4T60 - Damage by using 2nd gear?

[paulo57509]

I've often wondered about the warning that appears in the owner's manual ('92 Lumina Euro, 3.1L) that states something to the effect that transmission damage can occur from prolonged (?) driving in 2nd gear.

What exactly is the cause of failure? Excessive heat? Poor design?

I often drive in mountainous terrain and use second gear while descending some steep grades for what I consider more than a few miles.

Comments? Flames?

I performed a search but couldn't find much on the subject.

TIA

[SappySE107]

Probably due to the heat the trans is making in 2nd gear through high rpm and load. Hope you have a trans cooler on that thing.

[Quinky]

I'll be from the higher rpms and more heat generated.. mountaines terrain is gonna be hard on any transmission.. I highly recomend you install a good size external transmission oil cooler and have it by pass the cooler in the radiator.. this will help reduce heat and prolong the life of your transmission..

[gpse3400]

GM is just covering themselves. The only way you can carelessy damage the trans is to jam it into reverse, park, do an N-drop from a 2000 RPM+, or for the differential do a solitary wheel burn out for extented periods(not good for any differential). The Manual select can be used if you need to use it. The transmission is going to up shift and down shift regarless.

[paulo57509]

I got the answer from a good authority....heat related damage can occur.

Just posting in order to close the lop on this thread.

[gpse3400]

I had a few engineering courses in Transmissions plus I've rebuilt a number of them, so you can take my recommendation for what it's worth as well. As far as the 440 and 4T60E is concerned, you can hold gears if you need to. In fact its better if you are stuck in traffic than to have the trans keep upshifting and down shifting. Also on big hills where excessive up and down shifting isn't needed nor required. Holding one gear instead of constantly shifting means less actions are going on. The TC might be spinning faster but the load is pretty much the same. These are a few of the reasons why the manufacturers have the manual lever detents installed. The trans cooling system is excellent at keeping fluid the proper temperature regardless. if you want to help your car out, install an Aux cooler. Use the manual lever if you need to wherever and how long you need to, just upshift when you are at resonable engine speed(say 3000-3500rpm, just to keep things quiet, and to cut engine/accessorie wear). Keep your fluid topped off, change your fluid on time, and use DEX3/Merc.

[Dave]

As for why is "manual second bad for my trans question" well, here's an answer..

there's a "forward apply band" used only in manual first and manual second (when you put the gear selector in either 1 or 2) when you are using those manual selections the band will apply and bands tend to generate more heat. LOTS more heat - plus because the apply bands are not the primary source of shifting in the transmission they aren't as strong as some of the older setups (torque flight 727 anyone) so the newer GM bands will burn up a lot faster.

--Dave.

[gpse3400]

.......The 2-1 band stays on in manual low and 2nd gear. The Foward band is always applied in foward range... Anytime a clutch applies or a band applies there is heat. May as well park it then. The 2-1 band is not going to cause any longevity problems. Its there to be used. You wanna heat up the transmission, drive in heavy traffic and just let keep upshifting and downshifting. Or take it on hill and let it do the same. Holding it steadfast in gear is a better strategy to reduce heat and wear, mainly in traffic and hills. Beside you have engine brakeing that will keep wear off your brakes.

[Dave]

it goes much deeper then saying "use it all you want, shifing alot will just create more heat"

how 'bout an answer as to why...

when the 1/2 band is applied, it will hold the gearset tighter - at that point you're putting undue stress on the stater in the torque converter - also the 1/2 band was not made to hold that stress for extended periods of time - they say you can tow with it, or use it for engine braking, but I suggest against it as to the ill effects it will produce in the torque converter creating a much shorter transmission life.

--Dave.

[gpse3400]

2-1 band... So because that band holds the reaction sun it strains the stator in the torque converter?????

I don't see how that has anything to do with the TC. The TC has enough to worry about from just from initial take off all the time.


The reaction sun is held all the time in foward by the 1-2 Support Roller clutch via foward band. That 2-1 band acts like the old 1-2 band but its purpose is for "effective" engine braking otherwise its the 1-2 Support Roller clutch and foward band that holds the reaction sun solely. The 2-1 band is enabled all the time in manual Lo and 2nd. So as far as it holding anything, it's just there to augment the 1-2 support diode. Limted to the 2-1 system, it isn't working very hard and it doesn't need to.