New Discs and Pads required

Wheels, Tyres, Suspension, Chassis, Issues and Fixes
TheTraveller
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Post by TheTraveller »

Earlier this year I replaced the front pads only. Because it’s got Porsche warranty, I decided to replace with OEM parts. At the OPC, the guy who I know only advised me to purchase pad wear indicator sensors also, (good call as they are so brittle it’s virtually impossible to remove without damage). He never suggested new bolts.
I went ahead and replaced the pads. The bolts are a monster size, they need to be. And I torqued them down to my wrench max, 160 lb/ft. I couldn’t feel any stretch at all, even at that leverage. And I’m still alive and kicking. As said it could be a bit of profiteering by Porsche.

AndyC160
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Post by AndyC160 »

frankstar123 wrote: Mon Aug 23, 2021 10:47 pm How do,

Done 21,000 miles and Porsche have reported all brakes need doing. Front pads worn 95% :)

Porsche have quoted nearly £2000 for replacements. I'm capable of doing them myself but I'm actually struggling to find a place that can supply them or alternatives?

Anyone got any recommendations or links to the OEM part numbers?

Thanks

F
I guess the brake pad wear indicator came on at some point?
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Nuclear Nick
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Post by Nuclear Nick »

MCDK wrote: Tue Aug 24, 2021 8:03 pm So new bolts needed every time you get new tyres or a puncture repaired or even re torque your bolts to make sure they are tight as you are meant to do 100 miles or less after they were torqued. Sounds major overkill and Porsche profiteering.
The difference here is between Stress and Strain. Stress is when the bolt, for example, is torqued up to a value that does not exceed its elastic stretch limit and therefore will relax to its original length when released. It can be reused many times. Higher levels of torque will stretch a bolt more but take it nearer to its elastic limit. Designers will do this to avoid larger bolt sizes. Strain means the bolt has exceeded its elastic limit and will retain permanent stretch and be weakened. For safety reasons higher stressed bolts should be replaced. I can't think of a more safety related component than brakes, and bolts are cheap so it makes sense to replace them. In this case the manufacturer will be specifying replacement each time for safety, not profit.

While we're on the subject, just a reminder not to grease any fixings on wheels or brakes that are torqued to a specific level. Lubrication could mean the bolt going beyond its elastic limit and failing either during tightening or in service.
Nick

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CamGTS
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Post by CamGTS »

Traveller the caliper bolts should be torqued to 30 Nm, then further tightened with another 90o turn to provide the correct final tightness – this is as per official workshop manual instructions. If you've torqued them to 160 lb/ft (220nm) they will almost certainly be over stretched.
gasgas1
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Post by gasgas1 »

like to my purchase, got them at a2zmotorspares £168, pads and fitting spring all round, great guys to work with.


TEXTAR FR + RR Axle BRAKE PADS + SENSORS for PORSCHE MACAN 3.0 S Diesel 2015
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Tim92gts
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Post by Tim92gts »

Nuclear Nick wrote: Wed Aug 25, 2021 7:28 am
MCDK wrote: Tue Aug 24, 2021 8:03 pm So new bolts needed every time you get new tyres or a puncture repaired or even re torque your bolts to make sure they are tight as you are meant to do 100 miles or less after they were torqued. Sounds major overkill and Porsche profiteering.
The difference here is between Stress and Strain. Stress is when the bolt, for example, is torqued up to a value that does not exceed its elastic stretch limit and therefore will relax to its original length when released. It can be reused many times. Higher levels of torque will stretch a bolt more but take it nearer to its elastic limit. Designers will do this to avoid larger bolt sizes. Strain means the bolt has exceeded its elastic limit and will retain permanent stretch and be weakened. For safety reasons higher stressed bolts should be replaced. I can't think of a more safety related component than brakes, and bolts are cheap so it makes sense to replace them. In this case the manufacturer will be specifying replacement each time for safety, not profit.

While we're on the subject, just a reminder not to grease any fixings on wheels or brakes that are torqued to a specific level. Lubrication could mean the bolt going beyond its elastic limit and failing either during tightening or in service.
To be clear the WSM should spec grease and torque, a good graphite grease will reduce torque required by c50%.

In some applications an assembly grease is essential. Oil gives a lower torque reduction.
Tim
PP Turbo, LED PTV ACC Pano 20"Macans collected 6th September 2017
1992 928GTS
2003 996 Cab
TheTraveller
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Post by TheTraveller »

Tim92gts wrote: Wed Aug 25, 2021 2:51 pm
Nuclear Nick wrote: Wed Aug 25, 2021 7:28 am
MCDK wrote: Tue Aug 24, 2021 8:03 pm So new bolts needed every time you get new tyres or a puncture repaired or even re torque your bolts to make sure they are tight as you are meant to do 100 miles or less after they were torqued. Sounds major overkill and Porsche profiteering.
The difference here is between Stress and Strain. Stress is when the bolt, for example, is torqued up to a value that does not exceed its elastic stretch limit and therefore will relax to its original length when released. It can be reused many times. Higher levels of torque will stretch a bolt more but take it nearer to its elastic limit. Designers will do this to avoid larger bolt sizes. Strain means the bolt has exceeded its elastic limit and will retain permanent stretch and be weakened. For safety reasons higher stressed bolts should be replaced. I can't think of a more safety related component than brakes, and bolts are cheap so it makes sense to replace them. In this case the manufacturer will be specifying replacement each time for safety, not profit.

While we're on the subject, just a reminder not to grease any fixings on wheels or brakes that are torqued to a specific level. Lubrication could mean the bolt going beyond its elastic limit and failing either during tightening or in service.
To be clear the WSM should spec grease and torque, a good graphite grease will reduce torque required by c50%.

In some applications an assembly grease is essential. Oil gives a lower torque reduction.
Any lubrication, either oil, grease, graphite or whatever is at hand, would be ok around the threads, or the shank of the bolts. But should never be at the mating faces, as this is where the torque settings are arrived at the R and D dep’t. This goes especially at the wheel nuts/bolts.
MikeM
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Post by MikeM »

CamGTS wrote: Wed Aug 25, 2021 11:18 am Traveller the caliper bolts should be torqued to 30 Nm, then further tightened with another 90o turn to provide the correct final tightness – this is as per official workshop manual instructions. If you've torqued them to 160 lb/ft (220nm) they will almost certainly be over stretched.
Jeez :roll: Though OP is still alive and kicking, but wait a minute... What’s that “PING⁉️:o :lol: :lol:
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Tim92gts
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Post by Tim92gts »

TheTraveller wrote: Wed Aug 25, 2021 7:53 pm Any lubrication, either oil, grease, graphite or whatever is at hand, would be ok around the threads, or the shank of the bolts. But should never be at the mating faces, as this is where the torque settings are arrived at the R and D dep’t. This goes especially at the wheel nuts/bolts.
Whatever is at hand could be a bad idea!

For ferrous to ferrous not too crucial but alloy nuts on steel threads need Optimoly TA or similar.
Tim
PP Turbo, LED PTV ACC Pano 20"Macans collected 6th September 2017
1992 928GTS
2003 996 Cab
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