warped disks, can they be saved ?

[MassiveJim]

I bought a 2nd hand set of calipers/disks/pads off ebay but the disks were warped, the garage I used sent them to a local guy to have them machined, but they still vibrated badly under braking.

I replaced them with a set of genuine Ford disks and after a period of time they also warped.
So I then decided to replace disks and pads with brand new
i went for these discs (grooved only)
https://www.mtecbrakes.com/mtec1386.html
with mintex m1144 pads

fitted in Dec/Jan by Feb the disks had warped again.


Starting to get a bit fed up with the whole situation in honesty.
I spoke with the garage and he said that he has never had much luck with getting disks machined.

I can't understand why though, to my mind if a disk is machined flat then it should be no different than fitting a brand new disk.

I am not keen on spending £100 on yet another set of disks if there is anywhere that can machine the ones I have and get them to not vibrate under braking.

thoughts ?

 

[MassiveJim]

That's not what happens in any road car, even if it's tracked (nor does it happen in race cars).

As an aside, MassiveJim, one way you can potentially fix this is to go out and do a series of full-power emergency stops. I've cleared 'warped discs' this way in both my own and friends' cars.

I did try this with the current disks and it seemed marginally better for a few miles but now is worse than ever with noticeable vibration at speeds as low as 20/30mph

I got up to about 80/90mph and braked down to 30/40ish about 4 /5 times in a row

I did wonder if it could be caliper related as they were bought second hand off ebay.
the only thing is that my old disks also warped with my original calipers (upgraded my ST220 calipers to ones from an ST225)

 

[MassiveJim]

Don't think this helps in anyway but I kept the old disks and they look fine

https://imgur.com/gallery/fxpAY2b

Probably what is causing this is the last 15 minutes of my journey home is a good old b road. So when it's clear I give it the beans.

I have handed my notice in on current job though so that drive will come to an end soon

 

[MassiveJim]

Ecp have 50% off for the next 6 days so I could get a new set of either pagid, brembo or mintex disks for £75.

But it seems that warped disks may not be the problem here.
If the caliper is sticking and I get it freed up, I assume a heavy breaking session will clean the disk up and should alleviate the problem?

 

[MassiveJim]

So I've ordered a set of pins, I will ask the garage to give the calipers a good ole' cleanup. Including disk mating surfaces and the back of the alloys. Maybe can clean the disks themselves up with some cleaner.
Take it for a run do some heavy braking and then we'll see where we are at.

Then I'll have a think about replacing £180 quids worth of disks and pads.

 

[MassiveJim]

little update

given the advice in this thread, I decided to do a couple of hard stops this morning, on the 3rd or 4th hard stop I had huge brake fade and left a little cloud of smoke behind me.

After that the vibration was massively reduced, there was definitely some vibration still there although i cannot be 100% certain that isn't a wheel balancing issue.

That being said it does appear that this could be down to a caliper issue, when the car goes in to the garage I will have him service the calipers and hopefully that should resolve the issue.

IMO this was your biggest mistake, second hand brake components, just no.

As for warped discs, it’s largely unheard of tbh in anything other than hearsay, truck discs (which have a very much harder life than cars) don’t warp, even after getting red hot (you can see the glow through the wheels at night!)

As said, it’s the pads that tend to be the issue, assuming the callipers are ok which in your case OP it’s hard to prove they are ok given they were used to start with, if you do replace the discs & pads, get new (emphasis on new) callipers also.

I’m not sure why this is all bold?

The car is a 16 year old Mondeo ST220, and the standard brakes have a reputation for being poor so I upgraded the brakes to calipers/disks from a Focus ST. This is why I bought 2nd hand.

 

[MassiveJim]

I have no issue with second hand calipers as long as they were a good make/OEM rather than a knock off clone. If they looked too cruddy or rusty, then they would need the seals doing etc. 2nd hand pads and discs are false economy, unless you are totally skint

Its a common mod on the ST220 as the standard brakes are the same ones used on all engine sizes for that car.

As for the ones I bought, they still had the original red paint on them and did not look appear to be in bad condition, that said a cursory glance to my almost untrained mechanical eye does not mean that the internals are in good shape.

As I said I will get them serviced with new pins and see how I get on, by the looks of things I have probably wasted £280 on 2 sets of disks and a set of pads up to now thinking the disks were warped when they were not.