Gun Jam

Hello

I have 66 mustang with a rebuilt t5. The car develops a vibration at 80 that feels like its coming from the tailshaft bushing/slip yoke section. Once this vibration starts it gets bad very fast. This problem started after doing the t5 swap..it was okay with the c4 as far as i can remember.

DS is balanced
reared and axles are all new
rebuilt t5 with new tailshaft bushing
new U joints
tried adjusting pinoin angle with little success.

I am still running the old slip yoke out of the c4. I took measurements of the slip yoke to check for wear. The inside section is 1.502" the section that rides on the tailshaft bushing is 1.497"

When I push up on the slip yoke / DS with light to moderate force I can clearly see the slip yoke flex in the tailshaft bushing...It doesnt move a whole lot but i can see it clearly move.

I talked to Burce of modern driveline about this and he says there should be no noticble play... I tried sliding the slip yoke all the way in for fun and then pushing on it and it moved almost as much as it did when normally installed.

Im wondering if its possible to have no noticable play as Bruce says..

What do you guys think?

thanks

-Gun

mjr46

all have some play, mine did, make sure tranny is not touching cross member in anyway from the tranny mount.

Gun Jam

Okay

I guess the next step is to fire it up on jack stands block all the front wheels up real good. Tie a video camera to a stick shove it under the car and run it up to 85 and review video....

Its not touching anything I have checked for that

I have been after this vibration for about 5 months now....Nothing seems to help..maybe im chasing ghosts

what are the odds of the output shaft on the trans being bent? Its a Z-spec. Im guessing its impossible to measure any runout with it in the trans.

Thanks

-Gun

mjr46

one thing to check would be the driveshaft alignment and or pinion angle, given the slightly different dimensions of tranny it may change angle of driveshaft creating no concentric rotation at the u-joints, mine had a vibration too after t-5 swap but was only evident when clutch was pushed in at cruise speeds coasting. I sold the car before I ever got into troubleshooting it

Gun Jam

Mjr if it were a non concentric problem how would I remedy that? Raise the Trans up by cutting the cross member anchor brace at the tunnel then finding a creative way to reinforce it without taking up space???

Trans is hanging at -3.5 deg rear is hanging at about -2 deg right now

matching trans and rear (-3.5/ -3.5) had little improvement over the original (-3.5 / -4.0 no shims)

Setting rear to -2 (with 2 deg shim made no real improvement)

Attempting to set parallel (-3.5/ + 2) caused objects in mirror to turn very fuzzy at 70mph then clear up at 80 just in time for the second vibration to start up at the tail shaft.

thanks again

-Gun

mjr46

what flywheel did you use on the motor??? and what year is the motor??

Gun Jam

I have a modern style flywheel to accept a 10.5" clutch but it has the 28oz BF
the engine is a 65 I think...C5...something on the block

Engine and car is smooth at 4500 rpm in 2nd gear going 50 mph but develops vibration at 84 mph at 2350 rpm... Its not a mystery vibration where you feel it everywhere... its APPEARS (maybe its messing with me) very local...I can literally point to the source of it and hear the source of it which happens to be the shifter handle and tailshaft location (in that zone) im guessing the shifter handle helps amplify the sound. At 75 MPH shifter handle is totally smooth but is vibrating loud enough to hear at 86ish mph and gets slightly worse when you back off the gas you can really feel the vibration in the shift handle.

Unlike some vibrations you can not drive though this one its gets worse exponentially...I cant imagine how horrid it would be at 100...not going to find out that's for damn sure.

-Gun

mstngsule68

u joints good? just an idea.

Gun Jam

yep all new

Gun Jam

I made a video of the play in question...


http://www.3rflying.com/slipyoke.mp4

Is this excessive play????

Is this the reason I get a vibration at 83+ Mph?

It has NEW tailshaft bushing, Would a new Slip yoke fix the problem??

let me know what you guys think!!

-Gun