Suspension Weak Link? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Captain Snooze · 10-31-2013, 05:44 AM

I was at the suspension shop today having the rear camber altered and having a bit of a chat to the owner of the shop about some bent lower control arms that were sitting on the counter. (I didn't get around to asking what car they were from). I was told the owner had had an off track excursion, lost control and clipped the edge of the track going side ways bending the arms. I asked wouldn't stronger arms be the answer and was told fitting stronger arms would transfer the force somewhere else. Sure, all elementary but not something I had considered. (I don't know what I don't know). He said it was cheaper to replace the arms as opposed to potentially bending sub-frames or bodies.

Maybe something for consideration?

7thgear · 10-31-2013, 10:48 AM

yes this is an important engineering consideration

this is why i'm weary of super-stiff control arms. If they need to bend, and don't, something else will.

A properly engineered arm should have just enough stiffness to fight deflection generated by your grip levels, and let lose the moment it experiences anything greater.

full blown racecars generally have the attachement points made to shear off, so when you're fixing the thing you're just welding on the hookups and not having to straighten the whole frame.

J-W · 10-31-2013, 11:23 AM

I recently(over the weekend) bent an oem front control arm. The bend is visually noticeable. Weak points enginerred into a design is a good thing, but still, an oem arm is ~$250. At this time, there are no parts in the dealerships in the US, according to my local dealer. Add some adjustment points to that and the price alone is comparable to aftermarket options. I've decided to upgrade mine and be a little more careful in tight corners.

-Jay

ZDan · 10-31-2013, 11:27 AM

$250 is nothing compared to having to straighten a tweaked unibody...

J-W · 10-31-2013, 11:28 AM

Quote:

Originally Posted by ZDan

$250 is nothing compared to having to straighten a tweaked unibody...

True, that's why I'm going to be more careful. Curbs and 45 mph don't get along.

-Jay

CSG David · 10-31-2013, 01:04 PM

Quote:

Originally Posted by Captain Snooze

I was at the suspension shop today having the rear camber altered and having a bit of a chat to the owner of the shop about some bent lower control arms that were sitting on the counter. (I didn't get around to asking what car they were from). I was told the owner had had an off track excursion, lost control and clipped the edge of the track going side ways bending the arms. I asked wouldn't stronger arms be the answer and was told fitting stronger arms would transfer the force somewhere else. Sure, all elementary but not something I had considered. (I don't know what I don't know). He said it was cheaper to replace the arms as opposed to potentially bending sub-frames or bodies.

Maybe something for consideration?

Yup. A lot of guys who simply just street keep talking about control arm rigidity as if they are the suspension gurus. The arms bend because they are designed to bend during an impact. Obviously if you want to extract the very most out of your suspension, these control arms will be replaced by some nice pieces, but you're also trading it off for potential deflection in the chassis. The energy has to go somewhere...

mike156 · 12-17-2013, 02:12 PM

A control arm that bends easily also means it can end up pushing the tire and inner fender area into the driver's compartment. This is why many organizations require a bar as part of the cage that will protect the driver's legs from just this happening. The OEM pieces are likely designed in a way to fail but in a predictable manner that controls where the tire goes and how energy is dispersed.

But so is the intake manifold, radiator, engine mounts, hood... EVERYTHING in a modern car is designed around crash safety to some degree.

10-31-2013, 05:44 AM	#1
Captain Snooze Because compromise ® Join Date: Jan 2012 Drives: Red Herring Location: australia Posts: 7,818 Thanks: 4,050 Thanked 9,551 Times in 4,195 Posts Mentioned: 60 Post(s) Tagged: 0 Thread(s)	Suspension Weak Link? I was at the suspension shop today having the rear camber altered and having a bit of a chat to the owner of the shop about some bent lower control arms that were sitting on the counter. (I didn't get around to asking what car they were from). I was told the owner had had an off track excursion, lost control and clipped the edge of the track going side ways bending the arms. I asked wouldn't stronger arms be the answer and was told fitting stronger arms would transfer the force somewhere else. Sure, all elementary but not something I had considered. (I don't know what I don't know). He said it was cheaper to replace the arms as opposed to potentially bending sub-frames or bodies. Maybe something for consideration?

10-31-2013, 10:48 AM	#2
7thgear i'm sorry, what? Join Date: Jan 2012 Drives: Canada Location: I rock a beat harder than you can beat it with rocks Posts: 4,399 Thanks: 357 Thanked 2,508 Times in 1,268 Posts Mentioned: 40 Post(s) Tagged: 3 Thread(s)	yes this is an important engineering consideration this is why i'm weary of super-stiff control arms. If they need to bend, and don't, something else will. A properly engineered arm should have just enough stiffness to fight deflection generated by your grip levels, and let lose the moment it experiences anything greater. full blown racecars generally have the attachement points made to shear off, so when you're fixing the thing you're just welding on the hookups and not having to straighten the whole frame. __________________ don't you think if I was wrong, I'd know it?

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10-31-2013, 11:23 AM	#3
J-W Senior Member Join Date: Sep 2013 Drives: '13 Subaru BRZ Limited Location: Ohio Posts: 143 Thanks: 89 Thanked 37 Times in 21 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	I recently(over the weekend) bent an oem front control arm. The bend is visually noticeable. Weak points enginerred into a design is a good thing, but still, an oem arm is ~$250. At this time, there are no parts in the dealerships in the US, according to my local dealer. Add some adjustment points to that and the price alone is comparable to aftermarket options. I've decided to upgrade mine and be a little more careful in tight corners. -Jay

10-31-2013, 11:27 AM	#4
ZDan Senior Member Join Date: May 2011 Drives: '23 BRZ Location: Providence, RI Posts: 4,672 Thanks: 1,439 Thanked 4,011 Times in 2,097 Posts Mentioned: 85 Post(s) Tagged: 0 Thread(s)	$250 is nothing compared to having to straighten a tweaked unibody...

12-17-2013, 02:12 PM	#7
mike156 Member Join Date: Mar 2013 Drives: EVO Location: Utah Posts: 75 Thanks: 3 Thanked 49 Times in 26 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	A control arm that bends easily also means it can end up pushing the tire and inner fender area into the driver's compartment. This is why many organizations require a bar as part of the cage that will protect the driver's legs from just this happening. The OEM pieces are likely designed in a way to fail but in a predictable manner that controls where the tire goes and how energy is dispersed. But so is the intake manifold, radiator, engine mounts, hood... EVERYTHING in a modern car is designed around crash safety to some degree.

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