fishbone Posted November 9, 2009 Share Posted November 9, 2009 Replying to someon elses thread prompted me to open this one up. For those of you at Stage 2 power levels or beyond, which are also sporting the IPT valve body, does your transmission still uprev in 2nd to 3rd shifts? The situation that I observe is when I am in manual mode, 2nd gear almost floored, and I manually shift at around 3800-4000rpms, the transmission disengages the gear and the tranny uprevs about 400rpms in what appears to be neutral and then it grabs 3rd gear. Once 3rd is grabbed, there is no slip, it's a firm engagement. I am not 100% certain, thus the thread, but my conclusion is that the behavior is triggered by the fact that the transmission is not quite into "WOT shifting" mode if that makes sense, and modulates the shifts for a smooth tranzition. It doesn't slip the clutch, it just stays in neutral for a split second. If I just leave it in Sport or D mode I can never get this behavior because it doesn't quite shift at peak torque, but closer to red line where the PSI has already dropped down to 14 or less, from the peak 17PSI. Has anyone else experienced this? Link to comment Share on other sites More sharing options...
Habitual Line Stepper Posted November 9, 2009 Share Posted November 9, 2009 I have a 400 rpm uprev when i'm switching from 4-5. It doesnt happen all the time and it happens whether i'm in manual or D. It never happens at WOT, only when i'm feathering the gas so i can get the tranny to shift itself. Its a quirk thats for sure, i dont know if its anything serious but atleast 2 people here with IPT VBs are experiencing something similar. "I for one do not doubt you, dude. Your car is fast and an internet legend." -Gire Link to comment Share on other sites More sharing options...
fishbone Posted November 9, 2009 Author Share Posted November 9, 2009 That's kinda what I figured but wanted to get a discussion going and see what kind of behavior others are experiencing. At one point in time I started wondering if the VB should be stiffened up a bit, but then I shift from 2nd to 3rd under 3K and it bites hard enough in the gear to feel it and get the dash to shudder and all thoughts of tightening it up more go right out the window Link to comment Share on other sites More sharing options...
snow05gtRI Posted November 9, 2009 Share Posted November 9, 2009 try shifting at a different point to see if it still happens? why are you shifting at peak torque anyway? i feel like that would be the worst spot for the tranny. Link to comment Share on other sites More sharing options...
fishbone Posted November 9, 2009 Author Share Posted November 9, 2009 Valid point regarding the shift point, but if it can't handle 16PSI boost on the VF-40 then I'm affraid it won't handle an AVO380 pushing close to that at redline. Link to comment Share on other sites More sharing options...
snow05gtRI Posted November 9, 2009 Share Posted November 9, 2009 very true, but I feel like between 3k and 5k if you're going hard the transmission is not expecting you to shift (which goes along with your "not in WOT shift mode" theory). have you asked IPT about this? Link to comment Share on other sites More sharing options...
fishbone Posted November 9, 2009 Author Share Posted November 9, 2009 Didn't ask IPT yet but another tranny guy already told me along the same lines as what's been already said here. That and because of the revs there might not be enough line pressure built up. Basically I should just back the heck off of shifting at those rpms Link to comment Share on other sites More sharing options...
Yebbey Posted December 1, 2009 Share Posted December 1, 2009 ok, i think I have this same situation. I don't like it. It happens every time in regular drive mode. I installed the vb this weekend. I'd say it happens at the shift at 3k rpms. Link to comment Share on other sites More sharing options...
fishbone Posted December 1, 2009 Author Share Posted December 1, 2009 All gears? How do you know it uprevs? By how much? Link to comment Share on other sites More sharing options...
RIPjeep2002 Posted December 1, 2009 Share Posted December 1, 2009 Mine does the same, but only when I am at a weird throttle position. IT still up revs when its cold, or when i am somewhere between 50 and 75 percent on the throttle. At full throttle though, it works beautifully, still boost spike a little, but not as much. Gear wise, it goes an extra, maybe say 100 rpm before it engages. Link to comment Share on other sites More sharing options...
Yebbey Posted December 1, 2009 Share Posted December 1, 2009 right before the shift, the engine revs up about 400 rpms b/n 2 and 3rd....maybe b/n 3rd and 4th. I'll have to check again on the way home, but I don't htink it happens at WOT, but all the time in normal driving. Link to comment Share on other sites More sharing options...
Yebbey Posted December 2, 2009 Share Posted December 2, 2009 ok, so it seems to be getting better. Maybe it just needed some time. I didn't really notice it that much in the morning and not at all when I went to lunch. Link to comment Share on other sites More sharing options...
Yebbey Posted December 3, 2009 Share Posted December 3, 2009 It's definitely gotten less noticeable. Hopefully, with a little more driving, it will be even better. I gotta say, at first, I was thinking this vb mod was a little questionable, but now I'm liking the behavior of the 5eat a lot more than before. I guess I'll also add that I have my stock one ready to send to IPT for the next person. I didn't want to post this until I was sure I was happy with it. This was an expensive mod, but I got the mod done so I can finally have peace of mind when I'm hitting the gas....you can't really put a price on that....although ipt kind of did. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.