Porsche Motorsport North America
GT3 Cup Memorandum 202 / 2004
GT3 Cup Car Preparations for the 2005 Daytona 24 hour
At the end of the 2004 Grand-American Rolex season, certain rules and
specifications changed in the GT class of the series. Because of these changes,
Porsche Motorsport North America is suggesting the following checklist for running
a GT3 Cup car in the 2005 Daytona 24 hour race.
Brakes

The rules require rotor sizes to retain the stock diameters; therefore PMNA
suggests using the stock brake system, which includes the rotors, 6 piston
caliper fronts, and 4 pistons caliper rears. PMNA will offer the stock green
or yellow (softer) compound Pagid pads for the calipers.

If you are interested in using “floating” rotors, please contact Wrightwood
Racing @ (805) 385-7191, for information and purchasing.
Suspension

The rules will allow movement of the chassis suspension “pick up points” to
within a 1” radius of the original location. To take advantage of this rule and
improve the suspension characteristics of the car, PMNA suggests using
the following partso 1
o 1
o 2
996 331 051 9E
996 331 052 9E
911 347 031 91
Rear Subframe L/S
Rear Subframe R/S
Rear Track Rod Assembly L&R/S

The rules will allow the substitution of rubber joints to mono-ball type joints
on all suspension components. PMNA can supply all parts with mono-ball
joints as a replacement for the original ones.

For new stock GT3 Cup lower control arms, the rubber mounted center
bushing can be pressed out and replaced with the GT3 RS type metal
eccentric plates. Part # 996 341 244 9A. Mono-ball type spherical bearing
carriers can also be ordered separately.
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
The complete front and rear adjustable “blade type” sway bar set-up from
the 911 GT3 RS can be used. This set-up will allow for more adjustability
and faster setting changes during the event. The rear GT3 RS sway bars
will also provide clearance for rear spring adjusters and piggy back shock
canisters.

Lighter weight Cartridge 3-way adjustable dampers are available from
PMNA; please contact us for pricing and details.
5-stud Wheel Hubs

To convert the stock center lock hubs to the required 5 stud hub, please
refer to the following procedure:
o Parts Required – 20 pcs 911 331 671 00
Stud 66.0 mm long
20 pcs N 020 112 1
Steel Nut
o Remove the hub from the carrier and remove drive pins
o Drill the existing holes to 15.50 mm diameter
o Before stud installation measure the installed length of the stud
(including hub – rim center – nut).
o Machine off the thread surface above the nut (approx. 15 mm from
the end of the nut to the end of the stud) to provide easier installation
o After installing the stud, make sure the beginning of the thread
groove is smooth to prevent cross threading.
Power steering

GT3 Cup cars can run either the stock engine driven power steering pump
or an electric power steering pump. PMNA offers the following conversion
kit from a GT3 RS.
o 1
o 1
o 1
996 106 915 9A
996 314 915 9A
996 314 015 9B
Engine conversion kit
Power Steering kit
Power Steering Pump
In addition to the above suggestions, we suggest most of the procedures and parts
outlined in the 2004 Daytona 24 hour technical bulletins. Below is a copy of the
bulletins with some additions and changes that apply for 2005 (changes and
additions in blue):
Car preparation will be essential due to the enormous amount of stress on the car
and the engine when running a 24 hour race. The “wear and tear” on the engine
after running 24 hours straight will be a lot higher than if the engine had run 24
hours from a few sprint races. Therefore PMNA does not recommend running a
used engine with over 10 hours of running time (since a rebuild) on it for the 24
hour race.
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PMNA also does not recommend running the 24 hour race with a used engine that
has a total running time (including all rebuilds) of over 100 hours. Even with a
fresh rebuild, there is the possibility of a non-critical component (wire harness,
sensors, etc.) failure, which can affect engine reliability.
In addition to the engine requirements, PMNA suggests the following setup and
inspection procedures as a guideline for preparing the cars to run in long distance
races.
Engine

Use a Sobek water flush tank and pressurized fill tank. This will allow the
mechanics to quickly bleed and fill the water system in the event of a
radiator replacement. Replace all plastic water quick disconnects with
metal quick disconnects available from PMNA. The plastic parts start to
crack when subjected to heat for long periods. Sobek contact informationBernd Sobek-Mattern
Fliederstrasse 10
69517 Gorheimertal, Germany
Phone – 011 49 6201 205152
Fax – 011 49 6201 21834
Email – hydrosob@aol.com

PMNA will offer a remote auxiliary oil fill tank. This system will replace the
oil fill tube and will allow the driver to add oil to the engine during the race.
The system uses a remote oil pump operated by a button inside the cockpit
and will be programmed to add between 1.0 to 1.5 qts of oil for every push
of the button. The auxiliary tank will hold approximately 10 qts. Please
contact PMNA for details and pricing. (The engine will need oil during
the 24 hour race, for the 2004 participants who had low oil
consumption please keep in mind the majority of the ’04 race was run
in the rain and under yellow flags which kept the engine revs low)

Buy an electronic oil dipstick sensor and light display box (GT3 RS part #
996 641 135 9A (Display), 996 613 135 9B (Sensor)). The dipstick sensor
can be mounted on the stock oil tank bracket and the display box should be
mounted where it will be visible through the rear side window.

Install a new air filter for the race. Check for clearance issues with the rear
deck lid. For 2003 and older engines we suggest using the 2004-05 air
filter and carbon heat shroud to prevent engine heat from affecting the
intake air temperature. Part number 996 110 021 94.

If you are running a new 2005 engine, we suggest replacing the engine oil
drain plugs with magnetic plugs. Also, replace the stock black water pump
supply hose and clamp with a red Samco hose and adell clamp.
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
Check exhaust headers for cracks, replace if old.
Transmission

Inspect all transmission gears and differential. Replace all old gears and
the differential. We do not recommend running a used transmission with
over 15 hours of running time on it for the 24 hour race.

Check the transmission mount bracket for cracks, replace for the race (part
# 996 375 039 9B). See bulletin GT3 Cup 01/01.

Check shifter assembly for wear and cracks, replace if old. Install new
shifter cables before the final practice. Check for cable stretch and for
proper shifter alignment before the race (use alignment tool, part # 996 424
395 03.).

For 2001 and older GT3 Cup cars, PMNA suggests running a 2002 or
newer gearbox with the included heat exchanger.

Inspect transmission filter bracket for cracks, if possible install rubber
dampers to protect the bracket from vibrations. Install a new transmission
filter before the race (part # 993 307 324 00)

Replace the rubber and plastic water junction hose (for the transmission
cooler) with the updated metal piece, part # 996 106 905 RK. See bulletin
GT3 RS # 105/2003.

We suggest using a GT3 RS style metallic 5.5in clutch and flywheel (which
has been proven to last a 24 hour race). A kit is available from PMNA that
includes the clutch and flywheel assembly, flywheel sensor and sensor
brackets, release bearing, bleed line, adaptor supply line, and a
compression-fitting adaptor. You will be required to cut the stock supply
hard line for the compression fitting. Once the clutch has been installed,
you must install an adjustable clutch pedal stop, if the pressure plate
springs are stroked “over center” they will lose 50% of their clamping force.

If you are planning on using a stock clutch and flywheel setup, use the 993
RSR style clutch and pressure plate, part # 964 116 028 53.
Fuel

Install a fuel cell with a reserve tank and pump. Mount the switch for the
pump on the center dashboard. PMNA can order factory GT3 RS fuel cells,
which will work in the GT3 Cup cars. If you are interested in a Cartridge
fuel cell (lighter and stronger with a better reserve tank system), please
contact them directly for pricing and details, (212) 628-6778
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
A fuel map switch kit is available from PMNA, which allows the driver to
select between 3 different fuel maps. The fuel maps can be used for better
fuel management throughout the race. Part # 996 613 361 9A

Replace all old fuel pumps and fuel filters.
Chassis

Crack check all control arms and uprights. Replace parts if they have over
15 hours of use.

Install new radiators for the race. Check all lines (clutch and brake) and
hoses (water) for wear, cuts, and possible rubbing with other parts. Check
the metal tangs for cracking on the clip-in water hoses going from the
engine to the chassis. Make sure the proper clips are installed – “Short”
clip on the chassis lines and “Long” clip on the engine lines. Refer to the
2004 GT3 Cup Technical Handbook (page 12).

Install a new throttle cable before the final practice. Check for cable stretch
and full throttle before the race. Cable should not be tight when full throttle
is applied at the pedal, there should be a tiny amount of play in the throttle
body. Check throttle pedal for looseness at the bottom hinge, replace if old.

We recommend replacing the throttle pedal with the stock GT3 RS style
pedal. Install an adjustable throttle pedal stop behind the pedal.

Check all brake rotors for cracks. “Bed in” all new brake pads and rotors
before running in the race. You will need to change pads during the 24
hour race, so practice brake pad changes before the race.

“Bed in” new axles before running in the race. Recommended procedure is
to run axles in for approximately 100km at a maximum speed less than 200
kph, and with low torque (light throttle loads).

Aftermarket Cartridge drive shafts are available from PMNA. These drive
shafts are race proven and the individual components of the shaft can be
serviceable. Please call PMNA for pricing and details.

Crack check all wheel rims (especially the wheel spokes).

Install a GT3 RS type front air jack exhaust valve, part # 964 385 113 00.
This will decrease the amount of time it takes to retract the front air jack
when lowering the car.
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
We strongly recommend using only the original Porsche rear wing mount
plates.

PMNA is offering rebuilds for stock GT3 Cup Sachs shocks please call for
details.

If you are running the stock 2003 Sachs shocks, make sure the shock seal
cover has been tightened to the updated torque specification (see tech
bulletin GT3 Cup # 106/2003)

Carry spare windshields for the race (the Porsche parts truck will not have
any available). Depending on the rules, change from a “glue in” type to a
“clip in” type removable windshield.
Electrical

A lightweight Cartridge chassis and engine harness is available, please
contact Cartridge directly for pricing and details, (212) 628-6778.

We recommend installing a Motec Dashboard, which will provide valuable
information for setting up the car and also for engine data acquisition.
Please call PMNA for pricing and details.

Check battery charge; replace the battery if it has been used for a season.

Check fuse box for burned out fuses and corrosion. In case there are
electrical problems during the race, make sure there are spare fuses and
relays in the car (inform the drivers!)

Check all electrical connections in the car for loose connections and
corrosion, especially behind the dash panel.
Rules

Please consider that this checklist is a suggested guideline and does not
cover 100% of the required car setup procedures. Please read the Grand
Am rules carefullyhttp://www.grandamerican.com/Competition/Rules.asp
It is the individual team’s responsibility to make sure that the car is
setup properly and within the legal limits of the rules.
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