Pulsing vibration at around 55-65 mph

[chrismoore701]

Originally Posted by Keith Seymore

Usually if it's a "pulsing vibration" (what we call a "boom/beat") then there are two root causes that are combining, like a driveline disturbance combining with engine firing frequency.

What transmission do you have? Does it still do it if you pull the trans down from OD into Drive (for example), or from 3 into 2? That could provide clues.

Similarly, it could be a tire disturbance (imbalance, out of round) combining with driveline or a rear axle problem.

I think if you can find one potential root cause and fix it then it will take care of the "pulsing" effect.

Lastly, rear axle companion flange runout is when the flange (the part the driveshaft goes into) is not spinning true. If that is the case it whips the driveshaft like a jump rope, causing a vibration. You won't be able to check that for sure without a special (Kent-Moore) tool, other than using Rattenbury's techniques above.

In any case, I don't think it's a durability issue - just an annoyance.

K

How do you go about fixing the issue with the flange runout? I had this problem 20 years ago, and still have it. Did a frame off restoration and re-installed the axle. New tires and rims. Problem still there, so I believe it is in the axle. I have small front seal leak as well. replaced the seal and it still leaks. Making me think the rearend is the issue.