Patrick G

iTrader: (14)

Upgraded pcm tuning. I am considering having Ed Wright burn in a new program that would lock up the converter in 2nd, 3rd and 4th at any throttle position below 50%. So basically, you would start in 1st with the converter unlocked. On the 1-2 shift, the converter clutch would lock-up. This would continue for the 2-3 and 3-4 shift too. This feature could make a Pro Thruster 4600 as tight as a manual transmission in traffic, dramatically increasing fuel economy and lowering engine rpm and exhaust noise. If you need a little more acceleration, step into the throttle more than 50% and the clutch unlocks and you have a high performance converter! How cool is that? One important caveat. This would work best on cars equipped with steeper gears. A heads/cam car with a 3.23 gear may lug the motor a little too much for this to work well, but a 3.73-4.10 geared car (like mine) would have no problem.

You could take it a step further and have the converter clutch to lock up at any rpm over, say, 6000 rpms at WOT to increase efficiency (this would be especially helpful to the Vig 3600 folks). That's a lot of locking and unlocking going on, but in this age of technology, it's certainly possible. I'm calling EW on Monday.

If this program works, I'm getting a looser converter. I like having my cake and eating it too. <img src="gr_images/icons/wink.gif" border="0">

Slow Z28

iTrader: (19)

nice thoughts....

but wouldnt' it reak havoc on a transmission? especially for us stock transmission guys.

Chris

Patrick G

iTrader: (14)

I don't think it would hurt the tranny at light throttle positions. We're talking less than 50% TPS.

Now locking up the clutch under WOT over 6,000 rpms would be harder on a stock tranny...but did you REALLY think there would be NO downside?

Kenny H

Well, lets take this a step further. How about having a convertor that locks from say 4500-6100 in 3rd gear, then unlocks from 6100+. This way when I goto a Vig 3600 I get the lock-up in 3rd, but at the last split second before the shift it unlocks again and helps my tranny's life? What do u think?

BIGBOS

Well as long as your about 2000, I think if you were around 1000 and it kept locking all the time it would hurt the trans... <img src="images/icons/confused.gif" border="0">

Plum Crazy Rob

iTrader: (3)

Maybe this will become easily doable/tweakable when LS1-edit comes out <img src="images/icons/confused.gif" border="0"> <img src="gr_stretch.gif" border="0">

Ragtop 99

iTrader: (7)

Maybe the 50% TPS gets you out of trouble, but locking up second gear at WOT wiped out Andy's tranny in just a couple times of doing it. I guess on the YTP's kevlar clutches, the added strain of lock-up upto 50% will be ok, but I talked to mike about doing something similar to this six months ago, and he thought it would take its toll on the clutch. Maybe the 50% release point keeps the torque down enough.

Will the converter unlock for the shift or stay locked through the shift? Just wonder if you'll really feel it bang.

I agree with both of Onyx's points.
3.73s in 3rd gear at 20 mph is just about 1000 rpm. I don't like 3rd gear locked with a cam below 30 mph (1500 rpm) and I have my lock-up set at 40 mph. Maybe he needs to raise the minimum upshift speeds just a bit to solve that.

He would need to disable 2nd gear start on the newer models since 2nd gear will be locked at low TPS.

Pretty cool if it will work. <img src="gr_stretch.gif" border="0">

No Patience

I've talked to a few guys around me about the idea and always got the same answer it wouldn't work. The clutch just doesn't have the surface area to take that kind of load even at low throttle inputs (smaller diameter high stall verter wouldn't help). You'd need crazy high lube pressure to have enough clamp to take up the slack.

Patrick G

iTrader: (14)

Mr Hick...it WILL work because I've done it manually before...many times. See, I was using a manual lockup switch years ago...this is nothing new. The biggest problem is orchestrating clutch lockup to make for smooth driving and knowing when to unlock it for performance use. Don't be fooled, a good clutch like on that comes in the ST 3500 has plenty of holding capacity to hold the LS1 at lower rpms...even at WOT. The cool part comes when all this action can be controlled by the computer and not manually.

Ragtop, the shifts are done with the clutch engaged, but they are not harsh (remember, we're talking light throttle driving here). Think outside of the box guys. By the way, I spoke with Mike at Yank at great length about it and he thought it would work fine and pose little strain on the tranny as long as I run a mid-level converter. HE thought a problem might occur with a really, really loose converter like a PT4600. The differential between converter slippage and clutch lock-up is much greater than on my "relatively" tight ST 3500. I'll try it on this converter first before I graduate to a looser converter (again, gulp)

flyin red TA

Good idea but tough on the trans. I know of 4 or 5 4th gens that used to lock it up early and their transmissions took a dump. Including my own.

Terry Burger

iTrader: (4)

Good idea. I know LT1 guys who have LT1-edit play with stuff like this. Let us know what the results are. I'd love to see a stand alone setup for locking/unlocking the computer, maybe similar to a "smart spark" only it has MPH, TPS, and RPM inputs.

TwoFast4Lv

iTrader: (8)

I have actually been doing testing on thios in the past few week's.

There are a few problems with programing this way.

First the way the PWM system works. To get good L/U(lock up) this is usually removed. Here is the problem. this is what controls The L/U the most in 1st and 2nd gear. I am sure Ed can manipulate the tables better then I (Just LT1 edit) but the tables are not set up to support you idea's.

Here is the problem I found. The L/U tables are writen for Shift Lever position NOT acual gear comanded. so if you set up a 2nd gear lock up for say 20mph just must have the shift lever in the 2nd gear postion to acheive the lock up. if you have the shift lever in say 3rd and you have L/U set for 30mph there you will have to achieve 30mph before it will lock even though you set the 2nd gear tables for 20mph.

Many of the other GM vehicals use L/U in all gears but use PWM to control the L/U rate and percentage. They are doing the same thing you are thinking but the side effects have been horrific at times.

Good luck on your search!

BTW I am running a Yank 9in TP. I get about 3,800 stall rite now. I started using L/U to split 3rd and 4th. makes a nice 5 speed now <img src="gr_images/icons/wink.gif" border="0"> Using L/U at lower PRM IS hard on the trans and convertor....PLUS if you have a cam there will be the Surge price to pay <img src="gr_images/icons/wink.gif" border="0"> mine surges under 2k

[ January 06, 2002: Message edited by: TwoFast4Lv ]</p>

ONYXSS

Based on my custom tuning experience, you'd be playing with fire. It took the longest time just for Ed to get me lockup, period.

You can install a manual lockup switch for free and have the vert lock up whenever you want, at any rpm. Plus with my current programming, pcm lockup occurs at 30 mph in D3 and 40 mph in D4. I really wouldn't want the converter to lock up any sooner, as engine bog would come into play.

Remember, too, Patrick, that the steep gears (4.11's in my case) shift into third at around 15 mph at light throttle. NO WAY do you want the converter locking up at these slow speeds.

[ January 05, 2002: Message edited by: ONYXSS ]</p>

Slow Z28

iTrader: (19)

[quote]Originally posted by Patrick G:
<strong>I don't think it would hurt the tranny at light throttle positions. We're talking less than 50% TPS.

Now locking up the clutch under WOT over 6,000 rpms would be harder on a stock tranny...but did you REALLY think there would be NO downside?</strong><hr></blockquote>

hehehe, of course not.
but yeah i think a manual lock up switch would benefit you better. it's more work to do instead of letting the computer do it, but it's cheaper, and you wouldn't have to worry about it locking up at too low of an engine speed. but it's still and interesting idea, and if it works, great go for it man. let us know

Chris

01 SS Jay

window switch?

Tim98TA

iTrader: (7)

[quote]Originally posted by ONYXSS:
<strong>Remember, too, Patrick, that the steep gears (4.11's in my case) shift into third at around 15 mph at light throttle. NO WAY do you want the converter locking up at these slow speeds.</strong><hr></blockquote>
I agree. I have 4.10's and mine is in 3rd about 15 mph. You could destroy a tranny quickly like that. I'll stick with my simple lock up switch.

Tim

Patrick G

iTrader: (14)

Guys, part throttle shift points are easy to raise. If you're going to program in the complex locking points, raising shift points would be very easy. I agree Tim, a manual lockup switch is simple as an anvil. I'm just looking for something a little more in step with the times...because the times, they are a changin'. <img src="gr_stretch.gif" border="0">

ONYXSS

Patrick, I think what's being said here is that just attaining lockup was a feat for some of us (was 4 pcm's for me; ask PSJ what he went through)

To go for trick stuff at this point would be an easy decision for me....NOT!

I wish you luck in your experiments, but you'd have to show me on multiple cars/pcms that it works before I'd consider it. Our cars and our pcms seem to be different, even though they're supposed to be the same. If you don't believe me, ask Ed........

CHRISPY

Patrick
You would want it to unlock just before shifts and lock again otherwise it isnt healthy for the 2-4 clutch packs. Otherwise it is a great idea.
Cheers,
Chris

Nine Ball

iTrader: (38)

This is too confusing. I'm so glad I can control when to shift and "lock up" my drivetrain anytime I want. I can have my cake and eat it too, with the T56 <img src="gr_grin.gif" border="0">

Tony