I have a set of 3.42s going into my truck. Currently running a stock 03 TCM tune and I will have a tap shifter installed. Curious if anyone has played with shift points to let the truck rev a bit higher before upshifting or if I am overthinking this.
3.42s TCM Tuning
- Thread starter TROJAN366
- Start date
I've been running 3.42's in my BURB for 7 years since I did my swap. The TCm doesn't care what gears you're running. It's not like a gasser where you have to correct the shift points if you fix the speedo. I DID lower my 2-3, 3-4, and 4-5 shifts as well as lockup to keep it in gear at common speeds. With stock tuning it didn't want to shift into 4th until roughly 31-32, 5th would happen around 45, and lockup doesn't happen until 55. So I lowered my shifts down so it will stay in 4th when running 28-30, 5th at 40, and lockup happens about 49 now. Just helps to keep it locked up and not wanting to shift when I'm running the speed limit on some roads. I run the 01 TCM OS in mine. Chavez(think thats his name here) helped me with a CAX file to get lockup to hold below 55 when I let off the throttle which REALLY helped driving on normal highways(gets REAL annoying coming out of lockup AT 55, so everytime somebody dropped jsut below 55, it would unlock, then relock once I put my foot back on the throttle).
AJ I agree, this is annoying as hell.
Interestingly, the 04-05 LLY TCM OS does NOT unlock the TC on a throttle applied downshift (like if you're on the highway in 5th and floor it and it kicks down to 4th)...it stays locked all the way though.
All of the 01-03 LB7 OS's unlock the TC, then relock it. Which is annoying because you're on the highway, go to pass, floor it, it unlocks, downshifts to 4th, then sits there SCREEAAAMMMMINGGG in 4th and you hardly even accelerate...then it finally shifts back into 5th, then 5 seconds later relocks.
Then again the 04-05 LLY OS shifts like crap, so theres no win-win with the 5-speed TCM OS.
My concern was that when the trans shifts the following gear will be taller and increase the load. My thought was that by increasing the RPMs of the shift it will fall into the next gear and be a bit higher in the rpms and be able to handle the load better but I guess I was overthinking things.
If you have a heavy truck, or lack lots of low end power you will probably want to raise your shift points up a bit. I'm guessing ferms suburban is lighter then some trucks. But again, if your low end power is good it should be fine.
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Your one of the few.......
If it works for you great. And yes with a properly built transmission any of the OS will shift "fine".
But I prefer the 01 OS hands down. Especially on a built transmission. There is an 03 OS that is my second favorite.
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What do you like about an 01 OS compared to any other? Or are the differences seen in part throttle driving?
This is mine with an 05 os.
https://youtu.be/Xdabmk8BXzE
It learns in quicker. It doesn't "freak out" as easily. And the shifts are noticeably crisper.
Plus before efi released the converter lockup RPM limit the 01 OS I used would still lock the converter at high slip RPM. I don't believe those tables exist in that particular OS.
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Plus before efi released the converter lockup RPM limit the 01 OS I used would still lock the converter at high slip RPM. I don't believe those tables exist in that particular OS.
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Video looks good. Does your RPM always come up and then drop back down slightly when you first apply the throttle like that? Or did you back off the throttle?
Just curious because I had that same issue back when I first dealt with a 5" intake tube. The fix is in the torque tables. Once the MAF is rescaled properly of course. If you already know this just ignore me. Lol.
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Just curious because I had that same issue back when I first dealt with a 5" intake tube. The fix is in the torque tables. Once the MAF is rescaled properly of course. If you already know this just ignore me. Lol.
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I think they learn slower or sometimes not at all. I think this is the reason they don't freak out when changes are made.
No. he was working on just getting lock up to hit every time like it should in the 01 OS and hasnt played with that part yet. We were using my truck but i cant keep swapping back and forth between 01 and 02 OS when the 01 OS didnt work. the first few shifts tie up so bad until it learns im afraid of tearing my hard parts up in the trans. when i get this other truck out of my garage, ill have more time to drive my truck and see if we can get it worked out
yeah and damn does it not like my truck till they learn from swapping a 01 OS in!!! swear i feel like my truck will be showing up at your shop on a wrecker cause the c2 hub finally let loose :roflmao:
Yeah I agree. I think maybe I worded my post poorly.
They make changes to the adapts slower. But they will switch from "fast learn" to "slow learn" quicker. Basically they settle in and quit screwing with things quicker then the later OS. In my experience anyway. The lly OS will keep making drastic changes, and takes forever to switch from fast learn to slow learn. Especially the 3-4 shift.
I've actually seen an lly OS go from slow learn to fast learn on its own after a rough 3-4 shift.
I can run an 01 OS putting around town, or hauling a heavy trailer, and then go straight to the track and feel confident that it will shift clean and smooth. The later OS, especially the LLY OS will generally take a few WOT runs before it settles in.
If all you ever do is one type of driving the later OS will all work. But the 01 seems way more consistent and predictable to me.
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Do you have a second tcm you can just swap so you don't lose the learn in each time?
If not I have several I could send you one. If you think you might be able to figure out how to keep the converter locked during a part throttle downshift I would help any way I can. I would even chip in some beer money or something if that would help. Lol
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That i dont have but good idea. Let me talk to josh and see where hes at. i know hes been out of town this week for work and was working on some other tuning stuff in front of this. he may have an extra i can use to go back and forth with
on the topic of good shifting TCM tunes, i really have no complaints about my 02 OS. smooth shifts even after going WOT and spending a week of grandma driving. initially it had to do 1 pass of WOT to get it to relearn WOT but steve did a couple tweaks to the ECM tune and now its consistent as can be. doesnt do anything strange other than the damn TC unlocking on down shift.