Automatic overdrive shudder
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
My '91 had the shudder you describe.
I felt it MOST when I was cruising along with the TC locked and I'd press the accelerator enough to make it come out of lock.
At that point I'd feel a vibration that felt sort of like missing but it wasn't missing.
It seemd to be more apparent, on mine, in the higher gears , 3rd and 4th.
I never felt anything unusual when it would lock up. Just felt it when it un-locked. I guess lock-up happens so fast there's not a lot of revolutions when the clutch disc inside the converter is slipping.
Guess it must un-lock slower and those few revolutions with the clutch disc not totally disengaged would cause the shudder.
Once the TCC is locked or unlocked completely there will be no shudder.
I've never cut one open but 'my' theory is the clutch friction disc is warped ot else the part it interfaces to is warped.
It really feels a LOT like a stick shift car with a warped pressure plate or flywheel. It's 'close kin' to that same type vibration you can feel just as the clutch starts to engage on a stick shift car with that type defect.
Drove it that way for over a year before I got a 'round-tuit'.
Never seemed to hurt anything but it was one of those 'nagging' things that makes yo feel uneasy.
Since I had to pull the transmission I went ahead and got a 2800 RPM stall converter.
Replaced the transmission just 'because' with one of those prehistoric animal ones. A Dinosaur or Raptor. Something like that.
I really can't tell much difference at all in this converter and the stock one.
You'll never know you have it unless you really bury the throttle on take off. Then the engine will rev up a few hundred more RPM than stock which get's it farther up on the 'torque curve'.
THAT feels a LOT better than stock, LOL.
In normal driving, you'll never know it's not a stock converter and I like that.
I felt it MOST when I was cruising along with the TC locked and I'd press the accelerator enough to make it come out of lock.
At that point I'd feel a vibration that felt sort of like missing but it wasn't missing.
It seemd to be more apparent, on mine, in the higher gears , 3rd and 4th.
I never felt anything unusual when it would lock up. Just felt it when it un-locked. I guess lock-up happens so fast there's not a lot of revolutions when the clutch disc inside the converter is slipping.
Guess it must un-lock slower and those few revolutions with the clutch disc not totally disengaged would cause the shudder.
Once the TCC is locked or unlocked completely there will be no shudder.
I've never cut one open but 'my' theory is the clutch friction disc is warped ot else the part it interfaces to is warped.
It really feels a LOT like a stick shift car with a warped pressure plate or flywheel. It's 'close kin' to that same type vibration you can feel just as the clutch starts to engage on a stick shift car with that type defect.
Drove it that way for over a year before I got a 'round-tuit'.
Never seemed to hurt anything but it was one of those 'nagging' things that makes yo feel uneasy.
Since I had to pull the transmission I went ahead and got a 2800 RPM stall converter.
Replaced the transmission just 'because' with one of those prehistoric animal ones. A Dinosaur or Raptor. Something like that.
I really can't tell much difference at all in this converter and the stock one.
You'll never know you have it unless you really bury the throttle on take off. Then the engine will rev up a few hundred more RPM than stock which get's it farther up on the 'torque curve'.
THAT feels a LOT better than stock, LOL.
In normal driving, you'll never know it's not a stock converter and I like that.
From what I have been shown, the factory applied friction material was prone to delaminating. Sections of the lining fall off the plate. The friction lining is very, very thin. Maybe 1/2 inch wide and around the outside edge of a 12 inch diameter piston. I am suprised they hold up as well as they do.
My shop has been educating me and it seems that the adhesives that hold the lining to the plate are much, much, better than they were in the mid 80's. The type and quality of the actual frictions have improved alot.
I don't know why this stuff interests me, but it does
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
From what I have been shown, the factory applied friction material was prone to delaminating. Sections of the lining fall off the plate. The friction lining is very, very thin. Maybe 1/2 inch wide and around the outside edge of a 12 inch diameter piston. I am suprised they hold up as well as they do.
My shop has been educating me and it seems that the adhesives that hold the lining to the plate are much, much, better than they were in the mid 80's. The type and quality of the actual frictions have improved alot.
I don't know why this stuff interests me, but it does
My shop has been educating me and it seems that the adhesives that hold the lining to the plate are much, much, better than they were in the mid 80's. The type and quality of the actual frictions have improved alot.
I don't know why this stuff interests me, but it does
I'm surprised that little bit of friction material last as long as it does too.
That's an awfully small 1/2" strip of stuff. Doesn't look like it would hold up on a bicycle.
Yeah, I'm interested in stuff like this too, Pete.
Wonder if that strip is kevlar.........
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
My 93 had a shift kit, the guy said he put it in to save wear and tare on the 1stto 2nd shift. I have a bad back and when the car would come out of 1st, Id tense up for the shift that I knew was coming. When it hit it hurt my back.
Didn't care for it for that reason, but the trans is still going strong at 100k.
I never used overdrive till 45+. Its the constant shifting from OD to drive that will wear out the 3-4 clutch pack. The engine has enough torque to take the higher gear but the trans pays the cost.
If you treat the 700r4 well it will last a long time, abuse it and its like yesterdays news paper.
The newer 5+ speeds autos can cost $7,000 to replace.
Didn't care for it for that reason, but the trans is still going strong at 100k.
I never used overdrive till 45+. Its the constant shifting from OD to drive that will wear out the 3-4 clutch pack. The engine has enough torque to take the higher gear but the trans pays the cost.
If you treat the 700r4 well it will last a long time, abuse it and its like yesterdays news paper.
The newer 5+ speeds autos can cost $7,000 to replace.
Pro
Joined: Nov 2004
Posts: 716
Likes: 0
From: Evansville IN
St. Jude Donor '05-'06
Mine has the mentioned shudder too. It's a '92, and has been that way since I bought it. I thought it was just the normal thing, and didn't pay much attention to it. Only does it when it shifts down out of overdrive, and is accelerated to go back into overdrive around 40-50 mph. Never does it at higher or lower speeds. Strange beasts those auto transmissions.
Racer
Joined: Apr 2006
Posts: 329
Likes: 0
From: Antioch California
Hey there, Dale. Maybe you can get the dealer to run a couple of screws into the trans.
Sorry, couldn't resist. Seriously tho, I installed a new trans in my 86' with a 2800 stall converter and was a mazed how deep the OD was when the car drops into 4th. It goes from 3rd to 4th @ 41 mph...Feels like it's bogging. I believe that is what you are describing. If so, no worries. I run in drive until I'm close to 50mph and all is well.
Sorry, couldn't resist. Seriously tho, I installed a new trans in my 86' with a 2800 stall converter and was a mazed how deep the OD was when the car drops into 4th. It goes from 3rd to 4th @ 41 mph...Feels like it's bogging. I believe that is what you are describing. If so, no worries. I run in drive until I'm close to 50mph and all is well.
Thread Starter
Drifting
Joined: Dec 2006
Posts: 1,771
Likes: 1
From: Cuyahoga Falls Ohio
Hey there, Dale. Maybe you can get the dealer to run a couple of screws into the trans. Sorry, couldn't resist. Seriously tho, I installed a new trans in my 86' with a 2800 stall converter and was a mazed how deep the OD was when the car drops into 4th. It goes from 3rd to 4th @ 41 mph...Feels like it's bogging. I believe that is what you are describing. If so, no worries. I run in drive until I'm close to 50mph and all is well.
Sorry, couldn't resist. Seriously tho, I installed a new trans in my 86' with a 2800 stall converter and was a mazed how deep the OD was when the car drops into 4th. It goes from 3rd to 4th @ 41 mph...Feels like it's bogging. I believe that is what you are describing. If so, no worries. I run in drive until I'm close to 50mph and all is well.There's a wise guy in every crowd!
Yep, that's what I'm feeling. A kind of bog down at 35-40 if in OD. I drive it in drive, so no problem here.
And NO, I'm not taking it to the dealer for this.
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Drifting
Joined: Oct 2006
Posts: 1,694
Likes: 0
From: Beaverton Oregon
I noticed someone else in another thread has this problem. I have it on my '87, so rather than hijack, I figured I'd post a new thread.
When I put my '87 in overdrive and drive around town, it shudders. It's almost how a car feels when it's missing. If I drop it down to drive, no problem at all.
Anyone know what this is, and what it would cost to fix it?
When I put my '87 in overdrive and drive around town, it shudders. It's almost how a car feels when it's missing. If I drop it down to drive, no problem at all.
Anyone know what this is, and what it would cost to fix it?
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
I originally posted this issue a few months age. Believe it or not, replacing the plug wires and tightening down the distributor (which was way too loose) solved the shudder I was getting in 4th OD. Check your distributor, see if you can turn it. The nut that holds the distributor in place is very hard to get to without the proper tool, sometimes a home mechanic can't get it tight enough. I haven't had a shudder since replacing the plug wires and tightening down the distributor.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
Anything that will lug the engine will contribute to it. 2.59 gear cars that have a slight miss or stutter would amplify the "normal" chatter that these units generate. Most of the cars with 3:07 or numerically higher seem to have less chatter.
Racer
Joined: Dec 2004
Posts: 306
Likes: 0
Pete a very over simplified way of explaining how a torque converter works is put two fans in front of each other and turn one on, the other will start to turn.
Like I said its very over simplified. But that’s all most need to know
Like I said its very over simplified. But that’s all most need to know
3rd Gear
Joined: Apr 2022
Posts: 3
Likes: 0
From: Alexandria, Va
since I bought my 93 (73xxx at purchase, 84k miles currently) auto last February, it always has a heavy vibration/shudder/ drone like noise once I surpass 40mph(I think that's when my od kicks in as I always drive in od.
I am in the habit of driving under 40 mph everywhere because I try to avoid the shudder noise as I don't know what it is and its so hard to explain it unless you are experiencing it.
whenever I need to go above 40mph, I go to D and ride till I hit about 53 mph and go back to OD when the vibrations/shuddering stop. it feels like something is maybe grinding in the rear area of my Vette.
I am not mechanically inclined as I like to say I am and just out right avoid the 40-53 mph range whenever I can.
what could be the cause of this? I'm getting close to one year of ownership. and all I've had to do is replace the FPR myself.
thanks!
Maxwell
