Originally Posted by c00k1e
I am pretty sure one of the frount rotors (disks in UK) is warped. Don't know which one though.
Is there a good way of testing?
There is absolutely, categorically no way
a rotor can warp.
This is an old wive's tale that has been passed down from generation to generation by shade tree mechanics. It lives on to this very day.
What you are feeling is uneven deposition of brake pad material on the surface of the rotor, usually caused by improper bedding in or light braking forces. The typical scenario is that the rotor is checked for thickness variation (run out) - and low and behold - the disc is "warped."
You can attempt to clean it off with garnet paper and a palm sander, but the material that is deposited is extremely hard and abrasive. If you catch it early enough this will work, before the deposition has gotten thick. It is worth a try. Don't use regular sand paper since the aluminum oxides in it will leave a residue behind and make the problem worse.
You can also purchase some abrasive brake bads, install them for a while and attempt to clean them in this fashion. Unfortunately I don't think they exist for the LT.
The only other thing you can do is Blanchard grind them to get a new surface - but I think the LT's discs are made from steel, not iron - so this is probably not a possibilty unless you can find a specialist shop that would tackle this. Even if you go this route unless
they are properly bedded in during initial use you'll probably end up with the same problem again.
Unfortunately the only way to cure this is with new pads and new rotors.