Hey all, just want to see what you guys might know about this little issue I'm having. I have a 91 F250 with the 351 Windsor and a 5 speed manual trans. Everything is great at normal city/back road speeds up to around 50-55mph, but, when I get to around 60mph and above, the truck starts to shake and the trans makes noise if I let off or step on the gas. Also, if I push the clutch in at those speeds, it also makes noise. Kind of like a rough shaking sound. Doesn't sound like grinding or anything like that and like I said, it only happens at speeds in access of 55mph. Any input or suggestions would be greatly appreciated!

-Beast

 

Likely cause is the driveshaft and or carrier bearing if so equipped, I suggest removing the whole works and taking it to a driveshaft specialist for balancing after being rebuilt, they can also tell you if the shaft is bent which is annoyingly common with the aluminum shafts. If it's steel you can replace the u-joints and carrier bearing yourself and that may be enough to solve your problem, but it still wouldn't be a good idea to have to whole works rebalanced after the rebuild.

 

Have you checked the U joints ?