Weird shift at dragstrip
Weird shift at dragstrip Copied my thread from the drag section and bolded the relevant parts, but feel free to help with the rest.
Well long story short... 1999 NBM TransAm M6, Torquer V3 231/234 .643/.598 111lsa, LS6 Intake, Ported TB, PS LT, PS ORY, Cutout, SLP Lid
Car dynoed:
366.8@6200 HP DYNOJET
353.5@4700 TQ
Went to the track 2.3479 60' 13.265@ 112.84 on street tires.
After about 10 runs back to back it got really hard to shift. I let it cool down for 25 mins and went for another run and I shifted it into 3rd and there was resistance the whole time and when I pulled it out there was resistance (not just a click or tough point) the whole pull back into neutral. Think it went in between gears or bent a shift fork, I dunno. Regardless I didnt let out the clutch and it shifts fine now(this was the last run though). This is a Tick Perforamce 750hp built tranny. I am going to look into ways to insulate the clutch line.
Also I was launching at 1750 rpms and gradually releasing the clutch and still having traction problems(doing throttle blips until I got traction. Every run I got a little sideways in second. Shift light set to 6500 and I hit the rev limiter at 6700 quite a few times.
Any comments and ideas what I could run with better tires?
Well long story short... 1999 NBM TransAm M6, Torquer V3 231/234 .643/.598 111lsa, LS6 Intake, Ported TB, PS LT, PS ORY, Cutout, SLP Lid
Car dynoed:
366.8@6200 HP DYNOJET
353.5@4700 TQ
Went to the track 2.3479 60' 13.265@ 112.84 on street tires.
After about 10 runs back to back it got really hard to shift. I let it cool down for 25 mins and went for another run and I shifted it into 3rd and there was resistance the whole time and when I pulled it out there was resistance (not just a click or tough point) the whole pull back into neutral. Think it went in between gears or bent a shift fork, I dunno. Regardless I didnt let out the clutch and it shifts fine now(this was the last run though). This is a Tick Perforamce 750hp built tranny. I am going to look into ways to insulate the clutch line.
Also I was launching at 1750 rpms and gradually releasing the clutch and still having traction problems(doing throttle blips until I got traction. Every run I got a little sideways in second. Shift light set to 6500 and I hit the rev limiter at 6700 quite a few times.
Any comments and ideas what I could run with better tires?
Joined: Dec 2004
Posts: 1,294
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From: Dallas (Richardson), TX, USA
So, you only had the problem in 3rd, and it only happened at WOT? It's definitely possible that you are just having hydraulic issues (fluid is boiling in the line from heat most likely). If you have a built tranny, then you probably have a steel 3-4 shift fork, so that chance of you damaging the fork is very slim. The only think I'd expect to wear out in a built T-56 with your kind of power that could affect shifting like that is the synchros.
So, in short, my vote is for a hydraulic problem. Flush and bleed the system first.
So, in short, my vote is for a hydraulic problem. Flush and bleed the system first.
I assumed it was the fluid making it hard to get into gear, but my question was that one time it went forward like it went into gear. But it was really tight and had resistance all the way in and out and never felt like it engaged, almost like it was wedged in between gears. Just seeing if anyone had a similar experience or knew what this was. No apparent damage as of yet.
More than likely you just overheated the hydrolics by making back to back runs...especially if you were gradually slipping the clutch out of the hole to prevent wheel spin.
I've seen cars that slipped the clutch at the track and wouldn't want to go into gear at all until things cooled down. If it does it again, try and feel where the clutch begins to engage. If its right off the floor, the clutch is probably dragging enough to create the resistence you're feeling because the hydrolics aren't giving a full release.
I would replace the hydrolic fluid and give it another shot. If theres resistence going into gear because of clutch drag don't force it. Excessive wear to the fork pads and blockers will occur.
As for your times, you should be able to hit mid 12's easily with better traction. We've got customers with bolt on cars making similar numbers that run mid 12's or better. I'd think with that cam you should be making closer to 390 rwhp however.
I've seen cars that slipped the clutch at the track and wouldn't want to go into gear at all until things cooled down. If it does it again, try and feel where the clutch begins to engage. If its right off the floor, the clutch is probably dragging enough to create the resistence you're feeling because the hydrolics aren't giving a full release.
I would replace the hydrolic fluid and give it another shot. If theres resistence going into gear because of clutch drag don't force it. Excessive wear to the fork pads and blockers will occur.
As for your times, you should be able to hit mid 12's easily with better traction. We've got customers with bolt on cars making similar numbers that run mid 12's or better. I'd think with that cam you should be making closer to 390 rwhp however.
I stopped once it got hard to shift and waited 25 mins to let it cool. Then it shifted fine into second, but third felt as I explained above. So after that I called it a night, I just didn't know why it felt the way it did going into third and coming out as well. The hard to get into gear and most likely being hydraulic problems I am clear on though.
The clutch engages about midway cool, didn't think to check it after it got hot but I will if it does act up again. And as for the power, thats an entirely different story... I'll be happy when I get into 12's. No idea whats holding it back(on the dyno & the track).
Thanks
The clutch engages about midway cool, didn't think to check it after it got hot but I will if it does act up again. And as for the power, thats an entirely different story... I'll be happy when I get into 12's. No idea whats holding it back(on the dyno & the track).
Thanks
