Ask The Mechanic – Fitting reversing sensors

The Mechanic then received a question from Club Member,
Peter Rogers, who asked:
I have a T2 Bay 1978 model, and want to fit reversing parking sensors. I was planning on fitting the sensors to the rear bumper, but the installation instructions state that they should not be fitted to metal.
Is it possible to fit the sensors in the metal bumper with insulation around the sensor unit, or will the sensors still not work?

With no previous experience of fitting parking
sensors, this one got The Mechanic thinking.
From research, it would seem that parking
sensors work more effectively when mounted
into plastic bumpers and most retro-fit
instructions seem to state this also, however due
to the age of the vehicle, there is a lack of plastic
to mount the sensors on the rear of the vehicle
(or anywhere!), but there may be some possible
solutions, although they have not been tested
and are advice only.
A late bay rear bumper has a centre depressed
section for an optional rubber centre strip. The
sensors could be mounted into this strip and
that may stop any interference from the metal
bumper, they would also be virtually invisible
due to the black strip and black sensors.
These strips are available from Just Kampers for
£45 or you can buy the pair for the front and rear
so the bumpers still match for £85.
Another idea could be to make holes in the
bumper with larger diameters than the diameter
of the sensors. Then fit rubber grommets
into these holes and then fit the sensors into
the grommets, thus providing an insulated
mounting point for the sensors that should be
minimally distorted by the metal bumper.
Grommets are available cheaply in most DIY
stores or online