Pressure Modifier Settings for Kevlar 2-4 Band

[Baddy]

I've had my auto rebuilt approx 4 weeks ago until it started slipping last week in 2nd. So I took it back & found the problem:

The 1 month old 20% wider Kevlar band totally burnt out. Nothing to do with 1-2 or 2-3 WOT thrashes but ironically by light throttle cruising at 60mph on the freeways. It was caused by "smoking the band" due to the constant cruising in 4th gear and not enough band pressure was applied to it. I drive approx 50 miles/day on freeways in 4th, 60mph.

The builder says that there should had been much more pressure applied to the band during cruising in 4th gear (or WOT in 2nd). I know that the pressure modifier tables control the band pressure during cruising. Mine are factory standard so what should the values really be to avoid smoking it again? 10% higher, or 20% or 50%? What are the consenquences if this is higher than anticipated?

Thanks

[Baddy]

Anyone? ttttttt

[Baddy]

Is this thread visible? lol

[jimmyblue]

You want to log the input and output shaft speeds, and then check
that ratio against the ideal transmission gear ratio. That will show
you if there is slip happening in the box.

The stock tune on my year F-body commands 0% line for most
cruising. This is not zero pressure but it is low. I have been running
for a few years now with a lower force motor current in the low
line% ranges (did it to help out the gimp TCI converter clutch,
never changed it back). It's kind of a kludge that predates having
the General Pressure tables. Looks like you don't have these so I
think Force Motor Positive is your best bet. You can try the one
in here, I've been happy with this trans tune for a few years. I
wouldn't use the motor stuff necessarily. Check the gear and tires
if you want to use shiftpoints etc. but the force motor is fairly
sensible.

[Baddy]

Jimmyblue

I did a log as you've asked, mainly freeway driving in 4th gear, about a 5 mile run. I don't think there's any band slip.....please check for me & if there is how can minimise it.

I'm not going to do any 1-2 or 2-3 WOT runs as yet, so I accelerated gently.

I've also used your shift pressure settings for shifts 1-2, 2-3, 3-4 for both normal & performance modes, (I have a 2 button factory switch or a 'tow' switch as you guys call it) but I didn't use any of your Force Motor Currents or pressure modifiers because I'd like you to check this data first. (I've included Force Motor Currents & TCC in the log too).

I also noted that the gear change times are very high, ie 1.5 secs. Is this right? Higher pressure required?

I have reattached my tune with your settings & lower rpm shift points. I tried to covert the 'hpl' file to an Excel file but the file is too large so I can't attach it. Yours & anyone else's assistance would be highly appreciated. (Don't worry if the band fails again I will not blame anyone, lol)

Thanks

[BTLD_LS1]

this is where Im having my issue. Looking at your log, your 1 -> 2 shift time is .5 then 1.6 seconds. Yet your 3 -> 4 shift time is 0 which tells me there still may be a band issue.
You are commanding 0 for a desired shift time and are getting 1.6, there is no reason for that. Only thing I can say is up the pressures and see what you get. I still think 1.6 is rediculous for 1->2 shift time. I think my stock tables were like .6 seconds or so....

[Baddy]

I relogged using the "tow" or performance mode in the above program ie all the pressures are set to 90 & I mostly got:- (log not attached).

2 sec shift time for 1-2
2.4 sec shift time for 2-3
0.6 sec shift time for 3-4

ie much slower shift times!!!, but during the drive it felt like zero shift times & thought that the differential would fall off, yet they logged slower. Are these logged shift times real or theoretical or how are they measure/calculated?

I also tried your buddie's Z28 shift settings & although they felt real nice & crisp the car would fish tail between 1-2 & 2-3 at even 50% throttle & it would be almost impossible to drive in the wet, so I took it off. The Z28 must have very soft compound tyres or a lot less torque at the wheels than me, or whatever.

What do you or anyone else recommends next? Thanks

[BTLD_LS1]

This is when I become confused....

You said that with my buddies shift tables the car would fish tail, but in tow haul it didnt?

You have the base pressure for tow haul set at 90 straight across which should equal a blistering quick shift!

You may want to try using your shift tables with a different pressure modifier for the 1 -> 2 shift. your current setting of .85 means that its using 85% of the pressure you have when adding eveythign together. try something like .95, 1 or 1.05 since this will increase the pressure on the 1 -> 2 shift by 5% at a time....

can you log delivered trans torque and trans temp, along with all your current trans parameters on a drive so we can see a few 1-> 2 shifts and we can get an idea of what part of the table is being referenced? this will have a significant impact on shift time as some portions of you shift table are actually taking away from the base pressure...

good luck getting it all figured out man.....

[Baddy]

I used the Z28 'normal' settings only & fish tailed at 50% throttle, (I didn't try the performance mode at all). I then loaded Jimmyblue's both normal & performance pressure settings & made the above log whilst driving it gently. The normal settings are very streetable with the odd chirp between 1-2 change. The 'performance' mode (all 90 values) which is the same as the Z28 is a lot harsher but I'm keeping these '90' settings only for the track & only when driving on the freeways so as to apply more pressure on the band when in 4th gear - am I right with this more pressure on the band theory? I'm more interested in applying more hydraulic line presure in 2nd & 4th gears rather than high pressures during gear changes - so as not to wear the 2-4 band if the band decides to slips due to lack of pressure.

I'll do a log on the way to work tomorrow with all the pids you've requested, mostly highway driving but I'll cut through a town or two & do some gear shifting, (not WOT yet in case the band slips, lol). Hopefully we can sort this out dude.

Do you also think the Force Motor Currents may need changing? I'm not sure but does lowering these mA currents increase the line pressure or decrease it?

Thanks

[BTLD_LS1]

lowering the force current results in a hgher line pressure.

I still feel that the original issue was mechanical and not tuning related in any way.

we also know the band is grabbing the drum correctly because you said it fishtailed with the higher pressure settings

[Baddy]

I hope when the band failed back then it was purely mechanical or human error & not a software issue but we are all fairly honest down here. If the builder insists it's a software issue with the low line pressure in 2-4 band causing it to burn then I'll have to accept that. I respect technicians. However, with all due respect he doesn't know the difference between shit from clay when it comes to tuning with software but he knows his 4L60E transmissions. (He doesn't tune anyway). When the new band burnt out he repaired it for free on a good will gesture because it was only 1 month old. He's asked me to increase the band pressure so it doesn't happen again. Apart from the higher shift pressures I'm using stock pressure modifiers & stock Force Motor Currents. He insists the new band needs something higher than stock but what higher values?

Like you said in the other thread, if the Torque management is disabled then the tranny is very vulnerable. Turning the torque management back on to protect it is probably an excellent idea but not when you're using a 3500 stall or a 4500 which I'm thinking of using soon. I reckon I'm to blame too. At the track, this tranny goes though a lot of abuse - but if the band slips then it becomes fatally wounded (plus the fact that I'm getting reduced 1/4 mile times, lol).

Anyway, please have a look at the attached recent 40min log. I've also attempted a WOT from standing start, lol (frame 10122). If you look closely at this WOT thrash, from frame 10136 the 2nd gear band is slipping, (I worked out about 2%) & the shift occurs at 6400 & perhaps more if i hadn't backed it off, (this was dialed to happen at 6000, add say 200 & therefore should had changed at about 6300rpm hhmmm DeJaVu).

Summary
Frame 00556 - accelerated to merge with freeway traffic
Frame 03430 - WOT overtake to test downshift
Frame 03845 - exited freeway, driving through suburbs
Frame 07282 - back on freeway
Frame 09322 - WOT overtake in 'Performance' mode
Frame 09708 - exited freeway, driving through suburbs
Frame 10122 - WOT standing start in Normal mode (notice the 1.3s 1-2 shift)
Frame 10735 - WOT overtake in Performance mode

All I'm asking in this thread is whether my line pressure is sufficient when I'm cruising in 4th, (or WOT in 2nd) and what can I do to increase the pressure so as not to burn the band out again (or slowly burn it or smoke it). The above tune is still the one in the car but a new log is attached below.

There are so many views in this thread but only 1 or 2 guys trying to help. Hasn't anyone else experienced similar band failures. I really believe that if I leave all the stock settings this new band wont last long either.

Russ, anything you can do? (I've read a lot of your tranny threads).

Thanks

[Russ K]

Post your stock tune and the trans specs (shift kit?, corvette servo?, .500 boost valve?) What wot shift rpm would you like? Do you have the stock dia rear tires? Your tune shows 3.71 gears, is this correct?

Russ Kemp

[Baddy]

Russ

No shift kit; no Corvette servo; no 0.5 boost valve - just stronger clutches & band & o-rings & 3500 stall convertor. There are other internal mods but nothing to increase the oil flow except with software.

I have attached a dead stock tune of my car as it came out of the factory.

I am using 3.71 diff & the tyre sizes shown in the tune "Higher Shift Points" are correct,

ie 24.72" current tire size
& 25.35 calculated tire size (Use these).

WOT to change at 6200 for normal mode & 6300 for performance mode, change at 6000 & 6100 but allow the extra 200 rpm before the gear change occurs

Thanks a lot.

[Russ K]

Try this trans tune. The line pressure while cruising is controlled by the force motor current at the 0 psi column. As you can see, I lowered the force motor table in the operating temp areas to even out the table. At a minimum, you need a .472 boost valve for any V8 performance application. I also set up your upshift torque reduction tables to 50% of stock. In the Engine Torque Management > General > Max Torque, I see that you set this table to 640 ft lbs. According the the help files, raising this table on some Holden models will reduce the fuel pump voltage causing lowered fuel pressure.

Does your car have traction control? If so, you disabled it in your tune. I would rethink your spark knock tables, as your only allowing a max of 1* of spark retard from 4000 rpm & up. 27* of wot spark timing is too high.

Russ Kemp

[Baddy]

I really thank you for this Russ.

I will load it now & log it again tomorrow on the way to work.

My sparks were tuned on a dyno with absolutely no knock detection, so I thought 27deg was fine & 1 deg max retard was ok too, (this same tuner doesn't want to mess too much with the trans settings). I've even logged drag strip runs with the laptop computer under my seat & still had no knock retard at all. (I couldn't & can't hear any pinging/detonation either but I only use hi octane, 98% grade).

But, if it's going to protect my tranny and give me the same 1/4 times I will lower them all past 4000 rpm by, say, 1 degree & increase the MAX knock retard?

I would like the traction control back, if I knew how to do it properly. I tried to enable it once & the car was pulling back so much timing even without any wheel spin being detected. Sometimes the wife drives the car, (or she used to drive it, lol), and it worried me that one day it may rain on her way home & clean up a few traffic posts.

I'll post the results & thanks again.

[Baddy]

Russ

Completed the test drive to work & did a log, (attached).

I think we're there. The car feels good but feels a little 'slower' during gear shifts, especially 2-3 which I think may need to be increased by 200 or so more revs, I think it is shifting lower than the commanded rpm, (I can do this myself & also raise the rev limiter by 200rpm). (Ref frames 6697, 6851, 6909, 7008, 7115).

I also noticed from the log that the band slippage has reduced a lot & noticed the line pressure has logged higher than yesterday's. Do you think it may need to be increased more or not?

I don't know if I'm right or whether this is normal but during 3-4 shifts the band always slips for approx 1.5seconds (eg ref frame 8723).

Finally, when driving in 4th gear at constant speed the "delivered trans torque" continuously varies up and down, is this normal or is it slippage?

I also did a separate WOT in Performance Mode from almost a standing start in a separate attached log at the back of where I work in private property, lots of wheelspin, but....the shift times are all below 0.4 sec!!

PS Would it be a big ask if you could please also enable the traction control for me? (When enabled in the software I should be able to turn it off/on using the console switch, ie as from factory). Perhaps use 'jpg' table pictures attachments & I could type them in.

Thanks

[Russ K]

I set up the traction control the same as on my 2001 ZO6. The tires will still spin slightly, but the engine doesn't bog anymore, and the car stays under control.

You can raise the WOT shift rpm to suit, as I set it to 6000 rpm to see if the WOT shifts will work with out lifting the throttle. The shifts can be firmed up more if you want, but I already added a lot of shift pressure.

Not sure about the delivered torque, as I haven't really used that pid.

Russ Kemp

[Baddy]

Russ

This file will not open. It says "Unable to Open File." "Index was Outside the Bounds of The Array". Whatever it means.

I noticed this file is almost twice as big as a normal file, ie 1MB.

Thanks

[Russ K]

Fixed

[Baddy]

Runs Perfect. Thanks