Redrilling brake discs

[Lewy]

 as an engineer -

Who is? A what?

Publication flicker more like!

[pro-biotic]

personally as an engineer again - i`d do it.

on the basis that:-

1)the disc is held concentric using the centre hub
2) the location screw is mearly there to stop the disc turning during fitment of the wheels
3) the main reaction stopping the disc turning is the friction of the clamping force between wheel and hub.

this is on the basis that:-
 1)a reasonable amount of material is left between new and old holes
 2)the holes are done using a dividing head
 3) the holes are about 1mm oversize to the wheel stud - or whatever a std clearance is

perhaps the older holes could be inserted or welded.


i personally can not see anything wrong with the idea, the only thing you may have to watch out for is disc balance, but again if you have access to a machine shop i guess you know how to balance a disc

[JC]

 as an engineer -

Who is? A what?

Publication flicker more like!

 

[VeeDubGTI16v]

nova boys have been doing this for years on their v6 disc brakes. it will be fine

[jammac]

personally as an engineer again - i`d do it.

on the basis that:-

1)the disc is held concentric using the centre hub
2) the location screw is mearly there to stop the disc turning during fitment of the wheels
3) the main reaction stopping the disc turning is the friction of the clamping force between wheel and hub.

this is on the basis that:-
 1)a reasonable amount of material is left between new and old holes
 2)the holes are done using a dividing head
 3) the holes are about 1mm oversize to the wheel stud - or whatever a std clearance is

perhaps the older holes could be inserted or welded.


i personally can not see anything wrong with the idea, the only thing you may have to watch out for is disc balance, but again if you have access to a machine shop i guess you know how to balance a disc

Well id never do it. Basically vandalising something that stops your motor from moving is asking for trouble! by drilling another 5 holes in a brake disc you are weakening it beyond what its been designed to do whatever anybody says.

it might be ok, but it might not! from my experiance if something can go wrong it will.

[Conker]

Why drill one hole when you can drill hundreds of the f##king things - the less metal the better.  Weight saving innit.

Drill some holes in the brake pads as well while your at it.

 

[DarnPB]

They would need to be either,exceptionally good and very expensive disc's, or made of gold to even think about re-drilling them for fitment to another pattern. Like I said before, cheaper to go buy the correct ones for the application, rather than butcher existing ones.
If I bought a car and found that whilst having a wheel off for some reason, I would think WTF??.. and replace them immediatly.

[DOA]

"perhaps the older holes could be inserted or welded."

You certainly wouldnt want to weld them (too much stress and possible deformation, its a long process anyway with the sort of materials used) and inserts wouldnt do anything but Im with you on the other points.

[VeeDubGTI16v]

i cant see the problem, the holes are only there to allow bolts to pass through, wont the stress will be acting on the face of the disc/wheels? (since theres so many 'engineers' in this thread  )

basically i agree with pro-biotic.

[topher]

Since it's such a popular phrase around here..

as an engineer.. the wheels hold the brake discs on anyway.. BUT 4x100->5x100 is a tricky conversion. You'll use one original hole and space out from that, but that won't give you the (and this is the 'as an engineer bit') 3xdiameter of the bolt spacing you need. You'll end up with 2 situations of a smidge over 15mm c/c, which with a 1mm oversized hole for the M14 bolts means you'll have an overlap as per the pic below

Which means at any given time in any direction under braking you'll have the rotational resistance in the disc spread over 4 bolts rather than 5. I could now spend several hours in calculations involving applied forces for shearing but why bother when 4 stud cars drive around fine without shearing hub studs?