ctgreddy

Pretty much the only problem i'm having with my car is that now it shakes when you get above 75ish. it feels like its the driveshaft, because when I had my stock ds on it used to do the same thing until I swapped this one on, but it worked fine before. I also tried flippin it 180 degrees and same thing. any ideas?

67mustang302

Don't drive over 75?

Does the whole car shake, or just the column? Do you have poly mounts in anything? Did you get new tires suddenly? Has any change been made to the suspension or engine mounting that could effect pinion angle?

ctgreddy

I put a poly mount for the trans mount, I guess that could have changed the pinion angle, but it looks like its the same height as the stock mount. it is a new trans tho. Think it could be my pinion angle being off?

67mustang302

It's probably the mount itself, the poly doesn't really absorb vibration. I have poly trans and engine mounts and the car vibrates more with them, especially after the trans mount. On mine it tends to vibrate more between 2-3krpm(more engine vibration at that point that's transmitted) and in 4th gear over 100mph.

mjr46

if you think it's the mount then swap back to stock and see if the vibration goes away

ctgreddy

I'll have to try putting my stocker back on and see if that helps. Now I just gotta find it haha.

GGT

that angle is very sensitive only a degree or two

Tony71502

Measure the height of your stock mount vs the poly mount before swapping them. No point in wasting time.

As mentioned before, have you checked your front suspension? Are you POSITIVE that no suspension parts are damaged/worn out. Ball joints tend to have this effect.

ctgreddy

My ball joints are still in good shape. I didn't change any of that. Just dropped in the new motor/trans. I figure it's gotta be something like pinion angle or something. But I found out it only vibrates from 75-90 then it smooths out a lot

Jfsram

Driveshaft balance must be better than perfect when you combine drag racing gears and highway speeds.