Having all the horsepower and torque in the world is great but it does you absolutely no good if you cannot apply this power to the ground. Having a drivetrain that can hold up to the power an engine can create can sometimes be an afterthought to many people. If you have been around the Duramax diesel performance game long enough, you know the transmission can become a weak point quickly as you start to add power to the engine. The brand new 10L1000 transmission will be no different. While the computers are getting smarter and quicker at keeping the transmission alive by reducing engine torque when too much power is applied from a larger tune, this is no fun for the end user. The aftermarket industry is hard at work looking at how to improve this transmission as end users up the power in their L5P Duramax engines and limp/kill their 10L1000 Allison transmissions. That said, there is new stuff rapid coming out, much like the new Goerend DK Billet triple disk 10L1000 converter I was graciously given the chance to try out and run in my 2020 L5P Chevy with the 10L1000 Allison.
Mr Lovrich @ Inglewood Tranmissions gave me a call a few weeks ago letting me know that Dave Goerend @ Goerend Transmissions had just finished the first 10L1000 triple disk billet converter. We always seem to chat about new findings and issues that come with these trucks or ramble on about the world today and days of past. Never a dull moment with him but in our conversation, he had said that Dave wanted to know if he (Mike) knew of anyone willing to test out this new converter. Mike thought of me and asked if I would like to try it out. I don’t think my brain even fully processed the question before blurting out “Yes!”.
The Install
Come May 14th, I and my buddy Jon headed off for California to meet up at Mikes shop on the 15th. Spent the night at Hotel Fullerton just south of the shop and we were at mikes by 7:30am the next morning. After some chatting, we got the truck up on the rack and Roger got to work pulling the transmission out. It took some work and finagling to finally get that big transmission out but Roger is a master at his craft with installs and removals. I didn’t time him but I would say it took about 1.5-2 hours to get the transmission out. With it out, it was just a matter of pulling the stock converter out and popping the new one in. There were careful measurements made to the old converter to make sure the new converter dropped in without issue. When Sal dropped the new converter in, there was no typical “3 clunks” you usually get to line all the splines up as you spin the converter around. It fell right into place right off the bat! This is very rare and even had Mike and Sal wondering if the converter was fully seated. The converter was verified a few times over that it was dropped in all the way and all checked out good! Everything was put back together, we took a lunch and had the truck back on the ground and backing out of the shop by 2pm that afternoon.
Now, the first test drive was with the truck 100% stock power. There is no programmer, tune, deletes or any of that on this first drive. 100% stock truck so keep that in mind for this.
First Drive and Impressions
Mike hopped in the passenger seat and I was driving for the first test. Right off the bat, I noticed that the dead pedal from a full stop to applying heavy throttle quickly had decreased. The converter is looser than stock allowing the turbo to come up faster and not limiting fueling as bad. Sadly it does not mask the entire dead pedal but it does help. We drove around the block and I did some boosted launches in 2wd. This thing instantly comes onto boost compared to a stock converter but once you let go of the brake, hold on as it couples hard till lock up. Plenty of tire spin in 3rd gear on stock power with traction control off. I had to do some running around in the truck that day so Jon and I drove around. This allowed the trans to start learning all the change we had made with the converter. It seems when the batteries were disconnected, the TAPS were cleared and put into what I could only determine as a fast learn but there is no data to back that. First, upshifts were all over the place from flaring to stiff shifts but those cleaned up very quickly. After the next key cycle, downshifts started to vary in smoothness and firmness. It only took 3 drive cycles with varying throttle inputs and speeds to get the shifting back to stock. The converters adapts on the other hand, took longer and are still continually learning to this date. With 3 clutches in the converter, you got a VERY quick and harsh lock up right out of the gate. With every drive cycle though, the converter lock up application became a little smoother though. It took about 200 miles of city driving for the TCM to learn and adjust the apply of the new converter and finally smooth it out to a much nicer comfort level. Each day I drive the truck, the converter is slowly getting better and better. This was really my only gripe I had for the converter and actually worried me that the adapts may not clean the rough apply up, otherwise it excelled in everything else I threw at it.
Lets Add More Power!
At stock power, this converter is good. Above stock power, that’s when it really starts to shine. Once we got back from our little around town cruise, I decided to do a quick install of the banks derringer I had sitting in the center console. I was saving it for this day. Took about an hour to throw in, run the wiring nicely and we were out playing in the truck again. Ive seen tuned 2020 trucks, both deleted and emission compliant, and they just like to blow through the stock converter until lock up. This can easily be seen by the tach needle hovering close to the rev limiter with hardly any rpm change as each gear is up shifted. It just can’t handle the additional power very well. This issue only becomes increasingly worse as more and more power is applied to the stock converter. With this billet triple disk DK converter, it couples hard. You can watch RPM drop with each shift. Not one problem with lighting the tires up with the Derringer turned to 6, traction control off and foot to the floor from a stop (no boosted launch). I was extremely surprised with that! Jon, Anthony (he came out to pick up my old 2002 duramax from me) and I were laughing pretty hard about that
By this point, it was 6pm and we are still in California. It was time for Jon and me to head back to Arizona. We made the trip home with 0 issues. The real test on the converter came the following week as the family and I headed up north for a 5 day retreat. There were quite a few grades to pull and some slow creeping along. Again, as we set off in the morning with me grossing about 26,000lbs (truck and trailer weight), the converter just flat out coupled no matter how hard I got into the throttle from a stop. Enough that again, traction control would kick in from tire slip, something stock would never do. Mind you, I left the derringer on stock power for this as well. It wasn’t till we got down the highway that I turned it up to 3 and left it there. I eased off beating on it and headed north. I did run into a converter unlock issue while coming down a grade but this is computer related much more than converter related. The drive home was really uneventful and never did run back into the converter unlock issue, strange.
Final Thoughts
In the end, this is a very welcome addition to the 10L1000 Allison for guys needing some kind of transmission upgrade to get their new found power to the ground more efficiently. It is going to take some time for the TCM to learn the new adapts and varying your driving style will be crucial to getting it back shifting smooth. Hammering on it is not the way to go about this, lots of city driving with varying throttle inputs and gear shifts are what it needs to see. I have 200+ miles of city driving to get the converter back applying and releasing smoothly. Sadly, this is just one piece to many many other parts of a well-built transmission. The 10L1000 is going to take a decent amount of time to work right under higher horsepower conditions. It will take a combination of both tuning and hard parts to get it there. Mike and Dave have been hard at work on this transmission for over a year already and the information that can be obtained to improve the transmission correctly is nearly non-existent but that does not mean they don’t have tricks up their sleeves. Being they were one of the first with a 10L1000 transmission and converter a year ago, they nailed down the weak points quickly. It’s just going to be a slower process in the end to make sure you, the customer, get a reliable product that you will be happy with for years to come. Their phenomenal track record of the 6 speed Allison shows that!
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1st Allison 10L1000 billet triple disk converter from Goerend
