If its not an engine vibe or a driveline vibe. WTF is that vibe?
07-12-2010, 07:32 PM
#1
If its not an engine vibe or a driveline vibe. WTF is that vibe? Well here we go again trying to fix this problem. Still chasing this damn vibration. 
Vibe starts at 80MPH and is very noticable at 85MPH. It is much more obvious in 6th gear than in 5th gear.
I really dont think its the motor. No vibes can be detected free revving it or banging on it at all RPMs in the first four gears. Its only high speed 5th and 6th gears.
I am now convinced its not the drive line. The u-joint angles are good, the tailshaft bushing is replaced and the Strange cromeoly DS has been balanced. If you cruise at 85MPH (2100RPM) in 6th you get the vibe in the shifter and floorboard. Simpy clutch it or put it in neutral and it is totally smooth as silk which should emiminate the DS and angles at the least. Get on the gas again and the vibe returns. Drop under 80 and it is rather undetectable.
I am leaning toward something different like the T56 tranny or maybe exhaust drone from my TD's.
Is there any chance it can be something bad in the tranny?
What about exhaust drone? I know exhaust drone is always worst in the top gears when barely on the gas. Can an exhaust drone be confused with what one might think is a driveline vibe?
Thoughts.
Vibe starts at 80MPH and is very noticable at 85MPH. It is much more obvious in 6th gear than in 5th gear.
I really dont think its the motor. No vibes can be detected free revving it or banging on it at all RPMs in the first four gears. Its only high speed 5th and 6th gears.
I am now convinced its not the drive line. The u-joint angles are good, the tailshaft bushing is replaced and the Strange cromeoly DS has been balanced. If you cruise at 85MPH (2100RPM) in 6th you get the vibe in the shifter and floorboard. Simpy clutch it or put it in neutral and it is totally smooth as silk which should emiminate the DS and angles at the least. Get on the gas again and the vibe returns. Drop under 80 and it is rather undetectable.
I am leaning toward something different like the T56 tranny or maybe exhaust drone from my TD's.
Is there any chance it can be something bad in the tranny?
What about exhaust drone? I know exhaust drone is always worst in the top gears when barely on the gas. Can an exhaust drone be confused with what one might think is a driveline vibe?
Thoughts.
07-12-2010, 08:19 PM
#5
One more thing I will speculate on would be maybe the clutch. I did recently have to replace the pilot bushing that wore out to the point there was massive tranny input shaft wobble when the clutch was pushed. Never saw a reason for the pilot bushing to have so badly wear. Could a clutch problem cuase a high speed vibe?
07-12-2010, 08:20 PM
#6
I have something similar. Mine is at 70ish. I get vibration and some whine, but after 72ish it smooths out completely. same thing with the clutch, I put the clutch in and it goes dead quiet. I just don't drive my car on the highway enough for it to bother me yet.
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07-12-2010, 09:32 PM
#8
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wouldnt think an exhaust drone would vibrate through the shifter.
it might be dropping enough rpm's in the higher gears that its actually lugging the engine... does it do it if your accelerating?
how old is your tranny mount?
it might be dropping enough rpm's in the higher gears that its actually lugging the engine... does it do it if your accelerating?
how old is your tranny mount?
07-12-2010, 09:41 PM
#10
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When I had my LT1 DS my vibe was TERRIBLE now with my LS1 DS it has gotten much better but is still noticeable...
07-12-2010, 09:53 PM
#11
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how does the driveshaft yoke feel when you slide it up in the trans... does it have any abnormal amount of play in it? is the yoke up in the tranny good?
do you have a stock drive shaft you can throw in it to check?
do you have a stock drive shaft you can throw in it to check?
07-12-2010, 10:11 PM
#12
Keep the thoughts coming guys. Who ever fingers the problem gets all the free Guinness on draught from my garage kegerator they can dink assuming you come to get it. I seriously want this fixed ASAP.
07-12-2010, 10:54 PM
#14
Mine does it too,I had a custom steel shaft made to replace the stock steel shaft and it went away for awhile but it always comes back.I have had several different short block and clutch set ups,many 10 bolts and a 12 and it still does it.5th and 6th shake.The degree of shake has varied and changed rpms and mph through out the years.About five years ago I found a shop that does what is known as static balancing,meaning the shaft is put in a fixture and bent perfectly straight.There are NO weights on the shaft when it is static balanced because they make it perfectly straight with no run out.Shafts that are not straight will have weights welded to correct out of round.Every once in a while I take it to get re-straightened,and it does seem to help but I have never been able to get rid of it.Also all shafts have a certain rpm at which they will vibrate determined by length,materials and rpm. Might be time for aluminum or carbon fiber.... Or could it be the bearings in the tranny? What is your pinion angle,rear end centered? Did it do it before the nine inch?
07-13-2010, 06:00 AM
#17
I had the same problem after my T56 swap, it was most noticeable when in 6th gear putting some load on the engine. I did a tune up on the engine thinking it was missing under load, but didn't help. Checked the drive shaft, u-joints and pinion angles, all looked OK. So I just lived with it.
A few years later my T56 was in need for a rebuild. Sent it to Tick I and told them I waned every bearing replaced in the transmission as mileage was unknown. Got it back from the rebuild and it was smooth silk in all RPMs and speeds and has drove like new since. I also noticed that the pilot bearing was a little worn but don't believe that was the problem as it was new bearing after the T56 swap and there was always a vibe since the T56 swap.
Not sure if this is your problem or not, just sharing my hunt for a vibration that never seemed to go away.
A few years later my T56 was in need for a rebuild. Sent it to Tick I and told them I waned every bearing replaced in the transmission as mileage was unknown. Got it back from the rebuild and it was smooth silk in all RPMs and speeds and has drove like new since. I also noticed that the pilot bearing was a little worn but don't believe that was the problem as it was new bearing after the T56 swap and there was always a vibe since the T56 swap.
Not sure if this is your problem or not, just sharing my hunt for a vibration that never seemed to go away.
07-13-2010, 07:22 AM
#18
If I am correct, if it were an angle issue, it would vibrate either on the gas or clutched. When I clutch it at high speed, its smooth as silk.
I have a second aluminum DS as well. Does the same thing but maybe even a tad worse. Pinion angle if I recall is around 1.5 degrees. I cant confirm the rearend is centered as I have the NON adjustable PHB as mentioned above. If the rearend were not perfectly centered. Could it cause this problem?
07-13-2010, 08:03 AM
#19
i would say yes it could but my car does it too. LOL and i have an adj ph. also the cars been set up many different ways and still does it. seems to be a common problem.
07-13-2010, 08:07 AM
#20
Been doing some searching and some believe its the 5th and 6th gears getting sloppy and not being tight on the back of the main shaft due to wear. They say the press fit is gone and they can be removed by hand when rebuilding the tranny. So it makes some sense if gears are not very tight, there will be resonance and vibes.
Anybody ever heard of this?
Anybody ever heard of this?