What's actually holding the suspension together when you use an OEM crash bolt? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

2Wavy · 05-24-2019, 03:45 PM

So i had crash bolts installed during my coilover install. I was wondering, what exactly is holding together the strut to the wheel bearing piece? If the hole in both the strut and the wheel bearing is 16mm, but the crash bolt is 14mm, what is holding the two in place? I get the clamping force is holding the bolt to the strut, but how is the strut being held to the wheel bearing piece if the bolt is smaller than both holes?

JD001 · 05-24-2019, 03:57 PM

Magic.

jamal · 05-24-2019, 04:04 PM

The friction from the clamping force. That's how any bolted connection actually works. Even with the 16mm bolt in 16mm hole, try loosening them both and wiggling things around- there's a good amount of play there.

Mr.ac · 05-24-2019, 04:36 PM

Dude.....that's some good shit your smoking.
But seriously dude, pass that stuff over this way.

strat61caster · 05-24-2019, 04:49 PM

https://en.wikipedia.org/wiki/Bolted_joint

maslin · 05-24-2019, 05:31 PM

Magnets?

Spuds · 05-24-2019, 05:37 PM

Quote:

Originally Posted by jamal

The friction from the clamping force. That's how any bolted connection actually works. Even with the 16mm bolt in 16mm hole, try loosening them both and wiggling things around- there's a good amount of play there.

Just don't suggest that's how wheels stay on the car. All hell will break loose.

2Wavy · 05-24-2019, 06:05 PM

Quote:

Originally Posted by jamal

The friction from the clamping force. That's how any bolted connection actually works. Even with the 16mm bolt in 16mm hole, try loosening them both and wiggling things around- there's a good amount of play there.

So the two flanges of the strut are basically squeezing together the spindle and the friction keeps them in place? That makes more sense to me. So really the diameter of the bolt doesn't matter as long as it's thick enough that the bolt doesn't stretch right?

Mr.ac · 05-24-2019, 06:13 PM

Quote:

Originally Posted by 2Wavy

So the two flanges of the strut are basically squeezing together the spindle and the friction keeps them in place? That makes more sense to me. So really the diameter of the bolt doesn't matter as long as it's thick enough that the bolt doesn't stretch right?

Why are you seeking logical answers?
Your high as fuck now.

jamal · 05-24-2019, 06:43 PM

Bolts stretch when you tighten them. The important thing is having enough clamping force before the bolt starts to permanently deform or breaks (although some fasteners are designed to yield permanently at torque spec).

The OEM "16 mm" bolts are still M14 bolts, just with an enlarged shank. The threaded section is the same size and so are the torque spec and resultant clamping force. The larger bolt will stretch slightly less.

Capt Spaulding · 05-24-2019, 07:35 PM

Yep, bolts are actually springs. When you torque them down they stretch, preloading the spring/joint.

2Wavy · 05-25-2019, 12:37 PM

Quote:

Originally Posted by jamal

Bolts stretch when you tighten them. The important thing is having enough clamping force before the bolt starts to permanently deform or breaks (although some fasteners are designed to yield permanently at torque spec).

The OEM "16 mm" bolts are still M14 bolts, just with an enlarged shank. The threaded section is the same size and so are the torque spec and resultant clamping force. The larger bolt will stretch slightly less.

Oh yeah true, I guess bolts wouldn't work as fasteners if they didn't have an elastic deformation range and the axial deformation is where the clamping force comes from.

EAGLE5 · 05-25-2019, 01:06 PM

Bolt use magic.

86MLR · 05-25-2019, 08:54 PM

Red Loctite

Disclaimer: Don't use red Loctite

05-24-2019, 03:45 PM	#1
2Wavy Member Join Date: Jun 2018 Drives: 2016 BRZ Location: California Posts: 42 Thanks: 8 Thanked 18 Times in 8 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	What's actually holding the suspension together when you use an OEM crash bolt? So i had crash bolts installed during my coilover install. I was wondering, what exactly is holding together the strut to the wheel bearing piece? If the hole in both the strut and the wheel bearing is 16mm, but the crash bolt is 14mm, what is holding the two in place? I get the clamping force is holding the bolt to the strut, but how is the strut being held to the wheel bearing piece if the bolt is smaller than both holes?

05-24-2019, 04:36 PM	#4
Mr.ac [insert cool phrase here] Join Date: Aug 2015 Drives: BRZ Premium Location: Central Coast CA Posts: 2,369 Thanks: 709 Thanked 1,558 Times in 930 Posts Mentioned: 30 Post(s) Tagged: 0 Thread(s)	Dude.....that's some good shit your smoking. But seriously dude, pass that stuff over this way. __________________ New daily driver - Subaru BRZ Premium Weekend fun/track car - '91 MR2 Turbo Gen3 Old daily driver - '88 MR2 Supercharged

05-24-2019, 06:43 PM	#10
jamal Senior Member Join Date: Nov 2011 Drives: Legacy GT Location: compton Posts: 534 Thanks: 9 Thanked 365 Times in 204 Posts Mentioned: 11 Post(s) Tagged: 0 Thread(s)	Bolts stretch when you tighten them. The important thing is having enough clamping force before the bolt starts to permanently deform or breaks (although some fasteners are designed to yield permanently at torque spec). The OEM "16 mm" bolts are still M14 bolts, just with an enlarged shank. The threaded section is the same size and so are the torque spec and resultant clamping force. The larger bolt will stretch slightly less. Last edited by jamal; 05-24-2019 at 10:17 PM.

05-24-2019, 07:35 PM	#11
Capt Spaulding Persona Non Grata Join Date: Nov 2015 Drives: '15 BRZ (WRB) Location: On the Border Posts: 1,882 Thanks: 2,016 Thanked 2,780 Times in 1,200 Posts Mentioned: 10 Post(s) Tagged: 1 Thread(s)	Yep, bolts are actually springs. When you torque them down they stretch, preloading the spring/joint. __________________ Slow is smooth, and smooth is fast

05-25-2019, 08:54 PM	#14
86MLR Senior Member Join Date: Aug 2018 Drives: 2002 VX Commodore SS LS1 Auto Location: Sydney Posts: 2,203 Thanks: 500 Thanked 2,185 Times in 1,111 Posts Mentioned: 13 Post(s) Tagged: 0 Thread(s)	Red Loctite Disclaimer: Don't use red Loctite __________________ Disclaimer: This post represents the official views of the voices in my head at the time of posting. http://www.ft86club.com/forums/showthread.php?t=133311 I'm only here for the biscuits

05-24-2019, 03:57 PM	#2
JD001 Senior Member Join Date: Apr 2015 Drives: Subaru BRZ Location: UK Posts: 6,028 Thanks: 7,652 Thanked 6,187 Times in 3,474 Posts Mentioned: 25 Post(s) Tagged: 2 Thread(s)	Magic.

05-24-2019, 04:04 PM	#3
jamal Senior Member Join Date: Nov 2011 Drives: Legacy GT Location: compton Posts: 534 Thanks: 9 Thanked 365 Times in 204 Posts Mentioned: 11 Post(s) Tagged: 0 Thread(s)	The friction from the clamping force. That's how any bolted connection actually works. Even with the 16mm bolt in 16mm hole, try loosening them both and wiggling things around- there's a good amount of play there.

05-24-2019, 05:31 PM	#6
maslin Benz Tech Join Date: Dec 2018 Drives: 2017 BRZ Premium Location: Oregon Posts: 580 Thanks: 363 Thanked 562 Times in 308 Posts Mentioned: 6 Post(s) Tagged: 0 Thread(s)	Magnets?

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