Power:vibration roadspeed linked

[varesecrazy]

Got a weird vibration.

Car has done @20k with me..no issues.

Bought a replacement car ..swapped wheels around (mismatched stuff now on older car..
Good tyres for keeps)

Noticed a mild vibration @35/40 mph.. virtually 1st journey.. fine faster..or slower

Thinking it had thrown a balance weight..
I jacked front wheels.
Not running super true.. but no thrown weights evidence.

Same for @400 miles

Now its a really strong vibey shake..at 40 mph

Fine either side BUT

If you dip the clutch it stops..

Its roadspeed.. not engine rpm..

Wheels are a constant..

Driveshaft CV Maybe? ( diesel punto )

Ive never had a CV fail.. but the inboard boot was split.. so maybe joint compromised..

Would power on.off change it that much..?

Experiences welcome

 

[portland_bill]

Wheel balance normally shows around 50-60mph. Vibration at lower speeds, especially 35-40 would normally point to suspension joints, or with fwd, drive shafts. It's a long time since I encountered this, used to afflict early macpherson strut vehicles if the bottom swivel had play in it. Can also be caused by track rod ends.

Inner drive shaft joint could well be the culprit. They should run in a heavy oil, like a liquid grease, not the same stuff as the outer CV joints, but sadly most aftermarket joint and boot suppliers use the same stuff. The correct stuff is generally only available in large quantities.
This three toed joint uses roller bearings in spherical housings (you probably know this), and a loss of lubricant can cause them to give up quite quickly, although measuring or feeling any play is almost impossible.
In some cases a new inner joint is available, plus of course the boot kit, so much cheaper than the full shaft. If you can disconnect the sahft from the hub, you may be able to wriggle and jiggle it a bit and feel any slop.

 

[varesecrazy]

Thanks Nigel.

I will have a poke around when its raining less..