The exhaust system on the TD and TF is a straightforward three-component layout, manifold, front pipe with silencer, and tail pipe, but the detail differences between the two models, whilst subtle, affect the connection method and the pipe dimensions. The TD introduced a rubber-mounted layout that removed the need for the flexible section used on the earlier TC, and the TF continued this approach with revisions to the front pipe connection and an enlarged tail pipe.
Exhaust Manifold
The cast iron exhaust manifold is shared across all TD and TF engines, the manifold-to-head interface is common to both the XPAG and XPEG regardless of capacity, as the exhaust port spacing and stud pattern are identical. The manifold is secured to the cylinder head by the same four studs and clamps that hold the inlet manifold, sharing a single gasket between both manifolds and the head face. The three-stud flange connecting the manifold to the front pipe uses brass nuts to resist seizure caused by heat cycling, ordinary steel nuts will corrode and weld themselves to the studs, making future removal extremely difficult. The manifold-to-downpipe gasket should be renewed whenever the front pipe is removed.
A poor seal at this joint creates an exhaust blow that is both noisy and wasteful of engine performance through reduced exhaust scavenging.
TD and TF System Differences
On the TD, the exhaust followed the pattern of the earlier TC but was rubber-mounted to the chassis, which removed the need for the TC's flexible joint. The front pipe was bolted to the silencer with three bolts. On the TF, the front-pipe-to-silencer joint was changed to a push-fit connection secured by a clamp rather than bolts, and the tail pipe diameter was increased.
These differences mean that while the manifold and the manifold-to-downpipe gasket are shared, the complete exhaust system from the front pipe rearward is model-specific in original form. The modern stainless replacement system uses clamp connections for both front-pipe-to-silencer and silencer-to-tail-pipe joints.
System Mounting
The exhaust system is supported at the front by a clamp and bracket arrangement that secures the front pipe to the gearbox casing. The bracket bolts to the gearbox, with the clamp gripping the pipe through a spacer. At the rear, two rubber mounting kits suspend the system from the chassis rails, each comprising a mounting rubber, a pinch bolt, plain and spring washers, and a nut, with bolts securing the mounting to the chassis. These rubber mountings absorb engine and road vibration, preventing fatigue cracking of the exhaust joints.
Deteriorated rear mountings allow the system to hang low and sway, placing stress on the manifold-to-downpipe joint and accelerating failure at the welded connections.
Stainless Steel Exhaust Systems
A stainless steel exhaust system manufactured by Double S Exhausts is available as a direct replacement for the original mild steel specification. Manufactured from 309 and 401 grade stainless steel with a mirror-finish silencer, the system is produced to accurate tolerances for straightforward DIY fitment and is supplied with a lifetime guarantee. The stainless specification offers significantly greater longevity than mild steel, which is particularly beneficial for cars stored over winter, internal condensation attacks mild steel from the inside, and systems on cars used for short journeys, where the exhaust never reaches full operating temperature, can corrode through within a few years.
Exhaust Accessories
Exhaust manifold wrap is available for owners seeking to reduce under-bonnet heat and improve exhaust scavenging efficiency, supplied in rolls with a separate wrap fixings set. Aluminised fabric sheeting provides additional thermal protection for the engine bay and bonnet underside. High-temperature exhaust paint is available in black, silver, red, and white for finishing the manifold and system. Exhaust jointing seal provides a gas-tight connection at the manifold-to-downpipe and pipe-to-silencer joints for cars where the factory gasket alone is not sealing cleanly.