Recent content by Fogey

Sounds like they're replacing tripod-type CV joints with something a bit more sophisticated.

It's not that IC engines need gearboxes because they're (inherently) inefficient, it's because they are intrinsically constant-torque (with torque tailing off at very low speeds and very high speeds because of the practicalities of implementation). So a gearbox is needed in order that the...

Very interesting.

Hmm...

Yes - that corresponds to the findings described in Post 640. Three times the rotational speed - which prompted me to comment that maybe the root cause is something to do with a tripod-type CV joint.

Especially as the vibration has been measured as being 3x the roadwheel rotational speed. Unless there are 2 separate sources, and 2 different vibrations...

I wonder if this is the same vibration as in the Xpower?

If it's to do with rear suspension, we know that the Xpower rides higher than the others - has anyone noticed any difference in the vibration with the car carrying a heavy load in the rear (two large adults and/or stuff in the boot)?

Xpower is so tempting!

I read it as the first car was a non-Xpower MG4, then changed to an X-power after experiencing vibration.

(My Bold) You had the vibration problem with a non-Xpower?

Well, both sources of mechanical disturbance would serve to excite a resonance, though I'd agree that out-of-balance would be proportional to the square of the rotational speed, so is more likely to behave as seems to be commonly the case. Does the vibration disappear at higher road speeds?

Post 640 refers to a measured frequency of vibration - the fact that it's at 3x the wheel's rotational speed is probably a significant clue. I'm surprised it hasn't already been leaped upon! If the CV joints are the tripod type, then there's the source of the problem (surely!)... Not that it...

At 3x the rotational frequency, could this be pointing to the (probably inboard) CV joints - specifically "tripod joints" ? https://www.kmpdrivetrain.com/driveshafts/blog-tripod-vs-rzeppa-joint/ In which case the vibration would be an intrinsic shortcoming of the implementation?

Just a word of warning - the accuracy of tyre pressure gauges isn't something that you can necessarily rely on. Here's one which at least has something of an accuracy spec: https://www.pclairtechnology.com/tyre-pressure-gauge-in-line-head-psi-bar Watch out for cheap knock-offs though. Caveat...