Strange vibration at speed

[JTodd]

My Sub has a strange vibration above 60 mph. It sounds / feels like a bearing, but does not change when loading or unloading one side or the other. It does stop when I let off the accelerator. It starts immediately when getting back on, even if maintaining constant speed. Vibration is there when running in 3rd or overdrive.

Over the weekend I replace both front calipers, one rotor and the brake pads. There is no noticable vibration in the steering wheel, but it seems that the driver's side door mirror vibrates to the point of blurring. The only thing I can think of is a CV. When changing the rotor and caliper on driver's side, I had no trouble turning wheel by hand and heard no grinding from CV or hub.

Anyone have any ideas?

[BUZZ]

Have you checked drive line U joints?
Can you feel the vib in the seat of your pants? So to speak of course.
z

[Robyn]

I had the same thing in my Blazer.
Water pump. Though for sure it was bearings or drive line.
New water pump and all is well.

[JTodd]

Buzz
Yes, it is felt through the floor and seat. The steering wheel has no shake at all. To check the u-joints, do you just look for lossness, or just replace them? I will check that before waterpump.

[JTodd]

After doing a search on u-joints, I see a number of symptoms listed that I have - squeeking when pulling away, vibration under throttle, and some others. Do the u-joints need to be pressed in or is a driveway repair? Others I have replaced required removal of ubolts and popping/prying them out if stuck. Are these the same?

[BUZZ]

You need a vise or a press for press in style. You can take drive drive line to a machine shop and pay not much really to have replaced.
To check for bad joint jack up rear so shaft will spin and hold shaft and pionion and try to feel for free play. Replace if there is any.
Buzxz

[NH2112]

It's a driveway repair. First, mark the ends of the shaft and the yokes they attach to so you'll reassemble things the same way they were. Then remove the snaprings, place the end of the driveshaft on a block of wood with the yoke oriented vertically, and hit the angled portion of the yoke with a hammer - the U-joints will slide out pretty easily. If they're the originals you'll have to use heat to remove the injected plastic retainers the factory uses, so unless you have a torch having the shop do it will be easier. If you do it yourself make sure to remove the grease fittings so the old grease has somewhere to go, and definitely wear safety glasses or a face shield because sometimes the ends of the caps blow off. It's best to work at arm's length too. Inspect the bearing cap bores for damage and wear, smooth out any imperfections with emery cloth or a flapper wheel on a die grinder or Dremel tool (carefully, it's easy to remove too much metal), and clean the snapring groove if your joints use external snaprings.

You can install the new joints with a large C-clamp and 2 sockets. One has to be big enough for the cap to fit inside, and the other slightly smaller than the cap OD. Insert the spider from the middle of the yoke (being sure the grease fitting is in the same location as the original), put the caps in their bores as far as they'll go, position the sockets and carefully tighten the clamp. The cap should go in smoothly - it will probably be tight, but it should be smooth. Once the cap's in far enough that you can install the snap ring, and the dust seal seats fully against the shoulder on the spider, swap sockets and do the other side. This is where you'll have to be really careful since the snapring you just installed takes away any margin for error when you're squeezing the 2nd cap in. If a needle falls off the side of the cap and you try to force it, you'll most likely blow the end off the stationary cap. If it doesn't go in smoothly, swap sockets and press the joint back out far enough to pull the 2nd cap off, check for a needle lying crossways at the end of the cap, and try again. Once you get both caps properly installed and their snaprings in, hit both sides of the yoke several times to seat everything and loosen the spider - it was probably very difficult to move before, right? If it's still hard to move, hit the yoke a little harder, or try greasing the joint then hitting it. There shouldn't be any binding, if there is you'll have to find the cause which probably means disassembling the joint again.

Don't worry, it's much easier to DO than to read about LOL

[JTodd]

Thanks NH
It is to rain today (figures, first day of qualifications for the Indy 500), but if there is a window of dry, I will jack up the rear and check them. Based on what I have read, I think these are a major part of the problem. I will post the results.

[Patrick m.]

This could also be a rear diff bearing, better check it out soon, if its a side bearing and the outer race spins in the housing, you are looking at some money to repair.
pop that cover off while the driveshaft is out and inspect it very carefully, pay special attention to gear tooth wear pattern, make sure the pinion is not loose and walking in and out. Pinion brgs generally make noise no matter what is going on with the throttle, but side carrier brgs (if loose) can change with throttle.
I,ve seen more than one pinion nut come loose and let the pinion gear run in and out of the ring gear, the only symptom at first was noise/vibration on/off throttle.

just a thought.