Exhaust extension

The MG ZR rear bumper and valance, although subtle, really transformed the back end of the car.

However, I hadn't realised that the valance was actually fitted over the top of the standard Rover 25 bumper lower. (On later Mk1 models the ZR bumper and valance was moulded as one part). This meant the lower part of the bumper was actually further rearward than it was before.

When buying the Longlife exhaust, which was custom made to suit a Rover 25 bumper, I didn't account for this difference. Clearly, some modification was required to extend it.

Rather than cut and shut a section of the exhaust, be it mid pipe or back box, I chose to make a short extension section between them both.

I wanted the exhaust to sit flush with the bumper, not stick out, so by simply measuring from the end of the exhaust tip to the valance gave me 45mm (1 3/4").

Making use of those preschool skills, I took a rubbing of the joining flanges of the back box and the mid pipe. This could then be used to make two metal flanges and a set of 4 gaskets. For the gaskets I used Klingersil C-4400 which can tolerance constant +200°C temperatures and a maximum of +400°C.

To join the two metal flanges together I used a section of tube equal bore to the rest of the exhaust system, then welded the flanges to it.

Everything was going rather swimmingly, so it was time for the first minor hiccup. When test fitting the exhaust extension piece, the Longlife exhaust wasn't mating correctly. This was due to the flange on the back box being welded to the pipe at an angle, to match the mid pipe, but the back box pipe not being cut to the same angle.

Not a major problem, to rectify the problem I simply cut the pipe off flush with the flange.

Minor mod complete, the two parts now mated perfectly.

For such a subtle change, it's made all the difference, taking the car from looking like a clumsily modified car to something close to, if not better than, factory fit. I'm really pleased with the result, and must thank my Dad for his help throughout the mini project, without his skills I'd have been quite stuck.

Before and After