Vibrations come back after installed UCA/LCA

[Slow5.0]

Two night ago I installed UCA/LCA and after I start car and rev up little bit I fing vibrations 4500rpms and up and same thing when I driving car in any gear harder 4500rpms and up , A two months ago I installed balancer from 50resto http://secure.50resto.com/product1.cfm?SID=1&Product_ID=1733&Category_ID=571 because I had vibrations 5K and up , after I installed that balancer vibrations are gone , but now it's back , I check balancer this morning and looks good , so there have too be something else , meybe exhause touching something
What you guys think

 

[urban96]

http://forums.stangnet.com/showthread.php?t=423856

*edit- i read the rest of the thread and seen you posted there already.

 

[yellow1995Cobra]

you will get some vibrations from the UCA's and LCA's cause they use poly bushings. Should only be when your driving though.

 

[5.0 from 95]

Did you do anything with the drive shaft. If you did, you might not have put it back in the same spot as last time.


Paul

 

[Slow5.0]

Only thing with drive shaft I did I accidently put jack under rear U-joint for like a few sec but with light pressure BUT drive shaft isn't problem , problem coming between clutch (on one side) and harmonic balancer (on othet side) balancer is a few months old and I checked him this morning ,still looks good like when I installed
I find today , vibrations are all the time , it's like 70% of driving

 

[Slow5.0]

I forget to tell you guys I rev up for like 20 sec with open headers (because I have to take mufflers off two bolts on front od LCA is pain in a$$ so I take h-pipe and see how sound with open headers , meybe that can cause some problems , I put exhaust like before, I still can't find whats wrong , AND this weekend I going on track test all this new mods and I wanna find what cause vibration before saturday

 

[Slow5.0]

Last night I check whole rear end , evertthing is tight , I chech driveshaft with engine runing and trany in gears with rear wheels in air , driveshaft looks good BUT I thing something is wrong with drivetrain or so , because sometime I can't heard vibrationg in neutral , biggest vibrations come when is load or when I driving hard thru any gear over 4500rpms , meybe new UCA/LCA change axle position and whole axle/diffetential are moved forward to tranny and now driveshaft can't play forward and back like before , AND I tryed put two more guys in car and take ride hard ride ,with them vibrations are worst
What you guys think

 

[DougNuts]

Seth, did you check the balancer with the engine running? Make sure it's not wobbling at all?

 

[Slow5.0]

Yes I check out balancer like 10 times in last a few days ,
BTW I talk with my friend who is also good Mustang mechanic and who own 10s 94 Stang 347 with blower, he told me that he have same problem a few years ago and tranny mount was bad and he told me meybe driveshaft is bad (off balance) and that I need FRPP aluminum driveshaft
So I gonna change tranny mount and buy Aluminum driveshaft then we will see are those vibrations gone