josh99ta

iTrader: (1)

We all know to let the computer run through the gears on it's own when we're getting on it, but what about when you're rolling around on the street and want to get on it a little? For your transmission's sake, is it better to go WOT and let the trans downshift itself, or manually downshift while cruising or completely off the throttle all together, let the gear completely engage, nail it and immediately shift the selector to 3rd?

Scenario 1: You're cruising at 50mph with the selector in 3rd gear, you go WOT and the transmissions downshifts itself into 2nd gear and your pull starts.

Scenario 2: You're cruising at 50mph with the selector in 3rd gear, you pull the selector down into 2nd gear and allow the trans to downshift and fully engage 2nd gear under no or very light throttle application, you stab the gas and immediately shift the selector up to 3rd gear, the car continues it's pull through 2nd gear and shifts into 3rd on it's own just as it would have if you wouldn't have touched the selector.

Which puts less wear and tear on the transmission?

Scenario 1: You're cruising at 15mph with the selector in 3rd gear, you go WOT and the transmissions downshifts itself into 1st gear and your pull starts.

Scenario 2: You're cruising at 15mph with the selector in 3rd gear, you pull the selector down into 1nd gear and allow the trans to downshift and fully engage 1nd gear under no or very light throttle application, you stab the gas and immediately shift the selector up to 3rd gear, the car continues it's pull through 1nd gear and shifts into 2rd gear, pulls through 2nd and shifts into 3rd on it's own just as it would have if you wouldn't have touched the selector.

Which puts less wear and tear on the transmission?

======================================

Seems to me that when you have the selector in 3rd gear and you just stab the gas, how I've always done it and been told to do it, you have all that power hitting right during the downshift. That has to cause some extra wear and tear. Manually pulling the selector down into the gear so that it fully engages when not under a big WOT load, getting on it and immediately shifting the selector so that the computer can still handle the shift as normal seems like it would result in far less wear and tear.

My only concerns are what actually happens on the inside of the transmission (like what is engaged and what isn't and if something is different with the clutch packs that would make one or the other the better option). Also, pulling the selector into 2nd at say 50mph is pretty smooth, but I think I'd be VERY careful pulling the selector down into 1st gear at any speed that wasn't single digits just because it just feels like it's more rough on the trans.

So guys that build transmissions, lets get technical here. I'm not looking for the "do it this way because thats how it's always been done" answer, what is actually going on inside the transmission and which option is truly better for less wear and tear on the trans?

Trav's_TransAm

iTrader: (5)

Wondering the same thing myself. Good question.

ChocoTaco369

I've always been under the impression that manual upshifts are okay to do, but manual downshifts are not good to do. I manually upshift my transmission every now and again under medium to medium-high throttle and it doesn't worry me because my shifts are much more positive when the shifts are done manually.

However, I believe downshifting manually is a no-no. The rare times I do it, I drop my car from D to 3 at around 40 mph and I make sure to apply LIGHT throttle. I don't take my foot completely off the gas pedal. I'm under the impression that it's best to downshift under very light throttle. I'd NEVER drop it from D to 2, though. I'll never drop it more than 1 gear at once.

I can tell you that manually downshifting from 3rd gear cruising at 20 mph into first is a recipe for disaster. That is absolutely HORRIBLE to do. You should always let the trans downshift itself.

Gilbert@Ace Racing

To begin with, if your input drum is not reinforced with a sleeve you will find out why we sleeve them in short order if you drive your car like that often. Not being a smart ***, just telling it like it is. I have drum on my counter that a 285 H/P stock LT1 engine grenaded on a 3-1 hit with street tires.

The 4L60E is a very durable transmission when it is built properly by experienced professionals who have done their homework and who specialize in this unit. In stock trim, it is not so durable... especially in the heavier cars and trucks.

I personally would not manually force downshifts often unless I was prepared to be inside the unit to freshen it up or repair it a time or two per year. The transmission you have is not a race transmission. Even race transmissions fail, but they are expected to fail from time to time... or better yet it is not surprising when they do right?

So... again, like I preach all the time... it is about your expectations. If you expect it to break, drive it like you stole it! If you are afraid of it failing, are afraid of the associated costs to repair or maintain it... drive it with respect.

There is no holy grail of driving a 4L60E, there never will be. It is a medium duty transmission we take right past heavy duty service and right into severe duty service with todays power plants.

Good Luck! BTW... nice car man!


g

spy2520

iTrader: (3)

whats this about reinforced input drums and how do i go about getting one of those?

josh99ta

iTrader: (1)

Ratchthed, I don't know if you're missing the point or not.

Lets use my car for example...

'06 GTO, 4L65E

Anytime I'm even thinking about getting on it from any speed I move the selector into 3rd gear. I've heard of multiple people grenading their transmissions by just dropping the hammer with the selector in 4th gear (D in the GTOs, D or OD in F-Bodies) and I've heard that it applies another set of clutches so that 1st gear is be able to handle power and WOT computer-controlled downshifts when you romp on it from a roll.

So you're saying that if I'm rolling at 50mph and know I'm going to hit it, I should not continue to apply light cruising throttle and downshift from 4th-to-3rd, let it get fully into gear, then shift from 3rd-to-2nd again under light cruising throttle applications and let it fully engage in 2nd gear, THEN hit it? Instead you're saying that just stabbing the throttle from a 50 roll with the selector in 3rd or 4th gear and letting the transmission downshift itself? Thats the way I've always done it, but when I really stopped to think about it it seems like you're going to be going down into 2nd gear either one, just one way is under WOT power-on application, and the other way is a much more smooth application on getting down into 2nd gear by progressively pulling it down at a safe speed that would seem to be much easier on the internals since you're positively engaged in the gear before you get full throttle power application versus just stabbing the gas and letting the transmission downshift itself.

I'm not at all talking about yanking the selector from 4th down to 2nd while you're accelerating, I'm talking about slowly going from 4th to 3rd, 3rd to 2nd with very light throttle application (to keep the transition into the lower gear smoother and not jerky like a non-throttle downshift would have).

Just trying to clarify here and get a real, reason-based answer and the "why" behind it. Thinking about it logically it seems like if you're careful and go one gear at a time downshifting, and do so at safe speeds with probably 25-50 lbs ft or whatever it takes to keep the car cruising steady at speed, it'll have less wear and tear than going WOT and having 400 lbs ft of torque going through the trans as it executes the downshift itself.

I've always let the trans do everything, but the more I think about it the more it seems like its more logical to help it get into the right gear first before the hit.

spy2520

iTrader: (3)

as far as the extra clutches:
selector in 1, 2, or 3 = overrunn clutches engaged.
selector in 1 = lo/reverse clutch applied also i believe.

and i'm by no means an expert, i think depending on speed, its the act of downshifting that hurts, not whether or not you give it light or heavy throttle (although that wont help much). The reason i think this is because 1. going from coasting (in OD) to engine braking (in any lower gear) to WOT doesnt sound like its as easy on the trans as you might think. and 2. if you compare it to a manual trans, whether you give it gas or not there is still a shock transmitted through when downshifting.

if you drive 15mph and downshift to first it feels pretty harsh. why would it be any different driving 45-55 or whatever and downshifting to 2nd or 3rd?

just my guess. I dont really know **** though lol.

josh99ta

iTrader: (1)

Thanks spy, thats what I was thinking just couldn't remember the name. I knew the general end results of it, just couldn't remember overrun clutches.

So Ratchthed or any other trans builders or those knowledgeable in transmissions...

1. When you have the selector in 3rd gear so that the overrun clutches are applied, you're cruising at speed, and you got WOT with the car downshifts into 2nd gear, what exactly happens inside the transmission? What kind of wear and tear does it cause?

2. When you're cruising at speed with the selector in 3rd gear, and under light throttle you pull the selector down into 2nd gear and continue cruising at speed, what happens inside the transmission and what kind of wear and tear does it cause? If you're already in 2nd gear with the selector, whether by having it there from a stop or whether you pulled it down into 2nd gear, when you go WOT with it locked in 2nd gear does anything different happen or are any different things engaged or disengaged in the transmission versus going WOT at 80mph with the transmission selector in 3rd where the car doesn't downshift?

Gilbert@Ace Racing

There really is no holy grail of downshifting an automatic transmission. But I think you're on the right track to helping keep the unit in one piece but also enjoy spirited driving.


Not much happens mechanically... the 3/4 clutches release and the servo applies the 2/4 band.

It is the same downshift, one is being commanded mechanically with the manual valve, the other is based on electronic inputs. There is virtually no distinction between the two.

Basically, because your question pertains to the durability of the rotating assy and not the control side of the unit, we need to focus on the rotating assy.

Here are some photos that might help to illustrate some typical wear patterns and failures. Sometimes no matter what you do you cannot prevent the failure of a component or assembly. Some of the photos apply directly to this discussion. Others may seem to not apply, but they do. And the reason why is when it comes to getting your transmission upgraded you have to do your homework, don't make your decision based on popular belief or who has the best price on the market. Many, many shops build these units very well... others only say they do.

Excessively worn 3/4 clutches. This is a prime example of why an automatic transmission needs to be freshened up periodically. Notice how the friction material is in nearly pristine condition, but the lugs or teeth are worn significantly. Nearly 30% of the teeth are simply gone, worn away from many, many high rpm hits.



Next we see the drum I mentioned earlier in this thread. This Input Drum came out of an LT1 4L60E. The only 2 mods this car had were a cam and long tubes. The drum failed on a 3-1 downshift on the street with street tires... non stickies. The unit had around 60k miles if I remember correctly.



About the only way to defend against the hub stripping out is to have the drum sleeved. Here are some photos of the sleeve itself and of a drum this is fitted with one.






This is an Input Drum that came out of one of our direct competitors units that was running excessive Line Pressure. Notice how each and every lug is blown out of this drum! This is a study in how not to set one of these units up!


And here is another example of a part that failed at WOT. A Forward Piston that is cracked. This unit too was set up with excessive Line Pressure, it also had blocked Accumulators.


These are only illustrations of potential failures and weaknesses associated with these transmissions. All I can tell you is that if you are aware of these and treat your unit accordingly, then you'll be fine.

But, I will also tell you again that it is all about your expectations. Expect to have transmission issues if you drive your car to it's max potential often. If you don't, you'll be dissapointed when problems come up. But, when the unit does ask for attention think of that as an opportunity! An opportunity to take your car to the next level of performance!

Hope that helps to clear up some questions.

g

josh99ta

iTrader: (1)

Oh I definitely don't think my transmission is going to hold up forever. It's the nature of the weak stock autos. I am concerned with making it last as long as I can though, and like I said it seems to me the transmission would see less shock and therefore have less wear and tear on a careful executed manual downshift, rather than going WOT and letting the transmission control the downshift itself with all that power being transmitted through the drivetrain. Manual downshifting it with care would result in extended trans life over just mash-and-go, correct?

Great post Rachthed, hopefully you can verify what I'm thinking here as I'm not seeing a clear yes or no. Good info thus far though.

spy2520

iTrader: (3)

thats almost what mine looks like, its all cracked up but all the teeth that engage the input shaft are still intact

ls2pontiac

iTrader: (1)

this is why i hate this ****. i hate my automatic in my GTO. just driving it lightly it feels like it could just break like a twig at any second.

Gilbert@Ace Racing

Have you ever see all of the teeth sheered off of 2nd gear itself and on the cluster shaft in a T-56. I have. Ever seen an Intermediate shaft break in a TH400. I have. How's about a Converter that had some brazed fins come loose and take out the entire tray? I have seen that too. What are you afraid of?

If you are afraid of your car breaking, get a Yugo or a VW and hang out in the right lane.

What in particular do you "hate" about the transmission in your car? Never heard that one before.

g

PBA

In the 700R4 the overruns are on in all three "D", "2", "1" positions. In the 4L60E the overrun is on in the "1" position, but not in the "2", or "D" position until it is in "that" gear. In otherwords, if you have it in "D" position, the overruns do not come on till you have 3rd gear, same goes for 2nd gear. When downshifting an automatic, you need to match the input rpms with the gear you are manually selecting. It is like "double clutching" a manual transmission without syncros, or when you are riding a motorcycle and you downshift you "match" the input to output rpms, then you let off of the throttle to get the vehicle to decelerate. This takes about .2 - .25 seconds. If you do this way it will not hurt the transmission.

ls2pontiac

iTrader: (1)

i think it would be better if you just didnt downshift it at all. lol. I manually hold it in 1st sometimes then shift to 2nd, then let off the gas and shift to drive, give it a second then hit the gas again.

I just dont like autos anymore. Whenever they shift it just feels so light. It feels like something could break..just not a good feeling. I havent driven my car in months just because i hate it. Paying 515 a month just to let it sit there. I also havent even vacuumed the car in over a year or dusted it. Just lost all interest in it...lol. Cant wait til the lease is up. I'm going to do several huge burnouts before i trade it in though. Thats about all an automatic is good for is burnouts and easy donuts. And they are easier on rears. Thats about it.

RevGTO

iTrader: (12)

Man, I understand where you're coming from, but there is a fix. Years ago, I posted a thread in this forum "I hate my A4." I was really frustrated with it. The way it is tuned from the factory is just lame.

Tune it to raise the part-throttle up and downshift points, raise the lock-up speed, cut shift times in half, reduce or disable torque management, and install a Transgo shift kit, and you'll have a whole new animal. You won't complain about it feeling "light" ever again.

cals400ex

iTrader: (27)

what will cutting the shift times do?

RevGTO

iTrader: (12)

Make the shifts much more crisp. Think loooong shifts versus quick ones.

josh99ta

iTrader: (1)

After being in a properly tuned auto car for so long I had forgotten what a factory tuned one felt like. I got my GTO and immediately hated the transmission and the way it was controlled. With factory tuning they shift slow, sloppy, upshift way to fast, and all in all just feel like junk. Get some tuning as was suggested and it'll help tremendously. It'll still never be a 6-speed car, and I still often wish my car was a 6-speed, but it's my daily driver and there are plenty of times where the auto comes in handy.

Waiting on an answer to this one...

josh99ta

iTrader: (1)

TTT for a definitive answer to that last question...