Vibration and intermittent brake squeal.

[Doctor Gollum]

Mercedes w168 A Class 186k miles.

About a year ago it had two new Dunlop tyres and new Apec discs all round along with genuine Mercedes pads.

When I bought it, it had a bad vibration at speed which I put down to the crap front tyres. Replaced with Dunlops and better, but still gets a shudder going from 75 (indicated) and only obvious on the fronts.

Additionally, it has recently acquired an intermittent squeal from the NSR brake, goes when pedal is pressed and not speed related. Investigating this, I discovered that the disc on that wheel has a 5mm diameter discrepancy as the disc spins. This doesn't cause the squeal as the noise isn't constant, but it might make pads sit crooked which could cause the noise as they rock. There is zero hub play or bearing noise so clearly the disc is faulty.

It has occurred to me that if the front discs might be just as out out of round.

Question 1. Could an out of round disc cause the same sensation as an out of balance wheel?

Question 2. Fitting genuine would guarantee round discs but will also double the value of the car. If I take advantage of one of ECPs generous price corrections, my choices are Eicher/Pagid/Brembo with respective new pads.

Of those three options, which discs are most likely to actually be round rather than oval?

TIA

[Sir Tigger KC]

Maybe the Merc pads and Apec discs are a bad match? 

The pads are probably harder than the discs! 

[Doctor Gollum]

Maybe the Merc pads and Apec discs are a bad match? 

The pads are probably harder than the discs! 

good point... I started with EBC ultimax pads, but they faded horribly so switched to genuine

Discs have done about 15k and pads around 12k, so both are definitely worn rather than slightly used.

[aaronjb]

Yep, an out-of-round disc could give you a lovely wobble, same as an out of balance (or true) wheel 

I always had good success with EBC (ran Yellow pads on the MR2 for a long while), but haven't used them in some years now. Out of your list, I'd probably choose Brembo, though I bet they all come from Mao's Poundland originally.

[Andy B]

I learned with my 24v Senator that it's easier & cheaper in the long run to buy OE discs.  I had loads of problems with pattern discs from suppliers that just blamed me for fitting them wrong. OE discs just fit & work

[TheBoy]

Note that Pagid are now exclusive to ECP in the UK. Even when they weren't, they were a mid range option from their manufacturer TMD. Their budget range is Mintex, and higher end Textar.

Apec, as you have found out, is also a budget brand, and only suitable for the most Daisy of drivers.

If you occasionally drive spirited, its worth investing a decent brands (not the once decent brands that are now little more than a marketing exercise to shift shite quality stuff, like Mintex).

[Doctor Gollum]

Went with Brembo and 50% off*. Will find out by Wednesday whether the vibration has gone as replacing two pattern tyres with Dunlops to match the other pair and be getting them all balanced properly 

*I know that this means that I paid what they should have cost rather than saving lots. 

[Auto Addict]

Went with Brembo and 50% off*. Will find out by Wednesday whether the vibration has gone as replacing two pattern tyres with Dunlops to match the other pair and be getting them all balanced properly 

*I know that this means that I paid what they should have cost rather than saving lots. 

I had vibration on my Insignia, had the wheels 'force balanced' which cured it.

[Doctor Gollum]

New discs and pads all round, new tyres on the front and half worn tyres rebalanced and moved to the rear.

No brake squeal and no vibration upto 80ish. So job jobbed.

Needs an inner track rod end as slight play on the driver's side, but that's no big deal.