80/20 15 Series Slide-In Stainless T-Nut - 5/16-18 (3678 Equivalent)

Stainless, 5/16-18, slide-in. The single most-used fastener in any 15 series rack build — and the one people always underestimate.

A slide-in T-nut goes in from the open end of the extrusion and slides along the T-slot to where you need it. That makes it the strongest and cleanest option in the T-nut family, because the full nut body is captured inside the slot rather than being rolled or dropped in.

It also means you have to plan. Slide-in nuts have to be loaded before the extrusion end is capped or joined, so count the fasteners for every bracket on a member before you close it up. Stainless matters here because these live in the weather on a roof rack, and a rusted T-nut in a slot is a genuinely miserable thing to extract.

What it is for

• Mounting brackets, gear, solar panels, awnings and accessories to 15 series 80/20 extrusion.
• Anywhere you need maximum holding strength from a T-slot connection.
• Exterior and wet-environment use, where a plated steel nut would eventually rust into the slot.

Compatibility

The 15 series is the 1.5 inch profile — the size almost every van roof rack and interior framing system is built from. If your extrusion measures 1.5 in across the face and takes a 5/16-18 fastener, this is your hardware.

Specifications

What's included

• (1) 5/16-18 stainless slide-in T-nut for 15 series extrusion

Working with it

Load them before you close the extrusion. Slide-in nuts enter from an open end, so once a member is capped, joined or bolted at both ends you cannot add more without taking it apart.

Our habit on a rack build: count every bracket that will ever attach to a rail, add two, and slide that many in before the rail goes up.

• Load T-nuts before capping or joining the extrusion end.
• Count your brackets, add two spares per rail.
• Anti-seize on stainless-into-stainless threads prevents galling. Stainless fasteners gall more readily than plated steel.
• Snug, then check torque after the first few hundred miles of vibration.

Questions we get asked

How do I know if my extrusion is 15 series?

Measure across the flat face of the profile. A 15 series extrusion is 1.5 in wide (or a multiple — 1.5 × 3.0, and so on) and the T-slot takes a 5/16-18 fastener. If your rack came from Unaka, 80/20 Inc., or most van rack makers in North America, it is 15 series.

How many should I order?

Count your joints, then add 20%. Rack hardware is the cheapest thing in a build and the most annoying thing to run out of halfway through a Saturday. We have never once regretted having spare T-nuts in the drawer.

What is the difference between a slide-in and a roll-in T-nut?

A slide-in loads from the open end and slides along the slot — strongest, but requires planning. A roll-in or drop-in loads anywhere along the slot after assembly — more convenient, slightly less holding area. Use slide-in wherever you can plan ahead, and roll-in for the bracket you forgot.

Why stainless rather than zinc-plated?

Because it lives outside. Zinc plating on a roof rack in a salted winter climate will eventually surrender, and a corroded nut inside a T-slot cannot be persuaded out without destroying something.

Pairs well with

• Van roof rack, ladder and 80/20 hardware

Sold and shipped by Campervan Parts R Us, the parts counter of Noke Van Co. — a working van conversion shop in Roanoke, Virginia. If you are unsure whether this fits your van, email us the year, model and wheelbase and we will check it against a build sheet before you order.