BGTV8

Big call .... I have been involved in competetive motorsport for 40 years, raced 500cc motorcycles in the 70's and sports cars for the last 30 years.

I have 70,000klms on my Z34 and I have a problem with 6th gear syncro. Started after the 5th track day and the root cause I believe is transmission oil temperature related - it may be exacerbated by a lack of mechanical sympathy over time, but I can only report my experience which is that in my car, it is now possible to consistently "beat the syncro" on a skip-shift from 3rd gear and max rpm into 6th .... unless I wait for syncro-rev to sync the rpms, I can consistently beat the syncro's. Even 5th to 6th need to deliberately slow-paced (not condusive to a good lap time I know, but just another problem to drive around).

I agree - for one owner to have had 3 transmissions, there may be an element of lack of mechanical sympathy involved .... especially if the clutch driven plate was "fused to the flywheel" - sounds like the vehicle is subjected to arduous service, but don;t accuse the guy of not being able to drive - he may simply have a different definition of what Mr Nissan's transmission product should be able to tolerate.

I have a 6-speed straight cut gear and dog-engagament box in my race car (from Holinger Engineering - they do boxes for 996 GT3 RSR, the M3 GTS and up until this year supplied the V8Supercar control transmission), and given its level of engineering, I still strip it every 3 seasons (5000 race klms) to crack test the gears, replace bearings, dogs and oil pump bits because in that time it will have been subjected to ~160 race starts and around 2-3000 flat shifts.

Now if the originator of the thread beleives Mr Nissan;s transmission ought to tolerate that level of work, then maybe his (or her?) expectations are never going to be met, but I think accusing him (or her) of not knowing how to drive may not be the most positive point made on the thread .....

Like I said, it culd simply be a case of different expectations ... the NISMO Race Car comes with the same gearbox in the roadie, and NISMO "lifes" the box at 5000klm. So if a box is subjected to race-type service demands in a roadie, them maybe 3 transmissions is actually a predictable outcome as the "in service" requirement is outside what Mr Nissans designers have catered for.

All I know is that the OEM transmission in my car is exhibiting signs of syncro wear after 70000klms and that for me is a sign of arduous service (it has done a lrge number of track days) .... I'm now fiddling with oils to see if I can get some more mileage out of the box before I pull it out. If I do pull it out, I'll have the think about what it gets replaced with.

Making a statement like "3 transmissions = don;t know how to drive" is not logical - there are lots of other reasons behind "why".

BTW - if you read the signature - the car is a TT, so the box is being asked possibly to tolerate torque loads beyond its design limits - most TT kits that run more than 4-5psi boost are going to put at least 50% increased torque demand on the transmission ..... and if the guy is running more boost, the problem wil be worse .....