Spark Exhaust Bent Tube 45° Ø 40 × 1.0 mm Stainless Steel Universal G9102

Forty-five degrees at forty millimetres. If a fabricator owns one exhaust bend, statistically it is this one.

Key Features

• Mandrel-formed 45° bend, AISI 304 stainless steel.
• Ø 40 mm outside, 1.0 mm wall thickness.
• Straight tangents at both ends.
• Matches Spark's 40 mm straight tube, article G9001.
• Spark part number G9102, made in Mantova, Italy.

Mixing With a Right Angle

A 90° bend off a collector followed by a 45 into the silencer position is the standard two-bend run, and it covers a surprising proportion of custom builds. The ninety does the hard turn where space is tightest; the forty-five aims what comes after it.

Put a straight between them and two fixed angles become an adjustable geometry: lengthen it and the silencer moves back, shorten it and the whole tail tucks in.

Halving It With a Saw

Forty-five is the angle worth stocking because it can be reduced. Cut it in half and you have twenty-two degrees; cut a third off and you have thirty. The reverse is not possible, which is the argument for buying the larger angle when you are unsure.

Take the length out of the curve rather than off the straight tangent — the tangent is what you clamp and weld against.

What Goes Wrong Without a Mandrel

The inner heel folds. A crush bender presses the tube into an angle without supporting it from inside, and at forty millimetres in one millimetre wall the material buckles rather than stretching. The result is a crease, a smaller bore exactly where the gas has to turn, and a part that cannot be dressed straight.

Ovality After Forming

Even a good bend is slightly oval at the tangent point. It is rarely enough to matter for a butt weld, and often enough to matter for a tight slip fit. Two vernier readings at ninety degrees to each other take ten seconds and save a joint that will not go together.

Spares

Buy more than the drawing says. Trimming consumes the tangent, a bend clocked wrong is usually scrap, and the difference between finishing a build over a weekend and waiting a week is one spare elbow on the shelf.

Ordering

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