VT-VZ 6 Speed Auto (6L80e) Conversions

So those that know me, know I’m a big fan of the 6L80/90e transmissions, especially since the 4l60e is plain garbage when it comes to taking any power & so something I’ve been working on for the last few months & during the “COVID 19” lock down is installing the 6 Speed Auto (6L80E) gearbox’s from the VE commodore into the early VT-VZ chassis for a couple of mates.

Having already converted my own VY ute to VZ/VE ecu/transmission last year I knew they physically fit in the tunnel just fine & perform exceptionally well.

However the TCM (brains of the gearbox) expects to receive & send data to the ecu for it to work. Luckily a company in the US who does a lot of OEM integration work have a controller which allows you to run the gearbox with ANY engine combo, including Carb or Diesel motor’s (providing you feed it an rpm & tps or pedal signal) as it act’s as a “middle man” to transmit the required information to the transmission.

PCS Controller – TCM-2650 & Wiring Harness

Imagine that! a gearbox that when tuned correctly will take 500whp+ with ease & still have 2 over-drives & can be picked up for as little as $250 (probably start increasing now..) Wreckers, your welcome :-p

Anyway, the first car to receive a gearbox upgrade was a VZ Clubsport that was originally manual, however had been converted to a th400 for drag/roll racing due to being turbo’d, but due to the 3.46 diff the car was no longer enjoyable to drive on the freeway or long trips due to high cruising rpm’s.

Installation is straight forward, requiring a custom steel bracket cutout to suit the original gearbox rubber mounts, new 8.8 bolts/washer & hybrid VE/VX tailshaft.

Custom Transmission Bracket

For the Tail shaft the front half requires a slip yoke just like the VE/VF since the gearbox & diff side are fixed points.

Final Drive Engineering built the tail shafts

Being a VZ, it was really easy to integrate tap-shift buttons on the steering wheel as there is already a factory steering wheel option with them (VZ SV6), so with the simple addition of 2 additional wires into the clock spring harness below the steering wheel & plugging into the relevant 12v and signal wire to the TCM they worked straight away (besides programming changes in the gearbox).

VZ Steering Wheel with Tap Shift

So now you can drive the car in “D” mode for full auto or pull back to “3” and have manual shift control all the while doing a tad under 2000rpm @ 100kph in 6th gear.

For now this car is running a factory 2010 (0CPA) gearbox & converter for it’s new engine run in & tuning, but will eventually get a new All Fast converter to help spool up.

The second car to get an upgrade was a friends Auto VX SS with just an exhaust & OTR with 180k km’s in change & already running a 3.46 diff ratio.

Now your probably thinking why spend so much on a car you can pick up for $2000?

Well this car is a Dad & Son venture to go drag racing again & knowing that the 4L60 is the weakest link for durability & it would cost similar money to make strong enough to be reliable, I raised the question of why not go with the 6L instead, with the bonus of having better gear ratios & thus not requiring a further diff ratio change.

To start with they decided to go with a Yank 4000 rpm converter straight off the bat, knowing that they would eventually be doing a head/cam upgrade in the future.

This car is setup similar to the VZ in regards to tap shift mode, however for the moment manual gear selection is done via a small switch until a VZ steering wheel can be acquired & installed. Stock Shifters are still in use for both cars, so there is no visual difference between inside the car.

Power wise the stock LS1 motor is making a consistent 312whp for now & using a 2008 year (8CVA) gearbox, while the VZ is making a tad under 600whp on low boost & pump fuel.

Safety & Tuning Options

Just like factory, the cars will not start unless in Park or Neutral, this is done via the programming of PWM output’s on the PCS Controller. VZ requires 12v to start, LS1 is a Ground, A relay is required for reverse lights however.

PCS Configured PWM Output’s

To get as much longevity out of the gearbox (especially on high hp combo’s) it’s a good idea to do some form of torque management for shifts, on the VZ this is accomplished via a relay to “switch” the inlet air temp to a configured temperature to an area of the tune it would never normally get to & this is setup to pull a bunch of timing (which can be varied based on rpm), which is what the PWM9 above is configured for, initially set to 1 second for testing it has since been adjusted, remember it still takes time for the physical relay to turn on/off.

Spark Cut for shifts

The LS1 ecu however can have the Operating system code changed out to Efilive’s Custom OS 5 which has Boost & Nitrous support, so when an input is triggered it can retard timing at different rpm levels, though the same method deployed in the VZ is a universal solution.

LS1 Timing Retard vs RPM

Tuning of the gearbox is done just like normal via either Efilive or Hp Tuners for adjusting shift speeds/pressures etc, However the PCS controller does come into play as it can adjust the reported “engine torque output” sent to the transmission, for a normal sub 400whp engine combo the standard calibration is perfectly fine to use. Just ensure the TPS & engine calibration is correct.

There are 2 different versions of software for the adjusting the PCS controller & while the later version is the best to use to make changes, it’s seriously lacking in functionality with the live monitoring component broken.

Luckily the older software version will pull a smaller calibration area out & allow adjustment of pretty much all the same things & has a functioning monitor so you can calibrate/confirm your TPS settings & check inputs are working.

PCS Monitor Mode

Word of warning: There a lot of options in the software & most will have no effect on the 6L80 as it’s a “universal” controller for multiple transmissions, so don’t go uploading firmware that is not intended to run a 6l80e, also some of the available outputs like PWM 2&3 are what are configured to send the TPS & Torque information, so don’t re-define for other outputs.

I also found that the wire used as the speedo out, does not work with GM computers & needs to be moved to pin 17 on the controller labelled as the Zero Crossing Point. I Set the PPM to 2000 or 4000 & then adjusted the ecu settings as needed to get ecu & dash clusters lining up correctly. A Tech2 may be required to adjust cluster PPK values.

Ideally you need the use of a dyno so you can confirm the speed the transmission is reporting based on your tyre/diff ratio as it uses this to perform the shifts, the speed is then sent to the PCS controller over can-bus which then relays that out the speedo wire.

Cost wise:

PCS Controller/Harness = $900 usd
Tailshaft = $5-600 if providing both halves (original rear, with ve front)
Gearbox = Whatever you can low ball for a decent working one
*Converter optional*
Trans Cooler Adapter = $45 from memory
Trans Cooler & lines = $300? sky’s the limit, depends if you already have one or starting from scratch

Labour/Time to work out the wiring & programming shit? = Priceless (I probably spent a good week breaking/working things out)

The VX was done in 2 days, 1 day to swap trans, run lines for trans cooler.

2nd day to do wiring & work out speedo settings, this excludes driving/testing shift and converter lock up speeds etc.

Performance?

Well the VZ is always fighting for traction until 5th gear with it’s RE03’s & the VX goes surprisingly well for it’s power output & the current 17″ cheap street tyres.

Private Track testing

That’s it for now, I hope this post inspires you to get rid of your “4L shitty” or worse gearbox.

Dave

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