C4 General Discussion General C4 Corvette Discussion not covered in Tech

Automatic OD issue

Thread Tools
 
Search this Thread
 
Old May 13, 2007 | 09:39 PM
  #1  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default 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?
Reply
Old May 13, 2007 | 09:55 PM
  #2  
The Green Hornet's Avatar
The Green Hornet
Melting Slicks
Veteran: Army
20 Year Member
Liked
Community Favorite
 
Joined: Jun 2005
Posts: 3,069
Likes: 83
From: Everyone needs something to believe in, I believe I'll have another beer. Wisconsin
Default

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.
Reply
Old May 13, 2007 | 10:01 PM
  #3  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by The Green Hornet
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.
Bought the car in Feb/07. Did the fluids in March/07.
Reply
Old May 13, 2007 | 10:02 PM
  #4  
Pete K's Avatar
Pete K
Race Director
20 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Feb 2004
Posts: 12,517
Likes: 19
Default

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.
Reply
Old May 13, 2007 | 10:11 PM
  #5  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by Pete K
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.
My car has 3.07 gears.
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.
Reply
Old May 13, 2007 | 10:14 PM
  #6  
Pete K's Avatar
Pete K
Race Director
20 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Feb 2004
Posts: 12,517
Likes: 19
Default

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.
Reply
Old May 13, 2007 | 10:15 PM
  #7  
bogus's Avatar
bogus
Team Owner
25 Year Member
Conversation Starter
All Eyes On Me
Liked
 
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Default

meaning that the torque converter only locks in 4th gear.
Reply
Old May 13, 2007 | 10:15 PM
  #8  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by Pete K
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.
How difficult/expensive of a job is that? Want to do it for me?
Reply
Corvette Stories

The Best of Corvette for Corvette Enthusiasts

story-0

Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

 Joe Kucinski
story-1

Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

 Verdad Gallardo
story-2

Top 10 Corvettes Coming to Mecum Indy 2026!

 Brett Foote
story-3

Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

 Michael S. Palmer
story-4

10 Revolutionary 'Corvette Firsts' Most People Don't Know

 Joe Kucinski
story-5

5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

 Michael S. Palmer
story-6

2027 Corvette vs The World: Every C8 vs Its Closest Competitor

 Joe Kucinski
story-7

10 Most Common Corvette Problems of the Last 20 Years!

 Joe Kucinski
story-8

5 MOST and 5 LEAST Popular Corvette Model Years in History!

 Joe Kucinski
story-9

2027 Corvette Buyer's Guide: Everything You Need to Know!

 Joe Kucinski
Old May 13, 2007 | 10:17 PM
  #9  
Pete K's Avatar
Pete K
Race Director
20 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Feb 2004
Posts: 12,517
Likes: 19
Default

Originally Posted by DaleD
How difficult/expensive of a job is that? Want to do it for me?
Drop it off on wednesday, and I will hook you up
If it is easier, I could walk you through the process. A couple of butt connectors and an hour of your time will get it done. 2 beer job
Reply
Old May 13, 2007 | 10:20 PM
  #10  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by Pete K
Drop it off on wednesday, and I will hook you up
If it is easier, I could walk you through the process. A couple of butt connectors and an hour of your time will get it done. 2 beer job
I'm not real comfortable digging into the trans pan. Not to mention, I have no lift. You're in PA, I'm in Ohio, I think you're like 400 miles away. I could make a cruise out of it.
Reply
Old May 13, 2007 | 11:44 PM
  #11  
Repzard's Avatar
Repzard
Safety Car
 
Joined: Jul 2006
Posts: 3,696
Likes: 1
From: MA
Default

Originally Posted by Pete K
Drop it off on wednesday, and I will hook you up
If it is easier, I could walk you through the process. A couple of butt connectors and an hour of your time will get it done. 2 beer job

Dont they sell a kit they does that??
Some kind of switch?? I saw it for the 3Gen camaros
Reply
Old May 14, 2007 | 09:54 AM
  #12  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by Pete K
Drop it off on wednesday, and I will hook you up
If it is easier, I could walk you through the process. A couple of butt connectors and an hour of your time will get it done. 2 beer job
Hey Pete,
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.
Reply
Old May 14, 2007 | 10:14 AM
  #13  
Pete K's Avatar
Pete K
Race Director
20 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Feb 2004
Posts: 12,517
Likes: 19
Default

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.
Reply
Old May 14, 2007 | 10:56 AM
  #14  
redwing76's Avatar
redwing76
Le Mans Master
 
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
Default

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.
Reply
Old May 14, 2007 | 11:31 AM
  #15  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by redwing76
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.

Makes a big difference in gas mileage. When I leave the car in drive, it pulls down pretty fast compared to OD.
Reply
Old May 14, 2007 | 11:39 AM
  #16  
03whitecoupe's Avatar
03whitecoupe
Melting Slicks
25 Year Member
Conversation Starter
All Eyes On Me
 
Joined: Dec 2000
Posts: 2,629
Likes: 7
From: Lawrenceville PA
Default

Originally Posted by redwing76
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.
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.
Reply
Old May 14, 2007 | 01:07 PM
  #17  
Wheelman's Avatar
Wheelman
Le Mans Master
20 Year Member
 
Joined: Jun 2001
Posts: 6,694
Likes: 3
From: Less Talk, More WOT | Houston TX
Default

I just got the lockup changed to about 45mph in my chip. Much better driving it around town now.
Reply
Old May 14, 2007 | 01:42 PM
  #18  
DaleD's Avatar
DaleD
Thread Starter
Drifting
 
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Default

Originally Posted by Wheelman
I just got the lockup changed to about 45mph in my chip. Much better driving it around town now.
How complicated is that? Did you do it yourself or have it done? If you had it done, what did it cost?

If you can do it on odd increments, I think 48 would be ideal.
Reply

Get notified of new replies

To Automatic OD issue





All times are GMT -4. The time now is 09:04 AM.

story-0
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)

Slideshow: Ranking the top 10 Corvette engines by torque output.

By Joe Kucinski | 2026-05-05 11:58:09


VIEW MORE
story-1
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!

Slideshow: A Corvette pace car nearly matching IndyCar speeds sounds exaggerated, until you look at the numbers.

By Verdad Gallardo | 2026-05-04 20:03:36


VIEW MORE
story-2
Top 10 Corvettes Coming to Mecum Indy 2026!

Among a rather large group of them.

By Brett Foote | 2026-05-04 13:56:44


VIEW MORE
story-3
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!

Slideshow: the top 10 things Corvette owners want in the C9 Corvette

By Michael S. Palmer | 2026-04-30 12:41:15


VIEW MORE
story-4
10 Revolutionary 'Corvette Firsts' Most People Don't Know

Slideshow: 10 Important Corvette 'firsts' that every fan should know.

By Joe Kucinski | 2026-04-29 17:02:16


VIEW MORE
story-5
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2

Slideshow: Should you buy a 2020-2026 Corvette or wait for 2027?

By Michael S. Palmer | 2026-04-22 10:08:58


VIEW MORE
story-6
2027 Corvette vs The World: Every C8 vs Its Closest Competitor

Slideshow: 2027 Corvette lineup vs the world.

By Joe Kucinski | 2026-04-24 16:12:42


VIEW MORE
story-7
10 Most Common Corvette Problems of the Last 20 Years!

Slideshow: 10 major Corvette problems from the last 20 years.

By Joe Kucinski | 2026-04-14 16:37:05


VIEW MORE
story-8
5 MOST and 5 LEAST Popular Corvette Model Years in History!

Slideshow: 5 most and least popular Corvette model years.

By Joe Kucinski | 2026-04-08 13:25:01


VIEW MORE
story-9
2027 Corvette Buyer's Guide: Everything You Need to Know!

Slideshow: 2027 Corvette buyer's guide

By Joe Kucinski | 2026-04-17 16:41:08


VIEW MORE