What to do? 4T65E-HD (LONG)

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Decided to stop by, after all it's been I think almost a year since my last login. Life gets busy... So on my SS I have a decision to make. Anyone who knows anything about the 4T65E-HD knows it is not the greatest transmission, especially when coupled to a tire-shredding LS4. Everyone I talk to says the life expectancy is 60-80k, MAYBE 100k. Well, I am just shy of 125k, so I must be doing something right. But I have always babied it (that's a huge understatement!). PROBLEM: I have a "slip" developing. It is usually off the line, but twice I have caught it at ~50mph in O/D (4th). It is NEVER a slip between gears. Off the line the problem is gas->wait a 1/2 second->small thud->off we go. At ~50mph, the problem is under light throttle in 4th. When starting to go up a small hill and I start gradually applying more throttle it will also thud. Note, it never tries switching gears (as it shouldn't). Also worth noting, I do have a moderate trans fluid leak, not sure from where, but I don't think this will affect performace (I keep it topped off). I am not super knowledgeable in trans diagnosis, but I'm assuming this is a torque converter problem. I will go have it looked at before I do anything drastic. HISTORY: I bought it with about ~75k on it. I purchased a handheld tuner to disable AFM (lifesaver!), but I also tuned all the shift points and pressures in the trans (also amazing). It IS the original trans. No work done in my possession. But I did drop the pan and change the filter at 99k (no issues, just routine maintenance). Used Dex VI. Old fluid looked clearly used, but very very good. No traces of darkness or smell. QUESTION: What would you do? I am debating trying to fix it and selling it. I absolutely adore this car (except the trans) and bought it planning to go 300k+. If I sell it, I have equity, so I gain. If I keep it I figure a replacement trans is in order, and I figure a replacement is ~$2,500-3,000 (not doing this myself). Triple Edge Performance is my front-runner atm, as they are HIGHLY regarded amongst this transmission community. I just bought new tires too frown. I am on a very small budget atm, which is why I'm asking opinions on this predicament. I know... go with your gut, and you know what's best for you, but I'm torn. I love the car, and would love to keep it. But I would gain financially by dumping it, when $$$ is thin. And I'm an incredible car shopper. But I'm addicted to V8s and 4 doors (no kids), and that market is scarce. Especially when you eliminate the 4T65E from the pool. Sorry for the long read, but I REALLY value this community and it's input. But I also know that too much info is usually appreciated as well. Thanks for taking the time, and hopefully you'll give your 2cents. It is highly appreciated!
 
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that enging/transmission combo is notorious for filling up a dirty diaper. congrats on going so far, and good luck with your decisions.
 

tony1679

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^Not quite what I was after, but thank you. I will stand behind this engine 1000000% though, as long as AFM is disabled. This 5.3 is a freakin monster crzy grin2
 
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Sounds like a leaky/worn clutch cylinder if I had to guess. I'd fix it and keep it if you like it that much. I would assume that there's a big knowledge base of rebuild tweaks to make the 4T65 reliable- that seems to be the way of GM automatics through the years. Solid basic designs with some obvious production shortcuts that turn up as chronic weaknesses, but are easy to fix in the aftermarket. I know relatively little about the 4T65 specifically, but that was certainly true of the 700R4 and a few other rear-drive transmissions they made. The one concern Id have is that the 4T65, being a front-drive transaxle, simply CANNOT be made up to the task since all the components are going to be undersized to fit the footprint (one reason I hate front-drive). If it were here in my town, I know THE guy I'd go talk to about building it... if that's an option where you are it could easily cost less than a complete crate trans and be just as good in the end. IF you can find that guy...
 

tony1679

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^Interesting response. Yes, Triple Edge seems to be "that guy" with this trans. Thank you! (And thanks for the extra info!)
 
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Go for one from Triple edge and keep the car. I bought one from them and GMR in pieces 8 years ago and its living well behind a holy terror ever since. This one uses a 1" chain and torsen diff (both are GMR and are now unavailable) but they can build one that lives behind 600HP with a 7/8 chain if that's what you need. I have also bought parts from them to repair/rebuild others, all good stuff.
 

tony1679

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^Thank you! It's just a canned handheld 91 octane tune, otherwise 100% stock. But I share the fond opinion of the LS4. I have no plans to put the monster on steroids. That trans has enough help feeling ill...
 

tony1679

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Originally Posted By: Mr Nice
Tony, Spend the $$$ and keep the car since its a creampuff.
Thanks for your 2cents! And yes, other than this (unfortunately common) issue, creampuff is an understatement. Near-perfect cosmetically, and enough (routine) service records to require a small tree farm crackmeup
 
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Here's one in Phoenix with 72k miles for $12,900. It was a former rental. Other ones in their national fleet are around $14k. Or just budget for a new trans at 3k replacement cost. I'm guessing it would cost about $6k off the top of my head to get a similar lower mileage unit. Plus you know what you have. https://www.carmax.com/cars/chevrolet/impala/2008/12825273 Think of all the micro beer that will get you with the savings.
 

tony1679

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^So is that a vote for fix it or sell it? cheers laugh If I sell it, I'm not getting anything else with a 4T65E. That's silly, leave one problem, enter an identical problem.
 
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All the 4t65e-hd will do that if it is the problem I think you have. It will not get any worse. It is an annoyance and will not affect the life of your tranny. If you take it to a shop they will tell you it's toast and want to rebuild it. The internet will tell you the same thing. People fear what they don't understand. There is a small GM lipped seal that is ever slightly too short. It should only do it at certain temps. It will slip off the line and then bang into gear. Sometimes it will do it at say 35 mph +-. A lot of people have needlessly spent money on this issue or dumped there rides needlessly. The internet experts will argue this to no end. I would drive it and not worry about it. If you rebuild it with GM parts it will still do it. This usually shows up around 60 to 80k miles. Mine does about once in every 3 mos. around 80 degrees on the tranny temp. Mines been doing it off and on since new, 11 years ago. If you are getting the problem on a fully warmed up trans, then it is something else. A lot of cars have minor glitches like this. You can buy something else only to find it may have some kind of glitchy common issue. Plenty of 4t65e going over 200k miles. I run Dex III , it's a little thicker than IV, and change it our every few years. Take my advice for what it's worth. I am sure the experts on the web here are going to tell me I am all wet. Been a professional mechanic since 1979. If your problem is different than I have described it could be something else. Tranny shops are in business to sell you a transmission so get an independent diagnosis. Do not get one from a transmission shop.
 

tony1679

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Originally Posted By: sprite1741
If you are getting the problem on a fully warmed up trans, then it is something else...Plenty of 4t65e going over 200k miles.
Thanks for the input! frown You got me excited for a minute, until that. While I can't confirm if it has ever slipped colder, I can verify plenty of occurrences fully warmed (highway and city 35 mile commute 1-way). Not being mean, or saying you're wrong, but... You show me an original stock 4T65E-HD hooked up to an LS4 with 200k+ and no repairs or mods other than fluid/filter changes, and I'll show you Einstein, Jesus, Kennedy, Aristotle, and Gandhi are all alive in Tahiti drinking a cold one. cheers I'm sure some non-LS4 applications could make it to 200k though... (At second glance.... what's your mileage? whistle)
 
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If you like the SS, then fix it. If you are indifferent or don't like a car, then something like this makes a good excuse to get something different. But if you like the Impala (which you said you do) I would stick the money into it. Better to do that then to trade the car for one you hate or that has hidden issues (all used cars are a gamble)
 
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If you love the car, keep it. All you need is the right people and skills to be a happy camper. ZZPerformance is who you need to talk to: http://zzperformance.com/3800/transmission-drivetrain/4t65e-hd-transmission.html ZZPerformance has been building and installing high performance 4t65e’s for 12+ years. Our transmissions are used in the highest HP and fastest front wheel drive 3800’s in the world. We are currently the only company in the world producing all of the hard parts for the 4t65 and rebuilding them for customer use. The purchase of a ZZP transmission is an investment into your car that will give years of reliable service, even under the most abusive situations. Building and assembly is done with many proprietary techniques. This makes for very quick shift times, long clutch life, and higher HP capability than any stock transmission. Externally adjustable line pressure allows fine tuning of shift firmness. Hope this helps you!
 
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Originally Posted By: sprite1741
All the 4t65e-hd will do that if it is the problem I think you have. It will not get any worse. It is an annoyance and will not affect the life of your tranny. If you take it to a shop they will tell you it's toast and want to rebuild it. The internet will tell you the same thing. People fear what they don't understand. There is a small GM lipped seal that is ever slightly too short. It should only do it at certain temps. It will slip off the line and then bang into gear. Sometimes it will do it at say 35 mph +-. A lot of people have needlessly spent money on this issue or dumped there rides needlessly. The internet experts will argue this to no end. I would drive it and not worry about it. If you rebuild it with GM parts it will still do it. This usually shows up around 60 to 80k miles. Mine does about once in every 3 mos. around 80 degrees on the tranny temp. Mines been doing it off and on since new, 11 years ago. If you are getting the problem on a fully warmed up trans, then it is something else. A lot of cars have minor glitches like this. You can buy something else only to find it may have some kind of glitchy common issue. Plenty of 4t65e going over 200k miles. I run Dex III , it's a little thicker than IV, and change it our every few years. Take my advice for what it's worth. I am sure the experts on the web here are going to tell me I am all wet. Been a professional mechanic since 1979. If your problem is different than I have described it could be something else. Tranny shops are in business to sell you a transmission so get an independent diagnosis. Do not get one from a transmission shop.
While I do agree....Input Clutch Apply issues can be ignored for a LONG time! But that "Banging into gear" is not good for the Input Sprag or the Splines on various components in the trans, Of coarse it all depends on the frequency of the Input Clutch cutting loose & how hard your on the throttle & how long it takes for EPC to relay "torque signal" too the Boost Valve so the line pressure/pump output can overcome the leak. I bring this up because poor Line Rise is common along with low pressure Hot. His doing it Hot makes me suspect the Sealing Rings on the Input Drum itself. Solid teflon rings tend to shrink when hot, Along with Land wear & high mileage can cause a pretty good leak. The Input Clutch is off in OD/4th, Not related to Input Clutch apply concerns. Just so you know, All aftermarket seal kits come with a "long-Lip" input clutch inner apply Piston seal.
 
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Originally Posted By: tony1679
^Thank you! It's just a canned handheld 91 octane tune, otherwise 100% stock. But I share the fond opinion of the LS4. I have no plans to put the monster on steroids. That trans has enough help feeling ill...
Believe it or not its not a bad transmission once it has been tweaked. Some performance parts companies resell the Triple Edge units, they are the best at building these bar none. The 4T65E-HPS2 would probably be the best option for your car but call them for their recommendation, it may be worth going to a 7/8 chain with the V8. Most decent independents will swap a unit for $500 if you provide the fluid, I run Amsoil ATF (not ATL) in mine with a pickup screen mod instead of a filter.
 
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Hi all! I spent 20 yrs in the GM Tier I supply chain, horrified at what they insist on building and selling to the public! Hey I love GM cars - when all the deliberate glitches are fixed! For less then $20 per car 80% of all GM problems can be prevented up to the point of wear out. But GM knows the dealer network would go broke and leave GM! 4T65-HD / 4T65-E Hard Shifts - Root Cause & Solutions: Root Causes: Hard Shifts are actually delayed shifts where the computer detected a "Low Ratio" problem when the shift is not completed within a max of 600 milliseconds. It then boosts 'line Pressure' to make up for what it thinks is a slipping clutch pack. Most of the time it's a deliberately weak valve body, where apply valves(spool vales)are made so that they gall and stick in the bore of the valve body. If the apply vales where made from full-hard drawn aluminum bar stock, machined and hard anodized, the problem would disappear. Sonnax.com makes such parts for the rebuild market. The worst thing you can do is use new GM parts. I know, happened to me. There are other part failures to of course, but that's a biggy. If you have a PREMIUM OBDII scanner, the trans code will usually be P1811. Clear code or disconnect the battery for 1 hour to reset. Cheap Fix: If you have a P1811 code and delayed / hard shifts in 1st and 2nd, then the cheap fix is drop the pan and install the TRANGO 4T65E shift kit in the shift accumulator. The kit has parts for 3rd and 4th gear accumulators, but you'd have to rip the left wheel, CV shaft, trans cover, oil pump and valve body to access the channel plate, etc. I'll presume you're not overdue for a trans oil filter change, they easily cause shift problems too that look the same. While you're at it, be sure to find 5 to 8 2" long neodynium bar magnets to place on the oil pan near the factory ring magnet 'cause it does a terrible job of catching fine metal particles from normal wear. Note, no filter catches particles under 20 microns! I know, looked into it! Remember, the shift solenoids are magnets and will stick if particles get inside. Finally, when you slap it all back together, start the fluid fill with 2 cans of Seafoam 'Trans Tune' to free up sticky valves, (been using for the past 3 yrs) then add the rest of the Dextron fluid. Proper Fix: Visit the Sonnax.com website and search 4T65 parts and get all the valve body parts identified with problems. A pal of mine made up a PDF of the issues and part numbers, I'll find it and post here in a few days. Sonnax builds updated valve bodies with way better parts. Sonnax sells to distribution, so find a trany parts Distributor in your area and ask for a shops that buys/installs Sonnax from them or order and install yourself. I'm super disappointed that GM trannies still suck since my then new '85 Buick Century company car blew it's trans in just 30,000 miles. Yet I've driven 60's, 70's & 80's Chrysler Slant 6 & 318 V8s with Torque Flite A727 /A904 trannies 250,000 miles and more without a single hiccup. Go figure! See ya guys
 
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