I purchased an option one box a while back and had the all too familiar disappointment on opening and inspection. Three of the five syncro sets were beyond use and the 4/5 shifter fork had been subject to a very poor quality repair. In addition on crack testing the remaining parts only half the parts were able to be used. This was a challenge, but the man who does our gearbox work (Stan) had a plan that would make the box stronger than normal and shift quicker and cleaner. The box needed a new input gear set. I was lucky to be able to obtain a brand new old stock Holinger set with 40% wider gears than the stock input set. The set was originally made for the Bathurst Bluebirds turbos to increase reliability of their boxes. New first and second gears were  fitted with Warner syncro's as was third speed. One of the hardest parts to get was a 4/5 shifter fork. In the end I had to get the fork made up using a new one as a pattern, as these are no longer available as a part from Nismo. The forks were milled from 4140 and the forks were hard chromed. All shift forks are double pinned to the selector shafts.

Coupling rings that the shift forks operate were also replaced as they were missing some teeth. The quality of bearings used can make a lot of difference to the price of a rebuild. By using lowest tolerance bearings, the overall quality of a box can be improved, with less wear and increased reliability.  All stressed parts used in the box have been crack tested and are crack free. New seals are fitted throughout.  To prevent the mainshaft nut loosening from torsional loads on the shaft, two nuts are fitted and each is independently staked. All critical external and internal fixing are lock wired. The box is now back together 2/5/2008 and waiting for some work.

240/260Z & Stumpy Skyline "Competition Special" Gearboxes. 

Ratios   2.906,  1.902,  1.308,  1.000,  0.865

I now have 3 of these boxes built up by Stan Holmes to competition specifications. The box shown is an MR 30 "short casing" box popular with 510 and 1200 owners.

All these boxes have carefully selected 260Z components that have been checked for case hardening condition on all gears and selector forks and shaft quality etc. The boxes use the early 240Z wider/finer/stronger input set. For the three boxes a total of 8 240/260 boxes were used to get parts of suitable standard. All stressed parts used in the box have been crack tested and are crack free.

Special "highest grade/lowest tolerance" bearings have been used throughout the boxes. Lower tolerance bearing sets are available but do not offer the same precision as the higher grade units. New seals are fitted throughout.

Double roll pins are fitted to selector forks to prevent one of the most common causes of shifting failure in competition boxes. To prevent the mainshaft nut loosening from torsional loads on the shaft two nuts are fitted and each is independently staked.

The short MR30 box has a quick shift modification to reduce lever movement during shifting. To help prevent mis-shifting on 5-4 changes (accidental 2nd selection) access to the 1-2 gate has been stiffened. 

The box has a (rally ) breather system fitted and is also fully lock wired.