new tranny and still 3rd gear vibration!
11-30-2005, 12:00 PM
#1
Teching In
Thread Starter
iTrader: (1)
Join Date: Sep 2005
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
new tranny and still 3rd gear vibration! i have less than 600 miles on the transmission since the rebuild ( new 3-4 clutch packs, high energy bands, everything all burg warner) and the car vibrates in third gear only 
tranny guy seems to think its a u joint.
ive read a few posts saying its the 3-4 clutch packs but i dont see how it could be having 500 miles since a rebuild. also the car did this before i had the tranny rebuild..
i have a yank py3600, 373, 10 bolt w/ mac girdle, aluminum driveshaft,
any ideas would be appriciated...
tranny guy seems to think its a u joint. ive read a few posts saying its the 3-4 clutch packs but i dont see how it could be having 500 miles since a rebuild. also the car did this before i had the tranny rebuild..
i have a yank py3600, 373, 10 bolt w/ mac girdle, aluminum driveshaft,
any ideas would be appriciated...
11-30-2005, 12:55 PM
#2
Moderator
iTrader: (11)
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes
on
6 Posts
U-joint maybe, pinion / driveline angle is also a good
bet if you have an adjustable TA or have changed the
rear suspension much. Don't forget the possibility of a
tire being worn out of balance, lost wheel weight or
bulging/cupping. Try and figure out if this is simply
wheel speed related, or requires torque applied;
tire will be the same coasting or pushing pretty much,
pinion angle / u-joint will be different w/ level of torque
through the driveline.
bet if you have an adjustable TA or have changed the
rear suspension much. Don't forget the possibility of a
tire being worn out of balance, lost wheel weight or
bulging/cupping. Try and figure out if this is simply
wheel speed related, or requires torque applied;
tire will be the same coasting or pushing pretty much,
pinion angle / u-joint will be different w/ level of torque
through the driveline.
12-01-2005, 05:18 AM
#3
TECH Addict
iTrader: (61)
Join Date: Mar 2002
Location: USA
Posts: 2,304
Likes: 0
Received 0 Likes
on
0 Posts
Simple check for all the people that keep posting with vibration problems:
Put car in Park or Neutral rev engine to at leat RPM that vibration occurs - if you don't feel a vibration - then the problem is not with the tranny internals or engine.
But it could be any/all of the following:
Wheels out of balance
Suspension problems (aftermarket Tq arm - pinion angle incorrect)
Driveshaft problems (out of balance, u-joints, wrong length, etc.)
Rear end problems (carrier bearings, axle bearings, gear setup, etc)
I would check the above items in that order.
Wheels
> Pretty self explanatory - have balance checked and re-checked
Suspension
> If your pinion angle is correct at about -1 to -2 on street car with aftermarket adj Tq arm, but vibration is still present, set pinion angle to zero and see if that helps.
> Check tranny mount condition
Driveshaft
> If you have changed from stock DS - check for proper length. Unbolt rear u-joint from pinion yoke, slide DS back toward engine into tranny as far as it will go. You should never have more than 3/8" space between DS rear yoke and pinion yoke at this point (need some space to enable dropping of DS for removal). If you have >3/8" then DS is too short. Because of this the DS tranny yoke will be pulled out further than necessary. This will enable the DS to act as a lever on the tailshaft/output shaft, since u-joints actually travel in an eliptical path as they turn, it will wear the tranny tailshaft bushing rapidly first, and after that is trashed it will start to work on the output shaft bushings deeper in the tranny. Once these are worn vibration will not go away until fixed. Easy way to check is to remove DS, look for damage/wear to DS tranny yoke, remove tailshaft housing & look for damage/wear to bushing. Note: if this is the problem you can actually eventually damage the internals of the tranny.
> Have U-joints checked and balance of DS
> Sometimes simply unbolting the rear u-joint and rotating the DS 180 deg and bolting back up will solve minor imbalance conditions so mark original clocking of rear u-joint prior to unbolting.
Rear End
> Have all items mentioned checked by professional
If by any chance you do feel the vibration when revving in P or N then problem stems from tranny or engine. First thing I would check would be for cracked flexplate (if A4), and/or loose verter bolts, try unbolting verter, rotating to different clocked position and bolt back up, etc.
Just some quick thoughts...
-Jay-
Put car in Park or Neutral rev engine to at leat RPM that vibration occurs - if you don't feel a vibration - then the problem is not with the tranny internals or engine.
But it could be any/all of the following:
Wheels out of balance
Suspension problems (aftermarket Tq arm - pinion angle incorrect)
Driveshaft problems (out of balance, u-joints, wrong length, etc.)
Rear end problems (carrier bearings, axle bearings, gear setup, etc)
I would check the above items in that order.
Wheels
> Pretty self explanatory - have balance checked and re-checked
Suspension
> If your pinion angle is correct at about -1 to -2 on street car with aftermarket adj Tq arm, but vibration is still present, set pinion angle to zero and see if that helps.
> Check tranny mount condition
Driveshaft
> If you have changed from stock DS - check for proper length. Unbolt rear u-joint from pinion yoke, slide DS back toward engine into tranny as far as it will go. You should never have more than 3/8" space between DS rear yoke and pinion yoke at this point (need some space to enable dropping of DS for removal). If you have >3/8" then DS is too short. Because of this the DS tranny yoke will be pulled out further than necessary. This will enable the DS to act as a lever on the tailshaft/output shaft, since u-joints actually travel in an eliptical path as they turn, it will wear the tranny tailshaft bushing rapidly first, and after that is trashed it will start to work on the output shaft bushings deeper in the tranny. Once these are worn vibration will not go away until fixed. Easy way to check is to remove DS, look for damage/wear to DS tranny yoke, remove tailshaft housing & look for damage/wear to bushing. Note: if this is the problem you can actually eventually damage the internals of the tranny.
> Have U-joints checked and balance of DS
> Sometimes simply unbolting the rear u-joint and rotating the DS 180 deg and bolting back up will solve minor imbalance conditions so mark original clocking of rear u-joint prior to unbolting.
Rear End
> Have all items mentioned checked by professional
If by any chance you do feel the vibration when revving in P or N then problem stems from tranny or engine. First thing I would check would be for cracked flexplate (if A4), and/or loose verter bolts, try unbolting verter, rotating to different clocked position and bolt back up, etc.
Just some quick thoughts...
-Jay-
12-01-2005, 09:48 AM
#4
Teching In
Thread Starter
iTrader: (1)
Join Date: Sep 2005
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
hey thats some great info. thanks.
i know its not the wheels/tires.both are brand new and have been balanced.
also there is no vibration in park or 1,2,4... just 3rd..
all my suspension has been changed. agx adj. shocks, eiback pro kit, adj. panhard bar, poly-u tranny mt., bmr adj. torque arm, edelbrock lower control arms. ( stuff on the rear )
ill get the rest of the suggestions checked thanks.
i know its not the wheels/tires.both are brand new and have been balanced.
also there is no vibration in park or 1,2,4... just 3rd..
all my suspension has been changed. agx adj. shocks, eiback pro kit, adj. panhard bar, poly-u tranny mt., bmr adj. torque arm, edelbrock lower control arms. ( stuff on the rear )
ill get the rest of the suggestions checked thanks.
Last edited by ktktransam; 12-01-2005 at 10:13 AM.
12-04-2005, 05:16 AM
#5
TECH Addict
iTrader: (61)
Join Date: Mar 2002
Location: USA
Posts: 2,304
Likes: 0
Received 0 Likes
on
0 Posts
Some other things to consider:
Even if your DS checks out as far as balance goes it can still have the ends welded on, let's say .030 out - which will incur a vibration.
Also check the angle of your DS from side to side, i.e. check to see if the centerline of your tranny is lined up with the centerline of your rear. This is especially neccessary if you add aftermarket motor mounts which may not be highly accurate and will shift your engine to one side or the other.
If you do have a DS made make sure they use a tranny yoke that has the correct metric splines. The output shaft has metric splines. Many DS builders (and I'm not talking about the popular ones) don't know that the splines are metric and use a standard front yoke - which will work - and when the car is static the yoke 'seems' to slide in & out of the tailshaft as it should when worked by hand. But while the car is in operation, the difference between the metric and std. splines will cause the front yoke to bind under torque and not slide in & out as it should - causing a vibration. Check for shiny spots on splines that would indicate this.
Of course, if you are still using your stock DS, some of these items are not applicable.
I was given advice from a very reputable transmission/driveline vendor, who races F-bodies quite successfully, that the best aftermarket DS is Mark Williams, followed by Strange, then Denny's, etc. He stated to never use CF DS for the street, and aluminum DS (no matter how much they are touted as HD) are a no-no for high HP cars.
Even if your DS checks out as far as balance goes it can still have the ends welded on, let's say .030 out - which will incur a vibration.
Also check the angle of your DS from side to side, i.e. check to see if the centerline of your tranny is lined up with the centerline of your rear. This is especially neccessary if you add aftermarket motor mounts which may not be highly accurate and will shift your engine to one side or the other.
If you do have a DS made make sure they use a tranny yoke that has the correct metric splines. The output shaft has metric splines. Many DS builders (and I'm not talking about the popular ones) don't know that the splines are metric and use a standard front yoke - which will work - and when the car is static the yoke 'seems' to slide in & out of the tailshaft as it should when worked by hand. But while the car is in operation, the difference between the metric and std. splines will cause the front yoke to bind under torque and not slide in & out as it should - causing a vibration. Check for shiny spots on splines that would indicate this.
Of course, if you are still using your stock DS, some of these items are not applicable.
I was given advice from a very reputable transmission/driveline vendor, who races F-bodies quite successfully, that the best aftermarket DS is Mark Williams, followed by Strange, then Denny's, etc. He stated to never use CF DS for the street, and aluminum DS (no matter how much they are touted as HD) are a no-no for high HP cars.
