcraft Bonanza tail-feather skins.

CAUTION: DO NOT USE POWER-TOOLS/GRINDERS etc to remove corrosion from magnesium parts. Use hand-power. (Magnesium particles are flammable. That little fire-starter metal block found in survival kits is nothing more than magnesium.)

[hilltop170]

And do not sand blast magnesium either, it will dissapear in front of your eyes.

Once the surface of whatever material your wheels are made of is prepared, Krylon "Dull Aluminum" color spray paint is a very close match to the original Cleveland color. Home Depot carries it.