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      01-14-2021, 08:37 PM   #45
lebaaron
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Quote:
Originally Posted by joni_titi View Post
Just watch on ISTA+ and your right BMW says to replace the bolt. If you look a different torque spec chart on ISTA you can see that BMW says to replace most of the bolt that are related to suspension and brake. This way they protect themselve from any possible lawsuit.

Anyway, you win. I guess the ''right way'' is to replace those bolt if remove them, those and any bolt related to suspension.



Yes but only after washing them at delicate cycle .
lol I just can't hate the sarcasm 😁
however I ordered all my parts, thank yall for your precious feedbacks and recommendations
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      01-15-2021, 03:19 AM   #46
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Quote:
Originally Posted by joni_titi View Post
Just watch on ISTA+ and your right BMW says to replace the bolt. If you look a different torque spec chart on ISTA you can see that BMW says to replace most of the bolt that are related to suspension and brake. This way they protect themselve from any possible lawsuit.

Anyway, you win. I guess the ''right way'' is to replace those bolt if remove them, those and any bolt related to suspension.



Yes but only after washing them at delicate cycle .
It's not about winning or losing.
But the is difference between a "torque to yield bolt" and a normal torqued bolt, since the first one is streched and will not shrink during removal. Not sure if this is the right term but I'm sure you know what I am talking about.
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      01-15-2021, 11:26 AM   #47
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Quote:
Originally Posted by BWbimmer View Post
The wheel bolts are no "torque to yield bolds" , the caliper bolts are.
I can't find anything to indicate caliper bolts are torque to yield or require replacement after use. Please provide documentation to support.
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      01-15-2021, 01:00 PM   #48
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This is what I found.

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      01-15-2021, 06:31 PM   #49
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"The desired result of tightening a fastener is to obtain a proper clamping force between parts. The clamping force prevents loosening when the vehicle is in use and external forces act on the clamped parts. All fasteners have a specified torque. The method used for a particular application is determined by engineering and specified in the service information. It is necessary to apply the fastener torque to the specific fastener identified. Applying torque to the mating fastener can damage the fastener, mating components or provide insufficient clamp load.

There are three different methods for the specification of tightening fasteners:Closeup of Torque Wrench

Torque (T)
Torque + Angle (TA)
Torque + Angle-to-Yield (TAY) (a.k.a Torque-to-Yield (TTY)).

Torque

A fastener with a torque specification can be tightened with a conventional torque wrench. Generally, externally threaded fasteners (bolts, screws, studs) tightened to this specification method can be reused unless otherwise specified in the service information.

Torque + Angle

A fastener with a torque + angle specification must be tightened first to the torque part of the specification and then tightened further by the addition of the specified angle. The angle must be applied relative to the mating fastener, if present, or relative to the mating surface. A backup wrench must be used, if required, to prevent the rotation of the mating fastener while the angle is added to the fastener with the torque + angle specification. Generally, externally threaded fasteners tightened to this specification method can be reused unless otherwise specified in the service information.

Torque + Angle-to-Yield

A fastener with a torque + angle-to-yield specification is tightened in the same way as the fastener with the torque + angle specification. The difference between a torque + angle specification and a torque + angle-to-yield specification is that the tightening results in permanent deformation of the externally threaded fastener. Externally threaded fasteners tightened to this specification method must not be reused and must ALWAYS be replaced if loosened.

Tightening in Stages

Generally, service information specifies a fastener tightening specification in stages. An individual fastener with a torque specification is tightened to the specified torque in one pass.

For torque + angle and torque + angle-to-yield specification fasteners, the fasteners are tightened in stages. All the fasteners are tightened to a torque specification on the first pass. Next, they receive another tightening to a specified angle on the second pass. Sometimes more than two passes are required. Always refer to the appropriate service information for proper tightening in stages.

On applications with more than one fastener, such as wheel nuts or cylinder head bolts, the fasteners should be tightened to specification by alternating between the fasteners to ensure the parts are not distorted and that the fasteners are torqued evenly. Once a specified minimum of torque has been achieved for each bolt, the bolts should be tightened completely to specification.

Reusing the Fastener

Think of an externally threaded fastener (bolt, screw or stud) as a spring. As the threads are tightened, the spring is stretched. With a conventional torque or torque + angle tightening specification, the spring returns to its original length when loosened. In the case of a torque + angle-to-yield tightening specification, the spring is overstretched (plastically deformed) and does not return to its original length. For this reason, the torque + angle-to-yield tightening specification requires the externally threaded fastener to ALWAYS be replaced."

Whenever I've encountered TTY fasteners the manuals have always been specific that new fasteners must be used. I have a Bentley manual for our 328D and it does not specify that the fasteners are TTY or must otherwise be replaced after a single use.
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      01-16-2021, 08:07 AM   #50
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Quote:
Originally Posted by catskillclimber View Post
"The desired result of tightening a fastener is to obtain a proper clamping force between parts. The clamping force prevents loosening when the vehicle is in use and external forces act on the clamped parts. All fasteners have a specified torque. The method used for a particular application is determined by engineering and specified in the service information. It is necessary to apply the fastener torque to the specific fastener identified. Applying torque to the mating fastener can damage the fastener, mating components or provide insufficient clamp load.

There are three different methods for the specification of tightening fasteners:Closeup of Torque Wrench

Torque (T)
Torque + Angle (TA)
Torque + Angle-to-Yield (TAY) (a.k.a Torque-to-Yield (TTY)).

Torque

A fastener with a torque specification can be tightened with a conventional torque wrench. Generally, externally threaded fasteners (bolts, screws, studs) tightened to this specification method can be reused unless otherwise specified in the service information.

Torque + Angle

A fastener with a torque + angle specification must be tightened first to the torque part of the specification and then tightened further by the addition of the specified angle. The angle must be applied relative to the mating fastener, if present, or relative to the mating surface. A backup wrench must be used, if required, to prevent the rotation of the mating fastener while the angle is added to the fastener with the torque + angle specification. Generally, externally threaded fasteners tightened to this specification method can be reused unless otherwise specified in the service information.

Torque + Angle-to-Yield

A fastener with a torque + angle-to-yield specification is tightened in the same way as the fastener with the torque + angle specification. The difference between a torque + angle specification and a torque + angle-to-yield specification is that the tightening results in permanent deformation of the externally threaded fastener. Externally threaded fasteners tightened to this specification method must not be reused and must ALWAYS be replaced if loosened.

Tightening in Stages

Generally, service information specifies a fastener tightening specification in stages. An individual fastener with a torque specification is tightened to the specified torque in one pass.

For torque + angle and torque + angle-to-yield specification fasteners, the fasteners are tightened in stages. All the fasteners are tightened to a torque specification on the first pass. Next, they receive another tightening to a specified angle on the second pass. Sometimes more than two passes are required. Always refer to the appropriate service information for proper tightening in stages.

On applications with more than one fastener, such as wheel nuts or cylinder head bolts, the fasteners should be tightened to specification by alternating between the fasteners to ensure the parts are not distorted and that the fasteners are torqued evenly. Once a specified minimum of torque has been achieved for each bolt, the bolts should be tightened completely to specification.

Reusing the Fastener

Think of an externally threaded fastener (bolt, screw or stud) as a spring. As the threads are tightened, the spring is stretched. With a conventional torque or torque + angle tightening specification, the spring returns to its original length when loosened. In the case of a torque + angle-to-yield tightening specification, the spring is overstretched (plastically deformed) and does not return to its original length. For this reason, the torque + angle-to-yield tightening specification requires the externally threaded fastener to ALWAYS be replaced."

Whenever I've encountered TTY fasteners the manuals have always been specific that new fasteners must be used. I have a Bentley manual for our 328D and it does not specify that the fasteners are TTY or must otherwise be replaced after a single use.

Thanks a lot, you are the man
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      01-16-2021, 10:03 AM   #51
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Quote:
Originally Posted by paulymu View Post
Where can i purchase these rotors and pads from?
I got all my stuff from Bimmerworld.
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      01-17-2021, 01:45 PM   #52
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Quote:
Originally Posted by catskillclimber View Post
I have a Bentley manual for our 328D and it does not specify that the fasteners are TTY or must otherwise be replaced after a single use.
I believe this is from BMW for my 2017 F33 LCI (might be different for other years or chassis):

Attachment 2491929

It's quite clear that the 12MM bolts should be replaced.
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      Today, 01:43 PM   #53
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Quote:
Originally Posted by paulymu View Post
Anyone ever used this brand?
I've never tried that brand but I have to admit the lower price is attractive. The one fear I have of moving away from either BMW/Zimmerman/StopTech or other premium brands, is warping.

Way, way back on BMW #1 (e46 sedan) I tried 'eco-brand'. Warped in less than 4 months. I've been on BMW/OE since and never had a problem. It might have been bad luck but my experience does not seem to be unique.
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      Today, 02:13 PM   #54
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Quote:
Originally Posted by BWbimmer View Post
It's not about winning or losing.
But the is difference between a "torque to yield bolt" and a normal torqued bolt, since the first one is streched and will not shrink during removal. Not sure if this is the right term but I'm sure you know what I am talking about.
I see the practical advantage of TTY bolts say in the case of the guibo to prop shaft bolts, or the collar bolt that holds the rear (or front in xDrive) axle to the wheel hub. I would definitely replace those bolts. But consider the bolts that hold the strut bar to the strut tower. They too are qualified as TTY bolts. Are owners throwing bolts in the trash each time they do an alignment of the front strut or loosen that bolt to move the front strut bar?

No exaggeration when I say a lot of BMW mechanics do not chuck out caliper bolts each time a rotor is changed. Practically, around rotor change number 3, I chuck them out because the head can start to wear a bit. Those bolts require significant effort to loosen and re-tighten. Stripping the head of the bolt would be a huge pain in the a$$ to deal with.

TTY aside, I don't want to spend 4 hrs changing a single rotor due to a stripped caliper bolt . . . . or maybe I just love spending money on my car.

It's probably #2.
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      Today, 02:31 PM   #55
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Quote:
Originally Posted by johnung View Post
Akebono pads are no better than average and they are ceramic so they literally don't work when they are cold. Get in the car to go to work and no brakes!
My experience is similar but only when the car was parked outside in the winter. For the first couple of minutes of use it did take time for the Akebono's to warm a bit before pad bite became aggressive. The pads do work cold, you just need to press on the brake harder. As they warm, less input is required.

When garaged during the winter, time to max bite with less brake pedal input was less. By the time the car was at the end of the driveway, it was fine.

A nice aspect I like about the Akebonos was the included wear sensor. To avoid killing my calipers, I will drive the pads to the point where they just about hit the sensor then swap pads, reusing the sensor. But I have found in one example, even when not burned through, the sensor died. It seems sensor life is 'variable' so if one is included in the box, nice touch. No need to reuse. Nice touch Akebono.

Oddly, BMW says to replace sensors each time pads are swapped but then fails to include a sensor it in either the front or rear pad set. So, Akebono is at least more diligent about including the sensor than BMW.

Why?
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      Today, 03:23 PM   #56
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Quote:
Originally Posted by menncars View Post
I see the practical advantage of TTY bolts say in the case of the guibo to prop shaft bolts, or the collar bolt that holds the rear (or front in xDrive) axle to the wheel hub. I would definitely replace those bolts. But consider the bolts that hold the strut bar to the strut tower. They too are qualified as TTY bolts. Are owners throwing bolts in the trash each time they do an alignment of the front strut or loosen that bolt to move the front strut bar?

No exaggeration when I say a lot of BMW mechanics do not chuck out caliper bolts each time a rotor is changed. Practically, around rotor change number 3, I chuck them out because the head can start to wear a bit. Those bolts require significant effort to loosen and re-tighten. Stripping the head of the bolt would be a huge pain in the a$$ to deal with.

TTY aside, I don't want to spend 4 hrs changing a single rotor due to a stripped caliper bolt . . . . or maybe I just love spending money on my car.

It's probably #2.
I absolutely agree with you about #2 :-)
We easily spend 200 bucks on some fancy performance parts so I would feel bad not to follow BMW advices to replace a couple of screws

And I agree with you as well about the possibliliy to reuse some bolts. But only if I know how often they already have been opened. We might do break jobs ourselves and know about the condition of our parts. But again, if someone here ask how to do a job I don't know the history and condition of the car. With 155+ Tkm the screws could have been opened for more then once. OP's car could be a fixed salvage title or what so ever, water salt, outside parking. So rather save than sorry.

So keep on rolling and follow Tavarish's motto: Wrench every day
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