It depends on what you are trying to determine. If you only want to know what size drums are on the vehicle, you should be able to determine that by measuring the drum diameter roughly from outside, across the center, or widest point. I believe, but don't remember for sure, that these vehicles came with either/or 9 or 10 inch drums on them, depending on the brake system installed. However, if you're trying to find out if they are still usuable, i.e. you hear grinding, or think you have damage, you must remove them, then measure the inside diameter with a brake drum micrometer, or any large inside diameter micrometer. The discard, or max diameter spec is stamped on the drum.
Take them off and measure the machined surface for width and the diameter.
On a 1991 Ford Ranger : Either 9 inch or 10 inch brake drums
Remove the drums and take them to an auto parts store that has a brake drum lathe.
Friction.
You could have either 9 inch or 10 inch brake drums
measure inside diameter of brake drum (where brake shoes touch drum) and measure outside diameter of brake rotors. usually if you look at wheel side of drums and rotors the size is stamped in millimeters on each
Remove the tire and wheel from your 1988 Ford Ranger pickup truck. Remove the brake pads. When the brake drum is not loose you can tap on it with a hammer or mallet. Once the brake drum is loose it will slide off.
No, the drums can be cleaned with brake cleaner.No, the drums can be cleaned with brake cleaner.
start by taking the tires off
If you are inexperienced, you should not be messing around with the brake drums.
New brake drums are broken in the first time you go for a drive usually.
If the brake shoes measure less than 4/32nds thickness, if cracking or warping is observed on the brake drums, if the brake shoes and/or drums become coated in oil (as is what happens when a wheel seal goes bad), or if you hear escaping from the brake chambers when the brakes are released, then you know at least one component in the brake system is bad.