I like how you think grinding a little extra casting material off of a caliper would some how make the caliper weak and unsafe to use.

All you need to do is take a die grinder and take off the material on the caliper that rubs, no harm done and it costs nothing to do and wheel shops do it all the time...

Could you please tell me why you would need to heat treat a caliper after grinding it?

But maybe you know something I don’t

But I am a machinist and I primarily work with machining cast iron and I know from the foundry that when they remove casting they leave sprues on the part and they cut them off and grind them down flush and some parts I machine need to be ground to fit in some fixtures.
The parts I make will take 10X more stress than a little caliper ever would.

 

I agree that at a foundry people grind down sprues from casting but once a part is sold to you or I it is at net shape and size. Meaning that it is the designed size needed to resist stresses from breaking.

Now, It could be argued that you could grind away part of the caliper due to the fact that there is a safety factor involved when designing the component. But this would maybe only hold true if you were only removing under 0.100". But on a part that has a wall thickness of maybe half an inch, 0.100" starts eating into that wall thickness pretty quick. Chances are that more than 3mm of stock will be need to be removed. That is when you start pushing your luck.

Either way its a personal choice if one feels like running the risk of damaging a critical component of the car used for braking. Personally, spend the 200 bucks, and at the very least get a spacer(perferably new wheels cuz spacers are a whole other arguement). I will say it again: Do it once, Do it right. Do not short change your ride.

Also, heat treat is something done by someone who knows what they are doing, ie a fab shop. Changing material properties to match spec is very difficult and doubly hard if you are trying to RE-Harden parts of part.

 

I wouldn't use washers period. Maybe one might be okay, but for peace of mind and safety I wouldn't. If you need extra space and if it's very minimal, just go with a 3mm or 5mm spacer.

Some people have had problems with studs breaking, some haven't. If you're willing to pay the extra cost for extended studs or built in studs, then I'd say go for it....non-built in would be the most secure choice.

 

I agree pretty much with this 100%. One thing few understand with grinding is that grinding under very controlled conditions is in itself considered an acceptable heat treatment process. The inverse is also true.

Even as much as I don't like the options presented, to me the wheel spacers would be the best way to go considering those options. Even then you need to consider studs, etc. But the fact is none should be an option and obtaining a proper set of wheels is the correct course of action.