vibration

[Andy Jones]

hey guy's! i just re-balanced my wheels and im noticing a vibration between 35-45mph in the rear. i seem to think that I've always had it because my wheels have been poorly balanced in the past. this time my good neighbor balanced them at his wheel shop and it's still there!! any ideas what this could be? truck does need an alignment and new shocks, but i dont think this could be the Vibration problem could it??

[hobbyturnedobsession]

Possibly the drive line.

[Andy Jones]

what should i be looking for??

[philofab]

Check for side to side play in the double cardan. If the centering pin goes you'll get vibration.

[hobbyturnedobsession]

Also check the rear u joint, they tend to go too, and you'll get vibration.

[convoy]

From my past experience, typically vibration at a set speed range (ie. 35-45mph, 50-60mph, etc) is a rotational vibration caused by a misbalanced tire. Could be a drive shaft issue but you should feel that, or hear that, from light to med throttle and even letting off the gas. Could also rotate the tires from the back to the front and see if you notice a differance.

[Andy Jones]

well i'm still getting this vibration till this very day!!.. drive shaft seems to be good!.. wheels just got re-balanced on Friday!... so im stumped!!..
could it be a bad tranny mount?? the reason i ask is, when i drive my Bronco when its cold in the morning there's no vibration. but in the afternoon when its hot, it's there???... when i crawled under the Bronco this afternoon i noticed that the rubber that's in the mount seems very soft to the touch??!!

[F-150speed]

well i'm still getting this vibration till this very day!!.. drive shaft seems to be good!.. wheels just got re-balanced on Friday!... so im stumped!!..
could it be a bad tranny mount?? the reason i ask is, when i drive my Bronco when its cold in the morning there's no vibration. but in the afternoon when its hot, it's there???... when i crawled under the Bronco this afternoon i noticed that the rubber that's in the mount seems very soft to the touch??!!

I'm no expert but it seems plausible. I had a buddy with a Ranger with a 5 speed in it and it would vibrate any time it was in gear and the clutch was out. Turned out that the tranny mount was trashed and the small amount of vibration that was caused by the drive shaft not being perfectly balanced was causing the vibration. The new tranny mount absorbed that vibration and held the tranny in place but with that worn out mount the shaft had more leverage on the tranny and t-case and caused it to vibrate too.