Triumph Unit And Pre-Unit 1/4-inch Domed Head Fender Bolt / Primary Level Plug Bolt (6) PN# DS57 L, DS-57 L, 99-3517 L

The DS57 bolt is an important fastener as it was used as a fender stay bolt, license plate bracket bolt, oil level plug bolt and in other various capacities for many years of production. This kit features (6) bolts. The original DS57 part number is superseded to 99-3517.

The 1/4-26 TPI CEI bolt features a fully domed head and measures 15/32″ under head. The bright zinc finish adds just enough mass to the bolt to make a slightly tight fit with nuts and bosses that are threaded to 1/4-26 CEI. Made in the UK by LF Harris.

The DS57 is used in many applications on the pre-1969 Triumph models and is most commonly paired with the 82-0879 1/4-26 CEI nut.

The bolt is threaded into the nut and usually a flat or spring washer is placed under the nut. We have found that the bar-cut 82-0879 nut will thread onto the DS57 L bolt by hand for about three full turns before a spanner is required to engage the nut to tighten further.