Rear Sway Bar

F8L, Azipod, and Wilsid (or anyone else with an upgraded rear swaybar):

Have any of you been able to drive with the upgraded rear sway bar in heavy rain or snow to see how it has altered the vehicle handling dynamics?

I was driving home yesterday in heavy rain, and I entered a sharp curve too fast, and had the rear end try to come around on me. I was easily able to recover the skid, but was wondering what would have happened if I had the Progress Rear sway bar installed.

Some things I know about my situation:

1. I had my tire pressure too high (for less rolling resistance) so I’m more prone to hydroplaning right now. I’m defiantly letting some air out tonight before I drive home in the rain again.

2. I entered in the corner way too fast, and I said that to myself right before I entered into the turn. I don’t remember if I just lifted, or if I actually pressed the brakes. Most likely I tapped the brakes stupidly in the turn, which is what probably, caused the skid.

But I still wonder what would have happened in the same situation if I had the rear sway bar. Would I have been able to recover from the skid? Would the skid have happened at all?

I’m looking to upgrade my rear sway bar to get rid of the rear end body roll while cornering. But I’m concerned that the larger rear sway bar will alter the vehicle dynamics too much and make it more prone to oversteer in wet weather, or snow.

Have any of you experienced anything like this with the Progress bar? Do you think that is it more prone to oversteer in these type situations, or do you think that the bar would make the car more neutral? Or more likely to push, and understeer?

What are your thoughts?

 

Dave,

I have not had the chance to push it in wet weather but in theory the thicker rear sway bar should increase oversteer while decreasing understeer. I've always bee a rear wheel drive guy so I am very accustomed to oversteer. As such, I don't really worry about it. I think in your case you probably would have had the same reaction without the upgraded bar but this is merely a guess since I wasn't there to see what happened.

Be careful with dropping your tire pressure. If you go too low it will increase your risk of hydroplaning.

Tire Tech Information - Air Pressure vs. Wet Performance

I don't think the bar makes the car unsafe. I think we may need to drive it a bit differently is all and think more like a real wheel drive car. Glad you're ok and nothing bad happened.

 

Hi Daves. Glad to hear that you're OK. There's really no way of telling what would have happened if you had the larger Progress bar. I've driven the vehicle hard with the Progress Bar in an open lot with dry pavement. Even at the limit, the vehicle still understeers, just not half as much as it did with the stock rear bar. If I took a guess I would think that you would be OK in the rain, but can't say for sure until one of us decides to go to an open lot in the rain! Either way, in the rain or snow, we really should be driving A LOT slower. Personally, i would never push ANY car in the rain/snow.

 

Something to consider is that in a RWD car you get power induced oversteer under control by steering into it and partly backing off the throttle. I've sure you have experienced doing that in a RWD just for the fun of it. With FrontWD, oversteer usually isn't power induced and backing off the throttle is usually the wrong thing to do for oversteer.

 

Still waiting for my progress bar.. should be in today or tomorrow. (Actually, it just arrived as i was writing this! yey! gonna install it this weekend..) My theory is dry or wet, it will increase grip and response vs the stock rear bar and therefore increase your speed through a corner. however, being more stiff, you'll feel the rear wanting to loose traction a lot quicker which demands more driver awareness.

yesterday, after an all day downpour, a downhill right-left-right asphalt bend (see photo) was a little greasy and i felt the car understeer just a wee bit for me to feel but was able to keep it within the lane. my speed was just under what the car would normally take easily when dry. i'm thinking if i had the 24mm sway bar installed already, still can take that bend a bit faster. but after a certain limit, i would probably feel either a neutral slide (hopefully!) or my rear loosing traction in a controllable way (hopefully too!). We should remember though, in a front-wheel drive car, when the rear comes out, we should actually go against the natural tendency to lift-off completely the accelerator as the rear will all the more loose traction. we should actually give more gas to shift the weight back to the rear to regain grip. that's why it's also important for drivers to familiarize themselves with the new setup to know how far it has changed the handling of the car.

on a side note, i didn't see the traction control blink but noticed in my SGII "BTA" xgauge that regen was minimal (-15 thereabouts) when i was already steady going down the hill. i think the car still gives more priority to mechanical brakes after that kind of situation. still going downhill, i tried putting it in "B" which returned regen figures back to normal even after i put it back to "D" and just used the brakes for regen. looking back, it actually happened twice already i think on the same hill. but the first instance was dry, i think, and got puzzled why regen was particularly "low" and forgot about it. regen returned to normal on the next uphill-downhill section.

 

We hardly get rain and hasn't snowed since 04 it lasted 2 days. I don't think I would
push it around a corner in the rain, it might slide. Most likey would.

 

was able to install it a while ago. pretty straightforward and easy thanks to the available instructions in the forum.

i'll be driving out later with my family and will evaluate how it is in normal driving.

i'll try and track it soon as well and see how it handles in dry and wet conditions

 

I'm so glad you were able to get one. The shipping rates there are crazy!

 

i know, right?? i'm used to it, i guess... i am on the other side of the world, anyway.. and the thing is surprisingly heavy! the original one you can easily bend it when you place your weight in the middle of the bar.

for overseas buyers who want to purchase the Progress rear sway bar, ultrarev.com is the US distributor that ships internationally.

was able to do a short drive today to the mall and boy the change in direction has really improved and the car felt more planted to ground.

 

After installing the rear sway bar does anyone else hear a weird noise in the rear like something is loose? It may be coming from something else or my stereo equipment but there is a rather loud noise when hitting small bumps or even pulling into my driveway. It sounds like something metal is loose and rattling around. The sway bar is tight as is anything else I can push and pull on under the car. I sure hope it's not my springs that have loosened up at the upper strut mount. That would be a pain to tighten. Grr

 

I noticed this too mostly on uneven roads or bumps like you say. But honestly, I'm not blaming it on the sway bar yet. My car always squeaks and creaks and sounds like it's going to fall apart after long drives, especially after 20 min on the freeway. A long time ago I figured out that the squeak was coming from the rear seat - the metal latch was rubbing on the metal loop. I stuffed some foam in the area and that helped dampen the sound.

So I don't think I hear the same loose thing as you do, but it can be a million things. The Prius sounds like I'm on a creaky boat sometimes, literally and that hasn't changed since getting the sway bar. It's funny, I used to complain about dash rattles...I must have a dozen now and I don't even care. It's the squeaks in the back and feeling that my car will split into two that's the most unnerving. Maybe I'll get over that some day, or just keep turning the radio up...

You could always retorque the bolts - Id go for at least 120 ft lbs. I've been too lazy to try this though, since as I mentioned above I'm not quite at that point of concern.

 

I'm not sure of the wind noise.

However, the first time I installed it I hand tightened the bar on both ends. I couldn't get very good leverage while working underneath the car because I was only able to grasp my tool with one hand. I tightened it as much as I can, given my limitations, knowing that I was no where near the 120-lbs of torque it's suppose to be tightened to. After a week's worth of driving, the bolts started to come loose and I could hear "creaking sounds" while pulling into driveways and while backing up slowly. A few more days of driving went by and the bar starting to make "CLANK-CLANK" sounds when I went over bumps. I knew the bar was loose.

I went back to the garage and reworked the bolts. While I still couldn't tightened it with my hands, I figured out a easy way to get maximum leverage. I went ahead and jacked up the car on the passenger side, just high enough where I can lie down on my back going underneath the car. I carefully placed the large torque wrench to the tightened position and I positioned my foot on the wrench, and pushed gentley to tighten the bolt up. I used my foot and pushed, all the way to 120-lbs of torque.

I've driven 300+ miles since then, no more sound from the rear.

Good Luck!

 

Azipod,

Thinking along the same lines as you, I crawled under the car to check the bar. The bolts appeared tight but I gave them an extra twist or 2 thinking nothing would come of it but I have not heard the noise since I did that. It's been a few days and no noise. I guess you really have to crank those bolts down!

 

@F8L, I too have been hearing the creaking noises from my prius. They have gone away on their own at the moment, but once I hear them again, I will definitely recheck the bolts.

On a side note, have been loving the new sway bar, although driving like I do sort of kills my gas mileage :/

 

after a week of normal city driving with the progress bar, i haven't heard any creaks in that area.. though when i checked for tightness, the bolts needed just a bit of retightening.

Yesterday i did 814km (508 mi) of country driving and was very much impressed with the improvement in lane changing and negotiating bends. i have yet to crawl underneath the car again to check the bolts but i haven't heard of any creaking noises while driving on uneven tarmac. also did about 2 miles of rough gravel which rattled the whole car including my bones. but luckily after that, the noise was back to normal faint in-cabin rattles.

 

Mine are still gone so I can only think that tightening those bolts on the sway bar helped. If your noises come back try tightening it and let us know if it helps. It would be a good install tip for others.

I'm glad yours is working perfectly. After all the trouble you went through to get one!

 

After about 500 miles or so, I can tell you that I absolutely love the bar!

On another note, I ordered the Universal Bracket/Poly bushings for the stock front anti-roll bar. I didn't want to go through the expense/work to put in a whole new bar, and thought of just upgrading the front bushings to the Poly ones, which should really tighten and firm up the front-end a tad. I had to get the Universal bracket/bushing from Energy-Suspension, since their catalog does not have Prius-specific application.

I'll let you guys know how this turns out after I get it installed. I plan to do it sometime early next year, when I get my oil changed.

 

If you're talking about the front sway bar bushings, I just did it (and the front bar). You just about have to remove the whole front crossmember to get the old bushings out. They are up against the body and you can't get a wrench on all of the bolts without lowering the crossmember. It's just another 15 minutes to change the front sway bar.

BTW, when I did my rear sway bar, I greased the bolts and the ends of the sway bar. No squeaks.

 

@F8L
+1 confirm on the bolt tightening to for reduction of creaking noise. I think the bolts are just old, so they arent holding as well. They will need periodic re-tightening I am sure.

 

Has your car been aligned without doing a zero point calibration? I noticed some "slop" in my steering but it went away after doing a calibration. Can't explain why it would make a difference but it did.