So a new LS3 block was sourced and a new motor was put togethor using the original crank & rods for a low budget forged motor.
Once the new engine was put back in I changed out the HH122 to the larger “big daddy” HTV2300 and with some tuning done over a month of driving to and from work and with a few isolated back roads, entered in to a dyno competition which resulted in a run in figure of 587rwhp.
With that result I was looking forward to attending a Whoop Ass Wednesday at the Perth Motorplex 3 days later, but it wasn’t to be as during the drive home from work on the wednesday, as I was accelerating from the lights the car went for a downshift from 5th to 4th and though while the revs were there, the motion to go forward was not. A couple hundred meters up the road after a check engine/power train light come up on the dash and the transmission went into limp mode and locked to 3rd gear.
In typical fashion I was carrying my tuning cable, so I plugged it into the obdii port and checked the code, it had logged a transmission slip error & so I cleared the code and proceeded to continue driving home. For the next 30km’s the car drove pretty much like normal but it did not like to be loaded up with large amounts of throttle before it started to slip.
The next morning on the way to work where I was about half way I started loosing drive in 6th gear, then 5th, then 4th with anything more than about 20% throttle and going up any sort of incline was almost out of the question. At this stage I wasn’t sure if it was the stall or the gearbox that had given up, so I pulled over, modified the transmission tune to lock the convertor as soon as it hit 3rd gear and uploaded the changes back to the TCM. The result was still the same, and with the lower 3 gears still working perfectly fine I knew definitivily that the gearbox had finally had enough.
So with that knowledge and not wanting to drive the VN shitter I purchased while the VE was previously off the road during the engine rebuild. I started making calls to wreckers. I ended up finding a wrecker with 2 x 6L80’s, one was a 7CVA part number the same as mine the other an 8CVA from a “low km hsv clubsport” (the number generally specifying the year it was built) I had read that the early model auto’s had been known to have issues with seals that caused some slippage between gear shifts and that the 8CVA had this fix as part of the build phase, knowing that the only issue I could potentially have would be either a completly stuffed box (which I could return) or a software mismatch and so took the chance and purchased it for $1500 the next day.
That weekend, I removed the old box & moved the stall convertor to the new box, Yes I probably should have flushed the stall and new gearbox for any debris but the oil was clear and I’d plan to fit a custom or Cadillac pan to the auto eventually anyway and to be honest didnt want to waste $100 worth of fluids on a gearbox I didnt know would work.
In the end the gearbox was fine, but I had lost manual / tip tronic mode due to software differences with the TCM and ECU. This was easily fixed by loading my OS & Calibration data from my original TCM over the top of the new one and resetting the learned tcm settings.
With the new transmission installed and with a week gone by for the transmission to learn shifts and line pressures I took the car to the drag strip. With the first 2 runs hitting the limiter on the 2-3 shift, a quick adjustment to the tcm tune and perfect shifts were completed.
The best result of the night being an 11.2 @ 129mph on 20″ 275 street tyres.
The new box with same tune as the old one are worlds apart, the new box gives firm positive sometimes wheel chirping shifts at low throttle movements and as can be seen in the above video perfect WOT shifts, just as well as the old one.