Porsche training p30 drivetrain repair sports car

Page 2.4 Drivetrain Repair – Sports CarsZ1 = Number of teeth in 1st gearwheel in power flow of corresponding gear Z2 = Number of teeth in 2nd gearwheel in power flow of corresponding gea

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AfterSales Training

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Porsche AfterSales Training

Student Name:

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Instructor Name:

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Important Notice: Some of the contents of this AfterSales Training brochure was originally written by Porsche AG for its

rest-of-world English speaking market The electronic text and graphic files were then imported by Porsche Cars N.A, Inc and edited for content Some equipment and technical data listed in this publication may not be applicable for our market Specifications are subject to change without notice.

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© 2010 Porsche Cars North America, Inc All Rights Reserved Reproduction or translation in whole or in part is not permitted without written authorization from publisher AfterSales Training Publications

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Table of Contents

Transmission Type Designations 1

Boxster (986) Transmission 2

Boxster & Cayman (987) Transmission 3

911 Turbo (996) Transmission 4

911 GT2/GT3 (996) Transmission 5

Tiptronic Transmission 6

Porsche Doppelkupplung (PDK) Transmission 7

Final Drive Setup 8

Conversion Charts 9

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Drivetrain Repair – Sports Cars

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Transmission Type Designations

911, Boxster and Cayman Transmission Type Designations Since Model Year 1989

Model Transmission Technical Installed In

Transmission Number Identification

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Page 1.2 Drivetrain Repair – Sports Cars

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Boxster (986) Transmission

General Information 2

Boxster Transmission 2

Dual-mass Flywheel 2

Gears 2

Pinion Shaft Bearing 2

Lubrication 3

Boxster Gear Ratios 4

Synchromesh 5

Boxster Shifter, 5-speed 5

Reverse Gear Lock 6

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General

The Boxster came equipped with a Five-speed and the

Boxster S with a Six-speed manual transmission, both

models offered the optional Tiptronic automatic

transmis-sion This section will only cover the Boxster G86.00/01

Manual Transmission G86.01 – Boxster (986)

The transmission ratios of the 5-speed Boxster manual

gearbox have been adapted to the increased engine

per-formance respectively the higher engine torque

Dual-Mass Flywheel/Clutch

Dual-mass Flywheel, Pressure Plate and Clutch Disk

The working cycles and the firing order of the engine

cause speed fluctuations resulting in irregularities which

lead to torsional vibrations along the entire drive train

These torsional vibrations may cause all loose parts not

powered and with play to rattle, chatter, or bounce (loose

gearwheels, parts of the synchronization system, switch

components) This may result in annoying transmission

noise, especially at low engine speeds

As with previous Porsche vehicles, the Boxster has a

two-mass flywheel (TMF) to prevent these noises The

single-disk dry clutch with asbestos-free clutch plates is bolted to

the TMF

G86.00 Gear Sets – Boxster (986)

Gear Sets and Shafts

The G 86.00 transmission is a two-shaft transmission with

an overhead drive shaft and hypoid drive assembly All ofthe forwards gears as well as the reverse gear have exter-nal cone synchronization

The first, second, and the reverse gear are permanentcomponents of the triple-bearing drive shaft The pinionshaft runs on two tapered roller bearings

G86.00 Pinion Shaft Bearing – Boxster (986)

Longitudinal Adjustment Of Pinion Shaft Bearing

Installation of a rubber plate (1) at the rear tapered-rollerbearing (3) carrying the pinion shaft means that the setbearing tensioning is maintained within the specified toler-ances, even when the transmission case expands due toheating

Pinion Shaft Bearing

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G86.00 Transmission Cutout

G86.00 Oil Supply – Boxster (986)

To reduce losses due to splashing and to increase

efficiency, the oil level has been kept low with a 2.25 liter

oil capacity This means that oil must be supplied using an

oil drip shaft to lubricate the loose gearwheels on the drive

shaft and the rear transmission bearing

Note !

The transmission should be filled and topped off with the

transmission oil - Burmah TAF 21* only The oil should be

changed every 90,000 miles

* (Available through the Porsche Parts Department)

Notes:

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Z1 = Number of teeth in 1st gearwheel in power flow of corresponding gear

Z2 = Number of teeth in 2nd gearwheel in power flow of corresponding gear

iz = Transmission ratio

ia = Final drive ratio

V1000 = Calculated vehicle speed at 1,000 rpm engine speed

With 225/50 ZR 16 rear tires, rolling circumference 1,930 mm, (rdyn 307 + 1.5% - 2.5%)

Note:

The values in the transmission diagram are indicative and are based on a mean effective rolling radius Slight deviations due to the tolerance

of the tires, change of rolling radius, wear, and slip of tires have not been taken into consideration.

Note:

Transmission Ratios – Boxster G86.00

Gear Versus Road Speed Graph

Transmission Ratios – Boxster G86.01

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G86.00 Synchronizer 3rd - 5th & Rev – Boxster (986)

Synchronizer 3rd to 5th & Reverse Components

The effective diameter of the synchronizing rings is 84

mm for the 3rd to 5th and reverse gears The

synchroniz-ing rsynchroniz-ings for 4th and 5th gear are made of brass The 3rd

and reverse gears also have a molybdenum coating

G86.00/01 Gear Shifter – Boxster

The Boxster has a cable shift in order to disengage the

shift bracket from the gearbox (noise transmission) and to

ensure precise shifting behavior when the assembly

moves

5-speed Shift Pattern

Instead of the usual gear-shift linkage, the cable shift has a

selector and shift cable The cables to which tension and

pressure can be applied form the link between the shift

lever and the transmission The five forward gears and the

reverse gear are arranged into three shift rows,

G86.00/01 Shifting – Boxster (986)

Internal Transmission Shifting Components

The internal shifting system comprises:

● An inner shifting shaft (1)

● A deflection shaft (2) with locking device for the reversegear and shifting cams (7), which prevent 2 gears frombeing selected at the same time

● Two shift rods with a swinging shift fork and twoaluminum shift forks The shift fork for the 1st and 2ndgear (5) is mounted on the shift rod for the 5th andreverse gear (6)

● A central gear arrester (3)

● A reverse-gear lock (4)

Functional Description

When in its parked position, the inner shift shaft (1) is inthe 3rd/4th gear position It transmits rotary and axial motion to the deflection shaft (2) This slides the appropri-ate shift rod for the selected gear The central geararrester (3) ensures that the individual gears are fixed inthe precise position

The reverse-gear lock (4) prevents shifting from the 5thgear into the reverse gear The double-shift cams (7) onthe deflection shaft (2) prevent two gears from beingselected at the same time

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G86.00/01 Reverse-gear Lock – Boxster (986)

The reverse gear lock prevents shifting from the 5th gear

into the reverse gear It is installed as a complete

assem-bly and does not have to be adjusted

Reverse-gear Lock

If the driver attempts to shift from the 5th gear into the

reverse gear, the stop (2) of the deflection shaft (3) hits

the blocker (4) of the reverse-gear lock thus preventing

shifting into the reverse gear The reverse gear can only

be engaged from the idle position

The spring force then presses the blocker for the

reverse-gear lock into the housing by the axial motion of the

deflection shaft The path of the shift finger into the shift

rod for the reverse gear is thus released

G86.00/01 Central Gear Detent – Boxster (986)

The central gear arrester is installed as a complete

assembly No adjustment is necessary and no measures

have been taken to enable the device to be repaired

To detent ranges can be selected from the idle position

Detent range for gears 1, 3, 5

Detent range for gears 2,4, R

If the catch plate (1) is moved left out of its idle position bythe deflection shaft (2), the lower roller leaves the catchand enters the highest point of the curved path (3) Thedeformation spring (4) expands The pretensioning force

on the curved paths is increased via the rollers (5) and thecatch plate snaps into the selected position Apart fromlocking, this “snapping effect” also provides shift-forcesupport

If the catch plate moves to the right out of its idle position,the same functional procedure applies, but instead the2nd, 4th, or reverse gears are locked in

Notes:

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Manual Transmission G87.01 – Boxster/Cayman (987)

The Boxster/Cayman (987) feature a revised 5-speed

manual transmission, type G87.01 as standard The

following additional options are available:

- 6-speed manual transmission, type G87.20,

- 5-speed Tiptronic S transmission, 2005-06 Boxster

(987) type A87.01,

- 5-speed Tiptronic S transmission, 2007 Boxster/Cayman

(987) type A87.02,

Dual-mass Flywheel

The working cycles and ignition sequence of the engine

result in speed fluctuations which induce torsional vibration

throughout the drivetrain These torsional vibrations can

induce rattling, chattering or floating in all loose parts

subject to play which are not incorporated into the power

flux (loose gearwheels, synchronization parts) This may

lead to unpleasant noise, particularly at low engine speeds

combined with high transmission oil temperatures Similar

to previous Porsche vehicles, the Boxster/S and

Cayman/S (987) incorporate a dual-mass flywheel (DMF)

to prevent such noise

Clutch

The Boxster/S (987) and Cayman/S (987) feature ahydraulically actuated single plate dry clutch unchangedfrom the previous Boxster/S (986), with a pressure plate

in nodular cast iron GGG 60 and a clutch disk diameter of

240 mm The contact pressure has been adapted to theengine torque and the hub of the clutch disk has beenadapted to the new transmission input shaft

Manual Transmission G87.01 – Boxster/Cayman (987)

5-Speed

Transmission Ratio – G87.01

The rear axle transmission ratio has been adapted tocompensate for the 5 % larger rolling circumference of therear wheels and now stands at 3.75 This transmissionratio results in a sporty setup for the Boxster/Cayman andenables high performance with optimum exploitation of theengine torque and the maximum output

Notes:

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911 Turbo (996) Transmission

General Information 2

Dual-mass Flywheel 2

Clutch Ventilation 2

Transmission Cutout 3

Hydraulic Assist Clutch Operation 4

911 Turbo (996) Gear Ratio 4

Gearshift Mechanism 4

Gears 5

Lubrication 5

Synchronization 6

Final Drive 7

Shifter 8

Shift Forks 9

Shifter Interlock 9

Transmission Housing 9

Viscous Coupling 10

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Page 4.2 Drivetrain Repair– Sports Cars

Transmissions

General

The 911 Turbo (996) came equipped with a six-speed

manual transmission or optional Tiptronic automatic

trans-mission used in the new 911 Turbo (996) is an evolution of

the transmission from 1996 911 Turbo (993) G50.51

To adapt the transmission to the new vehicle, all of the

housing components have been redesigned and the

gearshift mechanism converted to cable operation

The major changes are as follows:

● Viscous clutch relocated to front-axle final drive (as with

911 Carrera 4)

● New transmission shaft mounting

● New differential

● New transmission ratios with stronger and quieter

running gear sets

Note !

The Porsche Stability Management system (PSM) is

stan-dard equipment on the new 911 Turbo (996) As a

mechanical locking differential would have an adverse

effect on the PSM system, the 911 Turbo (996) cannot be

equipped with a locking differential

Manual Transmission Types:

Dual-Mass Flywheel/Clutch

The working cycles and the firing order of the enginecause speed fluctuations resulting in torsional vibrationsalong the drive train These torsional vibrations may causeloose (nondriven) gear sets and parts of the synchronizers

to rattle, chatter or bounce This can result in annoyingtransmission noise, especially at low engine speeds andhigh transmission oil temperatures To prevent thesenoises, the 911 Turbo (996) has a two-mass flywheel(TMF)

Clutch Ventilation

Clutch ventilation is used in the 911 Turbo (996) Radialvanes arranged on the back of the clutch pressure plateact as a blower when the engine is running

Design

The clutch bell housing is completely sealed except for aninlet opening and an air extractor flange Fresh air isdrawn in via the inlet opening and flows through the pres-sure plate radially for cooling of the clutch frictionsurfaces

The exhaust air is expelled through the air extractor flangeintegrated in the clutch housing This clutch ventilation de-sign reduces the temperature in the clutch bell housing, resulting in less clutch wear and a longer clutch servicelife

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G96.50 Transmission Cutout

Notes:

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A tandem power steering pump is used to provide the

pressure for the power-assisted clutch The pressure is

generated in the second circuit of the pump and is limited

to approx 80 bar The accumulator (7) is filled via a

pres-sure limiting valve (3), which is located in the expansion

tank The power-assist servo unit consists of the

accumu-lator (7), poppet valve (8), power valve (9), and slave

cylin-der (10) The fluid reservoir for the clutch master cylincylin-der

is located in the fresh-air chamber (in front of the luggage

compartment) The system is filled with Pentosin hydraulic

fluid

Note !

The threads of the caps for the windshield washing fluid

reservoir (blue), brake fluid reservoir (black/yellow) and

Pentosin fluid reservoir (green) are identical The caps

could be mixed up by mistake.

Power-assisted hydraulic clutch components.

1 - Tandem pump

2 - Non-return valve

3 - Pressure limiting valve

4 - Expansion tank for servo pump

5 - Fluid reservoir for clutch master cylinder

Transmission Ratios – 911 Turbo (996) G96.50

The relatively short 1st gear reduces the load on theclutch when starting off and makes for comfortable driving

at crawling speeds 6th gear has been configured to allowmaximum vehicle speed to be reached

Gearshift Mechanism

Gearshift Mechanism Cutout

1 - Right angle drive

2 - Cam plate

3 - Retaining spring

4 - Lockout pins

5 - Detent (main shift rod)

6 - Shift fork, 3rd/4th gear

7 - Shift fork, 5th/6th gear

8 - Reverse light switch

9 - Shift fork, R gear

10 - Shift fork, 1st/2nd gear

11 - Main shift rod

12 - Detent

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Note:

Gear Sets

The two-shaft transmission uses an overhead input shaft

and hypoid final drive assembly The loose (non-driven) and

fixed gears have been ground and honed to minimize

noise Pairing of the gears was not necessary (hence no

pairing number) All loose gears have needle roller

bearings The fixed gears for 1st and 2nd gear are part of

the input shaft and are therefore not separately

replaceable parts

Reverse gear is synchronized and can be engaged even

when the vehicle is coasting slowly forwards The reverse

gear is located in the front transmission case The

intermediate gear for reverse is mounted on a shaft via

needle roller bearings and is secured with a circlip The

shaft is locked in place by a bolt mounted through the

transmission case

5th and 6th gears are also in the front transmission case

The fixed gears are attached to the input shaft and the

loose gears are mounted on the pinion shaft

Oil Supply To Bearings For 1st/2nd/5th & 6th Gear

Oil Drip Pan Location

The bearings for loose gears 1, 2, 5 and 6 are lubricated

as follows:

The rotation of the crown wheel (ring gear) transfers oilfrom the oil sump into an oil collector (1) attached to thetransmission case From there, the oil is fed directly to thehollow pinion shaft via a connecting pipe (2) The rotation

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When the guide sleeve of the 1st and 2nd gears is fitted,

care must be taken to ensure that gaps between the teeth

of the internal gearing are aligned with the oil bores

Oil Supply To Bearings For 3rd And 4th Gear

Location of Oil Hole in Hollow Drive Shaft

The rotation of the loose gears in the front transmission

case transfers oil from the oil sump to an oil collector (1)

integrated in the transmission case From there, the oil is

fed to the hollow input shaft The rotation of the input shaft

causes the oil to be supplied directly to the loose gears of

the 3rd and 4th gear via cross bores

This oil supply to the bearings allows uniform oil

distribu-tion, lubrication at critical locations, reduced cavitational

losses and lower oil temperatures

The required quantity of oil and the approved oil types are

given in the Technical Manual and Warranty & Maintenance

Manual.

Note !

The lower section of the gear case is sealed to prevent

the oil from flowing out of the front transmission case as a

result of extreme acceleration When filling the

transmis-sion with oil, it is critical that the specified filling capacity

is observed to ensure that all oil chambers are properly

filled

Since the oil change interval is specified at every 90,000miles, it is essential that only the approved oil types areused

Synchronization, 1st/2nd Gear

As with the previous transmission, the G96.50 sions use double cone synchronization for 1st and 2ndgears This synchronization reduces shifting forces by asmuch as 30 – 40% compared to single cone synchroniza-tion

transmis-Functional Description

Synchronizer Components

The synchronizing ring (2), friction ring (3), guide sleeve(4) and shift sleeve (5), rotate at the same speed as thepinion shaft (vehicle speed) The loose gear with clutchbody (6) and the tapered ring (1) rotate at the same speed

as the engine

When the shift sleeve is moved towards the guide sleeve,friction is produced between the synchronizing ring and tapered ring outer surface and between the friction ringand tapered ring inner surface This friction decelerates(1 – 2 shifting) or accelerates (2 – 1 shifting) the parts rotating at engine speed Doubling the friction surfacesconsiderably reduces shifting forces

Synchronization, 3rd – 6th And Reverse Gear

Synchronization for gears 3 through 6 and for the reversegear utilizes single cone synchronization The synchroniz-ing rings for gears 3 through 6 are identical and have amolybdenum coating The synchronizing ring for reversegear is not coated

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Gear Retention

To retain the gears in position once a gear is selected, the

loose gear (clutch body) gear teeth and the shift sleeve

gear teeth are bevelled When the torque is transmitted,

the bevelled surfaces are pressed against each other and

drawn together Stepped elevations on the clutch bodies

prevent “overshifting”

Shift Sleeves

The shift sleeves for 1st/2nd gears and 3rd/4th gears are

asymmetrical During assembly, it is important to ensure

that the groove (A) face 2nd gear and 3rd gear,

respectively

Shift sleeve showing continuous groove (A) that must face 2nd

gear (1st/2nd shift sleeve) and 3rd gear (3rd/4th gear shift

sleeve) during assembly.

The shift sleeves have three grooves in the inner gearing,

indicated by three punch marks (B) on the sleeve When

mounting the shift sleeves to the guide sleeves, the punch

marks (B) must be aligned with the ball bearings (2)

1 - Shift sleeve 2 - Ball bearing

C - 2nd gear side D - 1st gear side

1st/2nd gear shift sleeve assembly 3rd/4th gear shiftsleeve assembly is identical

Final Drive

The final drive gear set is a hypoid drive This means thatthe center line of the ring gear is 10 mm above the centerline of the pinion shaft Hypoid drives can (with the samering gear size) transmit relatively high torques since theteeth of the pinion shaft are designed to be more robust

In addition, the new position of the ring permits lower diffraction angles along the drive shafts The pinion shaftand ring gear are manufactured using the Gleasonmethod The pinion shaft is hollow-drilled to optimize lubri-cation and to reduce weight Recesses have been forgedinto the back of the ring gear to reduce weight

The adjusting dimension E (pinion depth) is 70 mm and isset at the tensioning plate and four-point bearing using adjusting shims

Notes:

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Transmission Shaft Mounting

The input and output shafts are each supported by four

bearings In the transmission case, the two shafts are

each mounted on one roller bearing Four-point bearings,

which are fitted in a tensioning plate, are used as axial

mounts There is also an additional roller bearing for each

shaft in the gear case and in the front transmission case

Gear Shifting

6-Speed Shift Pattern

The six forward gears and the reverse gear (R) are

arranged in four shift gates 6th gear is located at the

bot-tom right of the shift pattern A cable shift mechanism is

used This prevents assembly movements and vibrations

from being transmitted to the gear-shift lever

Two cables form the connection between the gearshift

lever and the transmission The advantages of this cable

system are small space requirements, low weight, and

effective isolation of movements and vibrations through

the gearshift lever without impairing shifting precision

As a result, the internal shift finger engages in the ponding shift rod and the gear plane is preselected Thegear planes are arrested with a springloaded cam plate

corres-The shift cable is connected to the external shift lever (5)

to allow the gear to be engaged The external shift lever

is, in turn, connected to an internal shift gate (6) which engages in a selector shaft attached to the internal shiftrod which causes the respective shift fork to be moved

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Shift Forks

The aluminum-alloy shift forks for 1st/2nd gears 3rd/4th

gears are fixed to the shift rods by rolled pins and are not

adjustable The shift forks for 5th/6th gears and reverse

are attached to the shift rods using clamping bolts and are

adjustable The surface of the shift rods are knurled to

help retain the shift forks in their adjusted position

Gear Detent

A neutral gear position detent is provided by the internal

mechanism Individual shift rod travel is also limited by

separate springs and balls

Internal Shift Mechanism Showing Shift Rod Spring And Ball

Detents

Shift Interlock

Lock out pins are attached to the tensioning plate and theshift rods to ensure that only one gear can be engaged atany one time During assembly and disassembly, it isimportant to ensure that these pins are positionedcorrectly

Cross Section Of Transmission Showing Shift Rod Lockout Pins

Transmission Case

The transmission consists of three sections – the clutchhousing, gear case and front transmission case The sec-tions are die-cast and made of a light alloy The individualsections are sealed using Loctite 574 without paper gas-kets The case sections are aligned with locating pins andbolted together with M8 bolts The reverse light switch islocated in the front transmission case A steel insert iscast into the bearing bores to minimize bearing clearance

on the input and output shaft when the clutch housing expands due to heat

Notes:

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Viscous Clutch

The 911 Turbo (996) has a multi-disc viscous clutch,

specifically adapted to the specific 911 Turbo

characteris-tics This has meant a further improvement in traction The

inner splines have been changed to prevent

interchang-eability with other clutch drives To reduce temperatures at

the multi-disc viscous clutch, the unit has been integrated

in the front-axle final drive No additional space in the

man-ual or Tiptronic transmission had to be provided as a

result of this measure The viscous clutch is filled with a

precise quantity of high-viscosity silicon oil and is

perma-nently sealed It is not possible to add more silicon oil or

to check the oil level

Viscous Clutch

The multi-disc viscous clutch housing (1) is connected to

the pinion shaft of the front-axle final drive The clutch hub

(2) is connected to the central drive shaft and is supported

by plain bearings If there is a speed differential between

the outer and inner discs, a torque is transmitted from the

fast to the slow rotating side through the internal fluid

fric-tion The discs are fully separated by the oil so that they

are not subject to abrasion or wear Since traction

distribu-tion is dependent on the difference between the tracdistribu-tion

slippage at the front and rear wheels and on the resultingspeed differential at the viscous clutch, a variable torquedistribution exists In other words, the distribution adapts

to the traction requirements

However, since tire slippage exists whenever drive torque

is transmitted, it is possible to obtain a permanent wheel drive system with variable torque distribution of approx 5 to 40% to the front axle

four-Front Axle Differential (Z96/00)

The front axle is driven by a spiral bevel gear, which isground and lapped to eliminate production tolerances Toreduce drag losses, grooved ball bearings (1) are used inthe differential gear instead of tapered roller bearings

A hole with M8 thread (2) is drilled into the side cover ofthe differential This is used for noise measurements dur-ing production and can be disregarded by service person-nel

There is a bleeder hole (3) in the underside of the neck tube This hole should not be sealed The discharge

long-of transmission oil from this hole is an indication that thesealing ring (4) is damaged

Note !

Performance tests should only be carried out on a roller test stand (dynamometer) with engine speed decou-pling If testing is performed on a two roller test stand, thedrive shaft must first be removed

four-1 - Grooved ball bearings

2 - Test (acoustic) access hole (M8

thread)

3 - Bleeder hole

4 - Sealing ring

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911 GT2/GT3 Transmission

Transmissions

General – Manual Transmission 911 GT2/GT3 (996)

The 2004 911 GT3 (996) 6-speed transmission is based

on the 2001 911 GT2 (996) 6-speed manual transmission

Both transmission types share components specially

designed for these two endurances tested 911 vehicles

Key features:

• Dual-mass flywheel

• Cable gearshift with direct translation of shift actuation

through shortening of lever ratio on the gearbox input

lever

• Transmission oil cooling through a transmission

mounted oil-to-water heat exchanger

• Oil-spray lubrication with pressurized oil supply through

an additional oil pump

• Asymmetric limited-slip differential

• Use of steel synchronizing rings

Manual Transmission Types:

General – Manual Transmission 911 GT3 (997)

The new 911 GT3 (997) is only available with a manual 6-speed gearbox without hydraulic clutch assistance Thegearbox has been modified in order to improve the accel-eration capability and to adapt it to the torque curve

• Steel synchronization rings for gears 3 to 5

• Shorter transmission ratios compared to the 911 GT3(996)

to rattle, chatter or bounce This can result in annoyingtransmission noise, especially at low engine speeds andhigh transmission oil temperatures To prevent thesenoises, 911 GT2/GT3 (996) & 911 GT3 (997) use a dual-mass flywheel (TMF) The 2007 911 GT3 RS uses a single-mass flywheel

Pressure Plate

The 911 Turbo (996) pressure plate is used on both 911GT2/GT3 models

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G96.88/96 Transmission Cutout

Notes:

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With 305/30 ZR 19 rear tires, rolling circumference 2091 mm)

Note:

The values in the transmission diagram are indicative and are based on a mean effective rolling radius Slight deviations due to the tolerance of the tires, change of rolling radius, wear, and slip of tires have not been taken into consideration.

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Transmission Ratios – 911 GT2 (996) G96.88

On level roads, it is advisable to start off in 2nd gear In

2nd gear the vehicle can also be driven away more

smoothly on slippery road surfaces The 6th gear has

been configured to allow the maximum possible vehicle

speed to be reached

Transmission Ratios – 911 GT3 (996) G96.96

The relatively short first gear is easier on the clutch and

the 6th gear has been configured to allow the maximum

possible vehicle speed to be reached

Clutch Ventilation

Clutch ventilation is used in the 911 GT2/GT3 models

Radial vanes arranged on the back of the clutch pressure

plate act as a blower when the engine is running

Design

The exhaust air is expelled through the air extractor flangeintegrated in the clutch housing This clutch ventilation design reduces the temperature in the clutch bell housing, resulting in less clutch wear and a longer clutch servicelife

Gearshift Mechanism – 911 GT2/GT3 (996)

Gearshift Mechanism Cutout

1 - Right angle drive

2 - Cam plate

3 - Retaining spring

4 - Lockout pins

5 - Detent (main shift rod)

6 - Shift fork, 3rd/4th gear

7 - Shift fork, 5th/6th gear

8 - Reverse light switch

9 - Shift fork, R gear

10 - Shift fork, 1st/2nd gear

11 - Main shift rod

12 - Detent

Gearshift Mechanism – 911 GT3 (997)

For high shift dynamics with short shift throws, the new

911 GT3 (997) has the shift block of the current 911Carrera (997) generation with a shorter shift lever ratioand a GT3 specific short lever ratio on the gearbox inputlever As a result, the entire shift ratio of the new 911 GT3

is approx 15% shorter than in the 911 GT3 (996) andapprox 33% shorter than in the current 911 generation

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Gear Sets

The two-shaft transmission uses an overhead input shaft

and hypoid final drive assembly The loose (non-driven) and

fixed gears have been ground and honed to minimize

noise Pairing of the gears was not necessary (hence no

pairing number) All loose gears have needle roller

bearings The fixed gears for 1st and 2nd gear are part of

the input shaft and are therefore not separately

replaceable parts

Reverse gear is synchronized and can be engaged even

when the vehicle is coasting slowly forwards The reverse

gear is located in the front transmission case The

intermediate gear for reverse is mounted on a shaft via

needle roller bearings and is secured with a circlip The

shaft is locked in place by a bolt mounted through the

transmission case

5th and 6th gears are also in the front transmission case

The fixed gears are attached to the input shaft and the

loose gears are mounted on the pinion shaft

Gear Sets – 911 GT3 (997)

To improve the ability of the new 911 GT3 (997) to

accel-erate and to adapt the gear-box to the torque curve, the

ratios of gears 2 to 6 were shortened This was enabled

through the advanced high-revving concept of the engine,

and offers even better power transmission with increased

maximum speed and shift speed when accelerating after

changing gear

Synchronization, 1st/2nd Gear

As with the previous transmissions, the transmissions use

double cone synchronization for 1st and 2nd gears This

synchronization reduces shifting forces by as much as 30

– 40% compared to single cone synchronization

Synchronizer Components

The synchronizing ring (2), friction ring (3), guide sleeve(4) and shift sleeve (5), rotate at the same speed as thepinion shaft (vehicle speed) The loose gear with clutchbody (6) and the tapered ring (1) rotate at the same speed

as the engine

When the shift sleeve is moved towards the guide sleeve,friction is produced between the synchronizing ring and tapered ring outer surface and between the friction ringand tapered ring inner surface This friction decelerates (1 – 2 shifting) or accelerates (2 – 1 shifting) the parts rotating at engine speed Doubling the friction surfacesconsiderably reduces shifting forces

Synchronization, 3rd – 6th And Reverse Gear

The synchronization mechanism used for gears 3 - 6 andfor the R gear is a single cone synchronization

mechanism The synchronizing rings for gears 3 - 5 aremade of steel The synchronizing rings for the 6th andreverse gear are made of special bronze The friction sur-faces of all synchronizing rings (except the synchronizingring for the reverse gear) have a molybdenum coating

Gear Retention

To retain the gears in position once a gear is selected, theloose gear (clutch body) gear teeth and the shift sleevegear teeth are bevelled When the torque is transmitted,the bevelled surfaces are pressed against each other anddrawn together Stepped elevations on the clutch bodiesprevent “overshifting”

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Shift Sleeves

The shift sleeves for 1st/2nd gears and 3rd/4th gears are

asymmetrical During assembly, it is important to ensure

that the groove (A) face 2nd gear and 3rd gear,

respectively

Shift sleeve showing continuous groove (A) that must face 2nd

gear (1st/2nd shift sleeve) and 3rd gear (3rd/4th gear shift

sleeve) during assembly.

The shift sleeves have three grooves in the inner gearing,indicated by three punch marks (B) on the sleeve Whenmounting the shift sleeves to the guide sleeves, the punchmarks (B) must be aligned with the ball bearings (2)

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Final Drive

The final drive gear set is a hypoid drive This means that

the center line of the ring gear is 10 mm above the center

line of the pinion shaft Hypoid drives can (with the same

ring gear size) transmit relatively high torques since the

teeth of the pinion shaft are designed to be more robust

In addition, the new position of the ring permits lower

dif-fraction angles along the drive shafts The pinion shaft and

ring gear are manufactured using the Gleason method

The pinion shaft is hollow-drilled to optimize lubrication and

to reduce weight Recesses have been forged into the

back of the ring gear to reduce weight

The adjusting dimension E (pinion depth) is 70 mm and is

set at the tensioning plate and four-point bearing using

adjusting shims

Transmission Shaft Mounting

The input and output shafts are each supported by four

bearings In the transmission case, the two shafts are

each mounted on one roller bearing Four-point bearings,

which are fitted in a tensioning plate, are used as axial

mounts There is also an additional roller bearing for each

shaft in the gear case and in the front transmission case

Transmission Lubrication

911 GT2/GT3 Transmission Lubrication and Cooling

Components

A separate oil pump (1) is used in transmission to ensure

optimum lubrication even at critical locations, uniform oil

distribution, reduced churning losses and a drop in

trans-mission oil temperature The gear pump (1) driven by adrive pinion mounted on the drive shaft draws the oil out ofthe differential housing It pumps the oil through the oil towater heat exchanger (2) and then feeds it to the variouslubricating points

The differential housing is divided into two sections by apartition wall to ensure that the oil can be drawn in reliablywithout air pockets One section contains the crown wheeland the other the settled oil and the suction pipe (3)

In the front transmission cover, the cooled transmission oil

is pumped into the transmission (4) and passes throughthe hollow drilled input and output shaft to lubricate theloose gear bearings The shafts have cross bores at theloose gear bearings This ensures that oil is supplieddirectly to the loose gear bearings

An oil spray pipe (5) also supplies oil to the 3rd - 6th gearmesh as well as to the bevel gear and crown wheel Theoil pump has a delivery rate of approx 8 liters at 6,000rpm The oil pressure is limited to 2.7 - 3 bar by means of

a ball valve

Transmission Cooling

Transmission Cooling Components

An oil to water heat exchanger (1) serving as a sion oil cooler is mounted to the transmission in order

transmis-to prevent excessive transmission oil temperatures, cially when the vehicle is used for racing This ensures thatthe oil temperature does not exceed 248° F (120° C.),even under extreme conditions A coolant shut-off valve (2)

espe-is fitted since the oil-to-water heat exchanger espe-is only usedfor cooling and not for heating the transmission oil

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The DME control unit is informed of the transmission oil

temperature by means of a temperature sensor (3) (fitted

to the oil-to-water heat exchanger bracket) If the

tempera-ture is higher than 221° F (105° C.), the shut-off valve is

opened, the heat exchanger is flushed with coolant and

the transmission oil is cooled The transmission oil cooling

system is deactivated again at 203 F (95° C.)

Note !

It is essential to observe the change intervals, filling

capacities and the approved oil types specified in the

Technical Manual and the Warranty & Maintenance Manual.

Gear Shifting

6-Speed Shift Pattern

The six forward gears and the reverse gear (R) are

arranged in four shift gates 6th gear is located at the

bot-tom right of the shift pattern A cable shift mechanism is

used This prevents assembly movements and vibrations

from being transmitted to the gear-shift lever

Two cables form the connection between the gearshift

lever and the transmission The advantages of this cable

system are small space requirements, low weight, and

As a result, the internal shift finger engages in thecorresponding shift rod and the gear plane is preselected.The gear planes are arrested with a springloaded camplate

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Shift Forks

The aluminum-alloy shift forks for 1st/2nd gears 3rd/4th

gears are fixed to the shift rods by rolled pins and are not

adjustable The shift forks for 5th/6th gears and reverse

are attached to the shift rods using clamping bolts and are

adjustable The surface of the shift rods are knurled to

help retain the shift forks in their adjusted position

Gear Detent

A neutral gear position detent is provided by the internal

mechanism Individual shift rod travel is also limited by

separate springs and balls

Internal Shift Mechanism Showing Shift Rod Spring And Ball

Detents

Shift Interlock

Lock out pins are attached to the tensioning plate and the

shift rods to ensure that only one gear can be engaged at

any one time During assembly and disassembly, it is

important to ensure that these pins are positioned

A steel insert is cast into the bearing bores to minimizebearing clearance on the input and output shaft when theclutch housing expands due to heat

Limited-slip Differential

Due to its rear-mounted engine and the resulting axle loaddistribution, the 911 GT2/GT3 are able to convert engineoutput into forward propulsion very efficiently (good trac-tion) even under poor road conditions (e.g wet surface), alocking factor of 40% is sufficient in the pull phase

Higher locking factors would have a detrimental effect onthe cornering ability of the vehicle without any significantimprovement in traction The locking factor in the pushphase is 60% The value for the push phase is higher thanthat for the pull phase since the engine drag torque is lessthan the maximum engine torque Additionally, this configu-ration prevents the vehicle from oversteering in the case

of load changes in corners

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The limited-slip differential was designed as an element of

the overall driving dynamics configuration of the 911

GT2/GT3 and should only be regarded as a complete

sys-tem with respect to the overall characteristics of this

vehi-cle

Limited-Slip Differential

The housing of the limited-slip differential (1) is driven by

the crown wheel of the drive assembly The pressure

pieces (3) and (7) interlock with the housing (1), but can

move axially and are shifted to the left and right-hand disc

sets by the differential pins (2) when loads are applied

The expansion force generated (Pax) depends on the

applied torque, the overrun angles (a) and the pressure

pieces (3) and (7)

The higher the expansion forces Pax acting in both tions on the friction discs are, the higher the locking force

direc-of the multiple-disc limited-slip differential will be

The limited-slip differential is preloaded by the diaphragmsprings (6) in both disc sets so that it is ready foroperation without torque having to be applied The staticfriction moment produced by preloading the disc sets is increased considerably under driving conditions by the expansion force which also acts on the disc sets

In the case of the 911 GT2/GT3, the overrun angles in thepush phase are such that a locking value of 60% can beachieved (expansion force Pax + preloading by diaphragmsprings) The overrun angles in the pull phase have beenconfigured such that a locking value of 40% can beachieved

Limited-slip Differential – 911 GT3 (997)

Like the 911 GT3 (996), the new 911 GT3 (997) alsocomes with an asymmetric limited slip differential asstandard The lock values are 28% under traction and 40%under deceleration Compared to the previous model (40%traction, 60% deceleration), the values have been slightlychanged and tuned to the specific performance of the new

911 GT3 with improved driving dynamics

Notes:

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