Brake Recommendations - w204 Coupe C250

[OneForTheRoad]

old pads on new discs are surely prone to warping the discs . maybe not if both mating surfaces are fairly true. definitely a no no if the pads have developed areas of grooves and high spots .

 

[Bellow]

old pads on new discs are surely prone to warping the discs . maybe not if both mating surfaces are fairly true. definitely a no no if the pads have developed areas of grooves and high spots .

Can you explain a plausible mechanism by which the discs can warp due to pads other than brand new - and bear in mind, pads aren't brand new for long?

Me and thousands of others have been replacing pads without new discs for decades and have never had discs warp.
Replacing everything with new needlessly is a wasteful fetish.

 

[OneForTheRoad]

Can you explain a plausible mechanism by which the discs can warp due to pads other than brand new - and bear in mind, pads aren't brand new for long?

Me and thousands of others have been replacing pads without new discs for decades and have never had discs warp.
Replacing everything with new needlessly is a wasteful fetish.

Yeah . Fitting pads that are used from another car that are misshapen. Like i said.

 

[markjay]

Can you explain a plausible mechanism by which the discs can warp due to pads other than brand new - and bear in mind, pads aren't brand new for long?

Me and thousands of others have been replacing pads without new discs for decades and have never had discs warp.
Replacing everything with new needlessly is a wasteful fetish.

You're looking at opposite scenarios here.

 

[Bellow]

Yeah . Fitting pads that are used from another car that are misshapen. Like i said.

That is no explanation.
The cutting tool on a lathe is 'misshapen' but it doesn't warp the rotating piece it is brought into contact with - the reverse.

 

[OneForTheRoad]

That is no explanation.
The cutting tool on a lathe is 'misshapen' but it doesn't warp the rotating piece it is brought into contact with - the reverse.

So youd fit a set of shyte pads to new discs and not worry about warping?

 

[markjay]

My view, as per what I was taught many years ago...:

1. New pads on new disc - fine, no problem.

2. New pads on old discs - fine as long as (a) the discs are not nearing their minimum thickness, and (b) the discs are still reasonably smooth i.e. they are not too badly grooved, otherwise the discs need to be skimmed.

3. Old pads on old discs - OK only if the pads and discs were matched together from new, but not OK if the old pads were originally bedded-in with a different set of discs.

4. Old pads on new discs - never.

But as I said..... things may have changed since. It was a very long time ago.

 

[Bellow]

Me and thousands of others have been replacing pads without new discs for decades and have never had discs warp.
Replacing everything with new needlessly is a wasteful fetish.

So youd fit a set of shyte pads to new discs and not worry about warping?

Can you read?


The reasons for warped discs is in how the brakes are used. Holding them on when stationary after a stop that heated them. Precisely the reason why rally drivers release the pedal at the end of a stage. But for many, the effort of applying a park brake selecting neutral is too much and therefor some myth is required to explain warped discs.

 

[OneForTheRoad]

Can you read?


The reasons for warped discs is in how the brakes are used. Holding them on when stationary after a stop that heated them. Precisely the reason why rally drivers release the pedal at the end of a stage. But for many, the effort of applying a park brake selecting neutral is too much and therefor some myth is required to explain warped discs.

now dont be rude, maybe you need to take a minute and read not just what ive said but others too. read it slowly and let it bed in , just like a set of old brake pads on new discs.


heres a scenario for you, youve just fitted a pair of front discs at £200 for instance , your pal who owns the same car type and has pads that have covered say 58,000 miles , hes changing his pads and gives you his old pads , would you fit them to your calipers ??

 

[ToeKnee]

heres a scenario for you, youve just fitted a pair of front discs at £200 for instance , your pal who owns the same car type and has pads that have covered say 58,000 miles , hes changing his pads and gives you his old pads , would you fit them to your calipers ??

If that was my scenario, I'd fit the pads that were on originally with the old discs if they were serviceable, if they weren't then I'd fit new pads.

 

[OneForTheRoad]

If that was my scenario, I'd fit the pads that were on originally with the old discs if they were serviceable, if they weren't then I'd fit new pads.

the old discs were on his pals car. so you agree youd fit new pads to new discs , never old pads from someones else's car .

 

[ToeKnee]

I wouldn't fit ANY old parts from someone else's car, and especially not brake parts! Happy to refit used brake pads from my OWN car with new discs though!

 

[OneForTheRoad]

I wouldn't fit ANY old parts from someone else's car, and especially not brake parts! Happy to refit used brake pads from my OWN car with new discs though!

Thank you. Point made...

 

[Will]

Unless they’re heavily grooved then I’d expect those used pads to bed in within a few hundred miles anyway. It’s friction material, it’s designed to wear away. The pad is the most sacrificial part - it has several millimetres of wear material, by comparison the discs don’t wear that much.

New pads wear in to old discs, not really any different in reverse. Likewise discs can be skimmed, to clean up the surface - you don’t always have to fit new pads if they’re healthy.

I’m fairly sure I’ve seen a MB document stating that this is acceptable - if you were replacing discs that were unsatisfactory (corroded, warped, perhaps worn) but the pads were in good order then no real harm in using them other than a longer bedding in period.

It’s an unusual question as most people don’t notice/measure the wear on the discs, they replace pads when they’re worn out and if the discs look past their best they change them as a pair. But just because it’s something that you wouldn’t usually do doesn’t mean it cannot be done.

 

[Deleted member 151559]

I wouldn't be bothered either way, however some questions:

Old discs new pads - will the discs last the life of the new pads?

New discs old pads - new textar pads are only £45 f £27 r, how long are the old pads going to last...

Is it really worth doing the job twice?

P. S. Disc warping is a myth. What you get is pad transfer of material onto the disc, this gives the characteristic pulse in the pedal and uneven braking. Improper bedding in or holding the car still on the brake with hot discs will do it.