Please help! I got the shakes
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 15
Likes: 0
From: Port Saint Lucie Florida
Please help! I got the shakes
1985 c4 5.7L coupe 4+3 manual trans. Has a shake at idle (like big engine shake from side to side slow), but while accelerating in each gear it gets worse as you push on pedal. If I turn on the overdrive(+3 part) in fourth gear it feels like the car is going to jump apart (only when you push the pedal). I have checked the timing (@ 6 degrees BTDC), all new distributor cap, rotor, coil, plugs (gaped @ .0035), wires (all double checked), throttle positioning sensor, and valve cover gaskets. Any ideas? Thanks! Scott.
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 15
Likes: 0
From: Port Saint Lucie Florida
I have double and triple checked the firing order both online and haynes manual. Thank you. It did this before for about three days then stoppped but since I re placed the above parts it has come back and seems to be here to stay. I'm lost.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
There are no "transmission mounts". There are two motor mounts, and the trans has a "c-beam" that covers the driveshaft and attaches from the rear of the trans to the diff housing, thus supporting the trans as well as the engine. The bolts on this could be loose, and while you're under there, check the trans-to-engine bolts to see if they are tight.
Pro
Joined: Dec 2010
Posts: 704
Likes: 1
From: Shillington PA
First I think we need to know if you have an idea if the shake is a "motor running" issue, or if it is a physical issue with the vehicle (IE: mounts as stated, DS out of balance, etc...)
Are you getting any SES light?
Are you getting any SES light?
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 15
Likes: 0
From: Port Saint Lucie Florida
At idle, it shakes like a side to side roll. with out the overdrive on it feels like I'm in to high a gear for the speed (remember 4 speed +3 Manual) (only when I push down the pedal, if i stay at steady speed it feels fine),I'm not. If I turn on the overdrive and push the pedal and it gets real shakey like I just ran over a metal grate (real bad feeling).
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
Pro
Joined: Dec 2010
Posts: 704
Likes: 1
From: Shillington PA
I'm sorry, i am totally new (just a few months) to owning a corvette. i don't know what a "DS" or "SES light" is.
At idle, it shakes like a side to side roll. with out the overdrive on it feels like I'm in to high a gear for the speed (remember 4 speed +3 Manual) (only when I push down the pedal, if i stay at steady speed it feels fine),I'm not. If I turn on the overdrive and push the pedal and it gets real shakey like I just ran over a metal grate (real bad feeling).
At idle, it shakes like a side to side roll. with out the overdrive on it feels like I'm in to high a gear for the speed (remember 4 speed +3 Manual) (only when I push down the pedal, if i stay at steady speed it feels fine),I'm not. If I turn on the overdrive and push the pedal and it gets real shakey like I just ran over a metal grate (real bad feeling).
SES= Service Engine Soon (commonly known as a check engine light)
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 15
Likes: 0
From: Port Saint Lucie Florida
No issues with the drive shaft. Rpm's were running up to 1600 at idle and check engine light would come on. This is what lead me to replace the throttle positioning sensor. Have have it happen twice since. Shut off engine and restart light went out and rpm's returned to normal.
Recheck very carefully
Thread Starter
Heel & Toe
Joined: Jan 2012
Posts: 15
Likes: 0
From: Port Saint Lucie Florida
I have a 1985 c4 L98 5.7L, but the order on the block looks the same. I have checked the firing order on the car again and it seems to be correct. I work at a VW dealer (sales) and we have a Cadillac (GM) dealer in our auto group. I made an appointment to have a diagnostic done on the car. I was hoping to not have to pay to figure this out (yes employees still have to pay). Thanks for all your help. I'm sure I'll be on here a lot, as I'm new to corvette and have a lot of work to be done on this car. This is how you learn right.....
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
I have a 1985 c4 L98 5.7L, but the order on the block looks the same. I have checked the firing order on the car again and it seems to be correct. I work at a VW dealer (sales) and we have a Cadillac (GM) dealer in our auto group. I made an appointment to have a diagnostic done on the car. I was hoping to not have to pay to figure this out (yes employees still have to pay). Thanks for all your help. I'm sure I'll be on here a lot, as I'm new to corvette and have a lot of work to be done on this car. This is how you learn right.....
