RPM WS6

iTrader: (3)

I know, it gets confusing because the Camaro's and bird's are different. That's why I always put a "3rd" after I mention "D".

02WS6Bird

iTrader: (2)

that totally makes no sense...

so your saying 3rd for them is D....and D for T/A's is Camaro OD??

samz28

camaro = 1 2 D OD

D still equals 3rd, OD = 4th

call it what you want but you can count 1 2 3 4 regardless of letters.

i prefer to use the gear # since thats what my logging software uses

Backfire

If the tc will lockup in both 3 and OD, what is the small change in rpm when shifting between the two? For example, with the shifter in OD and driving at a speed where 3rd gear is being used, if you move the shifter to 3 with no change in throttle input, there is a small jump in rpm (maybe 400rpm). When shifting back to OD the rpms drop again. It is not a change in gear as the trans will shift to 4th once speeds increase. I was under the impression that this was the TC lockup function engaging and releasing??

RPM WS6

iTrader: (3)

Firebird/TA has:

D (which = OD, or "4th" which ever you want to call it)
3 (which = D, or "3rd")
2
1

From what I remember in my '99 Z28:

OD (which = "4th")
D (which = "3rd")
2
1

Both cars will hit TC lockup in "3rd" or "4th" (4th being overdrive). Lockup is when your rpms drop down pretty low right around 35-40mph when the shifter is in overdrive position or about 30-35mph when the shifter is in the "3rd" gear position ("D" for the Camaro).

During the course of driving up to say, 45mph, here is what will happen:

1-2-3-4-lockup or, if the shifter is in "3" (pontiac) or "D" (chevy) it will be 1-2-3-lockup.

Make sense?

02WS6Bird

iTrader: (2)

i kno OD is for better fuel economy...

when the car shifts through the gears in D...at around 1800 rpms...and then hits that last gear thats your OD from what i understand...

RPM WS6

iTrader: (3)

Any time you move the shifter between 3rd and 4th you will kick yourself out of lockup, and of course in addition to knocking yourself out of lockup, the change from a 1:1 ratio (3rd) to overdrive ratio (.60) will cause an additional rpm change (assuming you where at a speed where the trans had already shifted into overdrive). Once you cruise steady for a while again, it'll lock back up in either gear.

RPM WS6

iTrader: (3)

The very last thing ("gear" if you want to call it, though it's not actually a gear; it's the TCC [torque converter clutch]) that the trans will engage if you cruise up to say 45mph is going to be lockup, if you are in 3rd or 4th. OD (4th) is not lockup.....

02WS6Bird

iTrader: (2)

aight i got what your sayoin tho

Backfire

There isn't a gear change in the situation I am talking about. You would be travelling in 3rd gear with the tc locked up. As you said when the shifter is moved down to third, the TC will unlock. However, I have never felt the converter lock back up if I continue driving with the shifter in the 3rd position. Only when I return the shifter to the 4th position, even though the trans is still using gear 3, will the TC lockup. How long a time are you talking about? I would add to that by saying that I don't feel the converter unlock when more throttle is applied when driving with the shifter in the third position. The car feels more responsive as there is no delay for the 'unlocking'. I should try this again as my posts are based on an older car, 94, which may have used different programming than the later models.

Ragtop 99

iTrader: (7)

Backfire:
Yes, the converter locks up in 3rd. With a stock converter you may not notice it happening (what GM intended ), but with a 4400 stall you'll notice it when it engages.

I use 3rd in town unless my sustained speed will exceed 45 mph for some distance. The car is much more responsive.

AK's WS6

Backfire I know what you are saying and I think the jump in rpm is due to the gearing in the trans in 3rd vs 4th (od), I believe the verter is still locked. It seems the rpm is higher even if the trans is in 2nd and the shifter is in 3rd and I believe it's because of the gear ratio in the trans when it's in 3rd opposed to 4th

BoneSS

iTrader: (9)

Is it hard on the tranny traveling around at 55-75 in third, and the tranny self-braking the car? That is what I am bad at, not the 4th WOT gear change. I usually travel around town at 35-45 in Drive or 3rd, and then get on to the Interstate, get up to 65-75, let off the gas, and then shirt to 4th or OD.

AK's WS6

BoneSS your best bet would prolly be to leave it in OD all the time. Driving in 3rd at 35-45 is'nt all that bad but you will turn more rpm's, but I would say 45mph should be the max mph to leave it in 3rd, maybe someone with a similar stall to you can shed a little more light on this, but i'm pretty shure the will agree with most of this

BoneSS

iTrader: (9)

Thanks. I haven't been doing it very much in this car, I did it all the time in my 93Z. I thought it wasn't too great for the car, but I liked the way it pulled. I knew I needed to stop it. Thanks for the advice!

RPM WS6

iTrader: (3)

Again, I really think we're not going to see any evidence that having the shifter in 3rd (3 for pontiac, D for chevy) is any better for WOT opperation than in 4th (D for pontiac, OD for chevy).

I prefer to use OD for all opperation because it seems to keep my trans temps cooler. Also helps fuel mileage. I don't really see why 3rd would be better for a launch from a stop, nor do I see how it would be better to manually downshift to the 3rd gear range before going WOT from a roll.

Is this the general opinion? If someone disagrees, let's here why......

900DollarZ

All I know is, I've had my '95 Z28 for a couple months of driving pretty vigorously in OD and now my 4th gear slips pretty bad if I give it even a little bit of the throttle while cruising at any speed.

I should have know the 4L60E had a weak overdrive, like every other damn overdrive gear on damn near every other transmission. I guess I gave it one too many half throttle squirts at 65MPH. Hopefully, driving in D (3) around town and OD on the highway will hold until I come up with enough for a replacement.

My (new) opinion is that D (3 for Firebirds) is best at speeds below 50MPH if you EVER drive like a enthusiast. It seems to risky to be toodling along in OD and then suddenly need to get past a slow vehicle by punching the throttle while the transmission lingers in OD for a second at full power. Why not just stay in D (3) until you hit the highway?

If you drive like an old lady everywhere, no matter what the circumstances, then OD (D for Firebirds). You'll likely get better mileage for both being in OD AND being an old lady!

samz28

you sure its just not your torque converter lockup clutch slipping? with the ls1 vcm you can program the tranny to do whatever you want, so it's pretty safe to drop it like its hot from 4 if you are programmed correctly.

with a large cam/stall in city i find D/3 to produce better gas results because the car has more VE at the extra few hundred rpm than lugging the motor in od/4th. the o2 system gets kinda sketchy at 1100rpm locked up cruising at 42mph and mpg is less based on my heavy city driving.

things such as detonation or misfires can cause your car to unlock the 'verter giving the appearance of slip, might want to keep an eye on that if someone disabled or detuned such. When i first had my cam installed and p0300 was still enabled it would unlock at low rpm's all the time or never lock up. just needed a bit more road tuning to get it right.

might you datalog your car and see whats really going on. rule of thumb i go by is that a auto trans is good for 100-120K (depends on how its driven of course) then its time for a rebuild/new trans whatever. Seems like all the auto's i've had have pooped around 120K regardless of manufacturer.

Rock-On

iTrader: (-2)

Hey heres my thoughts...while in d (3rd) your coast clutch is applied, why would you want engine breaking when your trying to go fast??? Secondly from a launch prespective your better off launching in manual 1st (thus recieving the benifits of the lo/reverse clutch holding on the launch) then shifting to OD. Thus getting away from the coast clutch. Seems the t.c. locks in either D, or OD, why would one be better than the other?? Is there something in the programing I'm missing? Jus my two cents. Hope this helps ...Dave

samz28

you can lockup in 2,3,or 4th by programming, many people do not lockup in 3rd at all, some do. Stock who knows, thats too boring anyways. Not many people lockup in 2nd, since you spend so little time in that gear even streeting around.

key here is to have a good trans-tune so you have your shift points set to what you desire most and feel is safest. Some folks lockup under wot at 3rd to bring it home but have the ecu never shift into 4 for drag runs.

I dont really have any time to drag race so i tune the tranny for how i drive most, and if i need to go the strip, i can pop in another tune or two to try out.

The 3rd gear engine braking is nice with converter if you don't want to apply the brakes so often going down hill in the city, but one must wonder what you'd rather wear out a transmission component or brake pads. I can do brake pads myself...