Pattern replacement caliper, unmachined mounting face?
Discussion
Morning,
Ordered a couple of replacement calipers from a well known online brake specialist.
The two calipers differ on the mounting surface which mates with the hub, one is machined and perfect, the other is much rougher and uneven across the surface.
As below (left vs. right):
I emailed asking to exchange the rougher example for one matching the other, but got told that they are 100% confident I won’t suffer any ill effect, they’ve been selling for years without a single complaint etc.
I’m fairly annoyed because obviously it’s not optimal, if it was then literally every OEM manufacturer in the wouldn’t bother with this extra machining operation.
Is it worth perusing and returning the calipers or just fit and forget? They’ll be going on a weekend toy which will be driven fairly spiritedly.
Many thanks
Ordered a couple of replacement calipers from a well known online brake specialist.
The two calipers differ on the mounting surface which mates with the hub, one is machined and perfect, the other is much rougher and uneven across the surface.
As below (left vs. right):
I emailed asking to exchange the rougher example for one matching the other, but got told that they are 100% confident I won’t suffer any ill effect, they’ve been selling for years without a single complaint etc.
I’m fairly annoyed because obviously it’s not optimal, if it was then literally every OEM manufacturer in the wouldn’t bother with this extra machining operation.
Is it worth perusing and returning the calipers or just fit and forget? They’ll be going on a weekend toy which will be driven fairly spiritedly.
Many thanks
Edited by Ryan_T on Tuesday 7th August 12:15
I'm interested to see how this goes.
It's alwayys hard to judge from photos, but it looks like the face HAS been machined, because you can see the step where the machining stock has been removed.
I'm guessing that this caliper was rejected by the OEM due to, for example, visible porosity on the machined face. This porosity or other damage has been welded or filled, and the repaired part sand blasted or painted over.
It could still function OK or you could have a loss in clamping load until the surface has been adequately compressed. You would have to keep retorqueing the fixing until it stabilised.
DIfficult to make a firm recomendation. It is safety relevant, so the tendence would be to reject it, but this is the reason they are cheaper than a perfect OEM part.
You could run a file over the surface to flatten it out a little, then should be OK.
It's alwayys hard to judge from photos, but it looks like the face HAS been machined, because you can see the step where the machining stock has been removed.
I'm guessing that this caliper was rejected by the OEM due to, for example, visible porosity on the machined face. This porosity or other damage has been welded or filled, and the repaired part sand blasted or painted over.
It could still function OK or you could have a loss in clamping load until the surface has been adequately compressed. You would have to keep retorqueing the fixing until it stabilised.
DIfficult to make a firm recomendation. It is safety relevant, so the tendence would be to reject it, but this is the reason they are cheaper than a perfect OEM part.
You could run a file over the surface to flatten it out a little, then should be OK.
I see what you mean. I wasn’t sure if the step down was part of the casting process, and then it’s just faced on machine. But also can see it also looks like an aggressive media blast (rest of the caliper, inc bolts share a similar finish).
The other concern is as they aren’t floating type calipers they’re going to be especially sensitive to how they are mounted.
Perhaps it’s best to source a set of 2nd hand OEM items and just rebuild them...
(Edit: just noticed one has been chamfered also and the other not..)
The other concern is as they aren’t floating type calipers they’re going to be especially sensitive to how they are mounted.
Perhaps it’s best to source a set of 2nd hand OEM items and just rebuild them...
(Edit: just noticed one has been chamfered also and the other not..)
They’ll both be reconditioned ones, one was probably rustier than the other when they refurbed it so had to re-face one at a guess, we sell loads at work and some look brand new and others, although have been reconditioned and painted have obviously been really corroded at some point and are all pitted
I'd want to confirm that the the two mounting faces are flat, in plane with each other, square to the bore and at about the right offset. That should be enough to ensure the caliper mounts correctly. A pitted mounting face is no problem as long as the 'high spots' are flat and in the right plane.
Edited by GreenV8S on Tuesday 7th August 15:39
addz86 said:
They’ll both be reconditioned ones, one was probably rustier than the other when they refurbed it so had to re-face one at a guess, we sell loads at work and some look brand new and others, although have been reconditioned and painted have obviously been really corroded at some point and are all pitted
I'd go along with this. The top one looks like new but the lower one is definitely reconditioned. It could be that the top one was rebuilt by a different re-manufacturer as the finish is different.BOR said:
I'm guessing that this caliper was rejected by the OEM due to, for example, visible porosity on the machined face. This porosity or other damage has been welded or filled, and the repaired part sand blasted or painted over.
That's not how manufacturing works! If a casting is faulty it's scrapped, not repaired; apart from safety issues, scrapping the casting is the cheaper option.As for the two calipers in the photo, the one on the left is obviously a used part which has suffered from rust on the mating face which has left a pitted surface after shot-blasting. To me it does look as though there's enough of the original flat surface left to give a proper location, but that's subjective.
It could be argued that the refurbisher should have refaced the mounting surface, but that could cause two problems. Firstly, without the OE jigs the new face could be out of square relative to the bore, etc., secondly, the removal of material from the mounting face would mean that the caliper was offset from its correct position on the vehicle.
What's kinda laughable about this is the calipers are going to get bolted to rusty old flanges on the hub which the OP has probably not given a second thought to. This is a not a cylinder head gasket face.It doesn't have to be flat to within microns. Calipers move about a bit. Find something more important to gripe about.
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