Car unstable after a disc and pads change?

Sometimes there are burrs left on the pads from manufacturing that need filing off. I live in a rust belt and many times I'll take my wire wheel and clean the carrier and it appears to be clean, but when I take a file and start scraping I'm surprised at how much corrosion is left on. Or you may have the wrong pads.

Well the carrier that the pads didn't fit into had its bolts cut at their head then a good 20mins of pounding with a hammer to turn and remove it, the bolts were rusted inside the hub housing section.

With this kind of information, your procedure could be wrong and making it altered.

I replaced a rear rotor and pads and also just pads on other side.

Never change the rotor to only one side, preferably both sides either both rear or both front or all of them. Because it will make your car imbalanced.

Also the pads were pretty tight fitting into the shim, I had to grind them down on one side but weirdly not on the other although pretty tight fit.

All pads manufactured as exactly as it is, either you have wrong parts or you get the cheapo sold it as the original one (likely the case on my 3rd world country). If you must grind it, do not use it.

Now I'm sure my cars handling is a bit wobbly, it slightly pulls to the right also.

If your car is slightly pulling to the right then your brake is slightly touched on the right side, please adjust a bit.

TLDR :

• If you need hammering too much, grinder, grooving for working on new pads or new rotor please don't use it (call the seller or bring back the parts to the seller and tell it does not match).
• If you need to change the rotor or drum brakes please change it on both sides.
• If needed go to the tire shop and do the balancing.