getshocked40KVolts

So i have a 1989 5.0 i have replaced the rear main seal, put ultra light flywheel on stage 3 zoom clutch, New T-5 it is only a month and a half old and i Ballanced the Drive shaft i have BAD BAD BAD vibrations when deccelerating from 4th gear at 2k rpm 1-2-3 good but reaching high way speeds is out of the question please any help would be awesome.

AdderMk2

check for play in your universal joints, see if there is excessive movement in both the trans yoke, and pinion on the diff... then if all of the above are good... balance your tires

mjr46

is the flywheel you put on have the correct balance weight on it?? meaning one for a 50 oz motor??

getshocked40KVolts

ok i have checked the dif and the slip yoke the drive shaft has very little play i would say not more then an 8th of and inch i have yet to balance the tires that will be the next thing i do as soon as the shops open up the fly wheel was bought specifically for my car along with the stage 3 zoom clutch more to follow ohh but i did see what would happen if i went to higher speeds going arround 95-120 in 4th gear arround 3k-4,500rpms it runs nice and smooth but when i clutch in the car Vibrates horibly

mjr46

I didn't ask if the flywheel was specifically bought for your car...........alot of the time the aluminum and ultra light flywheels come with a 50 oz weight and 28 oz weight, my flywheel was specifically bought for my car too and it came with both weights...see my point??

getshocked40KVolts

i balanced the wheels and problems still there i had a transmition shop put the fly wheel and clutch and trany on i will be takeing it to the shop on tuesday more to follow

greenstreak9205

Did the vibrations start before or after the driveline mods?

getshocked40KVolts

ok so i talked to a mustang tech. today and i think i found my problem i have an automatic slipe yoke on my driveshaft that has a balance weight on it remove the balance weight and put the manual one on it and that should fix the problem **** FORD dealerships they sent me a F-150 slip yoke and told me that was the one picture in rout more to follow on the job.