Why shouldn't I get on it in OD?
Teching In
Joined: Jan 2004
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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??
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
Originally Posted by 02WS6Bird
that totally makes no sense...
so your saying 3rd for them is D....and D for T/A's is Camaro OD??
so your saying 3rd for them is D....and D for T/A's is Camaro OD??
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?
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...
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...
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
Originally Posted by 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??
Last edited by RPM WS6; Mar 7, 2004 at 05:11 PM.
Joined: Nov 2001
Posts: 34,623
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From: Schiller Park, ILL Member: #317
Originally Posted by 02WS6Bird
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...
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...
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Brett Foote Teching In
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Originally Posted by RPM WS6
Any time you move the shifter between 3rd and 4th you will kick yourself out of lockup, and the change from a 1:1 ratio (3rd) to overdrive ratio (.60) will cause an additional rpm change (besides just falling out of lockup). Once you cruise steady for a while again, it'll lock back up in either gear.
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.
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.
TECH Fanatic
Joined: Oct 2003
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From: Grand Rapids, Michigan
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
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.
TECH Fanatic
Joined: Oct 2003
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From: Grand Rapids, Michigan
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
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!
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
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......
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......
Teching In
Joined: Jan 2005
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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!
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!
TECH Addict
Joined: Sep 2003
Posts: 2,065
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From: Atlanta, GA
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.
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.
hey 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
TECH Addict
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From: Atlanta, GA
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...
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...