Hancha Adjustable Rear Lower Control Arms - 2013 Scion FR-S Long-Term Road Test
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2013 Scion FR-S Long-Term Road Test

2013 Scion FR-S: Hancha Adjustable Rear Lower Control Arms

July 5, 2013

2013 Scion FR-S

With the front end camber needs of Project FR-S, our long-term 2013 Scion FR-S, handled, we turned to the rear suspension. It's a multi-link layout back there, so its camber loss with roll is less precipitous than in the front. As such, the rear won't need as much additional negative camber as does the front. But like the front suspension, there's no factory provision to dial in camber in the rear.

To right this wrong, Hancha developed a proprietary adjustable rear lower control arm (LCA) that's made right here in the US.

2013 Scion FR-S

Hancha first modeled the stock LCA and found that, while lightweight, it was lacking in longitudinal stiffness. Thus, their goal was to create an adjustable LCA that was more robust than stock without being heavier.

The body of the LCA itself is CNC-machined from aluminum and receives an oversized rod end and linkage adjuster that lengthens or shortens the arm in order to provide the necessary camber. According to their analysis, the Hancha LCA reduced mechanical stress by 900% and was 1100% stiffer than the stock arm, all without a weight penalty compared to stock. Proof of their confidence is found in the company's three-year warranty that includes motorsports use. Race parts with warranties are rare beasts.

2013 Scion FR-S

Pictured above are the QA1 rod ends and linkage adjusters that normally ship with the Hancha LCAs. They're beefy 3/4-inch aluminum, and the rod ends have a Nylon/PTFE race that is self-sealing and self-lubricating. They are, by design, not proprietary items so in the event replacements are needed they can be found with relative ease.

In our case, due to a shipping snafu at the last minute, the linkage adjusters and rod ends would need to be sourced locally. We were operating with only hours before departure to Laguna Seca, so Hancha scrambled some steel rod ends for us.

Linkage adjusters, however, were proving elusive.

2013 Scion FR-S

And then, John at Specialty Cars totally saved the day. "Jay, I'll just make them!" he said cheerily after chasing several leads that led to dead ends. In the space of a few hours, he located the necessary raw materials and fabricated the linkage adjusters from scratch. Then he dropped them off at my house. Talk about service!

Take a look at John's handiwork above. They fit perfectly. I think I'll be enlisting his services for other projects too...

2013 Scion FR-S

The rod ends in the Hancha LCAs also eliminate a source of squishy rubber found in the OEM arms. This will enhance precision at the price of some additional NVH, a tradeoff we're willing to live with. Likewise, when loaded up in a corner, the rod end will not deflect as much as the rubber bushing. The LCA is oriented aft of the rear axle line in the FR-S, meaning that during hard cornering there will be a touch less loss of toe-in with the Hancha arms compared to stock.

2013 Scion FR-S

Once I finished installation of the arms, I gave the FR-S an eyeball alignment and then set off to Stokes Tire Pros for a real alignment. There, they dialed it in to my specs. In the front we achieved -1.9 degrees camber and zero toe; the rear was -1.7 degrees camber and zero to 1/16" total toe-in.

It all came together with minutes to spare prior to our scheduled departure time for Mazda Raceway Laguna Seca.

Sources:
Hancha
Specialty Cars

Jason Kavanagh, Engineering Editor


Comments

  • Sweet! Finally some more mods for the FR-S, hopefully you guys can get forced induction in there before the car departs. I love these kinds of posts. Keep it up J-Kav!

  • bassrockerx bassrockerx Posts:

    that bare metal looks sexy down there but if it were mine i would be tempted to paint it body color to protect from weather and also atract some more attention to my undercarriage.

  • yefeiw yefeiw Posts:

    Hi, It may have already been answered, but just being curious, is there any adjustment needed anywhere if I want to install your set of wheels/tires?

  • meng_mao meng_mao Posts:

    Isn't that adjustment threading an example of rod-in-bending?

  • desoto_fins desoto_fins Posts:

    An adjustable eccentric bushing on the inboard end of a nice full (as opposed the 3/4 of an arm) aluminum arm would be a more elegant and sound engineering solution. It could have 3 degree of adjustment which cover street, autocross and trackday needs.

  • jpnpower jpnpower Posts:

    It's been a while folks, how've you been? I am surprised and let down, disappointed by the little progress made to this website. Edmunds, what have you done? Where is my insideline? I thought it would be back, but I must have been wrong. I don't even see the former regulars anymore.

  • fordson1 fordson1 Posts:

    I found an early post on ft86club.com that said "under $1,000," but later they said it's too expensive - it will be a special-order part, but they are trying to work on an entry-level part. So have to consider this is going to be over $1,000 (I would bet quite a bit over), plus installation and alignment.

  • jederino jederino Posts:

    Yes, can't wait for the results and analysis.

  • duck87 duck87 Posts:

    Since these kinds of links are only supposed to work in tension and compression, I don't see any major issues with the 3/4 arm concept ... except for the fact that it's also acting as a spring carrier. I would have to agree with meng that the bending forces introduced makes me a bit more iffy, although I'm guessing that the "brute force" thickness of the fastener should compensate. It's still not ideal. When those adjusters were made, were they coated too? Or is it bare steel against aluminum? The use of heim joints is a bit gnarly too, mainly because of the elimination of that rear toe-in on hard cornering (it's there for a reason, so beginning drivers don't kill themselves or lose confidence in rear end stability). There's also the NVH issues to work out, and self-lubricating or not, they'll be destroyed in any salt-states. Shouldn't be any binding issues at least...

  • duck87 duck87 Posts:

    Scratch the toe-in part of my post; you're right, it's located closer to the rear of the axle.

  • chrisnick04 chrisnick04 Posts:

    It may just be the clean freak in me, but those LCA's look like they're prime to build up dirt/debris in the voids. It'd be a nice feature if they had some build in slots/holes on the underside to clear any of that, even though it may reduce some stiffness slightly.

  • ansibe ansibe Posts:

    very cool. why the toe-in at the rear? do you expect some toe-out forces in hard corners which will result in zero toe-in?

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