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Discussion Starter · #1 ·
I'm seeking longer bolts for the rear subframe that will allow the bolt to extend inside the subframe so I can add a nut and washer for additional security. Can anyone recommend the perfect bolt that's easily available online? I took a few photos and measurements to help.

Desired Bolt Specs
  • Metric, obviously
  • Stainless steel 18-8 (A-2) or better
  • 8mm x 1.25 thread pitch
  • 35 mm length (original appears 23 mm length incl. shoulder)
  • 10 mm shoulder diameter
  • 5 mm shoulder length
  • 18 mm max head diameter
Examples Online
Based on what I've measured, I'm inclined to buy the following. The downside is that I'm adding a spacer, rather than having the shoulder built into the bolt like on the OEM bolt.

Does anyone have a better solution?

Here are some photos and links that show my research.

Motor vehicle Automotive tire Hood Bicycle part Bumper

Calipers Gauge Clock Measuring instrument Wood

Watch Calipers Analog watch Clock Grey

Watch Analog watch Calipers Wood Gauge

Watch Analog watch Wood Clock Measuring instrument

Watch Brown Analog watch Clock Wood

Circuit component Font Cylinder Household hardware Gas

Metric socket button head, Stainless steel 18-8 (A-2), 8mm x 1.25mm x 35mm
Buy 4 of these.

Metric hex nylon insert lock nuts, Stainless steel 18-8 (A-2), 8mm x 1.25mm
Buy 4 of these.

Metric flat washers, Stainless steel 18-8 (A-2), 8mm
Buy either 8 of these, just in case you want washers on each side of the 4 bolts.

Spacers, Stainless steel 18-8, #8 x 3/16" (3/8" O.D.)
Buy 4 of these, maybe some spares because you'll likely be drilling into them.

Spacer Calculation
Space Outer Diameter
  • 10 mm shoulder diameter
  • 3/8" OD = 9.525 mm OD
  • 5 mm shoulder length
  • 3/16" length = 4.8 mm length
Spacer Inner Diameter
  • 8 mm inside diameter
  • #8 ID = 0.1640" = 4.2 mm
  • I'll need to drill out the 4 mm ID to fit the 8 mm bolt.
Why Bother?
I heard that carrying luggage and/or a passenger can sometimes cause the subframe bolts to loosen and shear off. This causes the rear of the bike to drop onto the rear tire. See Ninja 1000 subframe reinforcement.
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