Fiesta booming noise at 45 mph

[arnieboy]

Hi,

I borrowed my wife's 93 Fiesta 1.8 diesel which she's had from new. At about 45 mph a sort of booming resonant noise appears and goes once past 50 mph. It comes back again around 65 mph but not as loud. The noise is different to a wheel bearing and the car drives normally apart from this. The noise is difficult to pinpoint but I think it is from the front. Can anyone suggest any cause, could it be a transmission noise? If you drive locally ie 30 mph zones you wouldn't hear any noise at all. Thanks.

[Steve]

have you checked all the tyres for bulges or splits?

Also hae you had the weehls checked for buckles or out of balance?

wheels bearings would be more apparent if you gently swerve the car left to right you should hear it change sound.

After this i would then look towards towards the transmission

[arnieboy]

have you checked all the tyres for bulges or splits?

Also hae you had the weehls checked for buckles or out of balance?

wheels bearings would be more apparent if you gently swerve the car left to right you should hear it change sound.

After this i would then look towards towards the transmission

Thanks for the advice. All tyres were changed this year at the same time and are the same as before, i.e. Michelins. I don't remember if the wheels were balanced but I don't get any vibration at all just the booming resonant noise. I had a wheel bearing go once before and it was much more high pitched so I am leaning towards a transmission noise now.

[Steve]

is the noise still apparent if you

1. press the clutch down at 45

2. coast in neutral at 45?

[arnieboy]

is the noise still apparent if you

1. press the clutch down at 45

2. coast in neutral at 45?

Thanks, I'd thought of 1. and pressing the clutch makes no difference. I am guessing 45 mph is a resonant frequency spot for something vibrating. It's weird as the car drives normally other than this noise.

I'll try No.2 to see what happens.