Vibration is back please help.

[mickyh7]

Hello, ongoing vibration when I use my brakes hard.
I'm on my 3rd set of discs and pads in 3 years. Thought the originals were warped so put on some ECP ones, Pagid.
Within 1000 miles the vibes were back, I've put up with it for 5k-6k
Just fitted some EBC Grooved 345mm Discs and Ferrado Eco Pads. Bedded them in for 500 miles. Awesome braking now, until they are really hot and the vibes are back.
Scrubbing speed off on a concrete section of motorway feels like a wheel is going to snap off. Steering wheel is rattling.
It has to be felt to be believed. I've done all of the pad material on disc stuff over the years. It's not that. Could it possibly be a goosed Caliper?
Just passed an MOT (I mentioned it to the tester, but he found no play in steering or suspension).
2014 Audi A7 3.0 Quattro 60k
Brakes are perfect until very hot.
Can anyone shed some light on this problem?
Thanks.

[stevieturbo]

Is this happening after serious track use or something ?

Is everything being fitted and checked by a competent person ?

All too often in cases like this the best thing to do is fit OEM parts ( and ensure the likes of the hub flange etc is true )

[Lincsls1]

How are you bedding them in? And who's fitting the new stuff for you? I heard over tightening the wheel nuts can also cause the discs to warp.
The one time I followed a 'proper' bedding in procedure supplied with some performance brakes, the discs warped.
So now I just drive very normally after fitting new discs for a couple of hundred miles, nothing heavy, and I haven't had a problem since.

[mickyh7]

stevieturbo said:

Is this happening after serious track use or something ?

Is everything being fitted and checked by a competent person ?

All too often in cases like this the best thing to do is fit OEM parts ( and ensure the likes of the hub flange etc is true )

Q1 no, just fastish road.
Q2 yes, then rechecked by a third party.
Q3 Hubs are fine, 3rd set of discs so I'm ruling out poor manufacturing?
OEM parts are supplied parts from Pagid, both discs and pads in the Audi's case. No better with that brand.
Audi pads (Pagid in an Audi box were £295, Pagid pads from ECP are £45. I spent 20 years in Car Manufacturing and am aware of how OEM parts are sold at ridiculous mark up).
Last two sets of discs were clocked when removed and had 0.001" runout. Spec is 0.005"
I've never experienced this in a different make of car, and I've owned heavy, fast cars for years!
Perfect until very hot. I'll rebuild the calipers at the weekend and replace the slide pins.
I was hoping for someone who has had this problem themselves to post.

[mickyh7]

Lincsls1 said:

How are you bedding them in? And who's fitting the new stuff for you? I heard over tightening the wheel nuts can also cause the discs to warp.
The one time I followed a 'proper' bedding in procedure supplied with some performance brakes, the discs warped.
So now I just drive very normally after fitting new discs for a couple of hundred miles, nothing heavy, and I haven't had a problem since.

Hi, I put in my OP 500 miles bedding in.
If the wheel nuts caused warping, surely it would be at all speeds?
I'm scratching my head here.

[stevieturbo]

mickyh7 said:

Q1 no, just fastish road.
Q2 yes, then rechecked by a third party.
Q3 Hubs are fine, 3rd set of discs so I'm ruling out poor manufacturing?
OEM parts are supplied parts from Pagid, both discs and pads in the Audi's case. No better with that brand.
Audi pads (Pagid in an Audi box were £295, Pagid pads from ECP are £45. I spent 20 years in Car Manufacturing and am aware of how OEM parts are sold at ridiculous mark up).
Last two sets of discs were clocked when removed and had 0.001" runout. Spec is 0.005"
I've never experienced this in a different make of car, and I've owned heavy, fast cars for years!
Perfect until very hot. I'll rebuild the calipers at the weekend and replace the slide pins.
I was hoping for someone who has had this problem themselves to post.

Unless you bought them from the dealer or that supply chain, they are NOT OEM parts whether you think the manufacturer is the same or not.

I have seen similar problems before....almost always it's just poor parts or fitting. Just because something has a certain brand name, people think they're good. Even when they've gone through 2, 3, 4 sets of discs/pads.

OEM discs/pads is almost always the fix ( provided hub flange etc is true )

[Lincsls1]

I'm inclined to agree with the above.
Assuming you can feel the pedal pulse along with steering wheel shake, then the discs are warped. Or rather warping when hot and then maybe returning to spec when cool.
Are the calipers fixed or floating type?

[mickyh7]

Floating, single Piston.
If we were to believe all we hear about non EOM parts, 90% of all cars would have problems.
Who on earth shops at the Dealers for an older car?

Edited by mickyh7 on Wednesday 17th November 21:18

[Lincsls1]

mickyh7 said:

Floating, single Piston.

Edited by mickyh7 on Wednesday 17th November 21:18

Being a floating, single piston caliper, I'm less inclined to think its a caliper problem, but certainly a good caliper service wouldn't hurt.
Hope you find the solution and be sure to update the thread.

[mickyh7]

OK, so it seems to be fixed.
Took the Calipers to a brake specialist, engineering firm. Explained my woes to the main man.
He said he had experienced this before, but on heavy Mercs.
Because my Calipers looked fine on strip down, his fix was to rebuild the Calipers, but install
Stainless Steel Pistons.
I don't know if it's the heat expansion rate over Mild Steel or a clash of tolerances between the Piston and bore (on this occasion).
But he did say that in the past this had cured the problem for other people.
Whatever caused the problem has disappeared.
I tried everything to replicate the Juddering, but could not.
Time will tell.

[mickyh7]

Still not cured!
Booked in to see a German/Quattro specialist who wants to check Driveshafts,Propshaft,Bearings, bottom arms etc.
I'm not so sure it's caused by heat now, just big speeds i.e. weight of car pushing/forcing the (obvious, but elusive,) problem.
Almost like ABS kicking in, but no lights or codes stored.
Always worse on concrete sections of Motorway???
Really like this car, but I'm close to giving up on it now.