Tips on lightening your Volvo 740Turbo from 1340kg to 1150kg
Definitely the cheapest and most effective way to increase your car's performance is to remove
excess weight! An instant increase in power-to-weight ratio without extra power!
The extent of weight shedding will depend on your planned use for the car. If you use the car
in hot summers you may not want to remove the air-con, and if you want a heater for cold winters,
that may have to stay too. Fortunately Sydney's climate is mild for most of the year so both
air-con and heater equipment can go, even if the car stays road registered for daily use.
A detailed list of items removed from Dick Prince's 740Turbo race-car, plus approximate
weights, grouped by location and function, follows:
- Battery: standard car batteries weigh approx.15kg and can be replaced by smaller, lighter
sealed wet-cell batteries as used with outboard motors. Mine is a 6kg sealed "Odyssey" brand
fixed to the rear seat floor, but even located in the original battery position behind the
headlights a 9kg weight reduction is worthwhile.
- Vibration dampers: many 740's carry three vibration dampers weighing 9kg in total. One lump
of cast iron can often be found bolted to the centre of the firewall immediately behind the
motor. Remove it! Two other dampers, 3.5kg each, are hidden inside the chassis rails over the
front crossmember. To access these remove the front bumper and unbolt the two impact-absorbing
strut units in the front of the chassis rails. Then remove the 4 nuts just above the
crossmember securing each damper, and remove the dampers by pulling with a hooked (coat-hanger)
wire to the front of the chassis rail. This operation is like removing a tumour, and very
- Aircon components: if you can live without aircon, you can get the system degassed at an
approved aircon service shop, then remove the aorcon compressor (4kg), aircon condensor
(another "radiator" in front of the radiator and intercooler) plus associated hoses and
fittings to the firewall for a total weight reduction of near 7kg. Items 1, 2 and 3 above
reduce weight by an amazing 25kg, and you've only just begun! If you're serious, you can also
remove the plastic "vacuum tank" which stores vacuum to operate the aircon/heater flaps and
valves. The vacuum tank is located either inside the front bumper ('87-), or bolted in front of
the crossmember under the motor ('83-'86).
- Horns: the twin horns and brackets behind the front bumper left side weigh approx. 1.5kg
and can be replaced with a lightweight "beeper". I run a light truck reversing beeper when a
horn is required by Class regs.
- Alternator: the standard Volvo 100Amp alternator weighs approx. 5kg with its double-row
pulley. Alternative alternators approx. half the weight (50-75Amp) can be found if you look
around. A larger-diameter light single pulley in two pressed metal halves from an old BMW
3-Series (any wrecking yard, or "Pick & Payless" in Sydney) will replace the Volvo double-row
pulley, and slightly reduce alternator speed if your Volvo likes high revs.
- Alternator/Compressor mounting bracket: if you've removed the aircon compressor you can now
remove the large alloy mounting bracket bolted to the B230FT block and replace it with a
smaller alloy bracket to mount the alternator only. I found one of these on an old 244 in a
wrecking yard. Try to match your light-weight alternator to the mounting lugs on the small
alloy bracket first time round. I had a few rounds of "trial and error" before I got it right.
Note: Volvo must have had an eccentric alloy casting specialist at Gothenburg in the 70's and
80's. There is a huge range and variety of alloy brackets on the Volvo model range. All light,
strong and beautifully cast.
- "Bonnet" hood: the sound-proofing material under the hood can be easily removed, but it
actually weighs very little. All 740's in Australia seem to have a steel hood, but I notice my
960 has an aluminium hood! Has anyone seen an alloy hood for a 740?
- Obsessive "Racers" only: if you're preparing a full-blown racecar like my 16V turbo, there
are many more weight-reduction and performance-enhancing steps open to you in the engine bay.
These include: replacement of standard air-filter box and air-mass meter with a "pod" filter
(some aftermarket Engine Management systems, like my Autronic SMC don't read the air-mass
meter); removal of the sloppy hydraulic engine mounts and brackets (on some models) and
replacement with solid rubber engine mounts and the matching alloy brackets from pre-'87 740's;
removal of windscreen washer bottle, pump and hoses; re-working of the power steering pump
bracket to lose another kg; chiselling and grinding off the battery restraint brackets fitted
to both side wells behind the headlights; removal of unnecessary "washers" under most nuts
around the engine bay bodywork (please leave washers on mechanical component fasteners!); and
finally complete removal of the standard wiring harness, and lightening of engine components
(see details in later sections).
Inside the Cabin:
If you plan to sell the car road-registered at some stage in the future you are limited in
what you can strip out from inside the cabin, as most of the weight-saving options here are
difficult to reverse without spending a lot of time and some money. For example, after I spent
two days to remove my heater box and components (15kg!) from behind the dashboard, I realised
that it would be almost impossible to get it back in there even if I wanted to! My advice is:
proceed with caution, unless you are sure you are building a racecar (at which stage you have
lost any sense of reason or practicality, and will do anything to follow your dream).
- Rear seats: these are easy to remove and replace, but surprisingly they are very light!
They do however open the way to more substantial weight reductions (read on).
- Front seats: the Volvo front bucket seats, though very comfortable, are also very heavy at
around 15kg each. For Club Sport or full circuit racing, replace the driver's seat with a
moulded race shell to suit your body. The passenger's seat can be removed in some classes of
competition, or replaced with a lighter sports seat. My driver's seat complete with Volvo slide
mechanism weighs less than 9kg, saving 6kg.
- Floor sound-proofing: a surprising 15kg weight reduction is available by removing all
under-carpet sound-proofing and fibre packing sheets front and rear. To do this, remove both
front seats, centre console, rear seats, and carpets. Huge thick layers of rubber, foam and
bitumen are now accessible for removal if you wish. The bitumen sheets are best removed with a
hot-air gun and paint scraper. I found a little rust beneath all this from trapped water
leaking into the front footwells. This required wire-brushing and paint treatment.
- Rear shelf: a) the two great big speakers on the 740 rear shelf can simply be removed
temporarily or permanently. They weigh 4kg! b) Remove the rear shelf fibre board trim to expose
a number of brackets associated with child-restraints and rear seat fixing which can be
unbolted and removed temporarily or permanently. c) The centre arm rest and the plastic "ski
door" behind it in most 740's can be unscrewed and removed to save a few more kg's. In a
racecar, you will have to cover with aluminium sheet all the holes and apertures created by
removal of rear seats and rear shelf trim to provide a fire-proof bulkhead between cabin and
trunk (or "boot" as we say in Sydney). For "Club Sport" purposes you can just remove these
brackets and put the rear seats back in!
- Doors: if you're keen, you can remove the central locking actuators from inside each door.
This still leaves the doors able to be locked with the buttons and opened with the key the
old-fashioned way. If you're really keen you can remove the electric window winders and replace
with manual window winders from base-model early 740's to save a couple of kg's. You can also
heat and scrape off the bitumen sound-proofing sheets inside each door panel.
- Headlining: Note - removal of headlining is a desperate act. Most of you shouldn't do it! I
removed the headlining from my 740 years ago when it started to sag. Only after I had it all
loosened did I realise that the headlining can only be removed intact through the front or rear
windscreen apertures! I had to crunch it and pull it out a door. On the roof under the
headlining are three long strips of quite heavy bitumen soundproofing which you keen ones can
scrape off like I did.
- Behind the dashboard/instrument panel: this area is a treasure trove of weighty things
which can be removed if you are really keen: the biggest lump is the heater box complete with
fan, heater and aircon coils. As warned above, removal of heater box is nearly irreversible for
home mechanics like me, and quite expensive to have replaced professionally. If you proceed,
remove glove-box and main fascia panels from the dashboard to get to the many screws, hoses,
electric leads and plugs securing and attached to the heater box. A few fasteners run from
inaccessible places through the firewall. Some bolts and nuts on the engine-side of the
firewall have to be removed to finally get the heater box out. It runs full width, from front
door to door. I put on a small party after I finally got it out of the car, and found it
weighed 15kg! Once you get the heater box out, you realise what a horrible mess of wiring lives
in the bowels and dark places of a Volvo 740! Up there, like snakes and other nasty creatures
are bundles of wires as thick as your arm. For months after I removed the heater box, I had to
keep adding more and more cable-ties to stop the huge rolls of wiring from falling onto the
cabin floor and my feet. Behind the steering column are several mysterious black boxes, in
addition to the usual Bosch Motronic or Jetronic computer. I have removed the Volvo
radio/cassette player and the graphic equaliser, and just left the fascia panels (with a few
little blank holes in them) to cover the spaces. Similarly, I have replaced the Climate Control
fascia panel, after removal of the knobs and levers from behind.
- Steering wheel: the standard Volvo steering wheel, while no doubt very safe and well padded
(before air-bags) is heavy. You can save a kilo or two by replacing the wheel with a suitable
"sports" wheel. Just make sure you get the correct hub/boss to fit the Volvo spline, and be
sure to get a smart "VOLVO" logo on the wheel centre trim plate. I found that the lighter the
wheel, the more expensive it was. Surprise!
- Complete Wiring Harness: when my mechanic the Rev Doctor started the 16V Turbo engine
transplant in the racecar, we decided to remove the whole wiring harness and start again. Three
people (Rev Doctor, Army mechanic/electrician Paul, and novice me) took four hours solid one
night to remove the complete wiring harness after the B230FT engine had been removed, and the
dashboard dismantled. Again, caution: this step is irreversible. It will be more sensible to
give your car (shell) away and buy a second-hand equivalent replacement vehicle than to ever
try to re-install the second-hand wiring harness. But, as a weight-reduction step it was
fantastic! The full wiring harness weighed 23kg! Paul re-wired the essential bits for the
racecar (ignition, fuel pump, headlights, wipers, tail lights) complete with switches, fuses
and relays adding only about 3kg back in, so the re-wiring program got rid of 20kg net.
Click image for a larger view
- Seat belts: if you have removed rear seats, and even front passenger seat, then the
associated seat belts can come out. Each seat-belt weighs about 1kg. In my racecar I run only
the driver's 4-point harness required by my class regulations. I use the rear seat belt
mounting points to attach the two rear harness legs.
- Roll cage: of course, the one thing that you have to add to a racecar is the roll cage.
This is the one weighty item (about 10kg for a half-cage) I don't mind in the car. It might
save my life!
Inside the Trunk ("Boot" to us in Sydney, Australia).
Whenever your car is used for Club events or circuit racing, you will remove spare tire, tools
and everything loose from the trunk. There are however a few other things in the trunk that can
come out, either temporarily or permanently.
- Top fuel tank: all 7 Series Volvos in Australia have 80-litre fuel capacity. This comes
from a 60-litre polyethylene tank under the floor, plus a 20 litre steel tank over the rear
axle, in the trunk. The top tank is easily removed after a) checking fuel level is low, or
draining it. b) removing mats, cover plates etc. and removing just four bolts fixing the tank
to the floor. c) carefully lifting the tank and placing it on 1" x 2" timber blocks while you
loosen the tube clips fixing the fuel hoses between top and bottom tank. d) removing the wiring
to the top tank fuel gauge sender unit. The top tank weighs approx. 5 kg! After removal of the
top tank you must seal the hose which stays fixed to the lower tank. I sealed mine with a
"spare" fuel filler cap and a hose clamp. A new fuel tank breather must also be fitted. The two
terminals in the wiring plug for the top tank fuel gauge sender need to be connected to
complete the circuit for the main tank fuel gauge. I found that the fuel gauge reads about the
same as before, except "full tank" now 60 litres not 80, reads a little way back from full on
the gauge. I insist that you get a qualified motor mechanic to either carry out, supervise or
check all this work to ensure it is properly and safely done.
- Trunk lid lock: as for the doors, the central locking actuator can be removed, leaving the
lid locking with the key like the old days. If you're really keen, you can remove the lid lock
mechanism altogether, and use race-style fasteners (straps or pins) to secure the trunk
- Plastic covers: covers to tail light assemblies, and the plastic trunk sill cover strip can
be removed by the obsessive. Of course by now I expect that the radio power aerial will have
come out and the ensuing hole filled with a small rubber grommet!
In October, 2000 we removed the modified, but original B230FT turbo motor from my 740 racecar,
and fitted a B234F twin-cam 16V turbo motor. During engine building, we took account of component
weight, for both engine performance as well as overall racecar weight. The B234F block is
approximately the same mass as the B230FT block and the crank and conrods are the same. The
twin-cam head and cam-carrier is a few kilos heavier than the single-cam head. The inlet and
exhaust manifolds are about the same for both. J&B Performance, the engine builders, took weight
from the harmonic balancer (crankshaft pulley) by machining off the third v-belt section not used
in the racecar, and dynamically balanced all engine components, plus flywheel and clutch pressure
plate. The race motor doesn't have or need the external balance shafts of the B234F motor. They
have been thrown away! Ironically, the rough idle which was a characteristic of the standard 16V
Volvo motor, and which probably drove Volvo to fit the external balance shafts in the first
place, is eliminated in the race motor by the totally programmable Autronic SMC engine management
computer. Even with 40degrees cam overlap in place of 20degrees for the 16V standard cams, and a
light alloy flywheel, the 400HP race motor idles smoothly at 900rpm. The new flywheel (4.8kg) is
an alloy replica of the standard Volvo steel flywheel (13kg) so we saved 8 kg there. The Volvo
M47 5-speed gearbox has been replaced with an M51 Getrag box with dog-leg first gear, and 1:1
fifth gear to handle the 400HP the twin-cam turbo motor produces. The Getrag plus its 32mm alloy
adapter plate is a little heavier then the M47 box, but it works!
Under the Car:
Many Volvos sold in Australia got a very heavy application of "rust-proofing" to everything
under the car: rear axle, trailing arms, coil springs, plastic fuel tank included! For the
serious weight reduction program much of this stuff can be removed with a hot-air gun, paint
scraper, time and sweat. I guess we pulled out about 4kg of rust-proofing from under the racecar
one night in the workshop, with the car on the hoist. Wheels and tyres can vary in weight
considerably! My Volvo 16x7 5-spoke alloys plus race slicks weighed only 15kg each. My new 17x8
3-piece "Speedy" wheels plus 245/45 x 17 Yokohama A0032 control tyres for my Class, weigh 22kg
each. I've just added 4 x 7kg = 28kg to the car's total weight! Road cars require catalytic
converters, mufflers and so on. Turbo racecars don't need these things, so you can eliminate
another 4-5kg by going to a straight 3" exhaust pipe under the rear axle. Other than that, there
is not much beneath a 740 that shouldn't be there. The Australian Confederation of Australian
Motor Sport ("CAMS") Schedule 3J "Improved Production" class rules under which I race the
740Turbo says "Hand brake - free". So my racecar is free of the hand brake. I took it out. The
handbrake shoes, cable, and the lever assembly from inside the cabin weighed 3kg in total. When
you get to this stage you need a dedicated pit crew on hand to put chocks behind the wheels when
you park on a slope so the car doesn't roll away when you walk away leaving the motor idling to
cool the turbo!
The final step in the transition from a high-performance road car to a full-blown racecar is
to remove the licence plates. These weigh at least 1kg, and cancelling the registration is the
only way you can save money owning a racecar!
By a combination of the steps discussed above, I have reduced the weight of my Volvo 740Turbo
from a beefy 1340kg as a standard road car, to 1150kg in race trim, just 10kg above the minimum
weight for my class of racing in Australia. The greatest single improvement in my lap times came
when I removed the first 120kg of this weight over Christmas 1999 - my lap time at Eastern Creek
Raceway went from 2m 02s down to 1m 57s, a full 5 seconds off my lap time through weight
reduction. This is more effective and way cheaper than finding another 50HP. Try it, you'll like
In 2000, I ran my first full season in Improved Production Over 2L racing, and further reduced
my Eastern Creek lap time to 1m 52.5s by learning to drive the car and other subtle power and
Watch this space!
E-mail us for advice on making your Volvo lighter.