Mazda 3 - Slight bouncing / bumping feeling at speed

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Sat 20 Apr 2019 08:33
Mazda 3 - Slight bouncing / bumping feeling at speed - bigshorty40

Hi All

I bought a cheap Mazda 3 1.6 TS as a second car, mainly for the missus to potter about in. Everything looked fine when I picked it up, has 10 months MOT with no advisories on recent MOT, 118k miles done, full service history, drives well (or so I thought during the test drive), a couple of minor things that need doing, and there are a few scrapes and dents on the bodywork, but for only £500 I wasn't particularly worried about the cosmetic condition.

Anyway, I took a mate for a drive in it yesterday evening to see what he thought, and I decided to push it a bit just to see what performance was like. When the car hit around 60mph, which was something I wasn't able to do on the test drive due to the location the car was being sold, we both noticed a slight and rather rapid bouncing / bumping effect produced by the car. As soon as I let my foot off the throttle the bouncing effect seemed to go away. We initially thought it might be road surface but the road we drove on is very smooth, so I tried it on another bit of road but due to the poor quality road surface on most of the roads around here it was hard to determine whether it was doing the bouncing or not. There are no unusual noises coming from the car at all, gear changes are fine, no unusual wear patterns on tyres, driveshafts and CV boots look fine, it's very strange.

Not owning a Mazda before I didn't know if this was a trait of Mazda's, or whether I should be looking at anything else as to what might be causing this. I don't know if loosing a wheel balance weight or two might be causing this. Any thoughts as to what this could be, or any ideas on what I need to check would be greatly appreciated.

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Sat 20 Apr 2019 10:11
Mazda 3 - Slight bouncing / bumping feeling at speed - mcb100
First thought would be a tyre. Get them on a balancing machine to see if one of them has gone out of shape.
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Sat 20 Apr 2019 11:06
Mazda 3 - Slight bouncing / bumping feeling at speed - Fernando P

Could be either wheel balance or defective shock absorber or even both. Rough and ready shock absorber test is to press hard down on body above each wheel then let it spring up. If it is firm and does not bounce it is good. If it bounces more that once then the shock absorber is done. Then get balance checked. Another test is for someone to drive behind, to see if a wheel starts to bounce when speed increases which means the shock absorber is done.

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Sat 20 Apr 2019 12:13
Mazda 3 - Slight bouncing / bumping feeling at speed - Peter.N.

I would suspect an out of round tyre due to carcass failure.

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Sat 20 Apr 2019 13:31
Mazda 3 - Slight bouncing / bumping feeling at speed - bigshorty40

Thanks for all the comments, much appreciated.

Our son came around to have a look at the car today, he's a trained mechanic and he says that the shocks look fine, rebound is good, but without getting it on ramps he can't be 100% sure. However, he did notice that neither of the two front wheels had balance weights on them, which he thought was very odd as even though it's possible, it's highly unlikely that wheel weights won't be needed when balancing wheels.

It looks like I'd better get all the wheels and tyres checked next. I'll update this with any updates. Thanks again.

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