odd vibration on the highway
Thread Starter
Joined: Jul 2005
Posts: 1,428
Likes: 2
From: Guilford, Connecticut
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
odd vibration on the highway
This happens at right about 70 or a tad more. If im cruising along and light on the gas i get a vibration for about 3 seconds...followed by a pause with no vibration, and then a vibration for 3 seconds. This pattern will continue until i either give it gas and accelerate or until i get the speed below 70. Its very annoying and i cant think of anything that would be causing it. I would think if it was ujoints i would just get a constant vibration. Anyone got any ideas? Maybe its in my tune itself? I was watching my wideband when it was happening and it didnt seem to change.
Supreme Member
iTrader: (2)
Joined: Sep 2009
Posts: 1,591
Likes: 5
From: WI.
Car: 1987 iroc
Engine: 383 TPIS intake, Dyno Don headers
Transmission: 700R4 w/Pro-built Auto/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: odd vibration on the highway
Maybe it's the harmonics of the steel drive shaft. Is this something that just started? Has there been any recent change to the drive system? (rear end, trans, etc.)
Joined: Sep 2005
Posts: 28,027
Likes: 2,498
Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: odd vibration on the highway
So when you did the commonsensical thing and swapped the U-joints, did it change anything?
Thread Starter
Joined: Jul 2005
Posts: 1,428
Likes: 2
From: Guilford, Connecticut
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
Re: odd vibration on the highway
Yea i have too much done to the car to know whats what lol. Rear is recently rebuilt (two winters ago). Driveshaft is a 4th gen aluminum with new U joints. Trans is a TKO 500. The only thing that makes me start to wonder if its actually drivetrain or not is the fact that there is a pause and then vibration again. With drivetrain i would think it would be a constant thing.
Thread Starter
Joined: Jul 2005
Posts: 1,428
Likes: 2
From: Guilford, Connecticut
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
Re: odd vibration on the highway
Im revisiting this. This vibration is driving me insane. Anyone got any suggestions where to look? Still does it. It will not do it in 4th at 70 but then again the rpms are a lot higher. I also tried 4th gear at around the same rpm (about 2200) and it did not vibrate in 4th at that rpm which i think rules out the harmonic dampener. It seems to a be 5th gear only thing.
I kind of have a theory that the engine computer is doing it since it seems to turn on and off. This car used to be a automatic so im wondering if its looking for the lockup torque converter? I thought they locked up at 55 or something however.
I kind of have a theory that the engine computer is doing it since it seems to turn on and off. This car used to be a automatic so im wondering if its looking for the lockup torque converter? I thought they locked up at 55 or something however.
Last edited by subroc; Aug 9, 2013 at 07:19 AM.
Joined: Aug 1999
Posts: 5,280
Likes: 473
From: RI
Car: 1984 Camaro Berlinetta
Engine: LT1
Transmission: T56 6-speed
Axle/Gears: 4.11 LS1 Rear End
Re: odd vibration on the highway
Seems like it's just 'one of those things' Steve !! Probably some combination of 6-10 variables that all need to be at a specific value for the vibration to show itself. ( Speed, angle of deflection, weight distribution, the amount of morning dew on the car, ect... )
Chasing vibrations problems SUCKs !!!
Most of the time it's a matter of replacing parts that probably don't need replacing in order to get lucky and find the part(s) causing the vibration. I usually start by swapping parts on the car with parts I've got already got available to me to keep expenses down. ( a different set of tires/wheels, a different driveshaft, swap tranyy mounts, ect. )
Try to focus on 1 aspect of the puzzle at a time. For instance,..... see if it's a "Rolling" vibration. Listen while rolling @ 70 in 4th, then 5th and neutral. (I'll even kill the ignition completely @ highway speeds just to listen to for a rolling vibration.)
Next; try to focus just on the speed, then try to focus on a specific RPM, and so on. You should be able to ( at least ) narrow the possible culprits throught the proccess of elimination. Again, vibrations are a BITCH because they can be caused by SOOOOooo many different reasons. Bearings at all 4 corners, balance issuses on the drive-line, proper lubricant, a stone stuck in your tires tread,,........... I could go on buy I'm sure you already get it !!
This is telling. If it's the only variable that remains constant with the vibration than it's very possibly ( NOT probably !) the cause.
I had a pretty significant vibration in 'Mean Green' at 80+ in 6th on the highway after the engine swap last season. It only appeared at higher speed when I was in 6th. ( You might remember that I busted a bolt on my pinion flange when I wanted to swap driveshafts to try and resolve the issue. ) I knew it wasn't the tranny because it rode in 6th at high speed fine when powered by the 355ci that was swapped out. But the shaft, clutch, flywheel, motor mounts, tranny mount, were all different. So were the wheels and the rear, but I had driven on those @ high speed without vibration on other cars. After the flange was swapped and a different shaft was installed - the vibration is no more.
Good luck dude !
P.S. I doubt it's the ECM trying to turn on the lock-out. Lock-out will engage in the mid 40 MPH range IIRC.
Chasing vibrations problems SUCKs !!!
Most of the time it's a matter of replacing parts that probably don't need replacing in order to get lucky and find the part(s) causing the vibration. I usually start by swapping parts on the car with parts I've got already got available to me to keep expenses down. ( a different set of tires/wheels, a different driveshaft, swap tranyy mounts, ect. )
Try to focus on 1 aspect of the puzzle at a time. For instance,..... see if it's a "Rolling" vibration. Listen while rolling @ 70 in 4th, then 5th and neutral. (I'll even kill the ignition completely @ highway speeds just to listen to for a rolling vibration.)
Next; try to focus just on the speed, then try to focus on a specific RPM, and so on. You should be able to ( at least ) narrow the possible culprits throught the proccess of elimination. Again, vibrations are a BITCH because they can be caused by SOOOOooo many different reasons. Bearings at all 4 corners, balance issuses on the drive-line, proper lubricant, a stone stuck in your tires tread,,........... I could go on buy I'm sure you already get it !!
It seems to a be 5th gear only thing
I had a pretty significant vibration in 'Mean Green' at 80+ in 6th on the highway after the engine swap last season. It only appeared at higher speed when I was in 6th. ( You might remember that I busted a bolt on my pinion flange when I wanted to swap driveshafts to try and resolve the issue. ) I knew it wasn't the tranny because it rode in 6th at high speed fine when powered by the 355ci that was swapped out. But the shaft, clutch, flywheel, motor mounts, tranny mount, were all different. So were the wheels and the rear, but I had driven on those @ high speed without vibration on other cars. After the flange was swapped and a different shaft was installed - the vibration is no more.
Good luck dude !
P.S. I doubt it's the ECM trying to turn on the lock-out. Lock-out will engage in the mid 40 MPH range IIRC.
Last edited by John in RI; Aug 9, 2013 at 04:05 PM. Reason: P.S.
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Thread Starter
Joined: Jul 2005
Posts: 1,428
Likes: 2
From: Guilford, Connecticut
Car: 1988 IROC-Z camaro
Engine: 355 TPI
Transmission: tko 500
Axle/Gears: Dana 44 3.31 posi pbr brakes
Re: odd vibration on the highway
Thanks John. The only thing that has me really scratching my head is the on again off again nature of the vibration. If it was constant i would be inspecting the normal things like u-joints and trans mounts but its not. I cant for the life of me think of what would cause the vibration to come and go and only at a bit over 70 (according to my speedo which i think is a tad off).
Joined: Jul 2000
Posts: 6,531
Likes: 94
From: Aridzona
Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Re: odd vibration on the highway
Shamelessly copied from a Ford site and edited a bit:
PINPOINT TEST A: HIGH SPEED SHAKE DIAGNOSIS
A11 REAR TIRES
Engage drive train while vehicle is raised on hoist. Carefully accelerate the drive wheels while feeling for vibration.
If vibration is felt, GO to «A12».
Else, go to «A14».
A12 DRIVETRAIN
Remove rear wheels, secure brake drums, if so equipped by installing wheel lug nuts, reversed. Carefully accelerate the drive train
while feeling for vibration.
If vibration is felt go to «A13».
Else, balance rear wheels. perform «Road Test»
A13 REAR DRUMS OR ROTORS
Remove the brake drums or rotors. Carefully accelerate the drive train while feeling for vibration.
If vibration is felt, go to «Driveline Vibration Diagnosis» .
Else, replace drums or rotors. PERFORM «Road Test»
A14 WHEEL BALANCE
Balance all wheels not previously balanced. «Road test» vehicle.
If wheels are balanced, Vehicle OK.
Else, go to «A15».
A15 SUBSTITUTE WHEELS AND TIRES
Substitute a known good set of wheels and tires. «Road test» vehicle.
If vibration is felt, REFER to «Driveline Vibration Diagnosis» .
Else, install the original tire/wheel assemblies, one by one, road testing at each step, until the defective tire(s) is identified.
REPLACE tire(s) as necessary and RETEST.
PINPOINT TEST C: DRIVELINE VIBRATION DIAGNOSIS
C1: WHEELS AND TIRES
C2: DRIVESHAFT
C3: DRIVESHAFT RUNOUT
C4: DRIVESHAFT RE-INDEXING AT TRANSMISSION
C5: DRIVESHAFT RE-INDEXING AT AXLE
C6: AXLE COMPANION FLANGE
C7: DRIVESHAFT VIBRATION
C8: AXLE PINION NOISE DAMPER
C1 WHEELS AND TIRES
Verify that the observed condition is not a high speed shake caused by wheels/tires.
If observed condition is a high speed shake caused by wheels or tires, REFER to «High Speed Shake Diagnosis» for drive-wheel
runout and balance procedures.
Else, go to «C2».
C2 DRIVESHAFT
Inspect driveshaft for undercoating or physical damage. Check index marks (yellow paint daubs) on rear of driveshaft and axle
companion flange. These marks should be no more than 90 degrees apart.
If marks are no more than 90 degrees apart,
CLEAN off undercoating or REPLACE damaged driveshaft. If index marks are misaligned, GO to «C6».
CHECK for vibration at road test speed. If still present, GO to «C3».
Else, go to «C3».
C3 DRIVESHAFT RUNOUT
With vehicle on hoist, measure runout at front, center and rear of driveshaft. Maximum runout is 0.89 mm (0.035 inch).
Is maximum runout 0.89mm (0.035 inch)?
Within specification
GO to «C7».
At front or center out of specification
GO to «C4».
At rear out of specification
MARK the rear runout high point. GO to «C5».
C4 DRIVESHAFT RE-INDEXING AT TRANSMISSION
l Note or mark indexing of driveshaft to transmission and axle companion flange. Disconnect the driveshaft, re-index 180 degrees
at transmission only and reconnect. Check runout at front and center of driveshaft, maximum runout is 0.89 mm (0.035 inch).
NOTE:
While driveshaft is removed from vehicle and manipulate U-joints in each direction of rotation. If a U-joint feels stiff or has a
"lumpy", "gritty" feel in any direction, replace U-joints or driveshaft.
If it is within specification CHECK for vibration at road test speed. If still present, mark rear runout high point. GO to «C5».
Else, GO to «C6».
C5 DRIVESHAFT RE-INDEXING AT AXLE
Note or mark indexing of driveshaft to axle companion flange. Disconnect the driveshaft. Re-index 180 degrees at axle and
connect. Check runout at rear of driveshaft. Maximum runout is 0.89 mm (0.035 inch).
If within specification CHECK for vibration at road-test speed. If still present, GO to «C7».
Else GO to «C6».
PINPOINT TEST C: DRIVELINE VIBRATION DIAGNOSIS
C6 AXLE COMPANION FLANGE
Compare the two high points of runout marked in Test Steps C3 and C4.
Marks within 25 mm (1 inch) of each other
REPLACE driveshaft. RECHECK vibration.
Marks 180 degrees apart
REPLACE axle companion flange. CHECK driveshaft runout and road test for vibration. If still present, GO to «C7».
C7 DRIVESHAFT VIBRATION
The driveshaft can be re-indexed at both the rear axle and transmission to minimize system imbalance. Refer to driveshaft
indexing procedure.
If driveshaft is balanced, Vehicle OK.
Else, REFER to «Driveshaft Balancing Test Step F1» , if vibration still present.
C8 AXLE PINION NOISE DAMPER
If vibration still exists after balancing driveshaft, install an axle pinion damper, as outlined.
If vibration is still present, Vehicle OK. REPLACE driveshaft if vibration still persists.
Else, REFER to «Group 05».
A11 REAR TIRES
Engage drive train while vehicle is raised on hoist. Carefully accelerate the drive wheels while feeling for vibration.
If vibration is felt, GO to «A12».
Else, go to «A14».
A12 DRIVETRAIN
Remove rear wheels, secure brake drums, if so equipped by installing wheel lug nuts, reversed. Carefully accelerate the drive train
while feeling for vibration.
If vibration is felt go to «A13».
Else, balance rear wheels. perform «Road Test»
A13 REAR DRUMS OR ROTORS
Remove the brake drums or rotors. Carefully accelerate the drive train while feeling for vibration.
If vibration is felt, go to «Driveline Vibration Diagnosis» .
Else, replace drums or rotors. PERFORM «Road Test»
A14 WHEEL BALANCE
Balance all wheels not previously balanced. «Road test» vehicle.
If wheels are balanced, Vehicle OK.
Else, go to «A15».
A15 SUBSTITUTE WHEELS AND TIRES
Substitute a known good set of wheels and tires. «Road test» vehicle.
If vibration is felt, REFER to «Driveline Vibration Diagnosis» .
Else, install the original tire/wheel assemblies, one by one, road testing at each step, until the defective tire(s) is identified.
REPLACE tire(s) as necessary and RETEST.
PINPOINT TEST C: DRIVELINE VIBRATION DIAGNOSIS
C1: WHEELS AND TIRES
C2: DRIVESHAFT
C3: DRIVESHAFT RUNOUT
C4: DRIVESHAFT RE-INDEXING AT TRANSMISSION
C5: DRIVESHAFT RE-INDEXING AT AXLE
C6: AXLE COMPANION FLANGE
C7: DRIVESHAFT VIBRATION
C8: AXLE PINION NOISE DAMPER
C1 WHEELS AND TIRES
Verify that the observed condition is not a high speed shake caused by wheels/tires.
If observed condition is a high speed shake caused by wheels or tires, REFER to «High Speed Shake Diagnosis» for drive-wheel
runout and balance procedures.
Else, go to «C2».
C2 DRIVESHAFT
Inspect driveshaft for undercoating or physical damage. Check index marks (yellow paint daubs) on rear of driveshaft and axle
companion flange. These marks should be no more than 90 degrees apart.
If marks are no more than 90 degrees apart,
CLEAN off undercoating or REPLACE damaged driveshaft. If index marks are misaligned, GO to «C6».
CHECK for vibration at road test speed. If still present, GO to «C3».
Else, go to «C3».
C3 DRIVESHAFT RUNOUT
With vehicle on hoist, measure runout at front, center and rear of driveshaft. Maximum runout is 0.89 mm (0.035 inch).
Is maximum runout 0.89mm (0.035 inch)?
Within specification
GO to «C7».
At front or center out of specification
GO to «C4».
At rear out of specification
MARK the rear runout high point. GO to «C5».
C4 DRIVESHAFT RE-INDEXING AT TRANSMISSION
l Note or mark indexing of driveshaft to transmission and axle companion flange. Disconnect the driveshaft, re-index 180 degrees
at transmission only and reconnect. Check runout at front and center of driveshaft, maximum runout is 0.89 mm (0.035 inch).
NOTE:
While driveshaft is removed from vehicle and manipulate U-joints in each direction of rotation. If a U-joint feels stiff or has a
"lumpy", "gritty" feel in any direction, replace U-joints or driveshaft.
If it is within specification CHECK for vibration at road test speed. If still present, mark rear runout high point. GO to «C5».
Else, GO to «C6».
C5 DRIVESHAFT RE-INDEXING AT AXLE
Note or mark indexing of driveshaft to axle companion flange. Disconnect the driveshaft. Re-index 180 degrees at axle and
connect. Check runout at rear of driveshaft. Maximum runout is 0.89 mm (0.035 inch).
If within specification CHECK for vibration at road-test speed. If still present, GO to «C7».
Else GO to «C6».
PINPOINT TEST C: DRIVELINE VIBRATION DIAGNOSIS
C6 AXLE COMPANION FLANGE
Compare the two high points of runout marked in Test Steps C3 and C4.
Marks within 25 mm (1 inch) of each other
REPLACE driveshaft. RECHECK vibration.
Marks 180 degrees apart
REPLACE axle companion flange. CHECK driveshaft runout and road test for vibration. If still present, GO to «C7».
C7 DRIVESHAFT VIBRATION
The driveshaft can be re-indexed at both the rear axle and transmission to minimize system imbalance. Refer to driveshaft
indexing procedure.
If driveshaft is balanced, Vehicle OK.
Else, REFER to «Driveshaft Balancing Test Step F1» , if vibration still present.
C8 AXLE PINION NOISE DAMPER
If vibration still exists after balancing driveshaft, install an axle pinion damper, as outlined.
If vibration is still present, Vehicle OK. REPLACE driveshaft if vibration still persists.
Else, REFER to «Group 05».
Joined: Aug 1999
Posts: 5,280
Likes: 473
From: RI
Car: 1984 Camaro Berlinetta
Engine: LT1
Transmission: T56 6-speed
Axle/Gears: 4.11 LS1 Rear End
Re: odd vibration on the highway
Did I mention that Vibrations SUCK !!!!
Now THAT"S a nice checklist !
My feeling is that is probably a combination of things leading to the ultimate vibration outcome. With any luck changing a variable or 2 on the car will quickly ID the culprit parts and replacing them will be enough to realign things a bit and cure the problem. Hell; Spinning the front coil spring 1/4 of a turn and swapping front end links from to side to side might be the miracle cure, ......maybe the exhaust is vibrating and only seeming like the driveline because 5th gear RPM is just 'right' ( your driving at 70 after all ! )
It's going to keep screwing with you dude; just be patient and persistent ( as usual ! ) and you'll find it.
Shamelessly copied from a Ford site and edited a bit:
My feeling is that is probably a combination of things leading to the ultimate vibration outcome. With any luck changing a variable or 2 on the car will quickly ID the culprit parts and replacing them will be enough to realign things a bit and cure the problem. Hell; Spinning the front coil spring 1/4 of a turn and swapping front end links from to side to side might be the miracle cure, ......maybe the exhaust is vibrating and only seeming like the driveline because 5th gear RPM is just 'right' ( your driving at 70 after all ! )
It's going to keep screwing with you dude; just be patient and persistent ( as usual ! ) and you'll find it.
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