964 Biography



was the first exclusively devoted to the 964 series of Porsche 911s
built between 1989 and 1994.  It not only covers the 964 series but also 964
owners and their charges from around the world.  John will happily acknowledge
that this web site would not be anything like it is without the huge personal
contribution of 964 owners around the world.  I am very pleased to
contribute this 964 Biography.


The Porsche 911 (964 Series)

In the early years, the motoring press
enthusiasm for this car was very positive and many times the 964 was proclaimed
to be the best 911 ever, especially the revolutionary Carrera 4.  As time passed
however, praise began to turn to criticism, some of which still exists.   One
purpose and major driver behind John?s creation of this web site is to help
overcome some of these myths and misconceptions of the 964.   It must also be
remembered that the 964 was born into a period of great stress and uncertainty
at Zuffenhausen.   Despite this over 57,000 964s were produced.

964 Timeline

bullet 1981 ? Concept AWD cabriolet
presented at the Geneva Motor Show.
bullet 1983 ? The AWD Paris-Dakar Porsche
953 is created.
bullet 1985 ? The AWD twin turbo Porsche 959
is created.
bullet 1987 ? The 964 Carrera 4 design stage
bullet 1988 ? The prototype 964 Carrera 4 is
road tested for the first time.
bullet 1988 ? The 964 Carrera 4 coupe enters
bullet 1989 ? First deliveries of the
Carrera 4 coupe are made.
bullet 1989 ? The 964 Carrera 2 manual and
tiptronic (automatic transmission) are introduced along with Targa and
Cabriolet versions of both the Carrera 2 and 4.
bullet 1989 ? The double mass flywheel is
introduced on the 1990 model year Carrera 2s and 4s.
bullet 1990 ? The 964 Turbo with a 3.3 litre
turbocharged engine is introduced.
bullet 1991 ? 20 special 964 Carrera 4 RSs
are manufactured.   The only thing they have in common with the Carrera 4 is
the 4.
bullet 1991 ? Many special edition models
are added to the standard 964, 1992 model year line up.   These include;

  1. Turbo look cabriolet (Rest of the
    Worlds (ROW) only)
  2. American Roadster (USA only)
  3. Carrera RS basic, touring and NGT
    (ROW only)
  4. Turbo S (ROW only)
  5. Turbo S2 (USA only)

bullet 1992 ? For model year 1993 the 964
Turbo undergoes a major revision with the installation of a new turbocharged
engine based on the normally aspirated M64/01 engine.   Three different
versions of the new Turbo 3.6 are produced.

  1. The ROW version
  2. The USA version
  3. The IMSA version.

bullet 1993 ? An anniversary model to
celebrate the 30th birthday of the birth of Porsche 911 is built.   911 Turbo
look Carrera 4s are sold worldwide except in the USA.
bullet 1993 ? The USA receives a special
lightweight Carrera 2 called the RS America.
bullet 1993 also sees the end of 964 Targa
bullet 1993 ? Production of the 964 is
terminated in December 1993 apart from Turbo 3.6 production and a special
model of Turbo look Carrera 4 for the USA.  The C4 TL was created to
compensate for the lack of new 993 series deliveries to the USA.
bullet 1994 introduced the 964 Speedster. 
3000 were planned to be built but only approximately 50% were actually
produced.  The vast majority of the Speedsters were narrow body versions built
on the Carrera 2 chassis however 15 Turbo look versions were produced.  Model
year 1994 for the 964 ended up with the delivery of a number of Porsche
Exclusive built Turbo 3.6 S models.  The very last 964 delivered was the
America GS which was delivered to its owner in the USA in 1995.

What Makes a 964?

To say that the 964 was an 85% redesign
of the previous Carrera 3.2 series is not truly accurate.  The 964 series was a
completely new series.  The 964 Carrera 4 was the first production series
normally aspirated 911 with all mechanical AWD.  It remains the first and last
series Porsche with an all mechanical AWD system.  The Carrera 4 was the first
911 fitted with an ABS system.  The C4 was the first and only Porsche model to
be fitted with an electronically controlled traction control system.  The
Carrera 2 series was born from the Carrera 4.  All the innovations introduced on
the Carrera 4 except AWD and traction control were installed into the Carrera
2.  There are some structural differences between the Carrera 2 and 4 at the
front but this is due to the AWD installation only.

The 4-speed Tiptronic automatic
transmission designed for the Carrera 2 was huge leap forward for Porsche.  The
previous 3-speed automatic transmission used by Porsche from 1967 to 1980 was
the Sportomatic.  The introduction of the Tiptronic brought with it full
electronic control, pre-programmed driving characteristics software and an
adaptive memory system.  The Tiptronic system can be operated in full automatic
mode or manual mode. 

The fuel injection system used on all
the normally aspirated 964s was a Bosch Motronic system extensively redesigned
as compared to the earlier Carrera 3.2 system.  Adaptive memory and fault
detection including impending failure was added.  The ability to plug a
diagnostic tool into the 964 brought with it a much reduced troubleshooting time
for many failures.

The 964 normally aspirated engines were
fitted with a dual ignition system to improve fuel/air mixture burning
efficiency to help with emission control.  The Carrera 4, all Turbo looks, RS
series and the Turbos were all fitted with a hydraulic brake boost system.  The
Carrera 2, RS America and Speedsters used the vacuum boost system.

A new central warning system was
introduced to advise the driver of various systems failures.

The 964 was the most aerodynamic 911
ever built.  Its drag co-efficient has never been bettered.

The 964 in Competition

The years of racing from 1989 and 1994
were not exactly highlights of the Porsche racing history for the 964 series. 
However they still made their mark.  A special Turbocharged 964 called the
LeMans GT was entered for LeMans 1993 and 1994.  A special twin turbo version of
the 964 was built and raced at Pikes Peak.  The Carrera Cup was used in many
single type series around the world and the 964 RSR dominated the GT class in
all the endurance racing world wide.  The Carrera RS basic and NGTs were used by
club sports enthusiasts and professionals alike for racing.  Special IMSA
version of the Turbo and Turbo 3.6 were produced and they raced in many
different sport car series and endurance races worldwide.

How to Recognise a 964?

The easiest way to correctly identify a
964 is to check the vehicle identification number (VIN).  The VIN is a 17 digit
international code.  Porsche use two versions, the ROW and the USA requirements
code.  It is much easier to identify an American 964 as compared to a ROW 964. 
The following brief explanation of key digits within the VIN will ensure correct
identification of type and for the US version more detail can be extracted. 
This is very important when trying to determine if a 964 is genuine and the
model is actually manufactured by Porsche and is not an aftermarket conversion.

Digit 4

bullet Z = ROW market
bullet A = Coupe (USA)
bullet B = Targa (USA)
bullet C = Cabriolet (USA)

Digit 5

bullet Z = ROW
bullet A = 3.3 litre turbocharged engine
bullet B = 3.6 litre normally aspirated
bullet C = 3.6 litre turbocharged engine

Digit 6

bullet Z = ROW
bullet 0 = No airbags installed
bullet 2 = airbags installed

Digits 7 and 8

bullet First two numbers of  the type
(auftragsnummer) number.  In all cases for the 964 these numbers will be 96

Digit 9 is a check number and is not
important.  However for the USA this will be a 0 to 9 or a X and for the ROW
will be a Z.

Digit 10 is the model year letter.

bullet K = 1989
bullet L = 1990
bullet M = 1991
bullet N = 1992
bullet P = 1993
bullet R = 1994

Digit 12 is the last number of the type
and this will always be a 4.

Digits 13 to 17 make up the serial
number.  Digit 13 also provides version identification but can only be used for
a specific model year.  The numbers were changed around so a 5 in 1989 may not
be the same as a 5 in 1994.

The use of this data is extremely
important especially if the 964 being offered is not contained in the list of
models found in the timeline section.  A number of turbocharged cabriolets are
being claimed as factory produced.  Their VINs do not support this claim apart
from the fact that such a model does not appear in the records of Porsche
production for the 964.

Another issue which causes
identification problems is the chassis number.  This is found on a plate
directly below the fuel tank in the luggage compartment.  This number will
always start WP0ZZZ regardless of version.  The important point is that the last
five digits of the chassis number match the serial number of the VIN.

964s can also be identified by type
number.  The type number is located on the identification label found on the
underside of the luggage compartment lid and a copy of this label is found in
the original service record book provided with every 964 upon original delivery.

Myths and Legends

As with any automobile model the 964 has
its fair share of myths and legends.  Ask many alleged experts and they will you
that the 964 is riddled with faults and is expensive to maintain.  This is
simply not true.  There were only a few problems (far less than many other
automobiles then and now) which were quickly rectified by Porsche which affected
the 964 series.

Engine Oil Leak

In fact this was an acknowledged design
flaw by Porsche.  The cylinder heads were mounted without a head gasket. 
Unfortunately the engine ran a little hotter than predicted and this caused a
slight warp at the base of the cylinder head and oil would weep out.  This
problem was rectified by the installation of a head gasket during the engine
production of model year 1991.  A fix was also approved for the earlier
engines.  The main problem is that the owners of the time did not have this fix
carried out.  Some of the 964s now weep oil.  The problem is fixable.  A caveat
has to be added as well regarding oil leaks.  This introduction is being written
in 2003 about engine produced from 1988 to 1993.  The Porsche engine is an
internal combustion engine and is dry sumped.  All internal combustion engines
develop oil leaks with age.  Not with mileage but with age.  Gaskets and seals
eventually fail.  The less the engine is used the more likely they will fail in
a shorter calendar time.  This is not a model or 964 problem this is just

Double Mass Flywheel

The second most discussed problem is the
double mass flywheel problem.  This problem does not affect the following

bullet 1989 Carrera 4
bullet 1991 Turbo
bullet 1992 Carrera RS
bullet 1992 Carrera Cup
bullet 1992 Carrera 2 versions fitted with
bullet 1992 Carrera 4 versions fitted with
new secondary flywheel mass
bullet 1993 All models
bullet 1994 All models

The DMF was introduced in model year
1990 to meet stringent new internal noise level regulations.  The DMF consists
of two flywheels mounted together with the starter ring sandwiched between the
two masses.  The problem was with the early DMFs was that one mass would move
too far.  This made the assembly make strange noises.  A very distinctive
?clunk? sound could be heard along with vibrations in the transmission.  If the
problem was not rectified gear changing problems would occur and the myth of
clutch reliability arose.  This is dealt with later.  Porsche quickly came up
with fixes for these problems.  For the Carrera 4 a new secondary flywheel mass
(the turbo version) was used and for the Carrera 2 an alternative supplier was
found for the DMF.  LUK was the name of the new supplier.  Porsche 356 owners
will be familiar with the name LUK.

Once the early DMFs are all replaced
this problem will disappear forever.

Dual Ignition System

The last problem related to the dual
ignition system of the normally aspirated 964 M64 series engines.  The turbo
charged engines only use a single distributor system.  The second or secondary
distributor drive is a belt drive from the engine driven primary distributor. 
This belt is made from synthetic rubber and it failed quickly under the effect
of Ozone created by the spark inside the distributor caps.  Porsche fixed this
problem quickly as well.  A vent kit was introduced to remove the ozone from the
assembly.  It is a simple modification it works yet many 964s even in 2003 do
not have this vent kit installed.  However please remember that even with the
vent kit installed the belt will still age and eventually fail.  It is no
different to a rubber cam or timing belt used on other Porsches.  Rubber belts
should be replaced every 100, 000 km (60, 000 miles) or every 5 years whichever
comes first.  In a very worst situation a broken secondary drive belt can cause
expensive damage to the engine.


The clutch plate used by Porsche in the
1989 Carrera 4s only was rubber centred. When the double mass flywheel was
introduced there was no further need for a damped clutch plate because the DMF
was now the damper. The clutch plate used in conjunction with a DMF is known as
a solid centre clutch plate. It has no springs or any other damper device
installed. The only thing that can wear out is the lining and this is a
consumable or expendable product that eventually wears out.  The life of the
clutch is highly dependent upon the drivers foot co-ordination and how fast the
clutch is let out.  A failed DMF can accelerate clutch plate wear.

Rear Blower Fan Resistor

Ensure the rear blower fan ballast
resistor (speed limiting device) is replaced with the newer version which
contains overheat protection. If the new ballast resistor is not installed there
is a risk of an engine bay fire if there is a specific sequence of events that
occur. Engine turned off whilst very hot and the air temperature in the rear
blower fan plumbing is above 95C. Fan bearings failed and rear blower motor is
seized. A very rare but easily avoidable potential problem. Inspecting of this
resistor should be part of any pre-purchase inspection.


All Porsches can be expensive to
maintain simply because parts costs are generally higher than your average
automobile. Labour costs are higher due to access issues especially in and
around the engine bay. The 964 is a true sports car, a Porsche and maintenance
costs are higher. The 964 is a high performance car and reliability is always
going to be less as compared to a daily plodder. The 964 likes being driven so
drive it often. Lack of use can be more damaging than too much.

My own personal Carrera 4, a 1989 model
has never broken down and left me stranded. Yes it has had the odd failure but
never one that made it undriveable. The 964 in the Porsche world represents
excellent value for money, is extremely powerful and a lot of fun to own and

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