TCC for 1st gear

[camomcharo]

What I want to do is close the gap between 1st and 2nd locking the TCC at 5k RPM in 1st and having the TCC unlock during the 2nd gear shift.
Is this possible?

[Bernard Fife]

camomcharo,

You might be able to use the full time lock up function for this. This locks the TCC at or above a user specified gear (1 in your case) and rpm (5000 for you). See: http://www.msgpio.com/manuals/mshift/V41tune.html#nt. I haven't tested it this way in the code, though, so it might need some tweaking. If you try it and find issues, we will fix them.

Of course you can set the TCC upshift behavior already, see: http://www.msgpio.com/manuals/mshift/V41tune.html#nu

However, depending on your transmission's design be aware that it may be fairly easy to burn out the torque converter clutch operating it the way you plan, so proceed very carefully and watch for any signs that the TCC is slipping excessively.

Lance.

[camomcharo]

Lance,

I cant seem to change the minimum gear to 1, in ( at or above ) It faults and flashes 3, I'm using 4138 code.
can i change the ini file if so how would i go about that?

Thanks for your help!

Rick

[Bernard Fife]

Rick,

In the INI, find a line near #694 like:

Code: Select all

 STCC_gear             = scalar,  U08,   627,                "",          1.00,    0.00000,        3,       8,     0    ; full time TCC lock up minimum gear

Chang the 3 to a 1. Like this:

Code: Select all

 STCC_gear             = scalar,  U08,   627,                "",          1.00,    0.00000,        1,       8,     0    ; full time TCC lock up minimum gear

Save the file and you should be done.

There may still be limits in the code (it may always unlock the TCC if the gear = is first (this is definitely in the code for the lever being in 1st, but I don't see it for other conditions in a quick look). So give it a try and we can tweak it as required.

Lance.

[camomcharo]

Lance,

Thanks for the info, I did a test on the jack stands and couldn't get the forced lock up mode to work do i need to turn something on?
How do you change from std TCC lock to forced lock?
But I was able to change minimum gear to 1 ok and ill do some more testing as well.

Again thanks for your help!

[Bernard Fife]

camomcharo,

You shouldn't need to do anything other than set the gear and RPM. However, I found what I think is a bit scrambled logic in the full time lock up code. The attached 4.146 test code and INI *should* fix this.

Monitor_4146.abs.s19

(73.32 KiB) Downloaded 465 times

GPIO_MShift_4146.ini

You will need to change the INI as above.

(221.4 KiB) Downloaded 447 times

Lance.

[camomcharo]

Lance,

I was able to get the tcc to lock in 1st like I wanted but cant get it to unlock when shifting into 2nd. I've selected unlock when shift to 2nd but it wont because the full time lock up
prevents it. The tcc stays in lock up mode until I touch the brake or the rpms drop below the unlock rpm. Can I adjust the unlock to 2nd feature?

[Bernard Fife]

camomcharo,

Okay, that's interesting. The full-time lock up mode wasn't originally intended to be used the way you are using it, so I'm not surprised it doesn't work exactly as you want. The question is: should the full-time lock up over-ride the TCC shift settings, or vice-versa? This has the hallmarks of a user option, and I will look into it.

Lance.

[camomcharo]

Lance,

I appreciate you looking in to this, The reason for the 1st gear TCC is because the trans is in a 1400 lb sand car. Sand absorbs torque and forward inertia like a sponge
normally one would use a close ratio manual trans but because of the expense 8k, I'm trying the auto. If I can get this Idea to work than i can cut the torque converter for more slip
and reduce the gap between 1st locked and 2nd. This would make 1st locked like an extra gear between 1st and 2nd, if that makes sense.

Again thanks and your help is much appreciated!