Nowhere in my instructions did I mention torquing the bolt & then doing this. It’s not a trick. It’s an order of operations.
I took the liberty of looking up hitting the crush washer for a banjo bolt with a hammer and found instructions for doing that. It said it was an old mechanic's trick to tighten the banjo bolt, then tap the bolt with a hammer, and then retorque the bolt to prevent leaks.
That said, although I have never had a printed shop manual for the modern Fiesta, I had one for my 1978 Fiesta, I have one for my 1994 Miata, and I had one for my 1970 F100. And I did brakes on all those cars. None of the manuals said to hit the bolt with a hammer.
My search revealed these instructions, which put optionally tapping the bolt after initial torquing.
Key Procedures for Tightening Banjo Bolts:
- Use New Washers: Always replace copper or steel crush washers to ensure a proper seal.
- Check Fitting: Ensure the washer is placed on both sides of the banjo fitting (between the bolt head and fitting, and fitting and component).
- Hand Tighten First: Thread the bolt by hand to avoid cross-threading.
- Torque Specification: Tighten to the manufacturer's spec. For many automotive brake applications, this is around
25−3025 minus 30
ft-lbs. Specific recommendations include
96−12096 minus 120
in-lbs (do not exceed 144 in-lbs) or
5−85 minus 8
ft-lbs for some specialized applications.
- The "Tap" Trick: After snugging the bolt, a light tap with a hammer on the hex head can help properly seat the crush washer for a better seal.
- Inspect for Leaks: Check for leaks after the initial installation. Over-tightening can break the bolt, so it is better to tighten gradually.
- Bleed the System: If the bolt is part of a hydraulic system (brakes/clutch), bleed the system afterward to remove any air introduced during the process.