The brake hoses i'm using on my bug have a 10mm thick banjo fitting on one end and an M10 x 1.0 female fitting on the other. From my understanding, the banjo bolt seals due to the copper washers on either side of the fitting crushing as its tightened up. The calipers have M10 x 1.0 thread in them with 10mm of thread depth (tested by lightly screwing a bolt in until it bottomed out). Would a 20mm long banjo bolt be the right length (i assume i don't want it bottoming out before the copper washers crush) or should i go with an 18mm long bolt? They're the two size options i can easily find.
Hello, If you only have 10mm of thread depth then surely a 20mm or 18mm banjo bolt would be too long?
Don't forget banjo is also 10mm thick, if you screw in the banjo bolt(20mm) with banjo but no washers how much gap is left? If you have 1 washers worth of clearance use 20 more go for 18
A normal 20mm bolt (as I haven't bought the banjo bolts yet) with the hose fitted doesn't leave a gap if snugged down. The banjo on the hose isn't tight though as its possible to move it. The washers would probably take up the slack i assume.
Given that you only need about three turns of thread to hold a bolt, the shorter bolt will do. Also look down the hole, the longer bolt may partially block a passageway coming in from the side if it is too long.
