ARB shape

[norcalpb]

It could also be for ease of removal with an exhaust that runs down the center-line of said sway bar. I have a Perrin exhaust and getting the rear sway bar “hooks” around the mounting brackets can be a real PITA sometimes. You get one hook on and the other hook just barely can’t fit around it’s bracket. You try to the raise both hooks at the same time but the exhaust gets in the way forcing you to only raise one side of the bar at a time.

Center GRMN exhaust:

[gpvecchi]

I don't think it's center exhaust related either, the GR model has center exhaust but standard bar.
Definetely I'd not say it's obstruction related.

[norcalpb]

Originally Posted by gpvecchi

I don't think it's center exhaust related either, the GR model has center exhaust but standard bar.
Definetely I'd not say it's obstruction related.

Can you post a picture of the "GRMN" rear end? I've always thought the 2016 GR was the only GR car made.

[Turdinator]

Originally Posted by gpvecchi

I just discovered that the 86 GRMN uses a 15 mm rear ARB like facelifted models, but with different shape.
Is there some expert that can explain what would change?

Are you sure that isn't a pic of a front sway bar used by accident?

[gpvecchi]

Originally Posted by norcalpb

Can you post a picture of the "GRMN" rear end? I've always thought the 2016 GR was the only GR car made.

If you Google "86 GRMN" you'll find a lot of pictures...
https://toyotagazooracing.com/pages/grmn/86/sp/#concept

Originally Posted by Turdinator

Are you sure that isn't a pic of a front sway bar used by accident?

No, the photo is correct, the part number is specific to GRMN...

[JIM THEO]

The two curves in the middle of the long straight part of the yellow OEM bar gives increased torsional rigidity compared with a same diameter straight bar.
Besides the GR one was introduced before the >MY17 thicker OEM bar so probably it's designed and produced by Toyota, not Subaru.

By the way the exhaust manifold of the GRMN car compared with the upgraded CS-R3 race car manifold (afaik produced by Rogue Motorsport quite similar with ACE350) is quite different design:
https://racing.tgr-europe.com/wp-con...ge_2017_02.pdf (page 6)

GRMN:

[NoHaveMSG]

Originally Posted by JIM THEO

The two curves in the middle of the long straight part of the yellow OEM bar gives increased torsional rigidity compared with a same diameter straight bar.

In all the formulas I have seen to calculate torsion bar stiffness , none of them have accounted for the geometry within the length of the torsional section.

[Turdinator]

If it is to suit the rally car it may well be designed to allow greater suspension articulation.

[Spuds]

Originally Posted by NoHaveMSG

In all the formulas I have seen to calculate torsion bar stiffness , none of them have accounted for the geometry within the length of the torsional section.

Bends basically vary the moment of inertia along the length. It does make a difference in stiffness, but it's a PITA to calculate without a full solid model and even then you might be better off just making and testing it if you really wanted to know.

Anyway, I don't know why the bends are more pronounced on one vs the other except if they wanted to give greater clearance to something either for heat dissipation or physical interference issues. Maybe one is easier to manufacture? Maybe they were actually less concerned with something like ground clearance or something on the GR vs the TRD.

[Spuds]

Originally Posted by Turdinator

If it is to suit the rally car it may well be designed to allow greater suspension articulation.

Now there is some merit in that idea. Or different articulation such as lowered or raised

[gen3v8]

Originally Posted by Spuds

Now there is some merit in that idea. Or different articulation such as lowered or raised

That is, as you say, different articulation

[Spuds]

Originally Posted by gen3v8

That is, as you say, different articulation

I was assuming that greater articulation meant a longer arc specifically, where I was adding that instead of longer travel, it may be the same amount shifted up or down.

[nikitopo]

Originally Posted by gpvecchi

I just discovered that the 86 GRMN uses a 15 mm rear ARB like facelifted models, but with different shape.
Is there some expert that can explain what would change?

It looks that they wanted to go into a much softer sway bar, one that was softer even from the old 14 mm bar. In general the GRMN 86 had a chassis that was 1.8 times stiffer than the base model offered at that time, so in such case you can go into much softer suspension settings and gain in overall mechanical grip.

Another thing to point out is that a few ideas that were tested in the GRMN car have passed to the new GR86 car. Sad thing is that they couldn't pass the revised FA20 engine with the output of 219 PS (19 PS more) at 7,300 rpm and 217 Nm (12 Nm more) at 5,200 rpm. Problem was that Subaru couldn't make such a well balanced engine and they didn't want to revise their engine production process. So for Subaru the easier route was just to increase the engine displacement, although the rest of the world was downsizing their engines.

[strat61caster]

Looks like a front bar to me. People upload the wrong picture to the part sites all the time.





Edit: actually the bends don't match up at all, I doubt that bar is even for an 86. Critical mount points aren't changed willy nilly on production cars.