jimmyblue

iTrader: (11)

The 3-4 shift has no torque management in the
factory settings. Putting even more of a hurt on
the weak link. Shifting at less than full power
(especially for folks who are letting shift extension
hold their RPM up, meaning torque multiplication
is happening and higher-stall converters tend to
have high STRs) is going to let it survive longer.

I -added- TM to my 3-4 shift.

CONVERTED

iTrader: (1)

I blew my A4 up on an upshift from 2-3... pwn....


Something just feels wrong with this... i'm calling a GM Tech hold please....

obZidian

iTrader: (2)

hey, jimmy, i deleted all of my tm. So your saying it would be wise to add a little bit tm to the 3-4 shift? Is there a way to have tm only during wot?

CONVERTED: What exactly happened to your trans? did you loose all gears or just 3rd and fourth?

CONVERTED

iTrader: (1)

why even add a 4th gear if you can't shift to it without harming it?

CONVERTED

iTrader: (1)

lost all gears.... well i didn't loose them loose them... If i ran it up to 3k I could roll forward... I have all new clutches and bulliet this bullet that hardparts so I'm good for a while... new servo, shiftkit.... ya know the works... $1638... decent deal... with a slightly higher stall.

blkZ28spt

Highway. That is what OVERdrive is used for. I for one don't want to cruise down the interstate turning 2,500-3,000 rpm.

That's like asking why add sixth gear to the T-56 when you'll never get above fifth without hugely steep gears and very high speeds and even if you made it to it....you would possibly go slower b/c it's so high. It's all about cruising at higher speeds.

GS_Geoff

Unless you're making a case for buying a th350/400...

It's the same reason GM put CAGS on the manual trannies. Gas mileage. They have requirements to meet for their overall lineup gas mileage. That's one reason Ford has been behind in horsepower (and displacement) in recent years with the Mustang. They sell a LOT of V8 mustangs, and they need to be able to keep their corporate fuel mileage up.

Guys with GTP's 4t65e-hd (what I'm currently driving - looking for an ls1 to add to my collection though) always lose 3-4 if anything other than a diff. Sounds like the same problem with the 4l60e, there just isn't enough room in the tranny for bigger clutches/friction. So it will always be a weak link.

obZidian

iTrader: (2)

so, let recap.... This seems like a discussion that people have there own opinions, which is fine, but a few things i feel should be touched up for all to know the consequences of their own actions.

All the info below is of my own reasoning and im not a professional trans builder, but im just curious about how these things work...

Our 4l'z have a distinct way of treating gearing and up/downshifts. The problem seems to be under WOT downshifts vs manual downshifts. On the upshifts, i think the only real issue relevant or that has been brought up is the upshift from 3-4 @WOT....

Here's a scenario, when cruising in 4th @ 65mph, you kickdown into WOT and you'll hit 2nd. The trans is designed for this and this is why the clutch is a 2-4 band. (i think the 3-4 cutch stays engaged but could anyone please chim in and help on this) The band will engage with enough line pressure at it is specified in oue trnas tables and when at the upshift to 3rd, release the band again with the according amount of pressure. Ok? Now, lets say you drop it only 50% tps, than you will hit 3rd gear and you will stay in the 3-4 pack an minimize shift speed, trans wear and maximize acceleration and holding power because the trans didnt have to change into another clutch assembly.

So, so far it would seem that leaving it in OD is the best solution (IMO). If you went ahead and manually shifted the trans into 2nd, the trans is going to register the 4-3 AND the 3-2; so increasing wear due to the extra movements it has to do to obtain what you have commanded it to do. (I see this as the one of the problems, if it is even this way....the computer should be able to distinguish or "see" what your trying to do and bypass the 4-3 and go straight to the 4-2.) Also, this could cause more damage if the line pressure isnt adjusted accordingly, therefore starving the trans of oil when it needs the most. In other words, metal on metal wear....there goes your "weak" 3-4 pack!!

Ok, lets say instead of keepin it in 4th @65mph, you dropped it to 3rd or 'D'? When you kickdown WOT into 2nd, the trans will engage the 2-4 while maintaining the 3-4 pack engaged. (this is of course if my theory of the pack staying engaged holds water.) Then when going into 3rd, it will just release the 2-4 band and stay with the 3-4 pack. SImple, the right amount of line pressure was there to treat the action. (of course, this is all held liable if your tables are "off")

Again, if you had it in third than manually shifted into 2nd, you would only have one movement yet, and this is my concern, since the line pressure isnt up high enough to compensate for the extra work needed, therefore causing damage, is this shift as deadly to the 4l as the 4-2 manual downshift?

Therefore, it seems that the trans is well designed to maintain holding power, and adequate line pressure, when you kickdown instead of manually shifting. Though im still unsure on a few things, for example, when does the computer compensate for necesary line pressure. Or in other words, will the trans have more or enough line pressure when manually selecting your gear or is this dictated only by your tps vs rpm tables or other applicable talbes? Anyone with this info please help me on this because besically this is the focal point of my discussion.

The "real" issue is when we see races on the highways, it is customary to downshift to the appropriate gear and go from there. ALso, it is "cool", or excting to hear your motor rev up like that before the race. This is all with a manual trans. Since we have the auto, we dont have that luxury/excitment/cool feeling/ whatever you might call it....you know what im talking about. We just have to slam on it and go. Though very minimal, the only problem when roll racing is the delay we have when downshifting when the other person has already taken off. This can be avoided by timing your WOT kickdown exactly on the third honk.

Ok, lets move on.....

So racing from a "high" roll (65mph), it all seems ok to just leave it in OD. You could drop it down to 3rd ('D') but you shouldn't go down to second manually because of my low line pressure theory.

Lets say if you were going under 65mph,for example 25mph or 30mph. You would be in 3rd gear and at a WOT kickdown, you would hit 1st. Now, this is were i get fuzzy because im unsure what exactly goes on or what clutch activates the 1st gear. But if you went ahead and dropped it down from OD to 1st, if your tune would allow this, you would go through a series of similiar movements to the 4-2 and cause possibly the similar yet specifc amounts of damage.

I hope im not boring ya'll but i wanted to get this out inorder to jump start a possible thread that would surface the truth behind the 4l'z.

From my understanding, the reason we even have the ability to select a lower gear is when we have to tow, or driving down a winding mountain road, for example, so you can have better control of you ride. In these situations, you wouldnt slam on the gas soon after selecting the gear. In other words, the trans wasnt designed to be raced out if these gears so the line pressure tables, materials and internal designs werent adjusted to adequately handle these specific types of situations. (roll racing)

To sum it all up..

Again, i would like to say that im not a professional. But i feel that there are two issues that draw my attention.

1) Line pressure...it would seem that when manually shifting, there isnt enough to compensate for the WOT that occurs soon after therefore causing more wear on the trans. (This is info that i have deducted without any really extensive research and anyone with opposing, liable info is more than welcome to correct me. )

2) Design: First, the initial design and preordained application for selecting lower gears in our 4l'z was in situations where you needed to tow a trailer, etc. Our trans software, and ultimately, the design of the trans (clutch locating vs gear location vs pump...etc) wasnt designed like a ferrari sequential trans. Basically that is a manual with electronic controls that specify clutch activation vs pressure, vs gear....etc. Also, the internals were designed to take the beating because that is what ther are selling. For example, when you paddle shift a ferrari enzo from 6th to 4th, the computer has already been programed for this and the appropriate parameters are set to achieve a fluid transition. Our 4l'z were not designed this way, therefore it is less efficient in the in simulating a similar shift scenario thus causing more premature wear.

Another thing on design, Our cars when equipped with an auto are natural drag monsters!!! I mean this. Add a stall, a lid, exhaust, leave your stock gears, get a good set of tires and blam...you have ALMOST single handly dropped close to a second of your stock quarter mile times. Add a cam, get close to 400rwhp or above, and you can expect to shave two or possibly three secs... 11'z or even 10'z have been seen with not al whole lot invested. This is what the auto fbody is about....and we should be proud.

But most of use dont live at the drag track and some (me included) would prefer other forms of racing. We just have to take all things into consideration, and act accordingly. IMO, from now on, and trust me i am and will be tempted to, would just keep the shifter in OD or 'D' (T/A= D or 3) and go from there. I would rather have both hands on the wheel when going 110mph+ or one on the wheel while the other is waiving my opponent goodbye!!!!!!

dorry for the thesis, maybe it could we jump start a discussion that would help us all completely understand of partially the 4l.

Or maybe it wont and it will just fade away untouched into the ls1tech database to be only resurfaced by the search function. I feel that we do this to much and hold back.... the issue should be addressed completely, initially, stickied, thus leaving the remainding available space for the next issue... Just some observations.

Angel

CRAZYCUBAN29

Ive rebuilt a few of these 4l60e's & they seem to burn up for bunch of diffrent reasons. Pickups , vans , cars , race cars. But the F-bodys & Vetts give the most trouble. I guess its the different programming in the software. About the wot 3-4 shift, Its allright till you start working on the motor.After that you have start changing stuff around.

cablebandit

iTrader: (37)

vacuum mod gets rid of the line pressure apply problems...you mat it and you have full line pressure. most important thing is to get the pressure to rise quickly when you need it to....2-3 shift is a killer!!!

RevGTO

iTrader: (12)

No, dude, this is where your theory is not holding water. Read my two previous posts. The 4-2 downshift disengages the 3-4 clutch pack - it is called the 3-4 clutch pack because it is engaged in third and fourth - the 2-4 band stays engaged. When upshifting from second to third, the band releases and the 3-4 clutch pack engages. Again, think of the 4l60e as a two speed with overdrive; engagement of the 2-4 band overdrives first and third.

buffman

iTrader: (9)

on the one a local yuppie rebuilt me, before I knew one a few select people can build 4l60-es, that thing only lasted 12k and not even a year. One of the things I did to it was the forward sprag completely turned itself inside out and it didnt' even break. Then again the rebuilder who looked at this "hi po" trans found old parts from a 700-r4 and lotsa poor worksmanship.

Matt

obZidian

iTrader: (2)

you see, that is what i though but i wasnt sure. BAsically, my point was more along the lines that line pressure, or a lack of necesary line pressure, with a combination of other elements, is the true killer of these trans. And that the trans shouldnt really be shifted down manually because of it wasnt designed to be manually shifted. Thanks RevGTO.....

Now, i keep herein about a vacuum modolation (spell check!) mod to the trans. Cablebandit: how those this affect line pressure?

chrisryn64

iTrader: (2)

I'm still confused

I was driving down a road today, going maybe 30-40mph, sorta eased on the gas for maybe a second, then put it to the floor.

Looked at the tach and the rpms jumped to about redline, car sorta went sideways a bit, tires squeeked and the car took off like a rocket, great fun

Now was this a 3-1 downshift or a 4-2?

I'm mainly just confused as to if it's alright to be crusing along the road at the speed limit, then go WOT?

Please explain this to a new owner, thanks.

blkZ28spt

That was probably either 4-3 then 3-2 or 4-2 all at once, depending on the specific sitational circumstances.

I don't worry too much about downshifts that land in second gear but do try to limit them more than I use to. I do 3-1 all the time though. (that would be speeds up to 25-30 mph when stock)

chrisryn64

iTrader: (2)

would 3-1 be better than a 3-2?

there's just so many varying opinions in this thread, i don't know which to follow lol

oh, also when I know I'm going to be punching it, should I put it in D(3) instead of OD?

jxaxsxoxn

iTrader: (2)

Its a car not the space shuttle. Don't know who's opinion to follow, make your own.

obZidian

iTrader: (2)

i think the general theroy is that it is better to just leave it in OD or D(3) and not manually shift the trans down to the available gear selection. I know its hard but i try REALLY hard to forget about them and drive.

Now, between either D(3) or OD, that is up to you. For example, i have tuned my trans to never lock the stall in third gear, which allows the converter to flash quick without having to first unlock and then go. Also, its a reminder since D(3) will stay in third gear, i wont accidently forget shifting wot into 4th. Now, this is where in still neutral on and im gonna see if adding torque management to the 3-4 shift will aid in the life of my 3-4 pack.

CrabhartLS1

Hmm it's almost like GM wants people to destroy the tranny lol. I got the car as my first F-bod, so i had no idea how the tranny was supposed to work.

It was in OD all the time, then i thought it would be a good idea to manually shift it, then i put it in D for sprints but left it in OD for normal driving. In the words of Joe Namath, "Struh-guh-ling".

I'll try driving around in D for a while, but OD kicks in at like 45mph. How is that not wasting gas if i leave it in D?

buffman

iTrader: (9)

I occasionally manually shift the car. heck I had to the other night at the track, because of some PCM tuning that I'm working on, that for some reason w/ the OBD-1 high stall fix the car is short shifting into 2nd even from a dead hook at the track. I do know for a fact on the street, from a dig to WOT the tires go spin spin spin to redline

Matt