MX5 NC intermittent vibration problem

MX5 NC intermittent vibration problem

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sideways sid

Original Poster:

1,396 posts

222 months

Thursday 21st March
quotequote all
I've had a 55k 2007 MX5 NC hard-top for a few months which has developed an annoying intermittent vibration at 50-70ish mph.

Its standard spec, unmodified, on standard wheels etc.

Recently replaced rear discs and all pads, then did a 300 mile trip which was fine. Tyres are decent and car drove perfectly.

Left the car parked for a week and did a 100 mile round trip on A roads and Mway over the weekend with an audible vibration that I could feel through steering wheel and both passenger and I could feel through the seat.

It then disappeared for a few miles but returned on and off during the journey on various surfaces with me driving around it at various speeds.

Changing gear (so engine speed) and sticking the car in neutral (its a manual) doesn't affect the vibration, so its drivetrain rather than engine.

Obviously I checked tyres visually and checked tyre pressures. 29PSI all round.

Next I had rear wheels balanced yesterday and the vibration is still there.

I think alignment is ok as it was set up a couple of thousand miles ago, pulls straight, brakes straight etc.

A quick google revealed many suggestions of possible component failures, but nothing definitive.

Before taking it to the garage, I would welcome any thoughts from owners here. Thanks in advance.

Edited by sideways sid on Thursday 21st March 11:14

Johnnybee

2,323 posts

228 months

Thursday 21st March
quotequote all
Possibly sticky brake caliper, did you notice if any of the wheels were hot?

sideways sid

Original Poster:

1,396 posts

222 months

Friday 22nd March
quotequote all
Good call; thanks.

After a couple of short journeys with plenty of braking - I'll take it further tomorrow - everything is as expected.

Both front wheels are slightly warm to touch and the calipers warmer. Rear wheels and calipers slightly above ambient temperature. No noticeable difference across each axle.

sideways sid

Original Poster:

1,396 posts

222 months

Friday 22nd March
quotequote all
Jacked it up just now and one front wheel was locked up with others moving freely so booked in for a new caliper next week.

reggie747

137 posts

134 months

Friday 22nd March
quotequote all
sideways sid said:
Jacked it up just now and one front wheel was locked up with others moving freely so booked in for a new caliper next week.
No absolute need for a new caliper, you just need a simple and cheap service kit which will comprise of pins and rubber sleeve (pistons if required). Try Frentech for this.
The rubber sleeve over the top pin tends to gunge up, swell up and stop the pin returning and thus letting the pressure off the pad on the disc.
Fresh rubber sleeves and silicone grease on the rubbers should see them nice and easy.
Also, this seems to be a common problem with the NC calipers so a little overhaul annually dependent on mileage works wonders.