Rear Sway Bar

Until you have pushed your car beyond it's limits a few times and found out how it reacts, pushing the limits on freeway ramps with no safe place to run off isn't the smartest move in the world.

A stock Prius will warn you by plowing more and more pig like when you push it in a corner. When you tighten up the suspension and change the front rear roll stiffness balance the car won't lose traction until you reach higher cornering forces, but when it does it the loss of control can be sudden.

 

The thing about this curve and only this curve, is that it doesn't have any overly difficult angles, as you can see. Rather, the blind curves give most drivers and those unfamiliar with it the perception of a lack of control. Plus in moderate traffic, one driver sees someone brake, they all brake. Lol. For someone who takes the ramp everyday, it doesn't even raise my pulse.

 

A few days ago I was able to take my Prius to an open lot so I can test out how the car handles with the 24 mm rear bar. Note, I was not able to do long sweeping turns nor was I able to enter into any turns greater than 30 mph, so for the most part, this test was conducted in low-moderate speed conditions.

The test consisted of driving straight through the center of the lot at 25-30 mph. Once I got to the center of the lot, I abrupt yanked the steering wheel to the right in order to make an abrupt 90-degrees turn while maintaining constant throttle. I repeated the test on the left side. During both turns, the vehicle held on great, minimal role, and the vehicle was totally in control. At the extreme limit, the car continued to understeer with no indication whatsoever that the rear end will break loose.

2nd test, setup same as above. This time half way in the turn, I would let off the throttle to reduce load on the rear end. I did this to see if I could get the rear-end to kick out. There was no appreciable difference in the response of the vehicle when compared to test #1.

3rd test, setup same as above. This time, I left off the throttle completely right before I entered into the turn. The car understeered heavily but it was still under control. The "stability control" came on with the vehicle alerting with an alert of "beep beep beep," signaling that the car had lost of traction (understeer).

Although all three tests were coducted at 30 mph at the turning limits, I feel pretty comfortable to say that the Prius is pretty safe with the 24 mm rear Progress bar. At no time did the rear end ever hint that it wanted to come out. In fact, at the limit, the car still understeers. I would love to be able to find a bigger lot and perform the tests at 40 mph, and to do longer sweeping curves like a 180, but that would require a BIG BIG lot with no light posts!

Just play safe guys. I think we're pretty with the bar. If anyone else decides to conduct their own tests, please be sure to share your review.

 

This. Nothing drastic with the bar, but subtle enough to be able to keep up in turns with bad BMW drivers. Ah-hem, BMW drivers.

 

I agree. The bar is makes the car very neutral when driven within the normal driving envelope. When pressed hard, the car still hints understeer. This is very safe for the street but is also HUGE improvement over stock.

I would say the bar is a "MUST BUY" upgrade.

 

Abrupt lane change and back maneuver while under light braking is usually the most effective at inducing oversteer - if the car has any oversteer tendencies it will show up in the turn back into your lane.

This is the type of maneuver you'd execute to dodge road debris and you'll find is most common cause of SUVs rolled over on the side of the road.

 

Just did that yesterday morning. I was changing lanes to the left at about 40 mph, but there was a van in my blind spot that I did not see until I was right on top of him (oops, my mistake). I turned the steering wheel sharply to the right while braking hard. No problem. The car went right where I told it to go. It did roll quite a bit to the left, but very stable otherwise.

BTW Mac ol'buddy, you take it easy around those corners. These aren't BMWs and we don't want to hear about you wrapping your car around a guard rail some time.

 

Righty then gents, after a week of driving around with the new Progress sway bar, I feel as though I can finally give a quick review of it.

Install: For me, the installation was a bit troublesome at the start. Someone here mentioned they were able to do it without jacking the car up, and Id like to say that they must be very very small to be able to do such a feat. Definitely jack the car up. The bolts holding the original bar in were corroded very badly, so after trying with an impact, my buddy and I had to use a breaker bar to get them loose. This is not a knock on the bar itself, rather my corroded bolts After that installation went easy. Pop old bar out, put new bar in. I did not place the little rubber stopper back in.

Performance: Just a refresher, the only modifications done to my prius have been a set of 205/60/R15 wheels. Handling is definitely much better after the install of the new sway bar. Ive tested it with just myself in the car, with a passenger, and with 4 people in the car, all taking the same "test" route I usually do. Body roll is greatly decreased, although there is still a slight hint of it around those fast corners. For about 120 bucks, this is one of the best upgrades you can do for your prius. It is amazing how far a new set of tires and this bar will change a stock gen2. It has also nearly eliminated that body sway at high speeds (70mph+) from crosswinds.

As others have stated, I highly recommend this bar. It is a fairly simple install if you have access to the tools needed.

 

I started to get some minor noises from the rear suspension. I suspect that the bolts on the bar isn't as tight as it should have been. Note I hand tightened the bar last week. I'll have to go underneath the car again later on this week for further rework. I'm 5'9, 155 lbs, I have no problem getting underneath the car without jacks. I did however, get my elbows, knees, and my face dirty from rubbing on the underside of the car.

 

Some body roll isn't a bad thing. It helps you judge how you are cornering:rockon:

 

That was the case with me as well. I'm 6' 2.5" and 180lbs and I could do it without the jack but it was a tight squeeze and required working with one arm basically. lol

I'm very impressed with the handling ability of this car with the springs, rear sway bar and 17" tires. It just sticks to corners. I think most people would be very surprised. Add a front sway bar and truly sticky tires and this thing would be off the hook for such a tall and heavy car.

 

I ordered the progress bar yesterday 11/17/11, am waiting to see how it goes when
you install the 06 corolla front sway on your prius.

 

I feel really good with the PROGRESS rear bar with the stock front anti-sway bar. Is it necessary to upgrade the front? Has anyone done this. Could you give us a comparison? I suspect that by enlarging the front bar, you're goign to bring back 'some' understeer since you're stiffening up the front.

 

Remember F8L went to the wrecking yard and got a 06 corolla front sway bar
but hasn't installed it yet. Am waiting for word from him on how it works.

 

Me too.

I 'mjust not in any shape to do it myself until this chemo garbage is finished. In the mean time I am trying to get my buddy at the stereo shop to do it. unfortunately I only have every other Monday open for the install. I'm eager to try it out.

I agree that I may introduce more understeer like our Toyotatech friend has stated but he also said that for racing it was too.much on the street it was awesome. I'll report back when I get it on.

 

For the street having the front/rear bars balanced is best, even on a car that understeers stock when it's got a strut based suspension. Reducing body roll keeps the tires flatter on the road which increases overall grip even if it increases understeer at the limit - especially on a front-heavy strut suspension car.

 

When I was doing my initial research, I found this thread which discusses upgrading both front/rear sway bars. Obviously, some of you are already aware of that one.

Also, one more thing. The front sway bar is not a quick half hour job. I think you're looking at at least a half to a full days work.

 

I got the progress bar today, a breeze to install, I'll get the torquewrench
tomorrow. The front still sways. Need a 24mm front sway bar and strut
tower bar. May still need low profile tires.

 

The suspension mods really help tighten things up even with the 15" tires. Unfortunately the 15s will squeal and hate you when you try to corner hard. They work but the 17s are MUCH better at taking corners.

I have an appointment to install the front sway bar in 2 weeks. I'll report back once it is installed.

 

I torqued the rear to 115 lb, and the stiffening plate to 30 lb, the front still
sways when you rock the wheel at 60, but it takes the corners a lot nicer.
I got the heavy stiffening plate off ebay for $47.50