Juddering Under Braking - FYI - Polo 9N 1.4 16v (Auto)

[ihpj]

Thought I'd post the following just in case it might prove useful to others:

I recently drove my Mother's Polo only to find that, under braking, there was a definite shudder - felt through the steering wheel - to the N/S/F.

I decided to have a wee poke and couldn't find anything obvious. The pads looked as if they had plenty of meat on them and the discs had (IMHO) a slight lip. Nothing obvious - so I booked it into VW to have a look (car has extended VW warranty).

A quick search of this forum (and Google) revealed that others had also suffered from this juddering and it was (almost always) attributed to 'warped discs' - and I fully expected VW to diagnose this as the fault

They duly came back and advised that both the discs and pads had worn down to below minimum spec. and that is why the car was juddering - their fix (helpfully) was for them to replace the pads and discs (£300).

Now, just to put things into perspective:

The car is a 2005/05 Polo 9N (auto), has covered only 28K from new and had pads changed in Jan '07 @ 16.5K miles.

They (VW) tried to imply that this level of wear was quite normal for such cars and anyway driving characteristics dictate brake wear etc. etc. - I asked them to give me in writing what the min. specs are for both pads and discs and then to measure the brakes in front of me to show me that they had indeed worn down to such a point; or alternatively if the were suggesting that the brakes had 'warped' then clearly this was an equally unsatisfactory situation and perhaps the goods supplied were not of merchantable quality in the first instance.

This resulted in furious conference with the elusive and never seen 'Service Manager' - then miraculously a solution was offered whereby that if we pay for the parts, VW (goodwill gesture) would pay for the fitting. Parts cost was £80 +VAT and I agreed.

I could have changed the pads/discs myself - but in any event, I would have had to spend that much on parts...with free fitting it made sense to let them do it.

I wanted to post this experience to assure other 9N owners that if you should you suffer from similar symptoms, stick by your guns and insist your dealer resolves the situation to your satisfaction. It is unacceptable for these cars to eat pads and discs as quickly as they do.

Anyways, happy (and safe) motoring to all!

[RUM4MO]

Well, I'm not sure how to take this info, to start with I am certainly not up for supporting VW when they are wrong, but, I must say that I have, only last week, measured the discs and pads on my wife's late 2002 reg'd 2003MY Polo 1.4SE manual trans with 54000 miles on the clock, and the front pads have >7mm of friction material left and the front discs are >20mm. I did this for my records and just in case my VW dealer tried to issue an official "advisory note" on the wear level of the pads (MOT guideline min 2mm pads new 11mm) - but in the event they didn't!

Auto trans cars do not offer any engine braking so they wear their pads and discs quicker than a manual trans - as there is less control of speed, this thinking is backed up by the fact that the front pads had been replaced already at 16500 miles. I'd reckon that my wife's Polo will not need its pads replaced - both front and back, until it has completed at least 60000 miles - that is almost four times the distance your mother's car's front brakes lasted - I think that the actual driving quality or brake duty used has contributed to the early demise of these brake parts - I mean both the way the car is being used and the fact that it is an automatic. If anything, my wife tends to under use the brakes by anticipating - this can lead to the rears rusting up and the fronts glazing in winter - but I tend to be hard on them when I use the car at weekends. BTW, my Passat 4Motion 2.8, known as a car that "eats" its brakes (as it is heavy) only needed its pads and discs changed at 35000 miles! The warping could be getting made worse by the driver holding the car on the brakes - this keeps one section of disc hotter for longer while the rest of the disc cols back down.

Splitting the cost this way seems to be the way the motor trade works, the bought in parts need to get paid for while the labour can get "lost" over the period of a working week due to some "slack" in the individual task time allowance - ie everybody paid for your free labour as you contribute to other's free labour.

For you to notice a lip would probably mean that the front discs had dropped in thickness from their new dimension of 22mm down to 20mm and the minimum dimension is 19mm.

[ihpj]

For you to notice a lip would probably mean that the front discs had dropped in thickness from their new dimension of 22mm down to 20mm and the minimum dimension is 19mm.

I think I am reading what you are saying correctly - that the minimum thickness for these types of discs is 20MM...if this is the case then I am shocked that VW discs have a life of only 3MM - I would have expected more.

I understand what you are saying about Auto's - but still, in relative terms the Polo is a light enough car. To put it into perpective:

E46 330i BMW - 60K miles on original discs and pads changed circa 30K.
Lexus RX 300 (New Shape) - 55K miles on original discs and pads changed at 33K.
Golf VR6 (2.8 Auto) - 50K on original discs and pads changed circa 28K.

That is a snap shot of the cars we have owned and driven well. None of them have gone through pads/discs at the rate at which this 9N seems to. But seeing as you mention 20MM being the MIN. thickness for the discs - thats a very low tolerance IMHO and no wonder they go through their discs so quickly.

In any event, I don't think I could have gotten the discs/pads changed for any less than I did - good value for money IMHO. But should these give out in the next 25K miles then I will have to look at alternatives as it is unacceptable that these cars go through discs so quickly.

[RUM4MO]

I was saying that the minimum thickness wa actually 19mm - from a new thickness of 22mm - so you guess correctly that there is only an allownace of 3mm - if I remember correctly, the rear discs (solid) star at 9mm and should get changed at 7mm - so that is only 2mm. What you must remember is that there is some "muddy thinking" in the car manufacturers that means some wise ones say change discs whe minimum thickness has been reached, while others warn that the pads you fit when the discs have reached their minium thickness should be th elast ones you fit to these pads. You must remember that it is not the car manufacturers that impose this start>finish thickness, it will be the brake designers - and they will be correct, as the calliper needs to traverse the disc from new disc + new pad thickness to old disc minimium thickness + old pads minimum thickness. Its just the way that these parts have been correctly designed, I'm sure BMW and Toyota will come under the same useage constraints.