car is a 91 with s5 t2 motor and NA tranny, dshaft and rearend. act HD clutch and lightened flywheel. less than 3000 miles on both. welded diff. and dtss eliminator thingies lol
so i was messin around on the highway last night. did a 4th gear pull to over 100mph. let off and all of a sudden the car felt like it was gonna fall a part. it feels like this whenever i go over 40mph in any gear and in neutral. if im over 40 it shakes until i get under 30ish mph. car has a welded diff but it only happens over 40mph. accel or decel it doesnt mater if over 40mph.

i did some research and it seems like the driveshaft u-joints. what do you guys think? should i look for anything else while i have the car up? also how would i know if its the u-joints, will there be play in a certain way i should look for?

thanks,
Ricky

 

its certainly possible that your u-joint **** the bed. there should be little no play in the joints. have the car in neutral and spin your drive shaft left to right while looking at the u-joint. you should be able to determine if its bad fairly quickly. sometimes they may not show any play but could be frozen. if you take down the drive shaft the u-joints should move freely in every direction.

 

Seems plausible. Has it gotten worse ? I know of two people who have had U-joints fail (completely) on them while driving.....it was NOT fun.

 

thanks thats what i was looking for! gotta take a look once it stops raining. good thing i followed my friends advice and got a daily

yeah its worse now. when it 1st started i felt it a little over 40 and, now i cant drive over 40mph without feeling like im going to **** myself.

 

Its getting worse? U-joints fo-sho

 

thanks man gonna replace it with a new "used" one tomm.

 

It kinda funny but the same thing happened to my friend and his ae86... we thought for sure it was a u joint or the wheel bearing. Jacked up the car pulled the axels then looked at the drive line, here his bolts from the drive shaft > third member somehow came loose(about 1/8in gap between the two). Same story tho, he did some pulls, sudden nasty vibration, and the vibration started at 40 mph... cranked those bolts and smooth sailing since.

 

fixed it! thanks guys my dshaft was coming loose.