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RX sway bar ??


Guest toybuilder
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Guest toybuilder

The front RX sway bar is larger than the stock sway bar on my ea82 Loyale wagon, right? Is this a good handling upgrade?

 

Thanks

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Guest james hogan

Put that larger swaybar on the front without doing anything to the back and you will be the Plow King.

Expect massive understeer.

 

Just an opinion.

Jay

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What I did is get the RX, GL and XT6 swaybars F&R and am planning on swapping them out until I find the one that suits my driving style. Putting GR2's on the back this week Should tighten up the rear even more.

 

I grew up on rear wheel driven, overpowered cars.

86 Mercury Capri (Mustang clone with built 5.0 and many suspension mods, 1971 510, with a severe 1600 with Mukuni's, again, many suspension mods( yes, that LSD), 1965 Buick Skylark GS 401, 16x8F 16x10R" wheels with Global West suspension. Blah, Blah.

 

The point I'm dancing around is it will take a bit of time to acclimate to the changes in handling.

 

Do things one at a time and drive the car for awhile. If it oversteers to much for you, go with the smaller front bar. Still to much, next biggest, and so on.

Remember tire pressure and toe have a lot to do with turn in and tire deflection during corners.

 

Jay

 

 

Jay

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What is understeer and oversteer?

 

On my '87 RX coupe, it came with 16mm rear and 18mm front. I replaced the rear with a 20mm and the front with a 19mm (have a 20mm too)

 

What would be the results of a stiffer rear bar? 20mm rear vs. 19mm front?

 

My car squeals the front tire going into a corner (pushing?) The back end doesn't feel like it wants to come around at all. Is this because of the bars or front wheel drive? Should I go to the 20mm front bar?

 

I didn't seriously test any corners until after I made changes, I know, dumb.

 

Also I put on the stiffer wagon springs on the back and lowered the car about 1.5 inches by removing a coil from the front and rear (further stiffening the spring ratio)

 

The car rides firm and corners noticeably flatter.

 

Ideas, comments?

 

 

 

BTW Jay~I had a '65 Buick Skylark GS401! I loved that car till a lady in a Honda pulled out in front of me (before the brake mods LOL) It was silver with the wine (light burgundy) interior. A Classic!!!

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"Put that larger swaybar on the front without doing anything to the back and you will be the Plow King.

Expect massive understeer."

 

Obviously the above statement is like he said "just an opinion". I find it hard to believe that going 1mm thicker on a front sway bar is going to create a "plow king". The car doesn't have a rear sway bar now and with an 18mm front they don't handle badly. You may even see some improvement with only the 1mm increase in front sway bar size. Someone else said it's going to handle like garbage either way "because it's a Subaru" so why bother (just another opinion?).

 

FYI to mount a rear bar on a car that hasn't ever had one you'll need the suspension arms, or a least the brackets off the arms of a car with a rear sway bar to weld on your suspension arms. Given that your modifying a wagon (I'm assuming a wagon has more weight over the rear axle than say an RX) then you might get the best performance from a slightly larger rear bar, i.e. the RX bar in front and the XT bar in back. Just my 2.

LenHorn

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Well Len, let’s break it down a little.

 

Sway bars are put on a car to limit the roll angle of the car during lateral acceleration and deceleration.

 

Since tires develop the maximum amount of traction when they are perpendicular to the ground (and the tread is parallel) that’s what you’re going after. Subarus are notorious for little to no usable camber adjustment. It has an innate inability to keep the outside front tire perpendicular to the ground during corners. In fact, they are forced to positive camber setting when pushed hard. Understeer.

Standard Subaru engineering.

 

It’s also a safeguard when Japanese manufacturers brought over cars to the US. The average driver can control understeer, not oversteer. Domestic cars too, for that matter.

 

Back to the topic.

 

Sway bars increase roll stiffness and they are, by far, the cheapest and easiest modification to increase roll stiffness on a Subaru. When you turn your car, one wheel will be up because of compression and one will be drooping down. The sway bars limit the roll angle of the car by using torsional stiffness to resist one wheel going up and the other going down.

 

If a car has understeer, too much of the load is on the front outside tire. By increasing the size and effectiveness of the REAR swaybar, some of the load can be transferred during cornering to the outside rear tire.

This will decrease the load on the front tires and make the car handle in a more neutral fashion. The very opposite is applied when increasing the front.

 

Simple. No not really.

 

The stiffness of a swaybar increases very quicky as its diameter is increased. The stiffness is a function of the diameter to the fourth power.

 

For example: A 1 ¼” diameter swaybar is 2.44 times as stiff as a 1” swaybar.

 

Now, I’m too tired to do the math right now, and you’re welcome to, but 1mm will change the understeering characteristic of the wagon enough to notice. Especially in sharp, on throttle turns. Let’s not forget about weight transfer. Get that long wheelbase car nose high in acceleration, with the weight transferred to the rear, then cut the wheel. Push.

Panic, jump on the brakes, overload the fronts, transfer weight off the rear. Push.

 

A rear swaybar will help balance out the weight in a lateral manuever by not letting the trailing wheel get too high and thus not help with traction. It will help take the load off the fronts, too.

 

 

You state that “The car doesn't have a rear sway bar now and with an 18mm front they don't handle badly.” Okay. You must not drive the same Subaru as I do, or do the same Autocrosses or Rallycrosses I do, or look to increase the handling as much as I do.

 

You post here and bust my chops about my opinion. Sad thing is, I’m going to have to agree on the swaybar choices you suggested for his wagon. See, you've got one.

 

You quoted someone saying that they(Subarus)handle like garbage. Well, fix it. Do some research, figure it out. I agree comments like this are also an opinion.

 

Yes, I stated outright what I said was an opinion. But opinions are usually based on fact if they are worth a damn.

 

James Hogan

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Now you've given Toybuilder (and everyone) something he can use. You are obviously very knowledgable. I guess my "issue" is more about my perception of your reply. I saw it as a critique of someones planned modification with no real help given (in my opinion).

 

Later

Len

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  • 1 year later...

See? I'm not a n00b. I searched and bumped an old thread...

 

Did we say that the RX front swaybar was 18mm? My XT (4cyl 4WD with air ride) has a 19mm front swaybar and it plows horribly. If we can confirm that the RX has an 18mm front swaybar, then I will post a thread in the Marketplace asking for one...

 

Thanks guys :)

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Here's the chart:

 

SubaruSpringsFull.jpg

 

In stock form the RX (and most cars) tend to understeer, as stated before in general this is safer. So if your not making other changes like spring rates, then leaving the front alone and add a larger rear makes the most sense. The stock front (18mm) with the XT6 rear (20mm) should be a good combo.

 

Gary

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