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Thu Nov 26, 2009 11:29 am

Started pulling my drums off and found that drums don't have any ridges but because bug has been sitting there is some rust on edges. Is there something I can use to remove this (e.g.sandpaper)? I dont think they need to be ground down as the surface looks pretty smooth. Or maybe I should?
Thanks for you help,
Lori

Thu Nov 26, 2009 11:41 am

If there are no ridges or grooves in the drums, you can use very fine wet-or-dry emery paper for this. Chances are that if you took the drums in for a re-surface ("turning" the drums), the shop would say that they're too worn and they couldn't do it anyway, would want you to buy new.

Thu Nov 26, 2009 2:24 pm

Thanks, what grit would you recommend. I have a bunch of that stuff lying around.
Lori

Thu Nov 26, 2009 3:12 pm

The finer the sandpaper the better. The usual procedure is to cross hatch the entire drum braking surface for a couple reasons. First after braking for years you develop a "glaze" on the braking surface that reduces braking power. Removing the "glaze" gives higher braking abilities. Cross hatching the drum braking surface with sandpaper (sanding in one direction then sanding the other [side to side then up and down]) gives you higher grabbing power also.

Thu Nov 26, 2009 6:05 pm

Or like a lot of folks do, is just grab what is handy and knock off the rust and move on to the next job. Once you apply the brakes a few times, they get resurfaced somewhat from the shoes anyway. If you have no ridges or grooves, they are either fairly new or have been recut without being driven much.

I am pretty sure that there are dimensions stamped inside the drum - but I don't know off the top of my head if the number is the max diameter allowed by wear or being cut or the original diameter. I am sure someone on here knows or its in your manual. I also think that if you mic'd the drum thickness, a brake shop could tell you if they are OK or not. New drums are not that expensive - Thinking around $40 each or so.

Thu Nov 26, 2009 6:08 pm

I chuck them in my brake lathe and use 40 grit. 8)

Thu Nov 26, 2009 11:15 pm

Max diameter should be either 9.112" or 9.822" - should be cast into the drum.

I'll use a flapper wheel in a die-grinder or some sandpaper...once I even had some custom shoes made and radius-ground to my drums - ended up costing a small fortune :x Then the glue they used failed and the linings came off the shoes :roll:

Fri Nov 27, 2009 9:55 am

If the car runs and is somewhat "driving", on the rears, with the car on jack stands, you can slide the drum onto the axle backwards. Then start the engine and put it in first or reverse and spin the drum that way.

To knock off the ridge, an old file works well, just keep it off the braking surface.

And all that stuff about removing the glaze and cross hatching the drum....

Forget about it! All that work goes right out the window after about 2 stops from speed.

Fri Nov 27, 2009 11:34 am

Since I'm lingering in the beetle forums...

I used to sand blast my brake drums if they werent riged too bad inside and out. But that was on my old Ford stuff,

VW's, you'd have to clean em good and do the grease and bearings stuff (minus all the sand) once you blasted them. Maybe stuff a rag in the bearing Races so you dont damage them as you just want the brake surfaces cleaned.

But, a good ol' sand blast did clean em up good, I'd always give em a repaint as well.
I used to use the old standalone sears sandblaster and used a mask with the hood and a facemask/breather to keep from inhaling the silica.
White play sand worked great, but you need a breather mask due to the silica, I never had a sandblast cabnet so I did it outside in the driveway, blowing the excess sand in a "safe" direction.

Just an idea.

T.

Fri Nov 27, 2009 12:14 pm

Thanks guys...that is a lot of information but I guess in the long run cleaning up those drums isn't the precision job I thought it was.
Lori

Fri Nov 27, 2009 12:58 pm

Hey Lori,

not really, but if you get an "out of round" drum it can cause strange
pedal affects (pulsing pedal) or the car can pull to one side or the other depending on which drum is out of round.

Basicly just roughing them up a bit, to get a bite in the new pads was key cause eventually the friction smooths the drum over time.

I suppose if you're really worried about it, you could get the drums turned but just be carefull on price gouging.
Have a good one.

T