Automatic OD issue
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Automatic OD issue
I've had lots of posts trying to get my car running as it should. I figured a couple of things out. I complained of lousy gas mileage, and the car drawing down, (seemingly losing speed when coasting too quick).
If I drive in OD, it coasts as I'd expect. And my gas mileage is better. Another thing that helped with mileage, not sticking my foot to the floor every time I take off. So, right now, mixed driving, I'm sitting about 17mpg.
Ok, here's my current problem. In OD, the car works pretty well, but at about 40mph if I lightly accelerate, it growls and seems it isn't responsive. If I let it coast down to under 35 and accelerate, no problem. If I'm doing about 50 and accelerate, no problem. If I'm doing about 40 and hit it harder, say 1/2 throttle, no problem.
Any ideas on what this could be?
If I drive in OD, it coasts as I'd expect. And my gas mileage is better. Another thing that helped with mileage, not sticking my foot to the floor every time I take off. So, right now, mixed driving, I'm sitting about 17mpg.
Ok, here's my current problem. In OD, the car works pretty well, but at about 40mph if I lightly accelerate, it growls and seems it isn't responsive. If I let it coast down to under 35 and accelerate, no problem. If I'm doing about 50 and accelerate, no problem. If I'm doing about 40 and hit it harder, say 1/2 throttle, no problem.
Any ideas on what this could be?
Melting Slicks
Joined: Jun 2005
Posts: 3,076
Likes: 83
From: Everyone needs something to believe in, I believe I'll have another beer. Wisconsin
Whens the last time you had the trans. fluid flushed and a new filter install?, might help, maby others will chime in with additional advice.
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
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From: Cuyahoga Falls Ohio
Race Director
Joined: Feb 2004
Posts: 12,518
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What you are feeling is the torque converter lockup. GM made them lock at approx 35 mph and they tend to bog. The cars with 2.59 gears chug the worst. You could do a 4th gear only lock up arrangement or reprogram the ecm to raise the lock up speeds to suit your preference.
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
What you are feeling is the torque converter lockup. GM made them lock at approx 35 mph and they tend to bog. The cars with 2.59 gears chug the worst. You could do a 4th gear only lock up arrangement or reprogram the ecm to raise the lock up speeds to suit your preference.
So this is normal? As long as it's normal I can live with it. In fact, it's a relief.
4th gear lock up arrangement? Can you explain?
Thanks.
Race Director
Joined: Feb 2004
Posts: 12,518
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It sounds normal. Gm did what they had to do to meet the mpg requirements of the time. On my own 87, I did a little rewiring in the trans pan. This allows the car to lock up as soon as it hts 4th gear. In my opinion, this is a smoother arrangement.
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
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Race Director
Joined: Feb 2004
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Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
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From: Cuyahoga Falls Ohio
Safety Car
Joined: Jul 2006
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From: MA
Dont they sell a kit they does that??
Some kind of switch?? I saw it for the 3Gen camaros
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
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From: Cuyahoga Falls Ohio
If you want to give me the details on that mod, I'll figure out a way to get it done. Also, if you know of any reading material, I wouldn't mind getting better educated on this. I am pretty much transmission illiterate.
Race Director
Joined: Feb 2004
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When you drop the pan on your 87 you will see a wiring harness. The black and red wires that run to the front of the pan go to the solenoid that is retained by 2 bolts.
Look closely at the red wire on the solenoid. It goes to terminal A on the plastic connector in the trans case. Leave this wire alone. You will also notice 2 pressure switches screwed into the valve body. 1 will have a single wire attached, one will have a 2 wires attached. You are only concerned with the single wire switch. Cut the wire that attaches to the single wire switch. cut the negative(black wire) on the solenoid.splice the pigtail that goes to the single wire pressure switch to the negative(black) side of the solenoid.
Viola, 4th gear only lock up. If the thought of hacking up a perfectly good harness bothers you, stop by your local trans shop and see if they have a used harness in the junk pile. You can molest it instead of the factory piece.
If locating one becomes difficult, check back with me. I may have one in the boxes of junk I have accumulated.
Although I prefer a 4th gear only lock up, some do not. If you chop up a spare harness and do not like it, you can put the factory harness back in.
Look closely at the red wire on the solenoid. It goes to terminal A on the plastic connector in the trans case. Leave this wire alone. You will also notice 2 pressure switches screwed into the valve body. 1 will have a single wire attached, one will have a 2 wires attached. You are only concerned with the single wire switch. Cut the wire that attaches to the single wire switch. cut the negative(black wire) on the solenoid.splice the pigtail that goes to the single wire pressure switch to the negative(black) side of the solenoid.
Viola, 4th gear only lock up. If the thought of hacking up a perfectly good harness bothers you, stop by your local trans shop and see if they have a used harness in the junk pile. You can molest it instead of the factory piece.
If locating one becomes difficult, check back with me. I may have one in the boxes of junk I have accumulated.
Although I prefer a 4th gear only lock up, some do not. If you chop up a spare harness and do not like it, you can put the factory harness back in.
Le Mans Master
Joined: Dec 2002
Posts: 6,715
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From: Santa Teresa New Mexico
This is what I do, (no rocket science involved) I don't use OD till 50+.
A constant cycling between 3rd and 4th is what takes its toll on the 3-4 clutch pack and band.
Going up da hill I down shift, going down the hill I down shift. City its Drive all the time.
Whenever a trans losses OD its usually cuz the of the wear from the trans cycling between drive and over-drive.
If the cars constantly cycling leave it in drive.
A constant cycling between 3rd and 4th is what takes its toll on the 3-4 clutch pack and band.
Going up da hill I down shift, going down the hill I down shift. City its Drive all the time.
Whenever a trans losses OD its usually cuz the of the wear from the trans cycling between drive and over-drive.
If the cars constantly cycling leave it in drive.
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
This is what I do, (no rocket science involved) I don't use OD till 50+.
A constant cycling between 3rd and 4th is what takes its toll on the 3-4 clutch pack and band.
Going up da hill I down shift, going down the hill I down shift. City its Drive all the time.
Whenever a trans losses OD its usually cuz the of the wear from the trans cycling between drive and over-drive.
If the cars constantly cycling leave it in drive.
A constant cycling between 3rd and 4th is what takes its toll on the 3-4 clutch pack and band.
Going up da hill I down shift, going down the hill I down shift. City its Drive all the time.
Whenever a trans losses OD its usually cuz the of the wear from the trans cycling between drive and over-drive.
If the cars constantly cycling leave it in drive.
Makes a big difference in gas mileage. When I leave the car in drive, it pulls down pretty fast compared to OD.
Melting Slicks
Joined: Dec 2000
Posts: 2,629
Likes: 7
From: Lawrenceville PA
This is what I do, (no rocket science involved) I don't use OD till 50+.
A constant cycling between 3rd and 4th is what takes its toll on the 3-4 clutch pack and band.
Going up da hill I down shift, going down the hill I down shift. City its Drive all the time.
Whenever a trans losses OD its usually cuz the of the wear from the trans cycling between drive and over-drive.
If the cars constantly cycling leave it in drive.
A constant cycling between 3rd and 4th is what takes its toll on the 3-4 clutch pack and band.
Going up da hill I down shift, going down the hill I down shift. City its Drive all the time.
Whenever a trans losses OD its usually cuz the of the wear from the trans cycling between drive and over-drive.
If the cars constantly cycling leave it in drive.
That's what I do with my 86. I don't know what effect it has on mileage but I don't really care. All I know is that it makes the ride much less annoying.
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio