(^78) MGE AUGUST 2019 http://www.mgenthusiast.com
TECHNICAL Q&A
Have you got a technical problem with your MG? If so, the combined
expertise of Roger Parker and the MGOC Workshop may be able
to help. For details of how to access this free service, see page 79.
Q
Having upgraded from an MGF
1.6 to a 2005 TF 135 Spark
the harshness of the suspension
came as a bit of a shock, thankfully
compensated for by the handling.
After approximately 2000 miles, the
current poor state of the roads turned
my thoughts to the Soft Ride pack.
Unfortunately the cost of the pack was
out of my budget but I’ve managed to
purchase a set of original equipment
KL dampers from an LE500, which
have only covered 9000 miles. I also
have two yellow rear springs.
Can I use the KL dampers with my
existing springs (my car has covered
69,000 miles)? If not, bearing in
mind I have the two yellow springs,
what would be the best or the most
cost-effective combination?
F
irst, some history that will provide
you with a little understanding
of why there are such ride
differences between MGF and TF:
In the first 18 months of MG Rover
the TF was being developed to take
over from the MGF and the range
was going to have a new sports
suspension to follow on from the
MGF Trophy 160SE, which had a very
uncompromising, hard-riding set-
up aimed squarely at those doing
Hard as nails
It was intended that mainstream
TFs would continue with the Hydragas
spec, which had wowed the motoring
press with the excellent ride/handling
compromise it delivered, but then
Dunlop, the Hydragas manufacturer,
dropped a cost bombshell. With the
Rover Metro’s production ending in
1998, it caused a significant drop in
demand for Hydragas suspension,
with only MGF continuing.
The projected requirements for
continued Hydragas supply for TF then
saw a significant unit cost increase, so
MG Rover took the late decision to adopt
the new steel spring sports suspension
across the whole forthcoming TF range.
However, the mainstream car’s detailed
suspension spec only altered in two
areas: the 348/343mm ride height
was raised to 358/353mm, by way of
moving the damper’s lower spring seat
upwards and, secondly, the suspension
geometry settings were tweaked.
Critically, the sports specification
hard spring and damper rates were
carried over to the mainstream cars,
and that’s why people like me, then with
current MGFs, who went on the press
launch in Portugal in early 2002, were
somewhat surprised at the hard ride.
track days or wanting that feel.
Hydragas and the MGF body damper
upper mountings were not conducive
to significant compression damper
loadings before serious body damage
would occur, especially at the rear
where loads are higher. This is why MGF
Cup racing cars have very significant
strengthening around the upper damper
mountings on the body. It’s also why the
external telescopic dampers of all MGFs
have absolutely no damping resistance
on the compression stroke, as all initial
damping is done inside the displacer.
To add any significant additional
damper loads would demand body
modifications, like the Cup race cars.
To avoid this, the better solution was
to contain all suspension loads within
the subframes. To this end the new
TF sports suspension option would be
a modified subframe(s) with a coil-
spring-over-telescopic-damper (coil-
over) contained in a new suspension
tower on the subframe, leaving
only minor changes for the TF body
structure. The spring and damper rates
for this new sports suspension were set
firm and the ride height set as the MGF
Trophy cars: 20mm lower than normal
MGF ride height at 348/343mm F/R.
Front damper upper mount in an MGF Cup racing car body showing clear additional
bracing and stitch welding required to strengthen the body from damper shocks.
ABOVE: Rear upper suspension of the
Cup racing car, showing cross brace
anchored to substantial new reinforced
steel which is added above and around
the rear dampers’ upper body mount.
c. jardin
(C. Jardin)
#1