Last year at BIR, Ronnie from RSMotors and I both blew our 4th gears. We were both running stock turbos which spool up quick resulting in high amounts of torque. Then put us on a track where 90% is all 4th gear. The result was both of us killing 4th gear just hours apart. Later that year, Brandon Ranvek ruined his 4th gear at a DCTC test event just a few weeks before the Las Vegas USCA event. Then we started to see reports of others with 4th gear problems. So we searched for a solution.
This is what we’ve come up with. A company in Australia (PAR) makes an OEM fitting synchro’d straight cut 4th gear. This gear comes in any ratio you want, but this specific one we are testing is a 1.0 which adds a little more top speed to 4th over the evo 8 gearing (and even more mph than the 9 gear).
Ron at RS plans to test the trans on his dyno doing back to back 4th gear pulls. No real track testing until the snow melts (or we travel south).
Update (Jan 31 2015)-
Installed trans and strapped it on the dyno. 4th gear held up to multiple 4th gear pulls from 2000rpms up to 7500rpms. The car we tested this with is making 430TQ before 4k rpms. The torque ramp is what will eat the 4th gears, so this seemed like a perfect car to test with. Not a single issue. We plan to pull trans back apart and inspect the gear, but we feel pretty confident this is the real cure for the weak factory 4th.
Also, the whine from the straight cut doesn’t seem all that bad. We’ll get some in car videos up shortly.
Stage 1 testing complete. More track testing to come in the next few months.
