REPAIRING REAR BRAKE PIN HOLES
There’s two reasons I made this tool…..
- To centralise threads thats stripped and re do an insert repair
- To get the pin holes in a better position
Every now and then some people pull out the threads where the brake pin fits. Some casings are poorly cast so the threads are weak, usually a correctly fitted insert with loctite repairs the hole. If its pulled really badly then they have to weld the hole and you need this fixture.
Some casings, especially lots of Indian SIL casings have one or two holes drilled off set – so one brake shoe can work and the other be so far off the brake drum, it doesn’t work – so the rear brake is only half efficient! It doesn’t matter what tricks and filing you do – it will always have a bad brake.
You can’t just drill a hole and hope for the best.
Our centralising tool was made and taken off a perfect Italian casing, making it the best way we can to centralise the brake shoes once done.
To do this, on a bare casing I fit the tooling into the rear hub bearing hole. This is a tight fit, some times the casing needs heating to open the hole a little. Most are just loose, so you can rock the fixture so the 4 screws can be fitted. Before it’s all tightened up you can wiggle the centralising pin into the casing where the brake pin holes are.
If the pin drops in place and screws into the casing then great. If not and its a millimetre or so off then its going to need an insert. An insert has an over sized outer thread this helps with an offset holes.
Once you’ve found the culprit, the casing needs fitting in the milling machine and locking down flat. You can then centralise the culprit hole with a drill and lock the bed.
Now the fixture can be removed with out moving the bed. All you need to do now is drill the hole offset to the old hole. Tap the threads out to the new insert. Fit which ever insert I want and lock it in place.
Once done thats as close to correct factory as you can and you hope it’s near as dam it in the right place.
If it’s right the two shoes will touch the brake drum, or at least with some miles on it, it beds in. Worst case you need the Innocenti trimming tool.
