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Discussion Starter · #1 · (Edited)
CPR's Transmission overhaul, rebuild and upgrade service stems from our understanding of the GTR's transmission through experience in servicing, upgrading and racing the Nissan GT-R. Our knowledge of this transmissions strengths & weaknesses in design has grown since importing a JDM Model early in 2008, well ahead of most other European Tuners. Having raced GTR's at the track across Europe, we understand the requirements of the transmission under normal and extreme conditions and have many upgrade parts for the GR6 Transmission to suit. We are also market leaders in Fault Diagnostic and Repair of this transmission, where we have supported both Import and UK GTR Owners in rectifying faults that have occured.

We believe Nissan UK have little experience and service to offer in terms of Gearbox Failure and Repair, where internal component failure can unnecessarily result in a GTR owner having to purchase a complete transmission assembly at a cost of over £11,000.00 !. CPR purchased a new transmission assembly early on in our GTR research programme, so that we could familiarise ourself with its internals and to assess ways in which we could improve on it to support racing and high hp applications. Nissan UK do not offer spare or overhaul parts for the GTR transmission and therefore, to support owners we have designed and manufactured our own line of products reflecting on the weaknesses in the stock gtr transmission components and improving on design flaws in other aftermarket attempts at solutions.

CPR Heavy Duty Clutch Pack Piston Seal Kits
The GR6 Transmission uses a Twin Wet Clutch Design, where R, 1, 3 & 5th Gear are controlled by Clutch Pack A, and 2, 4, 6 are controlled by Clutch Pack B. Each Clutch Pack is contained by a basket and piston, with rubberised bonded seals to retain high fluid pressure which actuate the clutches. Seal failure is one of the most common faults we have noticed on the GTR Transmission, leading to loss of drive in even or odd gears.

Symptoms: No Drive / Clutch Slip in Even or Odd Gears. No Drive at all

Image above shows original Nissan Clutch Pack B Piston with a faulty Seal.

Image above shows fragments of the Nissan seal that has broken away, causing clutch pack piston seal failure and as a result this GTR lost drive in all even gears (2,4,6)

Image above left shows original Nissan Clutch Pack A Basket with a faulty Seal.

Image above right shows fragment of Nissan seal that has broken away, causing clutch pack piston seal failure, and as a result, this GTR lost drive in all even gears (R,1,3,5)

These poor Nissan O.E seals are failing in cars even with less than 10,000 miles, we suspect down to a mix between infrequent servicing of the transmission fluids, poor seal manufacture and material specification from Nissan.

Replacement Seals are NOT available from Nissan, meaning that if this seal failure occurs, normally this would entail purchasing a whole complete new transmission assembly !!!!!!

This ludicrous prospect meant that CPR have engineered replacement upgraded seals and piston/basket housings, to replace the failed items in this case.

Various competitors have also approached this challenge with mixed end results.

Images above show an aftermarket competitor's Clutch Pack B Piston Housing. We cut this in half to examine it. You can see in image above the design of this product shows weak points where the housing's radius is too thin ! We would expect severe flex compromising clutch performance or even eventual failure if used.

Top Image above shows an aftermarket competitor's Clutch Pack A Basket Housing where the circular holes for fluid transfer are staggered, meaning the structural strength in tension is severely compromised, compared to the standard Nissan basket as pictured immediately above, where the holes are located in line, offering columns of support to prevent unwanted flex.

Above is the CPR Billet Clutch Pack A Basket. Note how the holes are positioned for maximum strength and minimum clutch clamp is therefore lost to flex. This component is designed and CNC machined with provision for our uprated Clutch Piston Seal which is supplied in each CPR piston kit. This seal is moulded from the highest quality material available in a high pressure hydraulic application. There is quite simply nothing better!

CPR Clutch Pack Piston and Seal Kits for Nissan R35 GTR.

CPR Clutch Pack A - Piston and Seal Kit. Photo above shows complete Piston Housing.

Right photo shows Piston Housing Base prior to final assembly and fusion welding, with the CPR Heavy Duty Vitol Piston Seal attached.

Close up photo of the CPR Heavy Duty Vitol Piston Seals, an extremely durable and tough material (as used in high temp racing Valve Stem Oil Seals), is capable of supporting high temp, high pressure, and aggressive transmission fluid. The internal groove is to add greater sealing (more surface area) and greater support to prevent any seal movement. As tested on our 650hp+ cars at the Nurburgring

CPR Clutch Pack B - Piston and Seal Kit, photo of front and rear of CNC Machined Billet Alloy Piston, with Heavy Duty Vitol Seal fitted, photo below shows groove on Piston Housing, a design improvement over competitors' products.


CPR Clutch Pack A Heavy Duty Billet Piston & Vitol Seal Kit - £700.00 + VAT

CPR Clutch Pack B Heavy Duty Billet Piston & Vitol Seal Kit - £700.00 + VAT

Typical Labour Rate to fit: Around 20 Hours x £65.00+VAT

Please call for more information or to book an appointment for diagnostic session or replacement.

We STRONGLY advice fitment of these seals on High HP Cars 580hp+!!!
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