Im trying to get a general idea on what people with nitrous and cam have their shiftpoints set at?

 

That is not an easliy answered question... or maybe it's better to say very few combinations are the same. It's not correct to ask about NoS and Cams because sooooo much more goes into that, Cylinder Head FLow, Exhaust, Torque Converter, Gears and Tire sizes make a huge difference on the timing of the shift in one of these 4L60E in my experience!

That's not to say you cannot draw general conclusins, but at the end of the day a given combination needs to be dialed in by itself... and that is going to take feedback from the driver to the tuner and may take an adjustment or two to get it right!

Are you having problems with your shift timing?

g

 

Well I was wanting to just to get a general idea I obviously know there is alot more that goes into the setting of shiftpoints. I did go from 90rw to 130rw on the nitrous and now the trans wont shift. I did add 28'' tires but its weird it shifted fine on the 90rw shot and now it bangs the limiter on the 130rw shot. The trans is a newly built unit with under 5k miles and it shifts fine any other time. I did lower my shiftpoints but didnt get a chance to test it yet do to a broken torque arm bracket. I know everyone has different setups so im just going for a general idea. I doubt I find someone with the same setup as mine so im just gonna go for a general idea.

 

I hear ya, thanks for the additional information. We have been working on that issue for a long time. It can be frustrating. It isn't so much where to set the shift points as it is the correlation between the shift at MPH and RPM tables. It has everything to do with the rpm's getting to the limiter before the command has been given to shiift.

That being said we worked long and hard to quicken up the shift hydraulically... in other words sometimes you can only do so much with the tune... been there done that. And then there is only so much one can do for shift timing in a computer controlled transmission! In some of our higher powered cars we have taken them to a full manual combination... those boys don't tear stuff up, their trannies shift and they are sprayinf the hell out of 'em! Thiis is one reason I think this poor shift timing condition is so hard on the soft parts in this unit, our experience at the track is extensive on this particular subject.

It is going to require patience in gettting this thing to shift. The problem is when it is not shifting and is well above 6k rpm's I believe that this is the most detrimental time in this transmissions life! Lot's of things happening on the 2/3 shift compared to the other shifts, so I feel that it is the most critical shift to focus on when tuning.

You should begin by data logging the shift commands. You absolutley need to know when the upshift command is given vs. the RPM and MPH. From there it will take some adjusting... that's why they call it tuning!

One other thing.... be sure to utilize a window switch when spraying... it's a tough unit but spraying through those shifts is hard on it.

Good Luck.

g

 

Ok well I guess ill do some logging and try to get things right im going to set the wot shift rpm lower to see if that helps. Iam using a window switch which I set to 6400 off and the trans was set to shift at 6500rpm. I am going to lower the 2-3 shiftpoint to 6000 and see what happens I may have to play with the mph as well. The nitrous should shutoff before the 2-3 shift occurs anyway because it will probably delay for a few hundred rpms. I am using hp tuners to tune all this stuff the stock tire size says its 24.91 I believe I guess for 28'' tall tires I would just make it 26.91 to compensate for the 2'' taller tire because I belive stock is actually 26.

 

Good! I think trying to dial the tune in by starting with the WOT RPM is the best place to start...and using a window switch is smart.

Right... you might want to start with a lower RPM, say somewhere in the 5800 area... it may stack shift on you (have seen that before immediately after a coarse adjustment... it may have been a tire spin issue on that particular car) but you would know you are going the right direction!

Right, the actual shift can take up to .4 second after the command... depending on the how the hydraulics are setup... and how fast can the engine climb through the RPM's in that much time?


Hmmm... the "26.91" number is a metric conversion right? I believe so, try to get it right, I don't have the info in front of me for that... but look around and see what you can find out, tire size is important here.

Also, make darned sure your gear ratio solution is correct.

It sounds to me like you can dial this unit in yourself and I think you are on your way... it will take patience... try not to hot lap it at the track... tuning can be hard on the 3/4 clutches when spraying N20. One odd shift can hurt those clutches... make one or two coarse adjustments and then dial it in. You'll get there.

g

 

Made a trip to the track friday had the shiftpoints set at 6000 instead of 6500 and still no luck. I then backed the shiftpoints to 5800 and still had no luck after that I tryed changing the tire size to 26.91 and it didnt like it at all and it wouldnt even think about shifting maybe because the mph went up in the shift tables. The trans will shift if I let out alittle but its still slowing me down. I dont know maybe next time I will turn the mph down some as well. The trans shifts fine on motor and with a 90rw shot. Btw whats stack shifting? I wonder if I could add more line pressure to the current tune.

 

Stack Shifting is when a transmission upshifts very rapidly. Too fast.

P.M. Sent.

g

 

For some reason I didnt get your pm.

 

Ok sorry for that... system locked up when I hit "send" last night... I'll be glad when the admins get that sorted out.

Try it now.
g

 

I got your pm for some reason my hp tuners bin file that I uploaded didnt seem to work im not sure if your a member of the hp tuners board but I just recently made a post over there and have a copy of my file over there. I may try and add some tq management to maybe reduce alittle power on the shift so maybe it will help. I guess im going to end up trying multiple things.



http://www.hptuners.com/forum/showthread.php?t=13160