Paging Russ // tcc Lockup chattering

[LS1]

Hi Russ,

as stated in your pm I'm enclosing my stock and current tune and a logfile.
The chattering is noticable in 3rd gear while tc is locked up (from 50kmh up) and by slightly accelerating (tcc still locked up).

Thanks for your help


Car:
1998 Camaro, 2.73 gears, FLT Level V tranny vacuum modulated, vigilante single disc converter 2600 stall

[Russ K]

LS1

Try this trans tune. Did you check the line pressure? Not sure about the vacuum modulator. Why are the VSS Pulses per mile & the Trans Revolution/Mile values changed from stock? Do you still have the stock dia rear tires on the car?

Russ Kemp

[Overclock This]

Hey Russ,

Just a question...

How come you don't use your "1-2 mph higher than shift point" and 1-2 mph higher than your downshift point on the release?

I've seen you say this many times on the board to setup a good lockup table BUT so far i've seen that the files that you edit for people, you don't apply the same technique.

I'm just curious how you come up with this table in the file above?

[Russ K]

I'm in metric, so the TCC lock up is 2 kph higher than the 4th gear upshift speed.
The TCC release is also 2 kph higher than the 4th gear downshift speed.

Russ Kemp

[LS1]

Russ,

thanks for the new tune. I will try it and let you know. As for the VSS changes, I upgraded my tires (front and back) from 245/50 ZR 16 to 275/40 ZR 17.

lata

Roozbeh

[Overclock This]

I'm in metric, so the TCC lock up is 2 kph higher than the 4th gear upshift speed.
The TCC release is also 2 kph higher than the 4th gear downshift speed.

Russ Kemp

I usually use metric as well.
In the "camaroTuneB" file that you posted doesn't apply this technique from what I see.

4th apply at 0 tps is 72km/h but the 3-4 shift is 50km/h and so on...
I'm just wondering if i'm not understanding...

Thanks!

[Russ K]

Russ,

thanks for the new tune. I will try it and let you know. As for the VSS changes, I upgraded my tires (front and back) from 245/50 ZR 16 to 275/40 ZR 17.

lata

Roozbeh

Then return the VSS tables back to stock, as a 275/40/17 tire is the same dia as the 245/50/16 tires.

Russ kemp

[Russ K]

I usually use metric as well.
In the "camaroTuneB" file that you posted doesn't apply this technique from what I see.

4th apply at 0 tps is 72km/h but the 3-4 shift is 50km/h and so on...
I'm just wondering if i'm not understanding...

Thanks!

Of course you don't want the TCC to lock lower than 72kph. That is the stock low tps tock up speed.

Russ Kemp

[LS1]

Russ,

You are the man! After running your trans-tune no chattering anymore
I compared the two files but couldn't find out what of your changes are preventing the tc from chattering when locked up.

Further I'm going to change the VSS settings to stock.

Anyway many thanks to you again for helping me out

Roozbeh

[Russ K]

Glad your TCC is working properly now. Just do a compare file to see the changes I made.
The main problem was that your TCC was locking at too low of a speed.

Russ Kemp

[LS1]

Russ,

In 4th gear I have still some chattering/grinding when locked up and trying to accelerate slightly. This happens between 70-100 Kmh. Can you please have a look to the tuneB file again?

As stated in my last posting all chattering in 3rd gear I was experiencing is gone

Thanks,

Roozbeh

[Russ K]

You need to check the trans line pressure. Like I said before, I can't help with the vacuum modulator. The TCC tables are set up right, changing them wouldn't fix the chattering. Sounds like your line pressure is too low.

Russ Kemp

[LS1]

Russ,

Today I went to a local dyno to get some numbers. Unfortunatly I was not able to lock the trans in 3rd gear thru VCM Controls??? When accelerating on the dyno it was down shifting into 2nd gear. So the guy said he is not able dynoing my car.

Do you know why I was not able to lock the transmission in 3rd gear via the VCM Controls? Can you please help me change the tranny tables for a dyno run in 3rd gear locked?

Thanks man.
Roozbeh