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Discussion Starter #1
After a lot of research, I finally figured out how to install a sway bar on my Insight. The closest thing off the shelf that fits is the Shine SRS rear sway bar made for VW A4 Golf/Jetta/New Beetle (99 - ??)
http://www.srsvw.com/parts/partdetail.asp?pid=57

Shine SRS rear swaybar
$195 MSRP
Internal axle-beam mounting
materials: "The bar has an OD of 1.125" and 0.250" wall thickness, TIG welded 4130 chrome-moly steel. CNC machined, Jig built, Normalized and heat treated. Bar weighs 6.5 pounds and uses USA made grade 8 3\8 inch hardware. 32 inches OAL. All bars are powdercoated."
specs: approx 359.2 lbs/ft calculated deflection
install tips: requires drilling 8 holes in axle beam with 3/8" cobalt drill
It does require modifying it by cutting the top protusions with a dremel tool so it will fit in the Insight twist beam rear suspension.

http://www.insightracing.ca/gallery/mods/june4_5_179

Installling it is much more time consuming and difficult then it looks but it's worth it. It took me 5 hours and the purchase of a 3/8" cobalt drill is essential. It also requires drilling blindly very close to brake lines :shock:

http://www.insightracing.ca/gallery/mods/june4_5_335
Since this photo was taken I have covered the brake lines with a protective sheath to make sure the brake lines to rub and wear on the nuts.

Here are instructions on how to install the SRS rear sway bar (on a VW keep that in mind):
http://www.srsvw.com/infocenter/install/docs/a2swaybar.pdf

Here are better instructions with photos from a similar manufacturer (but since the bolts are further apart from each other, this one will likely not fit the Insight.)
http://www.o-bars.com/install-sway.html

Does it work?
YES, this is the stiffest sway bar available for VW golfs and jettas that weigh over 3,000 lbs so it works specially well on my 1880 lb Insight :twisted:
I just finished installing it last friday so I have used it for only 2 club autoslaloms so far. The sway bar stiffens the rear during hard corners so much that there is instant "lift throttle oversteer" on demand when driving at the limit. 8)
This is the fastest way to drive a FWD car and finally for the first time my Insight 3 wheels with 1 tire high in the air like all the best handling FWD cars!

http://www.insightracing.ca/gallery/2005-06-4-5/june4_5_326

For more information on how sway bars work read this:
http://www.stealthtdi.com/SwayBars.html

To see and feel my Insight handle at an autoslalom come to the Southern Ontario Insight meet near Toronto on June 12.
http://www.insightcentral.net/forum/viewtopic.php?t=2929
 

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Interesting, but a bit puzzling. I guess I have a hard time seeing how lifting one wheel clear of the pavement is going to improve cornering. Instead of rubber meeting road in four places, it's meeting in three. Even if those three have the same total force, it's hard to see how you get a net benefit. Think of wide vs narrow tires...

Second, if you do lift your front wheel (in a FWD car) off the pavement, don't you lose traction, just like spinning one wheel on ice?
 

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Discussion Starter #3
james said:
if you do lift your front wheel (in a FWD car) off the pavement, don't you lose traction, just like spinning one wheel on ice?
That's exactly what installing a stiffer rear sway bar will avoid. 8)

In FWD cars, the key is to reduce understeer and increase motive traction............ Leaving the front bar stock and increasing only the rear bar allows the front wheels to articulate normally. As written above, the weight that's not sitting on the suspended inside rear wheel is now being applied to the inside front wheel, which is not being unloaded by a huge front bar and is now able to extend to the ground for more traction. Make sense?
Quote copied from the bottom of this page:
http://www.stealthtdi.com/SwayBars.html

The rear inner tire that is in the air of a great handling FWD car is useless during extreme cornering anyways. The fact that it's not supporting any weight of the car means more weight and grip is being transfered to tires that need it.
 

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Discussion Starter #4
WARNING: :!:
Installing a sway bar as stiff as this on light weight car like the Insight will result in advanced and dangerous handling characteristics not recommended for street use. When driving near the limit of traction in corners the car must be at a constant speed or accelerating or else the car will begin to agressively oversteer. Oversteer can only be avoided and corrected in a FWD by applying the throttle. :!:
 

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I just installed a rear sway bar on my MINI Cooper S. In auto-x conditions, lifting a rear wheel is perfectly fine because the rear swaybar causes it's load to be transfered to the front wheels which are driving the car. Lifting a front wheel will just cause it to spin (no limited slip diff) and you'll loose time.

The reason manufacturers make cars understeer fromt he factory is that on street driving (or even high speed track), the rear end will get unsettled and if your off throttle or need to brake. You get oversteer (rear end comes around). On an auto-x track, you just keep your foot planted and the car goes around the corner much faster. You can't do this when somebody's in front of you.

Guillermo, does the rear swaybar make the car neutral in the corners or does it have a tendency to over/understeer?
 

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Discussion Starter #6
kapps said:
Guillermo, does the rear swaybar make the car neutral in the corners or does it have a tendency to over/understeer?
I need to test it on a skid pad to be sure. It definitely doesn't understeer anymore, when I ease off the throttle it turns like a dream.
I will be competing in Solo 1 events #3 & #4 on June 18/19 at the Mosport DDT track and they have a skid pad there. So will give a more detailed impression on the sway bar after that.
 

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Wow, impressive mod, Guillermo! Thanks for being the Beta guy on this!

So I gather that the bar works by basically limiting twist of the twist beam, is that right?

Also, I have to worry just a bit that those 8 big 3/8" holes will weaken the twist beam. Can you respond to this? Any idea how the "beefy-ness" of the Insight twist beam compares to the VW this bar was designed for? In other words, is a weaker/lighter twist beam axle on the Insight likely to be jeopardized by this swaybar (which looks really massive in its own right)?

Finally, just how much material did you have to cut off the swabar to make it fit, and how much of a chore was that? What sort of Dremel attachment did you use for this?

Oh, and one other thing: Where did you get that cool harness bar that's pictured in your car?
 

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OK, I think I see that you can select the bars to have either front or back off the ground. I guess I shouldn't have been looking at the pictures :)

"The rear inner tire that is in the air of a great handling FWD car is useless during extreme cornering anyways."

Yeah, that's what I thought. But wouldn't it be better to have a weight transfer onto that wheel, so it would be useful?

Of course it's all pretty academic for me these days. My cornering is limited by when the dog starts sliding. Of course, I suppose I could always line the hatchback floor with velcro :)
 

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Guillermo,

Very cool!. I really like the harness bar that you have installed. What kind is it? Or is it a homemade job? If it is homemade it looks great! I love what you have done, but doing these mods in Solo II would push me right out of HS class. I could do a front sway bar. Maybe something a little beefier up front. Have you done anything to the front sway bar?
 

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Discussion Starter #11
Skimmer said:
So I gather that the bar works by basically limiting twist of the twist beam, is that right?
Yes

Skimmer said:
Also, I have to worry just a bit that those 8 big 3/8" holes will weaken the twist beam. Can you respond to this?
Looks strong enough, the twist beam is made out of very thick and strong steel. Only time will tell, but frankly i'm not worried.

Skimmer said:
Finally, just how much material did you have to cut off the sway bar to make it fit, and how much of a chore was that? What sort of Dremel attachment did you use for this?
I cut the top leaving only 5 mm protruding, it's about where the weld ends.
More photos will be posted in a few days. Cutting the sway bar with a dremel tool and small cheap narrow cutting disks was the was the easiest part of the installation. The cutting disks brake and shatter easily so wear safety goggles because I went through about 12 cutting disks at least 3 of them bounced off my safety goggles.

Skimmer said:
Oh, and one other thing: Where did you get that cool harness bar that's pictured in your car?
Thank you, The harness bar was custom made by a guy that makes roll cages for race cars. It has a welded tab with a hole for mounting a camera. It's also good at keeping large things like tires from flying forward during a collision.

http://www.insightracing.ca/gallery/mods/june4_5_259
 

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Discussion Starter #12
james said:
wouldn't it be better to have a weight transfer onto that wheel, so it would be useful?
No because it would mean reducing weight transfer from tires that need it more! It's a FWD car, the rear tires are only there to prevent the rear bumper from draggin on the ground :lol:
The front tires do everything: turning, accelerating, and 70% to 90% of the braking (depending on the tires and how hard the brakes are pressed).
 

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Discussion Starter #13
commuter said:
I love what you have done, but doing these mods in Solo II would push me right out of HS class.
In Canada the rules are a little different. In stock class we have 2 prep points we can use. The following are the most common mods used in stock class competition that are 1 prep point each:
* R-compound tires (these are essential to be competitive)
* Rim size of a different diameter and/or width and/or offset then OEM
* any sway bar additions or deletions

Last year I was using Rs on smaller rims. This year i'm using Rs on OEM rims and a rear sway bar. The race harness is free in any class and therefore no prep points.
 

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Guillermo said:
Thank you, The harness bar was custom made by a guy that makes roll cages for race cars. It has a welded tab with a hole for mounting a camera. It's also good at keeping large things like tires from flying forward during a collision.

http://www.insightracing.ca/gallery/mods/june4_5_259
Nice. Any chance your guy would be interested in producing more of these for the rest of us? Maybe a group buy?
 

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Discussion Starter #15
The harness bar cost me $200.
I suggest going to a place near you to make sure it fits and it's done right.
Where I got it done the guy didn't bother to save any sketches or drawings because he wasn't expecting to do it again. So he would have to start all over anyways.
 

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Discussion Starter #16
commuter said:
I could do a front sway bar. Maybe something a little beefier up front. Have you done anything to the front sway bar?
Since I've added a rear sway bar I'm not allowed to modify the front since I want to stay in H-stock. Since the SCCA rules only allow the front sway bar to be replaced/modified in H-stock so I suggest getting a front sway bar custom made by sway bar manufacturer:

http://www.angelfire.com/biz/tlssteel/index1A.html
or
http://www.sanerperffab.com/prod01.htm

Just send them an Insight front sway bar from a wrecker so they can copy it to make a thicker one.
 

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Guillermo said:
Skimmer said:
Also, I have to worry just a bit that those 8 big 3/8" holes will weaken the twist beam. Can you respond to this?
Looks strong enough, the twist beam is made out of very thick and strong steel. Only time will tell, but frankly i'm not worried.
You probably want to periodically check the subframe/twist beam. '99-'00 Si (SiR in Canada) with upgraded rear sway (to 23mm) is notorious for ripping out the rear subframe. You HAVE to run subframe brace, otherwise the tear. I can imagine that frail looking twistbeam ripping after a while.

Cool mod though. :)
 

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Highway Tracking & Oversteer

Hi Guillermo,
Read your thread and I have a question you can answer. Stock Insight toe-in is set to zero for mpg. So when on highway with side winds the little car want's to bounce all over the road. What effect does your rear stabilizer have on this? Would there be oversteer maintaining a constant highway speed, say, of 80 mph? What would you think of putting Koni's back there? Fabulous mod, by the way. Do they make a slightly less stiff bar for street use, the link I went to only provided one part number. Thanks and nice job, Jack
 

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Mix tires?

Why couldn't you just run stock tires, or skinny racing tires, on the rear to reduce the understeer? That way you could keep on the skirts, too.
 

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Guillermo has let me co-drive his Insight for a few events now, and I have to say that the sway bar is HANDS DOWN the best thing that could have happened to the car.

It's absolutely beautiful to drive: the slightest throttle adjustment controls cornering. The rotation is a dream!

I drove my own car today at at the HADA event/Insight meet, and I spent my first 3 runs cursing my lack o' sway bar. I compensated by dropping the tire pressures in the rear a little more (32 psi) and tossed the Insight around a lot. Ended up with some rotation, but it's just not the same. :(

Dougie: usually we do run auto-x events with the rear wheel skirts, it's just that Guillermo has one crazy set of tires, originally intended for solo1 events, that are too wide to accomodate them.

You can reduce understeer with weight transfer, by getting on the brakes hard, getting back off the brakes, then cornering (thus throwing the weight of the car onto the front tires, giving them more grip), but the sway bar is definitely a better solution.
 
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