Stainless Steel Exhaust

August 2017 (Improvement)

It had always been my intention to replace the NG’s exhaust with a stainless steel (SS) one once the original one wore out. The mild steel one had done sterling service, despite being thoroughly abused by sleeping policemen, but after 13 years it finally blew a small hole in the back silencer (photo 1).

 

The main problem, as most TF owners will know, is that the middle silencer sits under the central chassis giving very little clearance and is the section which most attracts the attentions of the aforesaid policemen (photo 2).

The MGOC accessories catalogue has a slimline bomb type SS system (B010) which gives a centimetre or two extra clearance. I also thought it would be a good idea to replace the cast iron manifold with a stainless one (for improved looks and efficiency). MGOC Spares being very helpful, I was able to order a SS “performance” system (B013) complete with tubular manifold but with the centre box replaced by the slimline bomb silencer.

 

The old clamps had been clouted and replaced regularly as they protruded even lower than the silencer (photo 2). So I sought out some Mikalor SS clamps (like beefy jubilee clips, tightened with a bolt rather than a screw) which can be positioned so they don’t stick below the line of the exhaust (photo 3).

The old exhaust and manifold came off without a fight but the new one posed a couple of problems. First, the centre branch on the new manifold swept out more than the old one. This would not have been a problem for a standard MGB but as the TF uses thinner spacers between the carbs and the inlet manifold (see Carburettors) the throttle could no longer swivel. So I found my other pair of thinner (8.5mm) spacers and worked out that, if I used both sets (11mm plus 8.5mm), the throttle would operate and the air filters could still be fitted (albeit only by releasing the bonnet side panel a little). I then had to obtain some longer imperial studs to cope with the extra thickness of these additional spacers!

 

The second problem was the centre “slimline” bomb silencer (photo 3) as the diameter of its ends were slightly too small to receive the intervening pipes. I bought an exhaust pipe expander which vaguely worked, although stainless steel is really hard, but by slightly extending the side cuts and using a clamp to close up the end once the pipe was in place, a reasonable seal could be made. I assembled the system dry and trimmed the lengths of the two intervening pipes to make sure the whole system fitted, then re-assembled it using Granville exhaust assembly paste.

All that remained was to replace the mountings, the front one to the gearbox and a new almost standard MGB one at the rear (photos 4 & 5). For the centre one I formed a new bracket based on standard exhaust bobbins (photo 6). The new exhaust has a lovely rich growl, which has softened slightly with a few hundred miles, and thus far I haven’t woken any sleeping policemen!