Getting parts flat - brake rotor warped

[rcx132]

This is an aftermarket drum to disk brake conversion kit. Contains a caliper mount bracket and a rotor that attaches the disk to the axle shaft.

It doesn't work because the rotor isn't flat. It looks laser cut from sheet steel so explains why it's not flat.

Could it be flattened? The shop that sold me it issued a refund and don't want it back.

 

[MattH]

Due to the thickness you'd probably have to look at getting it surface ground.

How much is it out?

 

[sasquar]

id probably just surface grind it flat depending on how out it is? But then i guess thats easy to say when you have friendly local subbies with surface grinders that dont mind the odd bit of 'special' work.....

 

[Fazerruss]

BFH to get rid of the worst then just put it in the lathe and take a skim off both sides. Surface grinding is a bit ott IMO

 

[Screwdriver]

You could have a go on my flypress or more likely, a nice flat anvil. I'm in Ealing...

 

[brightspark]

depends on how far its out. put some engineers blue on a glass plate and rub it over .depends on how long you want to spend on it to get it right . an angle grinder will take the high spots off if not to bad and you can get it very accurate with time and a bit of measuring

 

[Parm]

depends on how far its out. put some engineers blue on a glass plate and rub it over .depends on how long you want to spend on it to get it right . an angle grinder will take the high spots off if not to bad and you can get it very accurate with time and a bit of measuring

Work it through various grits of paper mounted on a glass plate, keep checking with some blue

 

[colnerov]

Hi, Some years ago I did some yard shunting and vehicle loading at a steel stockholders who did profile cutting as well, we would very often have to get some cut profiles out of the stress relieving ovens. Would that work now or does it have to be done when it's fresh cut?

Colin

 

[Morrisman]

How flat does it need to be? You can flatten plate simply by hammering it on a flat plate, but it takes skill and experience.

If it needs to be flat within a few thou then skim in a lathe, or surface grinding on a magnetic bed.

 

[Screwdriver]

I would be wary of knocking off any high spots on one side becuase if they are big enough to prevent the part from fitting, it could be enough to take the surfaces out of parallel and introduce runout.

The only critical issue is parallelism between the inner fixing points and the outerdisc mounting face. The best way to ensure they are co-planar is to turn the part on a lathe.

 

[PhillipM]

Heat it first to stress relieve it - my brake discs are just laser cut steel plate - I run them on the car, get them hot, vibrate a few fillings out in the process, and then they get skimmed back flat.

Otherwise you'll skim it and then find it moves from the stress in the material when they get hot anyway.

 

[bricol]

Careful when grinding plate on magnetic tables - had many instances of the plate being pulled flat to the table - when released it's still not flat.
Had to find a place in Italy once to sort of 30mm thick light testing turret - they glued it down. Returned to me absolutely perfect.

 

[Turbo]

depends on how far its out. put some engineers blue on a glass plate and rub it over .depends on how long you want to spend on it to get it right . an angle grinder will take the high spots off if not to bad and you can get it very accurate with time and a bit of measuring

That method won't work as you need both faces of the item parallel as well as being flat!

It will be difficult to hold that on a lathe as you need to skim the whole face in one cut. A surface grinder with a mag table would be better.

 

[brightspark]

could be done on a lathe using the faceplate .drill a couple of holes though the adaptor and countersink. then fasten it to the plate using countersink nuts and bolts then skim theres always a way depending on how far your prepared to go

 

[rcx132]

Thanks for all the feedback. I wont get to try anything for a while as I need to keep the drums for the IVA test so that the brake balance stays stock.