Monday, October 18, 2021

Project-Zero: Wing/Fender Mounts

I caused a fair bit of irreparable damage to the original front cycle fenders on the car.  I ordered a set in black gel coat GRP from Kit Cars Direct as a quick replacement.  I'm not super thrilled with them but they'll work.

To mount them to the car, I'm using M6x1.0 bond-in studs and 3D printed (PETG) saddles that will clamp over the fender stays.  To bond the studs to the underside of the fenders I'm using polyurethane adhesive that came with the GBS Zero kit that I have not yet used anywhere else in the car.

UPDATE: This process has worked well except that the Alpha 123 PU Sealant is stupid and you shouldn't use it for this application.  What you should use is 3M 3815 panel bonding adhesive...It's the stuff they use to glue McLarens together.   Also, you should use bond-in studs with larger base.  I've updated the materials section.


  1. M6x1.0x12mm bond-in studs -
  2. 3M 3815 Panel Bonding Adhesive -


  1. To place the fenders, I used a digital angle finder to level out the fenders before sketching out the locations where I wanted the saddles to sit with a gold Sharpie marker.
  2. Then I squeezed sealant/adhesive on the backs of the bond in studs before smooshing them into place on the inside of the fenders.
  3. Using nitrile gloves and a little bit of rubbing alcohol, I smoothed the adhesive over and around the base of the studs.
  4. Allowed to cure for 24 hours before mounting the fenders.
  5. The poly sealant has a sheer strength of about 7lb/ft.  That's fine, you really shouldn't need to torque very tightly anyway. (Torqe to 5-6lb/ft or 60-70lb/in of force)

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