Spark Exhaust Bent Tube 30° Ø 70 × 1.2 mm Stainless Steel Universal G9156

Seventy millimetres at thirty degrees. A bend at the scale where a tube has stopped being a pipe, with the wall stepped up to suit.

Key Features

• Mandrel-formed 30° bend, AISI 304 stainless steel.
• Ø 70 mm outside, 1.2 mm wall thickness.
• Thicker wall than the 32 to 60 mm bends.
• Matches Spark's 70 mm straight tube, article G9009.
• Spark part number G9156, made in Mantova, Italy.

Shaping a Volume

At seventy millimetres a shallow bend is rarely routing gas. It is giving a silencer body or a pre-silencer box a curve so that the assembly follows the line of a frame rail or a swingarm instead of cutting across it.

Thirty degrees is the angle that does that without making the shell a difficult shape to close at both ends — anything sharper and the end caps stop being flat discs.

Tooling, and Why You Cannot Borrow It

Forming this diameter needs a mandrel sized to the bore, a die matched to the radius and a machine with the capacity to pull it. That is a set of tooling per diameter, per radius — the reason a workshop that bends forty millimetre tube every week still buys its seventies.

What Goes Wrong Without It

The inner heel folds. Once a large thin tube has creased on the inside of a radius there is no dressing it out: the material has buckled rather than stretched, and the section is permanently smaller at exactly the point the gas has to turn.

Fitting to a Flat

A box built from this diameter usually meets a flat plate somewhere — a mounting face, a bulkhead, an end cap. Cutting a large tube to sit square on a flat is easier with a template than by eye: wrap paper, mark, cut, and check the fit before any heat.

Heat Input

1.2 mm takes more heat than 1.0 and takes longer to get there. Settings carried over from the smaller diameters produce a cold bead that sits on the surface rather than fusing — visible as a raised, shiny line that has not wetted into the parent metal at the edges.

Storage Before Use

A large thin bend is easy to damage in a workshop. Keep it off concrete, keep it away from grinding work, and cap the ends: embedded steel dust from an angle grinder is what makes stainless rust in spots.

Ordering

One bend per article. Spark builds 30°, 45° and 90° at this diameter.