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2006 Impala SS. Bad Transmissions???

Old May 1, 2006 | 01:25 AM
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Default 2006 Impala SS. Bad Transmissions???

I just bought a 2006 SS Impala and I hear people saying that the transmissions are only rated for 280 torque and the car puts out 323. Is this right? I cant see it being correct. Why would they make the car and put in a tranny that cant hold the torque load it puts out on it stock.
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Old May 1, 2006 | 03:55 AM
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Well thats kinda a loaded question. The specs on GM's website show 280 max engine torque and 400 max gearbox torque for the 4T65-HD... But it also lists improvements made to the model used with the 5.3L engines. The 280 rating is based on the transmission before the improvements listed below in bold. I have not been able to find an actual rating for the V8 variant (MN7) of the transmission.

I imagine they designed it to handle to torque of the V8, probably not overly built though... so a turbo may be a little too much. lol Also the torque management in the computer is very aggressive... It even feels like it pulls power with full throttle during lower rpms in 2nd gear. On the other hand several have reported blowing theirs at low mileage, but thats a very small percentage. The way I look at it... if its gonna tear up by god its gonna do it before 36000. I hardly ever cut my GXP any slack.

Posted the GM webpages, plus there is a thread over at ClubGP with a list of the modifications coming from someone with first hand knowledge... I think.

Overview
The Hydra-Matic 4T65-E (M15 / MN7) was introduced in 1997, and has applications from midsized to large front-drive sedans and minivans using V-6 and V-8 engines. It is a two-axis automatic four-speed transaxle with electronic controls, and features a unique dual chain and sprocket configuration that runs quieter than a single chain design. A stronger version of the chain, with heat-treated pins, is used with V-8 applications. In addition, for V-8 applications the starter motor is moved from the engine side of the engine/transaxle coupling to the transmission side, and the input sun gears are made with a process that increases durability, and the final drive shaft gets a shot-peen process that strengthens the metal of the shaft. The final drive planetary differential gets a larger pinion gear carrier, and the park position gear gets a stronger bearing. In addition, all pinion gears are made with a process to increase their strength.

The M15 is available with two different size torque converters (245 mm and 258 mm), while the MN7 features a heavy-duty final drive gear set.
Page 1 Specifications

Page 2 Specifications

ClubGP Thread
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Old May 10, 2006 | 10:09 AM
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was speaking with a engineer that works in the transmission area at the az proving grounds.said the trans is on the edge and that they incorporated a lot of computer managment to allow it to survive.
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Old May 10, 2006 | 02:24 PM
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Very interesting info guys. Too bad the 4T80E could not have been implemented into this car.

Hey, it is an excuse to mod...
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Old May 11, 2006 | 04:06 AM
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Originally Posted by TURBO306
was speaking with a engineer that works in the transmission area at the az proving grounds.said the trans is on the edge and that they incorporated a lot of computer managment to allow it to survive.
Yeah if the car actually hooks good under about 5 mph the computer basically closes the throttle and kills the engine. Alot worse while turning.
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Old May 11, 2006 | 06:55 AM
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that is why u get tuning software and say bye bye torque managment. if the trans blows, its warrenty
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Old May 11, 2006 | 12:15 PM
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If you turn off torque management completetly on an LS4 with a 4T65 you should plan on walking; not a real bright move.
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Old May 12, 2006 | 02:24 AM
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A smooth torque management would be fine with me instead of the off...on...off...on crap. Agreed if turned all the way off it would probably grenade pretty quick.
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Old Jun 2, 2006 | 10:41 PM
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What about the transmission parts that a bunch of GTP modification companies make? They have single chain drives, gearing, input and output shafts, and some other stuff for the 4T65-E (HD) transmissions. I wonder if this stuff would work with it.
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