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87gmc
January 29th, 2005, 06:06 PM
Normal driving my trans shifts fine but when WOT it seems from 1-2 gear it shifts as almost its slipping into second. It shifts slowly drops to 4000 rpms then fells like it locks and go. I have monitered spark it seems fine not loosing any.

It feels almost like your in a manual car shifting slowly letting off the clutch then all of a sudden letting it go.

Its on my 99Z71 5.3L 4l60e.

Anything I can tune to eliminate this or is my trans taking a dumb?
GMPX
January 29th, 2005, 11:43 PM
Can you please Email me your file, I'll take a look.

ross@efilive.com

Cheers,
Ross
GMPX
January 29th, 2005, 11:46 PM
I have monitered spark it seems fine not loosing any.


Strange, normally they do pull 'some' timing out, I know with my own car even with the PCM pulling timing down to 5deg or so it still shifted pretty hard.

I think as I said in an earlier post, when I changed my pressure tables the trans felt great for a month or so then started to feel like it was slipping a bit, after that I put a shift kit in.

I am not sure how aggressive (mechanically) the trans behind the trucks might be?, anyone know if they are any different to those in say a Camaro.

Cheers,
Ross
87gmc
January 30th, 2005, 04:43 PM
Can you please Email me your file, I'll take a look.

ross@efilive.com

Cheers,
Ross

My tune file?
GMPX
January 30th, 2005, 06:12 PM
Yes please.

Cheers,
Ross
deezel
January 30th, 2005, 09:37 PM
Mechanically, the 4L60E in a truck is the same as one in a f-body. The main difference is the converter,valve body, and the tune. I think the truck valve bodies are set up for a bit slower/softer shifts to lessen the stress from the heavier vehicle platform. A shift kit and some tuning can get a truck shifting like a fast car...

Have you done any trans mods? Shift kit? Servos? Tuning?

Tuning alone really doesn't go very far toward improving shifts. Tuning plus a shift kit and/or servos is a nice improvement.
GMPX
January 30th, 2005, 10:38 PM
Thanks Deezel, that's what I was not sure about, I guess you could play and play with the shift firmness all you want, but if the trans is going to mechanically limit you then you will get nowhere.

Cheers,
Ross