This an email I received from David who is
well travelled in France. He is refering to the Renault Trafic but is
equally relevent to the Boxer:
I found your site
looking for someone selling replacement rear springs for our
ancient Eriba camping car, Whilst accepting the truth of your
relations comments regarding the rear springs, I fear there may
be an error creeping in here, the major problem with
motorhome rear springs is that the rear springs are rated to
carry a percentage of the rated load a percentage of the
time, and almost never to carry that full load just sitting
around, which is the situation with motorhomes. They are bearing
about 90% payload every day and the rear springs, over a period
of time, quite understandably sag under the load.
The brake loading
valve is an unsophisticated mechanical linkage to a limiter,
merely reducing the rear brake effort when it detects the rear
ride height is higher, and permitting more braking if the rear
ride height is lower, i.e loaded. The idea is not to increase
braking power loaded but to reduce braking when unloaded to avoid
the rear brakes locking up when braking hard the rear
axle becomes unloaded due to weight transfer. The rear brakes
make little contribution to the overall braking, our race
cars have the rear brakes almost completely backed off to avoid
them locking up and it's still very hard to lock the fronts!!
If the owner of
the Eriba had to stand on the pedal coming downhill he
probably needs new genuine discs and proper EU-manufactured
pads from a proven manufacturer, most "motor factor"
aftermarket pads are either counterfeit or
Taiwanese/Chinese rubbish, you'd be better off with genuine
Renault parts from a dealer, regardless of cost!! You may even
be able to buy better pads to fit the Trafic caliper, if it's
used on something more exotic, from someone like Demon
Tweeks. Pads and discs aren"t "all the same"!!
heavier-duty springs do not raise the rear ride height to
a greater height than would have been the case when the vehicle
was new no harm will be done. Our Eriba, which is in France
currently, has detailed graphs on the drivers door detailing the
load valve settings, I would imagine an Eriba would have had the
load valve adjusted when the conversion was carried out, I
wouldn't be so confident about UK "back-street"
converters using used vehicles!!
springs will restore the original loaded ride height, for
another 16 years anyway!!
I'm a great
believer in the Airide rear suspension units, I've fitted them
to a Hymer, and had them on my Chevy which I've just sold,
and they work really well especially as we used to tow fairly
heavy race car trailers and this allowed the ride height to be
adjusted to correct the tail drooping down due to nose weight.
Coming down the Alps to Monza towing a 1t, 20' trailer is a test
of any braking system, and Chevys are notoriously
under-braked yet we've never had a problem with rear lock-up!!
Best of luck,
David's comments are
very relevant, and my thanks to him for taking the trouble to
comment. but my reason for using springs, were, they were
a lighter weight option.