[Aspen235]

Public service announcement. Don't reuse strut pinch bolts after changing your springs,struts or hubs because very bad things can happen.

[SW111]

That looks pretty bad. I hope no one got hurt

[Aspen235]

No injuries, just metal bits, expensive metal bits.

[freakystyly]

That's pretty wild, looks like the knuckle sheared right off. Lucky there wasn't more damage.

There's always insurance, but your premiums will likely go up for a few years... Hope you are able to DIY it on the cheap. Maybe do the other corner too if you're doing control arms, etc..

[Aspen235]

No insurance due to location.
Will definitely replace bolts and nuts on both sides.
The bolt snapped and fell out, the knuckle cracked later on one side, then the other side exploding separating from the strut.

[cooolone2]

Have reused these, on all of my vehicles for decades!
Maybe someone here didn't quite use the proper torque spec? And also, there "IS" a thing known as manufacture defect and QC to catch such things, but Ultimately, percentages that escape detection is the norm, not exception.

But hey, change them if you like, nothing wrong with being overcautious!

Good Luck!

[Aspen235]

Now that I have educated myself on TTY bolts, they can't grip as well the second time and they have to stretch more to get to the torque spec. You can see here that the bolt is drastically over stretched and corrosion got started.
I know that I will never trust one for a second use.
I got away fairly lucky that I only trashed the suspension and one fender. It could have easily been a writeoff and serious injury or death if I had slid into traffic or went offroading.

[HP Autosport]

What did you torque it to? It looks like the bolt was over torqued, causing the threads to stretch and creating a stress point.

[Aspen235]

Agreed, it is over stretched. I didn't do the install myself. However, these bolt permanently stretch with the first use so the second time around will not be the same.
The right side of my car is ok so far, but I will put in a new bolt
I recently did the oil filter housing on my X3 and tried to reuse one of the small TTY bolts on it and it could not be torqued to spec. One time only.

[HP Autosport]

Originally Posted by Aspen235

Agreed, it is over stretched. I didn't do the install myself. However, these bolt permanently stretch with the first use so the second time around will not be the same.
The right side of my car is ok so far, but I will put in a new bolt
I recently did the oil filter housing on my X3 and tried to reuse one of the small TTY bolts on it and it could not be torqued to spec. One time only.

Once stretched the bolt is done. It will no longer hold torque.

[M3SQRD]

Originally Posted by cooolone2

Have reused these, on all of my vehicles for decades!
Maybe someone here didn't quite use the proper torque spec? And also, there "IS" a thing known as manufacture defect and QC to catch such things, but Ultimately, percentages that escape detection is the norm, not exception.

But hey, change them if you like, nothing wrong with being overcautious!

Good Luck!

Same here on e92 M3s, f22 and f82. I’ve been doing this for as long as 15 years with considerable track time and not a single issue. Proper torquing is key.

[Aspen235]

Originally Posted by M3SQRD

Same here on e92 M3s, f22 and f82. I’ve been doing this for as long as 15 years with considerable track time and not a single issue. Proper torquing is key.

Respectfully, I think you are missing the point. A TTY bolt cannot be torqued to proper spec a second time. It will not be as effective and the downside is not worth saving $10.

[M3SQRD]

Originally Posted by Aspen235

Respectfully, I think you are missing the point. A TTY bolt cannot be torqued to proper spec a second time. It will not be as effective and the downside is not worth saving $10.

So when you change spring rates at the track, you’re supposed to come with a complete set of TTY bolts? Also, a TTY can be retorqued beyond yield and it will develop a slightly higher preload as long as you don’t exceed the ultimate strength of a bolt. Have you ever seen the stress-strain curve of a straincert bolts preloaded beyond yield, unloaded and preloaded beyond the new yield point? Do you understand how yielding works? Just look at a grade 10.9 alloy steel (or an A286 140,000 psi bolt), imagine the preload takes you 25% beyond the yield strength, unload on a line parallel to Young’s Moduls, E, of the material and then preload the bolt again on its same E but starting from a plastic strain - what does the bolt do on the second preloading?

My approach has nothing to do to cost saving when I have an $8k suspension and $10k brake kit on the car. Practically speaking you can reuse TTY and use a torque that doesn’t require the extra X deg turn. I, and a large portion of all dedicated trackers and race teams, reuse suspension bolts without issue. I was wrong on the number of years because I did this with my ‘03.5 e46 M3 since Aug 2023 so 21 years, not 15 years without issue. I have designed and analyzed 10000s of different types of bolted joints during my 35 years as a structural engineer so I fully understand how bolted joints work. If this was a space program you replace bolts and nuts that are only preloaded to 75% yield due to requirements. Bolts and nuts can be reused without issue.