Exhaust fixings and mountings are the hardware that secures the exhaust system to the MGA's separate chassis frame and joins the individual sections of the system to one another. They fall into two groups: system-to-chassis mountings, the brackets and rubber insulators that carry the system beneath the car while isolating it from road vibration, and pipe-to-pipe clamps and flange hardware, which join the individual sections of the system together along its length. Both groups are routine service items with a finite life in use, and both should normally be renewed as part of any complete exhaust replacement rather than reused from a worn system. Manifold-end fixings (studs, brass nuts and the manifold-to-head gasket) sit under the separate Manifolds and Fixings node.
System-to-chassis mountings
The pushrod MGA exhaust is carried by two mounting brackets attached to the chassis, one forward of the silencer and one behind it, with rubber insulating hangers or bobbins between the bracket and the pipework to absorb vibration and allow controlled movement during heat expansion. The rubbers are the principal wear item in this part of the system: they harden and crack over years of heat cycling and ozone exposure, and once a hanger has failed the system sags and transmits vibration and resonance directly into the chassis and cabin. Replacement rubber hangers, the steel brackets that clamp to the chassis, and the bolts and washers that secure the brackets are all available as service items. On a car being refreshed with a new exhaust system, the two silencer mounting assemblies should be renewed alongside the pipework as a matter of course.
Twin Cam mounting differences
The Twin Cam exhaust system uses the same mounting principle, brackets to chassis with rubber insulators, but the specific mounting positions are set to the Twin Cam's different pipe routing forward of the silencer, where the twin downpipes merge into the front pipe. Twin Cam mounting hardware is similar in kind to the pushrod items but positioned to suit the longer merged front pipe.
Replacement Twin Cam mountings should be ordered to the Twin Cam specification rather than substituted from pushrod stock.
Pipe-to-pipe clamps
Where sections of the exhaust join along the system, front pipe to silencer, silencer to tail pipe, the joint is secured by a clamp over the sleeved connection. Two clamp types are in common use on MGA-pattern systems: U-bolt clamps, which compress a saddle plate onto the joint from above and below, and band clamps, which wrap a stainless band around the full circumference of the pipe. Both types are available as service items, with the choice typically dictated by the profile of the pipework at the joint and by whether the system is original factory pattern or a reproduction with a slightly different joint arrangement. Clamp hardware should be tightened evenly and re-checked after the first few heat cycles of a new installation, as the rubber compresses and the pipe seats into the clamp bedding.
Downpipe flange joint
The joint between the manifold and the downpipe (or between the two manifolds and their respective downpipes on the Twin Cam) is a flanged connection, secured by studs and nuts rather than a clamp, and sealed by a gasket. This joint sees full exhaust temperature and vibration and is one of the more common exhaust-leak failure points on any MGA in long service, as repeated heat cycling works the stud-and-nut fixing loose over time.
Replacement downpipe flange gaskets, studs and nuts are available as service items and should be renewed whenever the downpipe is disturbed. On Twin Cam cars there are two such joints, one at each manifold, each requiring its own gasket and fixing set.
Pushrod versus Twin Cam hardware overview
For pushrod cars (1500, 1600, 1600 Mk II), the fixings package covers: two silencer mounting brackets with rubber insulators, the pipe-to-pipe clamps at each section joint along the system, one downpipe flange gasket and its stud-and-nut fixings, and the bolts securing the mountings to the chassis. The Twin Cam package covers the same types of hardware but with Twin-Cam-pattern mounting positions and, importantly, two downpipe flange joints rather than one. No fixings or mountings are interchangeable between pushrod and Twin Cam installations despite superficial similarities in bracket design.
Ordering considerations
Ordering begins with pushrod or Twin Cam. For a complete system refresh, the mounting brackets, rubber insulators, pipe-to-pipe clamps and downpipe flange hardware should all be renewed alongside the pipework.
Where only targeted replacement is being undertaken, for instance a single failed rubber hanger on an otherwise sound system, the individual item can be ordered on its own.