tommyukuk

Wheel wobble from 30mph that pulses in and out? mk2.5

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Morning all,

Our 2010 focus seems to have developed its own nice little steering wobble. It starts around 25 to 30mph, when travelling slow you can't see the wheel wobbling but you can feel it pulling up and down on the steering wheel. 

At around 40mph it turns to a more steady wobble which you can see on the wheel. 

At 60 to 70 it starts to pulse, so it will shake quite a lot for 10 to 12 seconds then fade away to nothing for 6 seconds, then slowly start to shake again for 10 to 12 fade away to being fine again. It doesnt last longer than 10 to 12 seconds vibrating at any time, or any more or less than 6 seconds of smooth driving.
I've not experienced a car that pulses it.. they usually either shake constantly or not.

I haven't gotten to changing the wheels around yet (front to back) going to try that this afternoon.

Feels like the front of the car vibrates a lot too, like you can put a bag on the passenger seat an all you see is it shaking around.

the car doesn't shake or vibrate when accelerating or breaking, no weird noises either.

was wondering if anyone has experienced this before - Just trying to get an idea of what it may be before i take it to a garage. 
 

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I have had cars that do this " At 60 to 70 it starts to pulse, so it will shake quite a lot for 10 to 12 seconds then fade away to nothing for 6 seconds, then slowly start to shake again for 10 to 12 fade away to being fine again. It doesnt last longer than 10 to 12 seconds vibrating at any time, or any more or less than 6 seconds of smooth driving."  

I might be wrong, but theory is that this is when two wheels are out of balance and they go in and out of sync with eachother as the two rotate at slightly difference speeds due to cornering or one having a different circumference than the other due to different amount of tyre tread wear.  Just my theory, I have never discussed it with anyone else so no idea if others would agree of laugh.

The worse car I had for that strange effect was a 1971 Vauxhall VX4/90 I had in 1982 when I was 19 years old.  I never had it investigated. In those days it was common to have 2nd hand tyres fitted at very downmarket tyre yards that did not have any wheel balancing facilities. New tyres were quite expensive in those days compared to now and I did not have any money to spare.

 

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Check to see if you've lost a stick-on wheel weight, one of mine literally dropped off while parked in the full sun last week! 😮  Would have to be a large one to cause your issues though, mine caused the normal 60+ wobble...I've just stuck that wheel on the back until I can get it replaced. 

I assume you've checked tyre pressures?  And checked for bulges in the tyre?

A wobble from as slow as 30mph is likely to be worse than wheel balance though, possibly wheel bearing, driveshaft, track rod/end or wishbone bushes.

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One thing to check is that the wheels themselves are seated properly and the wheel nuts are correctly tightened. I had a wheel wobble on my mk2.5 which was partially caused by the wheel not quite sitting right on the hub due to corrosion. 

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Finally got time to look at it this yesterday! Was going to test the back wheels on the front etc to try eliminate stuff. Took the drivers side tyre off, the whole inside edge was thread bare. no tread at all, but the rest of the tyre had plenty, passenger side was exactly the same no tread on the inside left but rest had plenty. also both tyres had 1 weight left on them, so im assuming since they were changed 6 months ago nearly all of them had fallen off!

 

Had both tyres changed this morning and theres virtually no shaking now, do need to get it all aligned tho to find out why its wearing on the inside.

Next Step.... working out how to get a Mcgard wheel nut off with a damaged key (dont want to buy another key or drill it) going to try weld something to it i think)

thank you for the help guys!

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if both had equally worn inside edges I am guessing it is tracking problem. Years ago I made myself a tracking gauge but it's a horrible job to do yourself on the driveway, particularly trying to get it so steering wheel is in absolute spot on correct position when driving straight. Years ago steering wheels were on fine splines and it was easy to take it off and put back on shaft in slightly different position. Not quite so easy now. 

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If you have a local National Tyres they have a voucher on the website for half price front wheel alignment.  I guess it's different prices depending on location but I only paid £14.50...

When I bought my mk2.5 it had exactly the same inner edge wear as yours on the original tyres, and a lot of others did as well at the time.  I think it was set 'wrong' at the factory tbh.  Not enough toe in at standstill, so when you're heading straight the wishbone bushes allow the wheels to toe out too much, causing excess inner edge wear.

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