1986 700r4 issue?
Thread Starter
Racer
Joined: Jun 2004
Posts: 392
Likes: 7
From: Massachusetts
1986 700r4 issue?
Hello my 1986 vette with the 700r4 has been acting up for awhile. The first three gears (1,2,D) everything works/shifts fine and usually around town I keep it on 3rd gear (d). However, when i hit about 42mph or so when the overdrive wants to shift in, the transmission starts to vibrate like crazy up until the 50mph range. It shifts fine into Overdrive its just when its in Overdrive theres so much vibration and I feel like It has no power and I really have to push the gas to get up. This does it around the 40s mph and low 50s mph range. Is this a common problem on older c4 700r4s? I was thinking maybe a torque converter issue? Or would a TV cable adjustment could cause this? I don't know much about transmissions but its really annoying. This year I did flush the ATF and added Mobil 1 ATF and it still didn't do anything. This has been going on for atleast a fews years and want to fix this problem b4 next summer. Thanks agian guys!
- Nick
- Nick
Team Owner
Joined: Sep 2003
Posts: 20,172
Likes: 672
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
How does the trans behave when your driving around at 60 or 70 in OD?
Something is definitely wrong. But is it in the trans or drivetrain?
I'm thinking you need to shake down the driveshaft and rear end for u-joints and bent shafts.
Pete K where are you?
Something is definitely wrong. But is it in the trans or drivetrain?
I'm thinking you need to shake down the driveshaft and rear end for u-joints and bent shafts.
Pete K where are you?
Thread Starter
Racer
Joined: Jun 2004
Posts: 392
Likes: 7
From: Massachusetts
- Nick
Race Director
Joined: Apr 2003
Posts: 17,698
Likes: 1,667
From: moraga ca
Sometimes when the lock up clutch in the converter is going, it will cause the car to shudder. When the clutch chatters it grabs and releases many times a second. This could be your problem.
Burning Brakes
Joined: Jan 2008
Posts: 1,187
Likes: 1
From: Superior WI
Team Owner
Joined: Sep 2003
Posts: 20,172
Likes: 672
From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Thread Starter
Racer
Joined: Jun 2004
Posts: 392
Likes: 7
From: Massachusetts
So maybe I might need a torque converter clutch which is causing it to shatter on Overdrive? Or maybe the torque converter itself? The car has only 58,000 original miles, but I guess age and being an early c4 doesnt help it much to I suppose. Thanks for the responses so far guys!
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
So maybe I might need a torque converter clutch which is causing it to shatter on Overdrive? Or maybe the torque converter itself? The car has only 58,000 original miles, but I guess age and being an early c4 doesnt help it much to I suppose. Thanks for the responses so far guys!
If it is the origional torque converter, the adhesive that holds the friction material to the lock up plate is 25 years old. The glue used in those days were crap. On the other hand, it did hold up for 25 years, so maybe my crap statement is not really fair. Todays adhesives are vastly superior. Disconnect the lock up plug on the drivers side of the trans. If it improves, change the torque converter.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
Thread Starter
Racer
Joined: Jun 2004
Posts: 392
Likes: 7
From: Massachusetts
If it is the origional torque converter, the adhesive that holds the friction material to the lock up plate is 25 years old. The glue used in those days were crap. On the other hand, it did hold up for 25 years, so maybe my crap statement is not really fair. Todays adhesives are vastly superior. Disconnect the lock up plug on the drivers side of the trans. If it improves, change the torque converter.
- Nick
Race Director
Joined: Feb 2004
Posts: 12,517
Likes: 19
Yea I know the torque converter is original because the vette has been with my family since brand new. So if I disconnect this lock up plug and the shattering goes away that possibly means I need a new torque converter? Is a tq converter difficult to change and how much do they usually run for? Also this lock up plug is outside the transmission on it? Thanks Pete!
- Nick
- Nick
Removal of the engine or trans is required to change it, with trans removal being the easier of the 2. Price on stock remanufactured torque converters vary from $75-$250, with your old one as a core. My recommendation would be to rebuild yours, using a local rebuilder.
It is also the perfect time for a performace torque converter, if a little more seat of the pants acceleration is desired. You will want to change the filter and fluid as well, while it is apart.
Melting Slicks
Joined: Mar 2004
Posts: 2,141
Likes: 2
From: Pittsburgh Pa
well i think half the problem is that you think you need to drive around in 3rd instead of OD like the car was designed to be driven in. your gas mileage would probably double. if you dont use something for a long time do you really expect it to work properly when you finally get around to using it properly. whens the last time the filter was changed? is the fluid level correct?
