The only comphrensive documents explaining how the 6L80/6T75 transmissions function are these documents from www.helminc.com:
- 6 Speed RWD Transmission Technician's Guide (HM6SPEEDRWDTG)
- 6 Speed FWD Transmission Technician's Guide (HM6SPEEDFWDTG)
There doesn't seem the be a .pdf version available yet
(neither are on the $100 CD)
how do you reduce the horrible torque spark retard function
on each gear change with the A6?
Is it in the PCm or TCM? pulls almost 20 deg.
TCM has those controls
I got rid of all that spark retard on the upshift
by turning off torque management.
It's in the TCM and they make it very easy to turn off.
Any idea how to get the Tech's Guide?
I tried a couple of times
and it appeared I needed a dealer code or it wasn't available..
Click on the CLICK HERE>> link under Vehicle Owner, Do It Yourself, Professionals in the upper left;
then select GM Powertrain in the dropdown and click Submit;
then look for HM-6-Speed-RWD-TG in the next dropdown and click Search;
that gets you to here: http://www.helminc.com/helm/Result.asp?
Style=&Mfg=GMC&Make=HYD&Model=HM6S&Year=&Category= &Keyword=&Module=&selected%5Fmedia=&mscsid=RVUAMPN P4QQQ9PT8GFLPKG2QEFQP640C
These tech guides contain the "theory of operation" specifically for the 6L80 and 6T75.
They show in very great detail (using very good artwork)
how all the internal hard-parts and clutches fit together and interact
as the PCM shifts from gear to gear...
they show how each component performs it's function,
and how each component is electronically/hydraulically applied and released.
They show all the hydraulic passages,
all the checkballs, all the solenoids and the valvetrains they control,
all the other valves, the pump, the torque converter...
they are not repair manuals,
they do not contain any repair information
(other than some mild diagnostic information
such as "if checkball X is missing then the xyz clutch will not apply")...
if you want to know extensively how these transmissions function,
then these are the books
(if only the actual hard parts were painted the same colour...
See the 4 speed RWD section of the forum
for some examples from the 4L60E/4L80E tech guides. http://forum.efilive.com/archive/index.php/t-8286.html?
The 6L80 Hydra-Matic Technician Guide covers the complete theory-of-operation.
The ATSG 6L80 "TechTran"
covers the complete disassembly/overhaul/repair
with some theory (but not as much as the HMTG).