Do "shift points" really exist?

[Only4U]

<blockquote>quote:</font><hr>Originally posted by PiLOTLiTE:



Oh I think it does change the signal before it reaches the computer. I noticed (thru my manual fan switch with LEDs) that my low side fan for the defroster came on at 40mph with the 3.08s. When I ran the 3.73s with no calibration, it still turned on at a speedo read 40mph, which was actually slightly less. Now with SLPs thing, it still turns on at a speedo read 40mph which means the computer does know its going 40mph, not just the guage cluster.<hr></blockquote>


i see what you are saying, however, i think fans operate partly off of gauge cluster (speedometer) anyway, meaning, i think when the cluster falls below 40 mph, it sends a signal to the fans to shut up.

i don't know if that's right, but it's just a thought, although, i still think your shift points are off.

can you explain mine and nachius' predicament where unprogrammed pcm is making the shift points the weak part of the drive?

[PiLOTLiTE]

<blockquote>quote:</font><hr>Originally posted by Only4U:



i see what you are saying, however, i think fans operate partly off of gauge cluster (speedometer) anyway, meaning, i think when the cluster falls below 40 mph, it sends a signal to the fans to shut up.

can you explain mine and nachius' predicament where unprogrammed pcm is making the shift points the weak part of the drive?<hr></blockquote>

I understand what you're saying about the fans, but the computer still has to know its going 40 in order to put the guage needle at the 40mph mark. It wouldn't make sense that once the needle went a certain distance (i.e. the distance it takes to get to 40), it trips the fans. It knows its going 40.

As far as your problems, I can't really explain them. Every tranny guy I've spoken to (even two GM techs) has said the shifts in an electronic tranny are only controlled by VSS, RPM, and the TPS. I can't understand why if your three things are correct, why the tranny wouldn't shift right. Mine does, and has since the swap. It even shifted fine before I calibrated the VSS.

One thing I can say is that I would find it hard to believe that as smart as our computers are, that they would let a problem like incorrect shifts recur until the tranny eventually died. You would think that would set an SES light or something, or maybe the computer learns and compensates.

[Only4U]

personally, not knocking at your statements and calling bs or anything, but i think you should race someone with an f-body similar in mods, and see if they don't lose you at your shifts. i NEVER could tell my shifts sucked until i raced someone and then it was obvious.

[PiLOTLiTE]

<blockquote>quote:</font><hr>Originally posted by Only4U:
personally, not knocking at your statements and calling bs or anything, but i think you should race someone with an f-body similar in mods, and see if they don't lose you at your shifts. i NEVER could tell my shifts sucked until i raced someone and then it was obvious.<hr></blockquote>

I'll see if I can do that sometime soon. I know I'm fast, and the gear swap made me faster. Before it, I raced my buddy with a '68 Camaro with a 327 and a 2-speed powerglide. He runs consistant 15.0s at the track and before used to pull on me by about a car to 90. Now I beat him by 2. If theres more in my car than that, I'd be very surprised.

It seems now that we just have to agree to disagree. :D

[nino]

my problem is i need to know how to adjust my shift points. i let them alone, but i am sure if i was to adjust them for the better, my ETs would improve. every shift has so many options i have no idea where to start. +/- 4 +/- 6 +/- 12 man i am so lost

[Camarorulz]

Does anyone know how much it would cost to reprogram the computer with Y87 programming (doesn't apply if you have 3.73s obviously) that would automatically set the shift points to a good setting.

Also, does the speedometer recalibrator at Thunderracing solve the problem with shift points, or just make your speedo work right?

[ January 11, 2003: Message edited by: Camarorulz ]

[ January 11, 2003: Message edited by: Camarorulz ]</p>

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by nino:
my problem is i need to know how to adjust my shift points. i let them alone, but i am sure if i was to adjust them for the better, my ETs would improve. every shift has so many options i have no idea where to start. +/- 4 +/- 6 +/- 12 man i am so lost <hr></blockquote>
To add to this...

What is the mph that a the computer is supposed to shift for each gear in 3.42 geared cars?

How high can we safely rev on the stock valvetrain?

[ January 14, 2003: Message edited by: HAZ-Matt ]</p>

[satellite98]

Haven't heard anyone mention this yet (on this post), but here it goes: If you were to go from 3.08 to 3.73 then couldn't you just set a Hypertech for 3.42 and change the tire size to 24? Or am I off topic?

[nino]

<blockquote>quote:</font><hr> Haven't heard anyone mention this yet (on this post), but here it goes: If you were to go from 3.08 to 3.73 then couldn't you just set a Hypertech for 3.42 and change the tire size to 24? Or am I off topic? <hr></blockquote>

that will take care of the speedo, but the hpp3 also has another option that lets you adjust actuall shift points. and that is what is confusing me.
hypothetically - for example lets say i shift right now for 4th gear at 55 mph. the hpp3 will let you choose to shift fom anywhere between 39 - 71 mph. dont want to shift too early and dont want to shift too late, its just confusing to the average man like me.

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by nino:


that will take care of the speedo, but the hpp3 also has another option that lets you adjust actuall shift points. and that is what is confusing me.
hypothetically - for example lets say i shift right now for 4th gear at 55 mph. the hpp3 will let you choose to shift fom anywhere between 39 - 71 mph. dont want to shift too early and dont want to shift too late, its just confusing to the average man like me.<hr></blockquote>

I think I'm going to make a thread devoted to shift point optimization, so as to get this out of the "How to fix shift points for gears" threads.

[nino]

ok, i got the hpp3 set to 24" tires and the speedo seems to be pretty accurate. but what about the shift points. are they right? my times at the track sucked and i was wondering if it might be because of the shift points. i was unable to use the programmer at the track (i was rushed and forgot it) to set the setting back to stock to see if that would have made a diff. but could it be because my setting is set to 24" tires????????????
????????????

[onoiocoko]

so, my dad switch the 3.42 rear end for the 3.23 or 3.08, does that mean its still shifting the same as the 3.42's giving the same performance? he switched them befor i knew the car was going to be mine, it wasnt my choice.

Edit: i do have 3.42's he said he switched just the axle and put the same casing back on w/everything in it. good news-i still have 3.42's. and just ignore this idiot post if u thin im a moron. [img]smile.gif[/img]

[ January 30, 2003: Message edited by: onoiocoko ]</p>