What to do with pitting on brake backing plate

TJ in KY · May 23, 2011

What should I do about this pitting on brake backing plate? I have not done any painting with epoxy primer, a little intimidated by that process but willing to learn. I have been reading old post to try to educate myself but dont know what to do with these backing plates.
Should I
1. Use Picklex 20 or Must for Rust first to convert rust deep in pits then prime with epoxy (2 coats), then filler primer (several coats) till i am happy with results
2. Picklex 20 or Must for Rust, but then body filler then, epoxy then sanding primer
3. Use no Picklex 20 or Must for Rust, Use some type of body filler, then epoxy then sanding primer
4. Buy new backing plates
When I first started this process I thought cost would be no object, but cost are quickly adding up. If I can save these I want to give it a try. It would probably be a good learning experence, could allways strip whatever I have done or buy new.
Or any other options that i may not have thought of??

showcrop · May 23, 2011

I would use phosphoric acid liberally and give it plenty of time to penetrate. You can use one of those that you mentioned or save your $ and go to a restaurant supply and pick up a gallon of limescale remover. It's the same thing. I would then prime with epoxy primer, then smear laquer putty from the auto supply store on to fill the pits.

TJ in KY · May 24, 2011

thanks for the information showcrop. should the laquer putty go on in the epoxy primer window? any particular brand i should get, or stay away from.

RandyB(MI) · May 24, 2011

The air dry laquer putty will never cure through in that deep of pits. It will eventually shrink into the holes. Use a "pourable" catylized polyster product so you can pour it on and it will self level over the pits and then chemically cure and then sand flat. Some call it pourable liquid bondo.Ask your auto body supply store.

circus · May 25, 2011

Don't use lacquer spot putty. It hasn't been used for 40 years. What a pain. If the pits really bother you, sandblast the plate, lightly go over it with a 9" grinder, smear bondo over the whole thing, sand level with the same 9" grinder, primer surfacer then DA. Doesn't take as long as it sounds.

TJ in KY · May 25, 2011

(quoted from post at 18:05:50 05/25/11) Don't use lacquer spot putty. It hasn't been used for 40 years. What a pain. If the pits really bother you, sandblast the plate, lightly go over it with a 9" grinder, smear bondo over the whole thing, sand level with the same 9" grinder, primer surfacer then DA. Doesn't take as long as it sounds.

Circus, what does "DA" stand for, I understand everything but that part

circus · May 26, 2011

DA is a vibrating sander (finish sander). First use a coarse sand paper to remove and level surfacer then fine sandpaper to remove the coarse scratches.
Tip: Spray a light misting of a contrasting primer color prior to sanding. Sand until all the contrasting color is removed.

GordoSD · May 26, 2011

Use the rust treatment of your choice. I use a metal prep, from the auto body store. Then mix up your bondoand run around the plate with your
applicator cut to the width of thatplate.
You can do you first sanding with a 6 inch Da and 80 grit dry paper. Second sanding with 240 dry.
You may have to spot fill a few areas that are too low.
Then your epoxy primer, lightly sand with 360 and topcoat.
As others said, DO NOT USE primer putty. That is for a few small pinholes in surfacer.

Inno · May 27, 2011

(quoted from post at 20:47:16 05/25/11)

(quoted from post at 18:05:50 05/25/11) Don't use lacquer spot putty. It hasn't been used for 40 years. What a pain. If the pits really bother you, sandblast the plate, lightly go over it with a 9" grinder, smear bondo over the whole thing, sand level with the same 9" grinder, primer surfacer then DA. Doesn't take as long as it sounds.

Click to expand...

Circus, what does "DA" stand for, I understand everything but that part

DA - Dual Action

john_Bud · May 28, 2011

Circus, what does "DA" stand for, I understand everything but that part

DA - Dual Action It can either spin centered or random orbit giving a finish with less chance of directional scratches.

I agree with the rust coat, then body putty method if you want those pits to vanish. But I would just spray and call it good, but my stuff is slated to be covered with mud and grime pretty quickly so it doesn't matter!

What to do with pitting on brake backing plate

TJ in KY

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showcrop

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TJ in KY

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RandyB(MI)

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circus

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TJ in KY

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circus

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Inno

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