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Old 5th August 2022, 13:58   #1
Retap
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Default Front Brake disc groove query

Hi all its been a while

Just changed front pads and discs on Nigel it was overdue and has resulted in restoration of great braking performance.

The only oddidty i keep puzzling over is this edge groove machined out on one of the Eicher discs, only on one disc though not both??? see photo below. The discs that came off did not have this any ether....

At first I worried this loss of material from the edge of the disc may cause inbalance but its closer to axle centre so maybe not to bad still a slight inbalance but still puzzling what it is. My only real rational is a wear marker but why not machine this on both discs then or evenly around the circumference to keep it balaned? Could this groove actuaally be the factory balancing process of the disc? Do we think this is a flaw or seconds reworked part?

Hmmm, any thoughts?


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Old 5th August 2022, 14:45   #2
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Never seen that before, I would guess at it being for balance but wow that disc was way out if that's what it's for
Just done a little search on Google apparently it's a disc wear indicator
https://www.pistonheads.com/gassing/...&t=720952&i=20
Just scroll down and all is revealed.

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Old 5th August 2022, 14:53   #3
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Default Never seeen it befpore

The old discs where well ready i reckon a good 1/8" was gone they where mentioned in last mot so planned to do them at this time but the wear on th eold discs was not far off these grooves in the new disc but i to have not seen it before and found it odd especially as just seems to be machined out on one of the discs and not both of them.


EDIT


Strange the disc wear indicator is only machined on one disc i will have to recheck that next time the wheels come off.
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Old 5th August 2022, 15:30   #4
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I've always assumed it was to balance the disc, I have a set of new rears to fit on my 190 and one of them has the same bit (more or less) machined out of the edge.
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Old 5th August 2022, 16:58   #5
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Hard to tell from the photo, but it doesn't look like a machined finish.
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Old 5th August 2022, 19:56   #6
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Looks like proper rough ar$€d grinding,if my surface finish was like that I'd get the sack you can see where the wheel has bounced
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Old 5th August 2022, 20:27   #7
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i dont like it but they could only be bothered to mall one disc so yay
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Old 5th August 2022, 21:35   #8
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Quote:
Originally Posted by Retap View Post
Hi all its been a while

Just changed front pads and discs on Nigel it was overdue and has resulted in restoration of great braking performance.

The only oddidty i keep puzzling over is this edge groove machined out on one of the Eicher discs, only on one disc though not both??? see photo below. The discs that came off did not have this any ether....

At first I worried this loss of material from the edge of the disc may cause inbalance but its closer to axle centre so maybe not to bad still a slight inbalance but still puzzling what it is. My only real rational is a wear marker but why not machine this on both discs then or evenly around the circumference to keep it balaned? Could this groove actuaally be the factory balancing process of the disc? Do we think this is a flaw or seconds reworked part?

Hmmm, any thoughts?


It's for balancing ����


https://www.youtube.com/watch?v=p8mfw3WYBAM


And how it's done.


https://www.youtube.com/watch?v=SS12QOByiN8
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Old 6th August 2022, 09:24   #9
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Looks like proper rough ar$€d grinding,if my surface finish was like that I'd get the sack you can see where the wheel has bounced

You would have to sack a very, very expensive machine.


I suppose the manufacturers are only interested in that is balanced, not the finish of the groove.
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Old 6th August 2022, 13:30   #10
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Its a lot of material to remove from the disc and i dont have much confidence in the manfacturer process especilly when considered the other disc has no groove so one would like to assume it was made perfectly balanced but has been through the balancing test and did not need balancing in that expensive machine. Then in my mind as a former production manager it leads to a question of quality and process if two discs from the same production process have such a difference. I am going to drive Nigel tho regardless and we are going to stop when we need to right where need to.
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