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Showing results for tags '8 speed'.
Found 12 results
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Hey guys, I did the thermal bypass conversion to active by pass on my 2018 8L90. Did a step by step video because I hadn’t seen anybody do an actual full replacement video nor had I seen one on a 8 speed. Trans runs about 45 degrees cooler now. Check it out and let me know what you think. It’s the exact same procedure on 6 speeds just mounts different on the transmission.- 17 replies
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I recently bought a used 2016 Sierra Denali 5.3L 4x4 in March with 48k miles. Truck has been great until yesterday (now 52k miles) when I ease into the gas it shudders and shakes like crazy until i punch it. The tach is bouncing up and down and it doesn't matter if it's in v8 or v4. It almost feels like it's a misfire but it's weird that it only does it when I'm easing into the throttle or going uphill. The truck has the 8 speed transmission. Has anyone else ran into something like this and would the manufacturer warranty cover the fix for this? -
Is this how most dealers do a trans service on MQE 8 speed? See link below. I would like to order some fluid from Black02Silverado and then test it. I am too crippled to do a pan drop anymore and since the filters on these things are screen doors on submarines I would like to do the fluid exchange by machine pump. Is this the procedure a dealer will do from the stand pipe fixture and trans oil cooler block assembly with adapter. No dipstick on this 2022 LTD Trail Boss. https://static.nhtsa.gov/odi/tsbs/2019/MC-10163890-9999.pdf -
So I've tuned my truck with and it has made a difference from what I can tell. A couple of questions, however. 1. Is there any way to truly fix the hard downshift from 3-2 and what I call lagging going from 2-3 under acceleration? I installed the 91 octane tune, disabled AFM, speed limiter and changed the shift points from 2-3. It seems like the shift point pressure is too much. The RPM's spike when i'm easy on the throttle after a stop. 2. There is an option to change the axle ratio via the tuner which I thought was impossible because the axle is ratio is mechanically fixed, yes? I think I have the 3.23 but I am not 100% sure 3. Side note, I have an Air Raid intake tube, k&n filter, installed a catch can and did a muffler delete. I took out the flapper valve out as well. Truck runs and performs better (sounds awesome too). When I go to pass cars on the highway, I can easily break 100 and you can tell the engine still has a lot left. I truly believe that this truck's engine life has been extended greatly after disabling AFM. Thanks guys.
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I have a 2017 Chevy Silverado 4x4 5.3l V8 with the 8 speed transmission. I already flushed out my transmission and filled it back up with the Mobil 1™ Synthetic LV ATF HP blue label. The question is, do i also use the HP fluid for my transfer case? Or do i need to use just a standard ATF fluid instead. I cant seem to find a straight answer on this. The owners manual states to use DEXRON®-VI Automatic Transmission Fluid. Would using regular ATF in the transfer case and HP ATF in the transmission cause any issues? Thanks in advance! -
So I finally gave up on waiting for a fix for the 8 speed and its many mis-behaviors and had my truck tuned by a local custom tuner that has been working with LS/LT motors and transmission tuning for many years. He plugged in his laptop and rode with me for over two hours. The truck is a new animal. Great at shifting and the engine acts like the beast it should be. My truck is a 2015, 6.2L 8 Speed, 23,000 miles. It has always had the low speed clunk and recently developed the shudder, especially in 8th at steady state highway speeds. Here is some of what was done. AFM shut off, Torque Management shut off, Variable cam timing adjusted to performance lift, 1st gear set to hold until 11 mph, higher shift pressure for next few gears, torque converter set to 0% slip, raised speeds for converter lockup especially in 8th. Other parameters were adjusted, but these were the main ones. Some of what was learned. The TC was slipping too much when trying to lock at light load (half in half out) causing the shudder. It was also trying to lock at too low of a speed/RPM almost lugging the engine (again most pronounced in 8th). No more shudder in any gear. It does take a decent speed (over 60-65 to lock up in 8th, but once locked it will stay locked below 60 unless I kick it in the pants or the load increases). As most of you experience, 1st gear was trying to get to third as quickly as possible. Now I can move through parking lots without trying to throw a U joint. There were more learnings but these 2 are the big ones. I will probably lose a bit of MPG in town driving (I am fine with that) but the 60 mile trip home at freeway speeds netted 20.1 MPG ... not enough loss to consider if any. Performance is incredible. I floored it from a stop a couple days later, and had to back off to preserve the tires as it started roasting them. Shifting at full throttle was impeccable. Longevity (as long as I dont drive it live a sports car) theoretically will be better than it was with all the clunks and shudders. I am thrilled with the results. If any of you live near Van Buren Arkansas, and are interested I will pass on the contact info.- 14 replies
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Looking at crew cab short bed 4x4’s with the V8’s. I just can’t wrap my head around not having low range so it’ll either be a Z71 or a Trail Boss. Been watching prices and I’m seeing Custom Trail Boss trucks starting to get close to the prices of the LT. As in within a grand or even less. Anyone bought a Custom and regret it? I have a 2011 Silverado 1500 4x4 and my wife has a 2017 Yukon 4x4. Both have the 6L80 transmission and hers has the Ecotec 5.3 V8. Very happy with that engine and transmission combo and even with less power my ‘11 moves and drives well with the 3.42 gears. Will I miss anything with a Custom instead of a regular LT Z71? 6 spd vs 8 spd? Gas mileage? Something else? -
Hi everyone, I just purchased a 2016 GMC Sierra SLT Crew Cab All Terrain X a few weekends ago. The AFM (Active Fuel Management) is such a pain when switching from V4 to V8 mode at low speeds (non-highway driving) because I hate the "bogging" or "hesitating" feeling the truck gives off and the exhaust tone is UGH... I had a 2007 Avalanche and used a Range Technology device to disable it. But overtime I would have to pull the device out and plug it back in because it wouldn't activate sometimes. Been reading on this forum about the Range device for the newer Sierra's and people have been having issues with them and could mess with the computer overtime. So I won't be going that route. Another option is to get a tune like BlackBear and get it disabled or set a minimum speed of when the AFM activates. But a tune isn't an option for me right now because I want to keep my warranty as long as I can. Someday BlackBear tune will in my future! So I decided to try something. For the last couple days I have been driving in Manual mode "M" and setting it to M7 (7th gear) and driving like normal (non-highway driving). I was shifting gears up ( + ) and down ( - ) because I thought that was what you were suppose to do but I found out I can just set it to M7 and not worry about shifting, it does it for me, it just doesn't go into M8 (8th gear), which I don't need when I am going less then 50mph most days. I watched it stay in V8 mode stay the WHOLE TIME! The only time it went into V4 mode was when I shifted into M8 and then I switched back to M7 and it went back into V8 mode. So I think I found a workaround without having to void my warranty with a tune or messing up my computer with a AFM disabler device. I want to get your thoughts guys, will running in Manual "M" mode ruin the transmission in anyway? Not using M8 (8th gear) for slow speeds have long term affects with that gear? I am going to do this for another week or two and report my findings. This guy is happy when my truck isn't "bogging" or "hesitating" and have full power!!!
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Is there a drive mode where AFM is shut off? -
Okay, I believe I am starting to get the dreaded shudder. Long story short, I am getting a shudder from 68mph-90mph ONLY under throttle, smooth as silk when letting off the throttle. Truck is a 2018 Sierra SLT CCSB 6.2 8 speed with 4,058 miles. Only Mods (that might have a remote chance of changing the stock characteristics) done are 2.25 level, 275/60R20 BFG K02 tires, Borla ATAK Cat-back, Denali cluster (don't see how but figured I'd list it), RXP dual catch can, Range AFM disable and Pedal Commander (set at Sport+1). I want to get OPINIONS on a course of action. I am considering foregoing the warranty by having the complete fluid flush, buying an unlocked TCM, having it tuned and pressing on. Is this going to cure the shudder or am I just grasping at straws? I do not know how to tune in today's world of tunes, I just want the darn thing to last and function as it should. I remember @1SLOW1500 mentioning the transmission is "stuck in the middle of a fight with the engine management and ever changing trans software" and that makes sense to me. So will a properly tuned (and yes I will have to pay someone to do it right) TCM along with the flush help/cure the shudder problems or is it just somehow masking it? Please don't start a pissing contest, I am seeking opinions. I was always one to believe that this would not happen to me and this is a rare occurrence only being highlighted in the forums...it still may be a rare occurrence but I am now part of that minority. -
Hello all! First post here! What brought me here was the 8l90 torque converter lockup shudder issue. Most times I'd just take this truck to the dealer and let them sort it out, but as it's out of warranty, this is not something I'd like to pay >$600 to repair (this price was quoted to me for the flush and filter change). After talking to a few service advisors I've found that each of them planned on using a different solution to attempt to alleviate the shudder. The first was going to proceed via one of the bulletins and do a triple fluid swap and filter change, the others were just going to do a standard flush and fluid swap. I plan on owning this vehicle for another few months until the 19's become a little more negotiable but cannot stand to let this shudder go on that long and am a bit worried about destroying the torque converter in the process and washing a whole bunch of parts down into the transmission. So.... my question is if anyone has performed this fluid swap themselves, if it alleviated the issue, and if the filter change is necessary? I saw that many of the Corvette guys were swapping to the Mobil 1 fluid with some success, however, I didn't think this was as much of a fluid performance issue as it was a suspended clutch material / dirty fluid issue. Any help would be greatly appreciated!!!!!! -
From the album: 8Spd5.3
