Seriously worried now

N

Nelly Welly

Active member
Today the story goes.....

2.5'C 5:15 am. Travelled six miles at normal local road speeds with no issues.

Accelerated to motorway speeds and as I got above 50mph violent, out of balance shuddering !!!


Reduced speed to below fifty whilst holding on to the steering strongly.
Four or five minutes later the oscillation that felt like running on a flat tyre, subsides gradually to an almost undetectable light vibration.

Continued journey of 100 miles at "normal" motorway speeds without further incidents.

No over temperature of brakes or tyres. No under inflation. No visible damage.

I just no longer know where to look ?

:headbang: :headbang: :headbang:
 
Sounds like you may have picked up something on one of your tyees and it's knocked the wheel balance off, and whatever it's been has gradually released itself. I had a similar thing a while back when a lump of road tar stuck to a tyre. All the same I'd have the tyres checked for any signs of damage or puncturing - you may well find that something is still stuck to it
 
pvr said:
simonlpearce said:
Wouldn't completely rule out a sticky caliper either.
Click to expand...

The wheel would be very hot though.
Click to expand...

It depends when you check though as in the OP he said he resumed normal driving after it stopped. You would have to stop whilst it was happening and check otherwise under normal driving the wheel/brake would cool back to a normal temp.
 
Sticky caliper is my guess. The symptoms you describe are exactly what happens when it gets stuck. Sometimes they free themselves if you brake lightly, and like Simon says ( :rofl: ) if you drove on normally for a bit you won't have an overheated wheel.

Had exactly the same issue on two previous cars (both BMW of course) and exactly the same caliper design as the Z has. It's easy enough to check, and replacements aren't that expensive if needed (you part-ex your old one).

If you have glazed and warped the disc, you'll feel it through the pedal under braking... :thumbsup:)
 
Had this happen around a year ago now the symptoms were the same as loosing a balancing weight of the wheel but checked over the car when I got home and nothing but was a light smell of burning rubber from off side left wheel but nothing since this happened.
 
Defo sticky caliper pulled off the M3 into Bracknell and used a hose to cool the discs and calipers in a huge cloud of steam.......


:o :o :o

The stuck caliper returned and I could drive slowly home..

The brake force oscillations were like driving on a flat tyre.
 
You'll probably need a new disc as they don't take kindly to that sort of heat (or the thermal shock you gave it by spraying water on it).

Actually, you'll need two as you need to replace them in pairs. And two new calipers, get refurnished ones from Euro Car Parts or similar and you get a rebate on your old ones when you return them (with the original receipt).
 
Will check with a DTI the run out but I played the hose on the wheel centre and not directly on the disc so to reduce the temperature without the radial stress playing on the disc would cause.

The caliper was sounding like the fluid was borderline boiling under pressure so needed to cool that area as an urgent requirement.

Have new calipers, discs and pads so will change all of it in one go. I was trying to find out what causes the caliper to stick but nothing has really given that indication so I am going to I vestige if the caliper is sliding correctly on the pins as that's the only thing that appears to be the issue as the piston appeared to be returning without a problem.

:wink: :x
 
Disc run out less than 0.003" so happy no distortion has occurred.

Replaced the callipers and pads to be sure on both sides and the brakes feel firm and the sound of the brakes applying and releasing is reassuring.


Will give them a 200 mile test on Monday and let you all know but the immediate feel is the wobble and instability seems to be gone.

:thumbsup: :thumbsup: :D :thumbsup: :thumbsup:
 
Subsequently I replaced both discs and calliper brackets as well and having done a 100mile motorway commute in atrocious weather conditions I am happy to say the relaxed drive has been restored. No more vibration and no more wobble even the imbalance that appears at around 65 is now no more than a slight tremour. (Wheels balanced next)

Driving pleasure has been restored.

:D :D :D :D
 
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