Bippu147

iTrader: (9)

You shouldn't be decelerating by downshifting aka engine braking, it absolutely KILLS the over run clutch when you do it in 3rd, and if you do it in 1st it kills the planetary.

RamAirRckt

Does it make any difference with using 3-shift vs manual shift?

Is it the downshift that is damaging or just engine braking itself?

Typically I blip the throttle first to trigger a normal say 5-3 kickdown and then pull the manual shifter to 3rd.

Just wondering... I haven't been in anything but a GM 4L60E. One thing you learn, is all trans are very different in how they work.

Bippu147

iTrader: (9)

Whether you blip it or not, I use to do the same thing until I pulled my trans apart and saw the damage it caused with my own eyes. Same thing happens on the GM transmissions too.

Bottom line, use your brakes to slow down, it's cheaper to replace brakes than to rebuild your trans.

fastryan

I run a few mile tracks, they require some first gear. High rpm and low gears don't overheat transmissions, a slipping torque converter trying to pull too tall if gear will overheat very quickly.....

fastryan

These engines have a four bolt main bearing, maybe even five, I c an't remember exacty. Anyways the engine is very strong, I have been bouncing off the limiter for years. I don't go insane on it, just a quick hit and shift. Usually because the trans is slow on the upshift.

TheDream

If you put the car in L, it will only go down to 2nd. It will only engage 1st when the car's speed drops below 11 mph. If you accelerate from zero with the selector in "L" it will keep the car in 1st until you push the selector into another gear. The only time I've used "L" is going down a circular parking structure ramp from the 6th floor so I won't have to ride the brake for those few minutes. FYI the car was rolling at about 10 mph...so it's not like the car was getting close to over-reving in that gear.

RamAirRckt

6 bolt mains. There is no such thing at 5. 2, 4 or 6.

http://www.lextreme.com/mainbolts.html

Take a look at the GM Gen III/IV V8 (6 bolt main), even my 3800 V6 has 4 bolt mains, but in similar fashion as the LS1 and Lexus/Toyota V8's. Just only 2 bolts into the main web and 2 bolts into the side. This makes for a nearly indestructable block and super stiff.

GS4_Fiend

iTrader: (22)

Exactly, downshifting regardless is bad. Let them do whatever they want, its their car.

fastryan

ok i will admit, that forcing a downshift is not healthy for the auto trans.. 6 bolt, yes even stronger. what kind of damage did you see to the planetary gears? are you talking differential planetaries?

RamAirRckt

Diffs don't have planetaries, just the trans. Diffs have hypoid gears.

http://www.zakgear.com/Hypoid_worm.html
This is a lot like what we have: http://www.enotes.com/topic/Spiral_bevel_gear

It is compound planetary gearset. The planets are in the sun shell, and the sun gear is in the middle. They are just cool....

http://www.familycar.com/transmission.htm

GS4_Fiend

iTrader: (22)

This website is astounding.