Dave Stribling
May 2, 2018

Factory Safety Wire?
My 1970 Mustang has factory disc brakes on it. I noticed that the bolts holding the caliper adapter brackets to the spindles have holes drilled in them and someone has run a piece of coat hanger or some sort of wire through the holes. Is this all factory? Thanks.
Dene M.
Wabash, Indiana

Yes, it is. Starting in 1968 Ford began using a locking bolt with a nylon insert and the holes that you mentioned. Racers had been locking down bolts for years, and Ford decided it was necessary on the caliper bracket bolts to prevent them from backing out. The Ford shop manual shows how the original safety wires were to be attached, but like many things on the assembly line the assembler didn’t always wire them in the proper manner or spec. I have seen the safety wire straight, and I have seen them twisted. I am not sure how the MCA wants to see it, but if you think it is the original wire, then reinstall it the way it was. When performing a brake job it is not necessary to remove the caliper bracket, but some people do anyway, and the wire is usually left off or attached incorrectly. The big thing is to make sure the twists and ends are far away from the flexible brake hose so they don’t rub and possibly cut the brake hose. If you prefer the twisted wire look you can purchase specific safety wire pliers that help make a nice and neat twist with little effort.

This photo is from the Ford shop manual and shows the safety wires holding the caliper mounting bracket bolts in place.
What I believe is an original wire setup. Note the twisted end is pointing down and can catch on something.
I have seen the originals twisted like this, and this is how the owner replaced his. Note the twisted end is tucked up nice under the spindle to prevent catching anything.
This safety wire replacement was done after a previous brake job—wrong! The bolts should be individually safety-wired to the spindle casting, as shown in the shop manual.