Vibration above 45mph after T-5 Swap

[monk302]

Hello everyone,

So I got my car on the road last week with the T-5 swap. Under 45 mph the car is fantastic. Absolutely love it. However, if I get on the highway and start going over about 45 to 50 mph and above the drivetrain begins to vibrate. I was thinking it may be the driveshaft. I bought the driveshaft from CJ Pony as a DS that was already put together for the T-5 swap. If you guys could help me figure this out I would appreciate it. I don't even know how to begin to troubleshoot this one.

 

[Cobain03]

i'd say its a transmission related problem

 

[6Stang7]

check the rear u-joints. see if you can slide the rear of the drive shaft from side to side, or up and down.

 

[a.vannoy]

I would guess driveshaft too, maybe out of balance or the u-joints. loose transmission mount might also be the problem or even transmission alignment.

 

[monk302]

hmmm, I figured there would be a handful of opinions. This is going to suck to troubleshoot. The u-joints should be good since new ones came with the driveshaft I purchased from CJ Pony. I will check the crossmember again.

COBAIN03, I think you might be onto something there.

 

[meanroy]

Bad Vibs

Some people have had problems with T5 swaps because the angle of the tranny changed.
Did the driveshaft/tranny angle change when you put the T5 in?
On '65-66 the drive shaft angle is supposed to be around 3 deg. I'm not sure about the '68.
Ronstang knows a lot about this problem.
Roy.

 

[dennis112]

Try disconnecting your driveshaft and rotating it 180 degrees.

 

[STSFCTN67]

I had the same problem after my swap and I ended up adding a thick flat washer between the tranny mount and the crossmember. This raised the back of the tranny just enough to stop the vibration. I would always recommend getting the driveshaft balanced with the yoke and ujoints.