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Hello anyone who is running a FWD DE-T. I'm taking a poll to try and validate a theory that I have on third gear shearing problems in SE-R trannys. Please respond to this thread stating three things: What size turbo do you run? How much boost do you run? Have you broken trannys/How many trannys have you broken? Your honest responses will be greatly appreciated. Thanks.
I can tell you a lot of it has to do with clutch selection. The more aggressive the clutch engagement, the more likely you'll bust 3rd gear do to the greater shock loading.
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Khiem
'96 SE-R.... boost, brakes, suspension, etc... sold
'05 Evo
'05 CBR 600RR
Thanks for the response. Do you run an electronic boost controller that is adjustable in RPM increments and if so, have you controlled the boost that way?
I'm running a Profec B, not rpm adjustable, nor is my nitrous shot progressive, though both make a lot of sense. Future plans for more power include both.
t3t4 / 10-12psi / cryo'd tranny / 20k boosted miles / 0 trannies broken. I agree that it's clutch selection and I'm running a JWT clutch - it's very soft.
I can tell you a lot of it has to do with clutch selection. The more aggressive the clutch engagement, the more likely you'll bust 3rd gear do to the greater shock loading.
A couple of guys here locally have sheared 3rd gear multiple times by just rolling on the gas in 3rd. They run smaller turbos (T25's and T28's) and their dyno charts at 10+ psi show BIG TIME spikes in third (like +100-130 hp in the span of about 500 RPM). I've seen dyno charts with larger turbos showing much smoother power increases without spikes and those fellows don't seem to have tranny problems. I want to see if the trend is consistent with more folks to determine if it will be safe to run 12 psi on a small turbo given that I control the boost in 500 RPM increments to hopefully prevent the spiking and thus hopefully prevent the shearing. Thoughts?
A couple of guys here locally have sheared 3rd gear multiple times by just rolling on the gas in 3rd. They run smaller turbos (T25's and T28's) and their dyno charts at 10+ psi show BIG TIME spikes in third (like +100-130 hp in the span of about 500 RPM). I've seen dyno charts with larger turbos showing much smoother power increases without spikes and those fellows don't seem to have tranny problems. I want to see if the trend is consistent with more folks to determine if it will be safe to run 12 psi on a small turbo given that I control the boost in 500 RPM increments to hopefully prevent the spiking and thus hopefully prevent the shearing. Thoughts?
I have a t25 and s3 cam setup. my dyno is just a nice fat torque curve on 12psi. Odd that they're getting spikes. They shouldn't with a small turbo. Only thing I can think of is maybe they're starting their dyno run at around 3.5-4k rpms, then their dyno will look like that I guess.
The spike could also be the wastegate or boost controller acting funky.
And concerning the gears ripping when you just roll on the throttle. Just a matter of fatigue. If you beat on it enough, then it'll break even at a light load. And shock loading has a detremental effect on the fatigue life of a metal. It'll reduce the life exponentially.
Still original tranny with over 120k miles now. Seen probably around 8 hours of road course time. about two dozen auto-x's, and probably at least 200 passes at the drag strip. I just don't use 3rd gear in everyday driving since I've been turbo (about 50k miles).
so far so good for me for the last 7k... i am pretty easy on 3rd though, i only shift hard when im in a race or somthing of that nature. i run a t28 at 12-13 psi
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-JON
93 SE-R: Blue Bird motor with T28
N/A time 15.1@91.8
