JBGRAYTA

Just wondering how much damage this can do to a transmission. I know at WOT, its just not a good thing to do. However, if I'm just cruising at around 35-40ish(setting up to do a roll race), downshift it to 2nd, lanching it, then manually shift it up to D when it hits my shift point(mines set around 6700), is it any more or less damaging? I did this last night after losing several races to M5s, from a 40 roll. I was just mashing the pedal at 40mph, while my car was at 1.5k rpms. They'd kill me from that speed, though up top I began to reel them in a bit, but we shut down before going that fast. My buddy told me to roll it from 2nd(it shot my rpms up to around 4.5k rpms), I mashed the pedal, and it felt WAY better. I was just always worried about damaging things when I do this, though I did it several times and everything runs fine. I don't plan on doing this often though.

I have a 232/240 cam, 3500 stall, 3.73s

josh99ta

iTrader: (1)

I see these questions all the time. Just drive the car. If you want to hammer on it on a 4-2 downshift, do it. The tranny is going to go one way or another, might as well drive the car and enjoy it. My stock tranny lasted 80K miles with me hammering on it, multiple 4-3, 4-2, and 4-1 downshifts. The new one is going fine after 35K miles with the same abuse.

blkZ28spt

It's just harder on the transmisson. Best way to make it last as long as possible is to avoid WOT downshifts into second gear (I think WOT into first gear isn't nearly as bad...anyone want to verify???), keep the tranny cool (don't let it get above ~230* at all), don't get on it if the temp is above ~210*, and don't go WOT into overdrive (shouldn't be going that fast anyway, ).

I did WOT 4-2 downshifts on my stock trans all the time. Didn't know it was bad. Replaced with a built trans at 58k miles. This was only two years after exhaust work, one year after converter and a few thousand miles after the cam.

jxaxsxoxn

iTrader: (2)

Just drive it.
I'd like to know who started this rumor that downshifting hurts the trans.
Now everyone on this board is in a panic about it.
Don't post an arguement with me about this unless you have solid proof. This doesn't include what your trans builder told you, what your friends trans did etc.
If you want to argue the point provide solid facts like what part fails and show us a few pictures of this part, or should I say these parts because if you can say downshifting causes the xxxxx to break then you must have seen several of them broken.

blkZ28spt

The 3-4 clutch pack fails.....

jxaxsxoxn

iTrader: (2)

3-4 clutch fails for a variety of reasons. The most common I've seen is from too much clearance and slow upshift under power.

The clearance needs to be corrected, some stiffer 3-4 return springs added (you know the bag of springs that never gets installed that comes with the transgo kit. No one installs them because the trans needs to come out and apart).
And the third release hole (IIRC) needs to be enlarged.

I've never had the problem, but I do build all my transmissions from cores so the internal work gets done along with everything else.

But there are many, many other reasons for 3-4 failure otherthan this, add them all up and you can imagine the attention you need to pay to the 3-4 clutch. feed ciruits and release circuits, etc.
I don't think a modified engine with a stall belongs in front of a trans that has no internal modifications. And by internal I don't mean inside the pan, I mean behind the pump.
Line pressure is also important.
I've been having good results with upshift and downshift pressure modifiers with hptuners. No one on their site seems to be messing with those settings.
I've modified my settings and seen results on an actual trans pressure gauge driving the car in the real world, not on a trans dyno.

josh99ta

iTrader: (1)

The point is, if you dont want stuff tearing up, drive the car like grandma. If you want to drive the car and wring it out, things are going to tear up. The tranny might be the first thing that goes, but my car had almost 50K of HARD and ABUSIVE driving on a daily basis and it was fine, plus about 50 passes at the drag strip over that course of time. Running to redline causes wear on everything, so unless you're Driving Miss Daisy just drive the car and enjoy it, and keep some money on the side for when the trans finally does let go.

waveoff

iTrader: (11)

My tranny died today doing a 4-2 downshift on the highway. It was on it's last legs anyway. And to top it all off I just found out my wife is pregnant with #2. How'd that happen? Just kidding...it's all good. But yeah, I can speak from my very limited (couple weeks) experience with 4L60-E's that a 4-2 downshift can be bad. Especially when you are showing signs of a failing 3-4 clutch pack.

James B.

iTrader: (1)

A 4-2 downshift is easier on a 4L60-E than a 3-2 downshift. The 4-2 is just a single clutch-pack release event. A 3-2 is a clutch pack release AND a band engage. The 2-1 downshift is the easiest downshift for a 4L60-E, just a band-release. A 4-3 downshift is a band-release too but it's done while the 3-4 clutchpack is holding. The 4L60-E's line pressure does not raise instantly enough in response to rapid increases in throttle position. That lapse between full WOT power and when line pressure gets to where it should be can result in a litle bit of slippage in the 3-4 clutch if it is holding during a downshift. For this reason, if you're making a lot of power in front of a 4L60-E and have torque management tuned out of the PCM, a 4-3 downshift going from coast to WOT very quickly came create excessive heat in the 3-4 clutch pack. It can be partially corrected for in transmission tuning.

blkZ28spt

Great info. I still wonder about one situation, the one I find funnest: 3-1. I find myself in third gear from about 20 mph and I love going from a 25-30 mph roll. Does it matter if the shifter is in D or OD, and how well does the tranny take the 3-1??

James B.

iTrader: (1)

In OD the overrun clutches are not engaged. The sprag will allow input shaft speed to drop below tailshaft speed for the given gear. In "D" the overrun clutch is engaged and engine braking can occur. (Engine braking is not recommended with a 4L60-E because the overrun clutch has a very small total surface area.) In "D" (third) the overrun clutches assist the sprag in transfering torque. So, to answer the question, "Can a 4L60-E handle more torque in D or 3 than it can in OD?" The answer is yes, asuming no hard parts shatter.

During a 3-1 downshift the 3-4 clutch lets go. That is a single event, the band does not have to change its status. That downshift can be hard on the sprag because it will be snapped into holding when engine RPM comes up to the right speed. It can also be hard on the forward clutch pack that has to take the jolt as well. There's just a lot of aluminum torque-transferring parts in a 4L60-E. It's not a very rubust design, but still superior to anything Ford or Dodge has in this class!

blue2000Z28

So...Then what is the best way to go from a roll. In D or OD?? I was always told when you launch put it in 1 and once you step on it switch to D. On the highway, go to d also so you dont blow out your OD>???????