WR35 GTR Transmission Internals



WR35RR GR6 REPAIR SERVICE

Utilising our in-depth knowledge and hands-on engineering experience of the GTR GR6 transmission we are now offering a full rebuild and repair service to get your GTR back on the road as quickly as possible. Our trained technicians can quickly diagnose any problem with the GTR transmission and then apply our repair technology to not only have the transmission fully functional again, but also more durable than it was originally. Due to the specialised nature of this work we will require that you contact us directly for information regarding both costing and timeframe for repair.

transmissioin repair


WR35GS GR6 Gear Stops

gear stops

The GTR Transmission is prone to gearbox syncromesh damage due to overselection from the factory hardware. Put in laymans terms the transmission is shifted until the selector bangs against the stoppers on the dog ring which are shown as missing in the photograph. Many GTR transmissions have experienced failures with the stoppers breaking off and jamming the synchro position in the transmission. When this happens the GTR goes into limp mode, and in extreme cases could cause the selection of two gears at once which would deliver a catastrophic transmission failure. The fragments in the sample below are these exact teeth that are missing from the synchro, left to float around in the GTR transmission and jam both other Synchro actions and also stick to the magnets of the mechatronic control system in the gearbox.

gear stops

WR35GS Gear Stops are a set of specially machined 'stoppers' that control the gear selection distance at the driven end of the process - ie. they control the hydraulic piston travel and pull the selector up just short of the stoppers on the synchro ring. This means that gears can shift without mechanical damage in the transmission cause via over-selection. The WR35GS kit contains eight machined stoppers that only require the valve body of the transmission to be removed to fit, which makes it an attractive transmission upgrade without requiring full disassembly. WR35GS is a sensible upgrade for any GTR owner that doesnt want to risk permanenet transmission damage.

gear stops


WR35CC GR6 Gear Fastener System

Being involved with some of the quickest and fastest GTRs in the world via our GR6 transmission fluids and parts we get to see the results of continued high stress levels on the transmission, effectively giving us a window after only a few months as to what may happen a couple of years down the track. An issue that is starting to raise its head is one of circlip failure on the transfer drive of the GR6 transmission. The main culprit is the thin clip that holds the transfer gear onto the shaft. You can see it clearly in this shot. Its only this small clip and the press load of the gear that keeps the whole thing together, and when it comes apart be prepared for a mess. A new transfer gear, shaft, speed sensor etc. is often the result when it all goes wrong. Track cars may suffer from failure of this clip first, with the initial symptom being a weird noise in the gearbox followed shortly after by a lack of front drive.

transmission

Our solution is the Willall Racing WR35CC Upgraded Gear Fastener system. The actual design is far superior to a simple clip, capable of taking thrust loads, and holding the gear securely in position without any chance of failure. The two hardened steel 'halves' clip into the existing O-ring groove, then the thrust ring pushes up against the machined edge, before a high quality, high strength improved clip holds the whole lot in place. This design has proven itself over many years of motorsport and is a worthwhile upgrade to a GTR transmission to add durability and power handling capability.

gear fastener

WR35CC comes as a complete kit of three clips that replace all of the the weak factory parts in the GR6 transmission. Professional heat treatment, high quality clips, and excellent precision machining makes them an excellent investment for the health of your GTR. WR35CC is a must for those that have had their transmission apart to replace gears, as the factory clips are really only designed to be used once, then replaced. Re-using an old clip that has been 'spread' once greatly increases the chance of catastrophic internal failure.

transmission


WR35PC GR6 Piston Clip

As the GR6 transmission wears over time the selector piston edges can become rounded off, and when they do the piston can spin putting it out of alignment and bringing on the dreaded transmission warning light. WR35PC is designed to stop this piston rotation from happening by clipping on to the centre of the piston and providing a stronger more durable edge for the selector fork to work against. WR35PC can be seen here clipped over the lower of the two pistons providing a much broader area to work against.

transmission

Slipping over the top of the WR35PC is the Selector Fork of the transmission proper. For the sake of this photograph we have installed the WR35PC in the selector fork to show exactly how it mates up with the piston/fork relationship. Simple to install and fantastic insurance when the transmission is out WR35PC should be part of any sensible transmission strengthening plan.

gear fastener


WR35PS GR6 Piston Seal Replacement

A common failure starting to show up on the GTR GR6 Transmission is seal failure in the clutch mechanism due to the factory clutch seal failing and tearing along its edge. There are three of these seals in the GR6 transmission and failure can affect one or all of them at any time. With this in mind we used our years of seal engineering technology to come up with a precisely engineered and far more durable solution known as WR35PS.

stock seal

A picture of the stock GTR GR6 transmission seal shows how the rubber body of the seal can tear, at which time the clutch pressure is released and the transmission will either go into full fault mode locking the transmission in gears 1-3-5 or 2-4-6 or will simply slip the clutches to the point where the vehicle is un-driveable and permanent damage can occur.

upgraded seal

WR35PS solves this problem by having a high strength flex resistant seal body assembly which presses straight into the place of the original seal. A high quality temperature and wear resistant seal replaces the easily damaged factory arrangement and provides exceptional and improved sealing along with precise clutch actuation and engagement.

WR35PS seals can be purchased individually to allow for cost effective and rapid GR6 transmission repair.




WR35TPU GR6 Transmission Pressure Unit

NOTE: WR35TPU CAN BE USED IN ANY OF THE THREE SENSOR POSITIONS IN THE GR6 TRANSMISSION. CLUTCH A/B/LINE PRESSURE. WR35TPU CAN ALSO BE MOUNTED REMOTELY IN THE TRANSMISSION SUMP SO THE TRANSMISSION CAN STAY IN THE GTR SHOULD THE SENSORS EVER NEED TO BE CHANGED OUT FOR ANY REASON

There are three pressure sensors in the GTR transmission. Two of these are for clutch pressure (Clutch A/B) while there is a single sensor in the valve body for overall Transmission Line Pressure. Over time these sensors can fail either slowly by drifting out in their specification or rapidly, but either way the result will be the same, an engine check light and a transmission in limp mode.

transmissioin pressure unit

With no sensor being available to repair the Nissan transmission when the factory part breaks the WR35TPU is a replacement that incorporates more durable sensor technology and also the opportunity to remote mount the sensor as shown here. Coming as a complete kit comprising wiring, a braided stainless mounting line, and a new high quality sensor WR35TPU is a logical choice to get your GTR back on the road again.




WR35TPUK GR6 Transmission Pressure Unit Kit

NOTE: WR35TPUK IS DESIGNED TO BE USED AS A REPLACEMENT SYSTEM FOR ALL THREE PRESSURE SENSORS IN THE GTR TRANSMISSION USING A REMOTE MOUNT INSTALLATION METHOD

WR35TPUK is an innovative upgrade of the Pressure Sensors in the GTR GR6 transmission. Normally a sensor change requires the transmission to be removed and disassembled, but with WR35TPUK all pressure sensors are designed to be remote mounted in the transmission pan making future servicing quick and simple

transmission

WR35TPUK comes complete with 3 x Pressure sensors to replace Clutch A/B and Line Pressure sensors. All stainless braided lines are included, teflon coated heat resistant wiring looms for each sensor, and a remote mounted (in the trunk) signal calibrator unit that allows fine tuning of the sensor outputs to adjust transmission behaviour and to also keep the sensor output spot on specification over the life of the vehicle. This is a complete solution.




WR35CCL GR6 Clutch Retaining Clips

When removing the clutches from a GR6 for repair with a WR35PS upgraded piston seal or to change frictions the factory clip that retains the clutch to the main shaft can deform which can lead to problems once the clutch pack is re-assembled. In short if the factory clip fails the entire clutch assembly can come apart and result in a loss of drive. Willall fix this with a new upgraded pair of clips that replace the small factory part. Codenamed WR35CCL the new clips feature a wide flange for much greater strength and are manufactured from high quality steel before being heat treated and hardened.

clips compared

Note the factory clips on the left of the picture which can change shape when removed, and makes them no longer useable in service. WR35CCL is a sensible upgrade that we recommend to any technician looking to rebuild a GR6 transmission. Note the picture of WR35CCL in its installed location on the clutch assembly below.

clips installed


WR35CP GR6 Composite Clutch Packs

Designed using high friction coefficient clutch face materials and extreme bonding agents WR35CP uses its fine woven composite structure to provide up to 30% greater drive clamp and torque transfer versus standard clutch frictions at the same hydraulic apply pressure. High quality backing materials are used to promote clutch stiffness and plate strength, while friction transfer slots to eliminate heat build-up and promote fluid scavenging under extreme conditions. This high quality engineering delivers less clutch slip more grip and most of all improved street and track performance for your GTR.

transmission

WR35CP technical specifications are as follows -

WR35CP Composite Clutch Packs (12 clutch plates per GTR)
Material: Composite Kevlar carbon high friction
Drive Coeff: up to 33% improvement with 0.125 friction index
Surface Area: up to 16% improvement in clutch face surface area vs factory
Temperature handling: Increase maximum clutch temperature point 400F versus 350F factory
Bonding: Double bonded up to 600F resistant, chemical resistant
Stiffness: Heat treated high strength steel construction at 68 Rockwell
Drainage: Deep wide fluid transfer slots for maximum fluid scavenging and heat transfer
Compatibility: Designed to work with factory and Willall transmission fluids




WR35CPR 7 STACK GR6 COMPOSITE CLUTCH PACKS

For extreme high performance applications where high performance GTR engine and transmission combinations are being pushed to the limit the WR35CPR 7 Stack competition clutch assembly gives that crucial edge. With 7 plates per clutch (giving a total of 14 clutch plates in a WR35CPR system) this clutch system retains the unique high friction properties of WR35CP and adds 15% more drive area for increased power transfer and lower heat loads.

transmission

Developed and tested in a 700awhp+ big turbo equipped GTR WR35CPR has proven to deliver greater torque transfer than a conventional 6 plate (12 in total) clutch replacement system, and do so with lower overall wear levels. Each WR35CPR Composite clutch system comes with both friction plates and also new steels to allow for ease of fitment and maximised overall performance.

transmission
WR35CPR equipped 700awhp GTR testing on track

WR35CP-R technical specifications are as follows -

WR35CPR Composite Clutch Packs (14 clutch plates and surface ground steels per GTR)
Material: Composite Kevlar carbon high friction
Drive Coeff: up to 46% improvement with 0.125 friction index
Surface Area: up to 33% improvement in clutch face surface area vs factory
Temperature handling: Increase maximum clutch temperature point 400F versus 350F factory
Bonding: Double bonded up to 600F resistant, chemical resistant
Stiffness: Heat treated high strength steel construction at 68 Rockwell
Drainage: Deep wide fluid transfer slots for maximum fluid scavenging and heat transfer
Compatibility: Designed to work with factory and Willall transmission fluids




WR35SRK GTR Mainshaft Repair Kit

A large number of GTR transmissions have had the Front Wheel Drive gear come loose and damage the shaft due to the stock retaining circlip springing out of position. Obviously our WR35CC Gear Fastener System stops this in the first place, but some haven’t got that far yet with the upgrades, and the result of a circlip failure can do this -

Repair Kit

Note the shaft is damaged and the splines have been chipped, which makes a conventional locking arrangement for the FWD transfer gear nearly impossible - or at least not up to a high horsepower standard. The previous solution has been to purchase a whole new shaft assembly, and fully strip down the gearset to fit an aftermarket shaft in place. Lets say now, the stock shaft is a - very - good and high quality piece and many aftermarket replacements are inferior in both material selection and finish

Repair Kit

Signs of the circlip failing (partially) are a noisy operation of the transmission, which you will hear at idle, and this is due to the bearing pictured now taking part of the main shaft thrust as the shaft moves forward and allows the transmission gears to rub against their opposing synchro hub. Transmissions in this state are not far from total failure....

Repair Kit

This is where Willall Racing designed the WR35SRK (Shaft Repair Kit) that uses a rifle bolt principle to internally brace the mainshaft and allow a high torque, high clamping load solution to hold the entire gearset together. Machined from Chrome Moly and with very careful design put into its oil pathways and 'anti-whip' structure WR35SRK slides inside the original Main shaft and provides a proper bolt up clamp where the existing circlip groove has been destroyed.

Repair Kit

Precision machined and with the correct taper to make it an interference fit inside the factory Main shaft WR35SK doesn’t require the gear cluster to be disassembled for fitment, which makes the repair a quick and easy process once the transmission is out of the vehicle.




WR35DS Rear LSD Super Lock Kit

Making the GTR rear differential work properly under track conditions has proven to be difficult. When the power and grip levels come up over stock the lack of pre-load on the factory LSD can lead to the inside rear wheel spinning, which costs time and loses outright lap pace. With the only current solution being an expensive replacement high performance LSD centre Willall decided to have a look at the factory differential and come up with a Super Lock tensioning system that retains the factory hardware and gives genuine racetrack performance.

transmission

The factory LSD has that little pre-load you can break it away by hand at zero setting, which means there will be definitely more drive and engagement to be had with the WR35DS Super Lock kit which uses hardened and heat treated differential packers to adjust the internal loading on the differential from 'mild' to all out 'wild' depending on your application.

transmission

Internally the factory differential is a high quality design. It has superbly machined 1.5 way ramps for great action, and good solid steel assemblies that ensure that the diff will be high quality. Modifying this basic package cheaply and simply for track performance then made logical sense to us.




WR35GM GR6 Isometric Transmission Mount

Circled in red on this cutaway picture of the GTR are the frontal transmission mounts. Due to the physics of the GTR mounting system and the torque reaction of the transmission under high load the frontal transmission mounts take the most stress during competition work and general high performance usage. Prone to failure via rubber construction these mounts once failed can lead to increased gearbox case stress (eventually resulting in gearbox case failure) and wayward handling as the transmission is free to pivot at the front end.

transmission

Solving the problem of front transmission mount stress and failure is the totally re-engineered WR35GM GR6 Transmission mount. Crafted from high quality steel with special high density polymer internals WR35GM delivers stress free operation for the transmission mount and bolts directly in as a replacement for the factory soft rubber mounts. WR35GM strengthens the GTR transmission mounting considerably without the harshness and torsional vibration problems that solid mounts can deliver. See the Price List for more details

transmission
WR35GM Isometric Transmission mount is externally identical to the factory piece but up to 300% stronger in high demand conditions

transmission
All of the locating pins are there to ensure that WR35GM Isometric Transmission mounts fit directly into place with no modification



WR35SMK GR6 Solid Mount Kit

Under extreme power usage conditions the GR6 transmission can bend and flex across its mounting system which can in turn create all sorts of undesirable stresses on the transmission casing and internals. WR35SMK is a new solid mounting system designed to stop this from occurring under even the highest duty useage.

transmission

A set of four solid mounts, WR35SMK literally ties the GR6 GTR transmission to the rear subframe and alleviates the build up of undesirable stresses in the outer exoskeleton of the transmission. Due to the nature of vibration transmitted back through the cockpit under normal driving conditions the WR35SMK GR6 Solid Mount Kit is not designed for daily road use GTRs. However in instances where transmission casing and mounting failure have been encountered, or in the case of a full competition use GTR then WR35SMK is highly recommended. See the Price List for more details




WR35BR GR6 HIGH PERFORMANCE GTR SYNCHRO BAULK RINGS

Damage to GTR synchro assemblies is starting to become more common with age and typical wear and tear. Something that is becoming more frequent is damaged baulk ring. The factory baulk ring is stamped from metal and then has a friction lining glued to it to help brake the gear and match speed on shift. In other words it makes the shift nice and quiet, and it works very well until this happens -

R35 baulk ring with adrift lining

This is an R35 baulk ring where the lining has come adrift from the inner and outer surface which means that the gear selection can start to 'graunch' and get crunchy in the background. We have seen this happen on reverse gear and first gear. The noise can be quite shocking and certainly doesn’t do anything any good inside the transmission.

R34 Getrag 6 speed baulk ring

Here is the difference in design between R35 and earlier model GTR with the R34 Getrag 6 speed baulk ring shown here it’s a nice piece of gear in comparison, alas it simply doesn’t fit the GR6 transmission so we have designed and engineered our own WR35BR replacement baulk ring for each gear to give a much more durable and smoother shift action.

R34 Getrag 6 speed baulk ring

WR35BR fits inside the factory synchro assembly as shown and works flawlessly.

WR35BR inside the factory synchro WR35BR inside the factory synchro


WR35BRS GR6 High Performance GTR Synchro Baulk Ring Steels

Factory GTR GR6 baulk ring steels are not starting to fail with several having cracked in cars that are approaching the four to five year old mark. Normally there is no replacement for these parts, so a unique high strength design has been produced using special Moly steel for improved durability and strength over the factory component.

transmission

Specially machined transfer galleries allow WR35BRS to perform the same function as the factory item but to do so with much greater strength, and ability to last almost indefinitely rather than a certain number of cycles. WR35BRS is a great upgrade to make when changing the baulk rings, or of course to replace an already broken part.




WR35TB GR6 TRANSMISSION BRACE

An important reliability upgrade for upgraded power drag raced and track raced Nissan GTRs WR35TB GTR GR6 transmission brace is designed to stop shock loads from imparting rapid and high yield bending forces on the transmission that the casing simply was not designed to handle from the factory. Obviously wheel hop of any kind is an eventual killer for the transmission case, as is constant bending over time as you would find in a race track driven GTR which has the capability of work hardening the transmission case and causing stress fractures. Get a thin piece of metal and bend it backwards and forwards a few times in your hands to see what this does to the structure - eventually it breaks. When the transmission spine does snap, the damage is catastrophic and will require the purchase of a complete transmission to repair.

transmission
Broken GTR Transmission/Differential housing caused by excessive case flexing

WR35TB GR6 Transmission Brace fixes to the transmission assembly over several axis to act as a stress relief mechanism to prevent the different moments of the transmission and the differential creating a bending load across the centre of the transmission casting, which is its weakest point. WR35TB is Designed by a factory engineer that specialised in the field of transmission mounting system. WR35TB is constructed from steel and bolts to the transmission rather than any part of the body or sub-frame assembly giving a completely integrated and isolated result.

transmission

WR35TB Comes in a ‘blackened’ finish to prevent corrosion and can be installed without dismantling the transmission in any way

transmission

WR35B final mounted to the GR6 transmission complete with supplied mounting hardware

transmission


WR35FG GR6 HEAVY DUTY FIRST GEAR UPGRADE

When upgrading power and launch control strategies of the GTR its the factory first gear assembly that can cop a lot of punishment. Narrow from the factory the standard gear will start to fracture over time before the gear teeth are torn completely away causing severe internal carnage in the transmission. The best way to avoid this damage is with an upgraded first gear featuring wider design, improved metallurgy, and superior power handling.

transmission

WR35FG has been carefully tested with over 50 launches using the brutal original LC1 4500rpm program and when inspected has seen no visible sign of wear or damage, where the factory piece would be in most cases damaged beyond repair. WR35FG is good insurance then in cases where upgraded power and heard launching driving style are all part of the equation.




WR35FWDS GR6 FWD TRANSFER SHAFT/GEAR UPGRADE

On the left you can see the factory FWD Transfer shaft where it has sheared across its section due to the combination of excessive torque and less than perfect factory metallurgy. In high horsepower applications this can cause instant and rapid failure of the GTR AWD system, and when this failure occurs the transfer gear is normally damaged at the same time.

transmission

WR35FWDS has been designed and engineered in Australia to not only repair existing transmissions that have encountered this failure, but also to provide an extra level of strength to the transmission before this kind of failure occurs. Every serious race GTR, and even those hard driven on the street are going to encounter a FWD shaft failure if the circumstances are right, so consider WR35FWDS a sensible GR6 upgrade




WR35FWDTS GTR FRONT WHEEL DRIVE TAILSHAFT

transmission
WR35FWDTS is a completely engineered bolt in replacement that has so far proven to be indestructible after intense testing

How powered GTRs that are used for hardcore track work are now starting experience front wheel drive shaft failure as the ATTESSA all wheel drive system channels large amounts of torque to the front wheels. The reasons for these failures are pretty obvious with the factory component 'sized' to cope with stock power, and then only just in extreme driving conditions. When the factory shaft fails it can throw out and whip around damaging the under-body of the vehicle and drag along the track surface.

transmission
WR35FWDTS A typical factory front wheel drive tail-shaft failure showing the twisted/sheared shaft spline, and the components that get thrown out down the road under/behind the car

WR35FWDTS Features include:

  • Larger Drive Spline (some 65% larger than stock)

  • Stronger shaft material (thicker walled, and higher shear strength material)

  • Billet bearing carrier

  • Larger more durable bearing

  • Stronger drive flange (billet)

  • Upgrade and significantly larger CV joint assembly

Fitment is simple and extremely straight forward due to the plug and play nature of WR35FWDTS. It should be a serious consideration for any heavily tracked GTR build




WR35TSB GTR BELL HOUSING SHIMS

NOTE: WR35TSB IS ONLY TO BE USED WITH JDM 2008 MODEL GTR. LATER MODELS HAVE A DIFFERENT DESIGN BELLHOUSING

It's a well-known fact that the GTR bell-housing assembly can make a fair bit of noise. The issue is actually a design problem in the bell housing machining process. The clearances are incorrect, which can lead to some massive float in the shaft, which is where the noticeable noise comes from.

transmission

WR35TB shims go at each end of the shaft and stop it from moving back and forth, locating it in the correct manner and eliminating excess bell-housing noise.

transmission transmission

Consider WR35TSB to be a sensible upgrade if you have the annoying bell-housing rattle ruining your GTR experience or a great pre-cautionary measure should you have major work being performed on your GTR where these WR35TSB shim are easily accessible.