Wheel vibration

Technical Area Wheels, Tyres & Brakes
1
  1. My model of MX-5 is: 2002 reg
  2. I’m based near: __Brighton
  3. I’m looking for technical help or recommendations on: vibration at speed

I recently changed all four tyres, and the performance of the car improved significantly, especially in the ride which became much softer. However when speed rises to above 60 mph you can feel a vibration in the vehicle. Cruically this does NOT feel as though it is unbalanced wheels because it does not transmit up the steering column, but feels as though it is coming through the suspension to resonate the whole car.

I want to emphasise that this was not present before the tyre change, and became apparent immediatelty afterward. I intend having the steering geometry checked at the upcoming MOT and svce. Meanwhile on anything other than fast road at speeds below 60 there are no symptoms.

Any clues guys ?

2

If nothing else has changed except the tyres, it figures that one of them is out of balance, buckled, out of true or similar. My moneys on a rear being out of balance- it’s not uncommon for tyre fitters to get it wrong.

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3

Agreed, also check the wheel nuts are done up properly!

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4

Thanks guys. I’ll look into those two thoughts.

Cheers

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5

Or a stick on inner weight has unstuck.
Or…they just got it plain wrong!

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6

what tyre pressures are you using?

7

What tyres did you have fitted? I had some cheapo ones fitted to mine when I first got it. Never again, no amount of balancing would get rid of the shake above 60. Got decent ones on now & no problem.

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8

If you don’t feel it through the steering it will be the rear !

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9

Thanks everyone for your help, I will follow all this up.

Cheers

10

Just to mention that I had something similar but it turned out to be a seized caliper which then warped one of the discs…

Check the temp of your brake discs after a run, IR thermometers are handy for this - mine was 60 degrees on one side and over 200 on the other!!!

Hope it’s nothing serious.

11

Have you solved this yet?

Could well be a dodgy tyre or balance of course.

Are your wheels original, or aftermarket? I had a similar problem, without going into tedious detail, on a Mk2 years ago. There was a spigot ring missing on one corner and I put it down to that. I only noticed when I removed the wheels to swap them so I couldn’t absolutely confirm it, but the car had a noticeable body shake at 60/70, no steering wheel shake though.

MX-5s have spigot mounted wheels, I imagine a wheel doesn’t have to be far off-centre to cause a vibration at speed.

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Clean up the wheel hub face and the part of the wheel that mates on the wheel hub, dirt and rust can unbalance the them. Also prop shaft can be out balance or rubber mountings dried out or cracked.