Brakes

Picture's worth a thousand words?

Hi guys. Yes there is. Most people don't notice those grooves or understand how that makes the pads hang up. You'll need to heat the pad mounts with an acetylene torch for a good 5 - 10 minutes. It's not necessary to get them red hot but since cast iron is porous, the goal is to get the trapped air to expand slowly so the piece won't shatter from the heat of welding. Preheating also helps the weld penetrate and melt into the cast iron, otherwise it will just build up uselessly and crack off.

Once it's hot, use a wire feed welder to fill in the grooves. After it cools, use an angle grinder to shape the surfaces. Use a high-temperature brake grease on those surfaces to prevent that from happening again.

I've used that procedure to repair cracked ABS tone rings on my mother's '95 Grand Caravan as a demonstration for my students. Saw a former coworker repair a cracked exhaust manifold that way too, but he had to pack it with sand and heat it for over three hours with a few spurts of welding during the heating. Arc welding will get too hot and is too hard to control. To get hot enough to melt the metal, it will make it spatter and blow away instead of smoothly filling in the grooves.

I was thinking about shims too but I don't think that's the answer for a couple of reasons. First, they are standard equipment on some import cars, but then the notches in the pads are sized to fit over those shims. Your pads are not designed for the extra width the shim would create. Next, once the grooves are already in the knuckle, hard braking could cause the pad to push the shim down into the groove and make another low spot. If the shim crinkles, the pad won't want to move at all.

I didn't look for any such repair method, but if there is something available, my guess would be it would require grinding down the knuckle to make the shim fit while maintaining the old outer dimension.

Something else you might consider is a product used extensively in paper mills called "Belzona". It is mixed like epoxy, spread like glue, then machined just like metal. They use it to build up damaged shafts where they could loose a million dollars per each day the machine is down waiting for a part to come from Germany! I used it to repair the square end of the speedometer cable on my '88 Grand Caravan that I damaged earlier, and it's still working after 80,000 miles. This material can be cut on a lathe just like metal, but it is REAL expensive. It's also available in small packets but I don't know about the cost.