u/furfuzz

Whenever I add a little or large amount of throttle at around 1,500rpm to 2,500rpm on gears 3-5 I get this loud clunk followed by a rattle noise from the transmission which fades away at around 3,000rpm. When feeling and pressing against the shifter, I can feel it move back and forth as it clunks which makes me think there is some sort of thrust issue which is transferred through the shift forks into the shifter.

I’m not finding any odd looking wear or any loose bearings especially in comparison to an R32 GTR gear set.

At this point I’m not sure what else to look at and I’m considering swapping the GTR gear set into the Z32 housing (transfer 5th/reverse output shaft and rear shift fork shaft)

Are there any checks I can do to find out why this is happening?

Here’s a video exaggerating the clunk sound: https://youtube.com/shorts/CTm2cuVhni4?si=4wMYfOAdt2B970iT

I’m replacing my clutch release bearing and noticed the “aftermarket” release bearing from both aftermarket clutch kits are thicker than the OEM Koyo release bearing, although, the difference is pretty minor.

With the new clutch, transmission and slave cylinder installed, I’m able to move the release fork so the bearing moves away from the pressure plate so there is room to spare and I suspect no issue. However, I just want to make sure there won’t be any further problems.

Guess it’s time to weld up the subframe

With my current VE fuel table I run about 16-18:1 AFR at cruising, and run rich at cold start at 11-12:1 AFR with post start/warm up enrichment adding fuel all the way up to 50°C coolant temp.

Today I hit the rolling launch button in the middle of a hard acceleration and had a large backfire and started to misfire on bank two (bank 2 wideband O2 reading 10-11 AFR at idle) until I turned the engine off for 1 minute and it was back to normal.

I’ve had this exact same issue once previously before I had switched to a Link wire-in and R35 coils, but the spark plugs were the same since.

Still needs to be tuned but I’m suspecting the spark plugs may have caused this issue.