Transmission clunk when rolling to stop
Thread Starter
Instructor
Joined: May 2011
Posts: 103
Likes: 0
From: Lithia FL
Transmission clunk when rolling to stop
My 1986 with 90k miles runs well and I have resolved the codes related to the MAF. Engine is stock. Anyway, the trans seems to behave like it should, according to the threads I read. It clunks into D, which appears to be normal normal. My question is more about when it rolls to a stop. It feels like a clunk when down-shifting (I assume) when you are about 10-15 feet from a stop. It's noticeable enough for my wife to ask what it is. The fluid looks fine and the level is correct. Is this normal? Otherwise, it shifts well. Firm up shifts when on throttle. I have no idea if it has ever had a shift kit installed. It's just that last downshift.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
My 1986 with 90k miles runs well and I have resolved the codes related to the MAF. Engine is stock. Anyway, the trans seems to behave like it should, according to the threads I read. It clunks into D, which appears to be normal normal. My question is more about when it rolls to a stop. It feels like a clunk when down-shifting (I assume) when you are about 10-15 feet from a stop. It's noticeable enough for my wife to ask what it is. The fluid looks fine and the level is correct. Is this normal? Otherwise, it shifts well. Firm up shifts when on throttle. I have no idea if it has ever had a shift kit installed. It's just that last downshift.
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
I will wait for Brian to confirm my opinion, before I sign it in ink. 
As you can see from the link below, he is the transmission expert.
http://forums.corvetteforum.com/1578315291-post6.html
As you can see from the link below, he is the transmission expert.
http://forums.corvetteforum.com/1578315291-post6.html
Last edited by Pete K; Dec 18, 2011 at 11:06 AM.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
I will wait for Brian to confirm my opinion, before I sign it in ink.
As you can see from the link below, he is the transmission expert.
http://forums.corvetteforum.com/1578315291-post6.html
As you can see from the link below, he is the transmission expert.
http://forums.corvetteforum.com/1578315291-post6.html
Don't forget he is ASE CERTIFIED as well!
Instructor
Joined: Dec 2011
Posts: 105
Likes: 0
From: El Paso TX
Well, I am not ASE certified or an expert on vettes either. Matter of fact just bought my first one this month. But normally when a tranny clunks when shifting into D or R and when loading and unloading ie. getting off or on the pedal, it is the U-joints. You can usually recreate that type of noise by shifting back and forth between D and R.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
No worries Pete... they have a 24hr online coarse!..
From my experience with the early 700r4, they just clunk whenever putting them in gear. In the beginning I also thought U-joints. Had them all checked when the rear was changed out and they were fine. B&M shift kit will make it clunk going thru the gears if your not on it. Looking forward the the new tranny sitting in my garage to go in this winter...built by Pete.
Over the past few years Pete has never steered me wrong. I have a official PeteK motorsports vette by him, and it runs with the stock C6.
From my experience with the early 700r4, they just clunk whenever putting them in gear. In the beginning I also thought U-joints. Had them all checked when the rear was changed out and they were fine. B&M shift kit will make it clunk going thru the gears if your not on it. Looking forward the the new tranny sitting in my garage to go in this winter...built by Pete.
Over the past few years Pete has never steered me wrong. I have a official PeteK motorsports vette by him, and it runs with the stock C6.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
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
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
No worries Pete... they have a 24hr online coarse!..
From my experience with the early 700r4, they just clunk whenever putting them in gear. In the beginning I also thought U-joints. Had them all checked when the rear was changed out and they were fine. B&M shift kit will make it clunk going thru the gears if your not on it. Looking forward the the new tranny sitting in my garage to go in this winter...built by Pete.
Over the past few years Pete has never steered me wrong. I have a official PeteK motorsports vette by him, and it runs with the stock C6.
From my experience with the early 700r4, they just clunk whenever putting them in gear. In the beginning I also thought U-joints. Had them all checked when the rear was changed out and they were fine. B&M shift kit will make it clunk going thru the gears if your not on it. Looking forward the the new tranny sitting in my garage to go in this winter...built by Pete.
Over the past few years Pete has never steered me wrong. I have a official PeteK motorsports vette by him, and it runs with the stock C6.
For the benefit of the OP, the 700r4 trans (pre-88 model year), had different valving in the trans. They added the aux valve body in 88 to remedy 2 problems.
1) Park to drive or reverse clunk.
2) Drive to reverse abuse (such as when stuck in snow, and trying to rock the car out of the spot).
Assuming no worn driveline parts, the following contributes to pre-88 clunk:
1) Trans design
2) Rigid drivetrain mounting, compared to other GM cars and trucks.
Thread Starter
Instructor
Joined: May 2011
Posts: 103
Likes: 0
From: Lithia FL
Thanks All!
Thanks guys. I have been happy. I snagged this car for much less than I imagined I would and have been pleasantly surprised that it's in good working order. Burns a bit of oil, but that's no biggie. I appreciate your thoughts. Thanks PeteK for the insight!
Pro
Joined: May 2010
Posts: 679
Likes: 18
From: Vernon Hills Ill
I will wait for Brian to confirm my opinion, before I sign it in ink.
As you can see from the link below, he is the transmission expert.
http://forums.corvetteforum.com/1578315291-post6.html
As you can see from the link below, he is the transmission expert.
http://forums.corvetteforum.com/1578315291-post6.html
Pro
Joined: Apr 2000
Posts: 696
Likes: 18
From: Jenkintown PA
Thanks Ed
For the benefit of the OP, the 700r4 trans (pre-88 model year), had different valving in the trans. They added the aux valve body in 88 to remedy 2 problems.
1) Park to drive or reverse clunk.
2) Drive to reverse abuse (such as when stuck in snow, and trying to rock the car out of the spot).
Assuming no worn driveline parts, the following contributes to pre-88 clunk:
1) Trans design
2) Rigid drivetrain mounting, compared to other GM cars and trucks.
For the benefit of the OP, the 700r4 trans (pre-88 model year), had different valving in the trans. They added the aux valve body in 88 to remedy 2 problems.
1) Park to drive or reverse clunk.
2) Drive to reverse abuse (such as when stuck in snow, and trying to rock the car out of the spot).
Assuming no worn driveline parts, the following contributes to pre-88 clunk:
1) Trans design
2) Rigid drivetrain mounting, compared to other GM cars and trucks.
Any thoughs???
Many thanks!
SAVE THE WAVE
Pro
Joined: Jun 2007
Posts: 626
Likes: 2
From: Coquitlam British Columbia
Race Director
Joined: Feb 2004
Posts: 12,518
Likes: 19
When in lower gears there is an additional clutchpack that is applied. It tightens things up, making the accumulator less effective. There is probably a way to manipulate the springs to achieve a clunk free downshift, but I never cared to try. Most of us have gotten used to it, and forget it is even there.
