Snapped an RE trailing arm bolt.. UPDATE With better pictures

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09-29-2012, 08:05 PM

#16

jasonlp

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Quote:

Originally Posted by TonyG

Extremely rare. I've seen it, but not with those adapters.

What rear shocks are those and is the lower shock eye in the center of the shock or offset?

TonyG

Bilstein Escort Cups and offset

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09-29-2012, 10:13 PM

#17

TonyG

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Quote:

Originally Posted by pontifex4

That looks like a Bilstein shock body.
Yikes! Here's hoping the BMW Grade 10 bolts I'm running don't do this.

Use 12.8 bolts.

TonyG

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09-30-2012, 01:54 AM

#18

reno808

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Quote:

Originally Posted by jasonlp

It's so rare it's not worth thinking about. This is the first picture of a broken trailing arm bolt on rennlist that I have seen. RE or not I have only ever herd stories and never seen a picture.

there is a couple of threads

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09-30-2012, 05:56 AM

#19

mikey_audiogeek

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Quote:

Originally Posted by DDP

Was that possibly over torqued when installed?

More likely the opposite. The bolt failed by fatigue, as evident by the beachmarking at the top edge of the fracture. This usually indicates insufficient tensioning of the bolt.

Also the area at final fracture is only about 65% of the area of the fastener, which is hard to achieve if the fastener has been tensioned to >70% of its ultimate tensile strength.

Last edited by mikey_audiogeek; 09-30-2012 at 06:15 AM.

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09-30-2012, 06:08 AM

#20

mikey_audiogeek

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I'm concerned about the mark shown here (circled inred): is there any chance that the bolt wasn't sitting square and flat against this surface? This mark seems to correlate with the oter edge of the fastener shank.

Attachment 668016

Last edited by mikey_audiogeek; 12-11-2012 at 05:34 PM.

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09-30-2012, 06:14 AM

#21

mikey_audiogeek

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...which might correlate with this edge here. I'd be concerned at the dark coloration between this edge and the fracture, seems to indicate insufficient contact.

Attachment 668017

Last edited by mikey_audiogeek; 12-11-2012 at 05:34 PM.

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09-30-2012, 11:35 AM

#22

s14kev

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What happened when it broke? Loss of control? Did your tire bind up in the wheel arch? Any damage to the remainder of the car?

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09-30-2012, 01:05 PM

#23

TonyG

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Quote:

Originally Posted by mikey_audiogeek

Show this picture but zoom out a little so I can see the bottom of the entire shock..

TonyG

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09-30-2012, 02:09 PM

#24

black944 turbo

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I think it was about 7-8 years ago this happened on another members car (a gold one) if I remember correctly. It shows it with the wheel tucked up in the body all the way.

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09-30-2012, 02:48 PM

#25

jasonlp

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Quote:

Originally Posted by TonyG

Show this picture but zoom out a little so I can see the bottom of the entire shock..

TonyG

Attached

Quote:

Originally Posted by s14kev

What happened when it broke? Loss of control? Did your tire bind up in the wheel arch? Any damage to the remainder of the car?

Thankfully nothing exciting, just pulled over and called a tow truck

Quote:

Originally Posted by black944 turbo

I think it was about 7-8 years ago this happened on another members car (a gold one) if I remember correctly. It shows it with the wheel tucked up in the body all the way.

You are correct, insufficient torque on that one.

Quote:

Originally Posted by mikey_audiogeek

It was it was one of my concerns, it was flush and torqued to RE spec with two torque wrenchs one standard one digital

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09-30-2012, 06:16 PM

#26

mikey_audiogeek

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Oh well, that's all the easy options ticked off.

Anyway, sorry to hear of the failure, hope you get up and running again soon!

Are you going to send the failed parts to Karl for assessment?

Best regards,
Mike

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09-30-2012, 06:20 PM

#27

jasonlp

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Quote:

Originally Posted by mikey_audiogeek

Thanks, I am going to send the pieces back to Karl, it's important to know what happened for obvious reasons.

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09-30-2012, 06:39 PM

#28

MM951

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I had the same issue with Ground Control shock mounts. After the second failure I upgraded to the Racers Edge mounts. I hope It doesn't happen again, a tow and new tire isn't cheap!