Violent shaking while braking

Akagi

Akagi

Akagi

Caporegime
Joined
29 Jul 2011
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Hi guys, I have been experiencing vibration while braking for a little while, and it has now got to the point where I need to get it sorted as soon as possible.

It was like it before my MOT two months ago, which I passed with flying colours, but one of the advisories was relating to "play" in the steering rack.

I don't believe that it is to do with the steering rack however, I think that it is probably due to warped disks?

It happens under braking only as far as I can tell, I haven't noticed it with gradual non-braked deceleration, nor have I noticed any vibration at motorway speed.

If I were to decelerate fairly firmly from 80MPH to zero (in say, 200 to 250 yards) the shaking is really quite bad to the point where you can hear things/trim in the cabin rattling and you can see the steering wheel shaking.

My disks were fitted new by the garage just before I bought the car a year and a half ago, and since it is a low value car, I suspect they just put £15-a-side eBay specials on.

Other points to note, the tyres are new, it was the same before getting the new tyres fitted, the wheels have been re-balanced, but I still need to have the tracking & alignment re-done.

The car is a 2002 VW Polo 9N 1.2 AWY, and yes the notorious bushes have been replaced, as have several other components to the front of the car which are known for wear and tear. :)
 
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I had the same problem, just to be sure i acted a bit 'thick' and went to a local kwik-fit and explained problem, they confirmed 'warped' discs...and quoted £235!

I bought the discs & pads from GSF for around £35 and done it myself (don't skimp and buy just the discs, I done that before and ended up knackering the new discs!)
 
Brake disc's, new pads, & make sure the brake calipers are not seized. At this price point I would also "check the brake lines/hoses" and make sure the brake fluid is also changed on a 2002 car - when changing the disc's + pads.
 
Have had this in both a Fiesta and Focus. In both cases a disc and pad replacement sorted the issue.

It's a cheap and easy fix like others have said. :)
 
Find the route cause first.

If they are worn evenly and just coming to the end of their life replace. If the wear is uneven then find the cause first, you may have a sticky caliper. A good way to check for a sticking caliper is to feel the heat from the centre of the wheel after a run. A sticking caliper wheel will be scorching.
 
If it can't be cured with several 60-20mph attempts (until the brakes are fading/pedal is squishy) then a 5-10min drive without using your brakes, you will have hotspots on one or both of your discs which as it rotates are affecting the amount of friction that disc is giving. Think of it as sticky bits on your brakes which when it passes past the pad, creates a lot more friction causing the steering to pull slightly. Obviously when this happens at speed, a series of small pulls on the steering wheel = judder/shimmy.

Just replace the discs and pads if so.
 
You'd know if you had a sticking caliper, the wheel would be burning hot. It takes a lot more to warp a disc than you think, one of my old cars had a sticky caliper and it would pull up even but the wheel would be burning hot, I drove it for about 1000 miles like it (naughty me I know) and the disc was fine. It's far more likely that it's play in one of the track rod ends, especially seeing as play in the steering was mentioned when your car passed with 'flying colours'.

Gaygle said:
you will have hotspots on one or both of your discs
Click to expand...

No you won't, the heat will just transfer across the disc. You could probably spot where it's warped or deposits from the pads on visual inspection but as I said it's probably something else.
 
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Thanks all. Will try the things mentioned and do some reading. :)

Okay perhaps "with flying colours" wasn't the right term. There were 3 advisories, 1 was a tyre which is sorted, 1 was something I knew about and expected relating to the rear light being discoloured, and the steering rack was the third.
 
acemastr said:
You've chavved the rear light haven't you? :P
Click to expand...

Haha no I haven't chavved the rear light, the seal on the light has gone, and some water has gone in it, which has made the colours darken. It has since been emptied of water, dried out and sealed up, but it is still discoloured. Will probably replace it somewhen. :)
 
Janesy B said:
No you won't, the heat will just transfer across the disc. You could probably spot where it's warped or deposits from the pads on visual inspection but as I said it's probably something else.
Click to expand...

Yes, you will.

When the pad transfer stays on the disc for a decent amount of time without being cleared and going through multiple heat cycles, it forms an incredibly hard, crystalline structure which gets hot at a different rate to the rest of the steel disc around it, therefore creating a variant in friction levels.

This is what characterises hot judder as opposed to normal judder.
 
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