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post #1 of (permalink) Old 03-09-2017, 08:41 AM Thread Starter
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Transmission upgrades

I have a 2008 Impala ss. I'm on my third transmission. It always baffled me that Chevy, GM, installed the same transmission that was used in all V6 Impala models that was used in the Impala ss that is equipped with the 5.3 V8. As I said this is the third transmission. GM did the right thing and warrantied my transmissions issues. I am being exceptionally rough on the latest transmission in my car, I'm wondering if anyone knows if GM did any upgrades on the re-manufactured trannys? This transmission I've been running in the car for two years now has been problem free, slip free. I downshift the transmission at high and low speeds with no issues whatsoever. I'm kind of waiting for the other shoe to drop.
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post #2 of (permalink) Old 03-09-2017, 09:29 AM
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I do know that the 4T65-E received upgraded valve bodies, upgraded 4th gear shaft, ratcheting input sprags and internal electronics in the early 2000's. I would assume that any re-mans would have the same upgrades, but I do not know if GM or a remanufacturing company would do anything beyond that.

However, it may be worth nothing that the SS actually does not use the same transmission as the other V6 Impalas. The V6's up to 2012 used the 4T65-E (RPO M15), whereas the SS used the 4T65-E-HD (RPO MN7), a heavy-duty version. The trans in the Impala SS also has a different gear ratio than other 4T65-E-HD transmissions, I believe it is a 3.06:1 ratio.
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post #3 of (permalink) Old 03-10-2017, 02:04 PM
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I'd at least run full synthetic trans fluid and change it every 5 years/50k. A tune will also firm up the shifts and potentially prolong the life of the clutches. But it sounds like the way you want to drive that transmissions wont last :-) unless you got one rebuilt to handle it.

The 4T65E isnt known to be the most robust, especially earlier ones that spec Dex III, which oxidizes and has a low tolerance to being overheated, and that people rarely have the fluid changed. Alison TES-295 approved fluid is a good replacement for Dex III - this is what I have in my 02 Impala + shift kit + overkill tune, 122k miles and its still running sweet. My 2013 LTZ with the newer 6 speed box has 43k on it and I'm going to change the fluid in the next few weeks with full synthetic Dex VI.

As TeeRev noted, the SS cars have the HD version which is uprated to handle the higher torque.
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post #4 of (permalink) Old 03-11-2017, 06:47 PM
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Get a good reman from Dave at Triple Edge along with a new torque converter when yours blows up. His rebuilds actually last.

Install the updated pan magnets according to the TSB. GM TSB 08-07-30-040C

Install a Low Pressure Drop self regulating plate cooler, after the radiator trans cooler in the fluid return line, to get your temps down from 200F to 230F into the much more reasonable 160F to 180F range.

Install a transmission drain plug in your stock pan so you can drain and refill every 10-20K miles along with the engine oil.

Install a Real Australian made Magnefine transmission filter in the fluid return from the cooler. Avoid the China made counterfeits from Raybestos etc they are cheap crap. This accomplishes three things.
1-- It'll catch the pieces of the old trans before they destroy your new unit and the magnet will catch all the iron that's poisoning the shift, torque converter clutch, and pressure control solenoids.
2-- It's a real filter that can be changed every time you drain and refill the trans pan.
3-- Since it's a real 25 micron filter the 100 micron pickup strainer will not need service so you won't have to drop the pan when you change out the trans fluid.

DON'T bother with synthetic fluid. Despite the hype it's not better than Dexron VI for these transmissions. Dexron VI is what these transmissions call for. It's not expensive or hard to find. Use it.

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Last edited by hatzie; 03-12-2017 at 04:33 AM.
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post #5 of (permalink) Old 03-12-2017, 05:11 PM
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All of the supercharged GTPs, Regals, Impalas and Monte SS card got the HD version of the 4T65E also... And it was a failure waiting to happen behind those 240 HP engines stock. The only way to get a sure-fire built right trans is to go to a shop that knows these transmissions and knows there weaknesses and has good parts to build them right and make them last. If you are choosing a local shop, grill them. Don't be afraid to question them on what they do and how they warranty them. Avoid the dealership because you will just get a pile of shit, ticking time bomb, again. TEP knows the 4T65E and can build them right, but you will pay for it. I wish I would have gotten a tranny from them from the get go... But then again, I wouldn't have bought my 2014 Impala and be here complaining about the 4t65E transmission, again... I am a GM fanboy to the end, so I have no problem telling them about a piece of shit failure when I experience it.

I love the 06 up SS, but the transmission stopped me dead in my tracks from buying one. And I won't recommend for anyone to buy one unless it can be proven that the trans has been rebuilt right.

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post #6 of (permalink) Old 03-15-2017, 12:11 PM
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Heat along with crud and Iron particles that flow right through the 110 micron pickup strainer are the main 4T65E-HD killers.

220F will kill a transmission in around 40,000-60,000 miles. Add fluctuating line pressures from iron poisoned control solenoid coils and heat and crud from iron poisoned converter clutch solenoids you have a recipe for a transmission that only lasts 30,000-50,000 miles. Coincidentally this seems to be about the lifespan of many of the 4T65E transmissions in the 06-10 cars.

I still have the original 4T65E-HD in my 2009 Impala SS... I have a little over 40,000 miles on her and I have no issues at all.

What did I do before I got to 10,000 miles?

Install a 25 micron filter with a Magnet in the low temp return line and change it on 10K intervals after swapping out the first one at between 3K & 5K.

Install the TSB magnets in the pan and on the strainer.

Install a drain plug in the pan that will allow easy fluid swaps at 10K or 20K intervals. No need to change the strainer when you have an easy to change filter that's 4x more efficient.

Install a decent plate oil cooler for the fluid so it doesn't run at engine coolant temp of 200F to 220F and more.

2009 Impala SS
"Speed never killed anyone. Suddenly becoming stationary... that's what gets you." Jeremy Clarkson

Last edited by hatzie; 03-15-2017 at 12:32 PM.
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