Stiffening plate question

I have been fighting this battle with mine for quite a while so I know exactly what you mean. I have no objective evidence that the plate helps but I think it does, and for the price it's definitely worth a try.

A couple of other things I have found:

1. Increase your tire pressure to 42 lbs or so (most people here use 42 front and 40 rear). This helps by making the tires a bit stiffer in the sidewalls and they will be more stable. It will also improve your mileage quite a bit over the factory recommended pressures.

2. Have the alignment checked. Have them give you a bit of toe in in the front (+.05 degrees on each side) this makes the car more stable and it will track better when you are at highways speed. Make sure you tell them toe in, thats the + number, if they give you toe out, the - direction, it will get worse. +.05 is still well within the specification so it will cause you no problems, either warranty problems or mechanical problems.

 

Basically what the plate does... it hold the back end together.. Have you ever had the "back end is wagging" type of feeling. You'll know it.. it's the only sensation that tosses your head from side to side. Lack of good suspension is what makes the car dip from side to side.. but what i'm refering to is the bounch from side to side. Sometimes it can be part of that highway uneveness. I have an 04, and i can do 90 comfortably on the highway.

oh yeah.. change out your tires. Nothing good can be said about the integrity tire.

what really causes that wonder ( kinda 50/50) is the front end moving indipendently. It needs a brace too, so the front end can move as one part.

To make it feel like a real solid car, expect putting about 2 grand in little parts on your prius. BT. plate (unless you go with a larger brace... but the problem isn't side to side.. it's center shift.. .anyways..) front tower brace, and front end stabelizer. (that can be a few parts.. many options here)

 

<div class='quotetop'>QUOTE(Renocat @ Aug 4 2006, 08:18 AM) [snapback]297602[/snapback]</div>

You're also feeling the effects of the wind wrapping around the back of the truck, and, depending on how close to the truck you are, speed, size of the truck, etc., it can feel pretty pronounced when in a light vehicle. If you were to sneak in right behind the truck (I do NOT recommend this), you would feel it calm down, since you'd be "drafting", what the NASCAR racers do. Likewise, increasing the distance between you and the truck should also lessen this effect.

 

<div class='quotetop'>QUOTE(Renocat @ Aug 4 2006, 08:33 AM) [snapback]297677[/snapback]</div>

I would rather visit my dentist than a car dealer's service department. But you will get a free alignment if you complain about handling or stability within the first 12 months or 12K miles. Toyota will pay because they realize that the alignment could, and often is, effected during shipping.

Here is some pretty good info on tires and alignment: http://john1701a.com/prius/prius-tires.htm

I agree with V8Cobra about the Integrity tires, I was happy to be rid of mine.

 

<div class='quotetop'>QUOTE(Renocat @ Aug 4 2006, 10:18 AM) [snapback]297602[/snapback]</div>

Hi Kim,

Highway wandering is more like when you are all alone on the highway, set course then 1/2 a mile later down a straght section the direction the car is travelling is slighly off from what it was. There is also the reaction to grooves cut in some highways too avoid hydro-plaining that can make the car wander.

In your situation it sounds like there were what are called "sheer vorticies" coming off the upper corners of the rear of the truck. They are like little horizontal tornadoes, one from the right side of the truck, then one from the left, back and forth. When each one hits your car it will roll in reaction to it (rotate about an axis in line with the car). It may "yaw" a little too (turn side to side about a vertical axis through the center of the car). This is normal. What is not normal is if you hold the steering wheel firmly and steer straight, for the car to go severely off course after one of these sheer vorticees hits the car then another. If everything is proper with the car it should feel like ruts in the road and the car is buffeted around, but stays on-track.

It does not sound like you are having a problem, other than normal wind buffeting. Before I put the plate on , and after this was the same with my 2006 Prius. Its more an issue with the truck travelling at a speed that reinforces the generation of the sheer vortices. With a hit from the left and then from the right, in relatively rapid succession, the car should stay on the average track.

The reason I got the plate was the cross-winds here in the midwest, especially in the spring. A wind gust can hit a car from the side, varying from 0 to 30 or 40 mph, within a second. Before the plate the car was all over and I had to slow down to 55 on the highway to be able to hold the car in the lane. After the plate, I could cruise at 65, hear a gust hit the side of the car, feel the car roll in reaction to the gust, but now the car had a minor steering reaction to the gust. It mostly stayed on-course.

Without the plate the car jiggles more. I think this is the back end of the car is wiggling. If this is disconcerting, your car is alligned well (tracks well on the open road without any wind), they you might try the plate. It will reduce the jiggling sensation. But the car will roll left, the right when hit with wind vorticies off the rear of a truck.

 

I'll offer a wee bit of counter-view. The one thing I noticed immediately after installing the plate was the *increase* in wander. Go figure.

 

<div class='quotetop'>QUOTE(darelldd @ Aug 4 2006, 10:15 PM) [snapback]298049[/snapback]</div>

I think you have (figured it out...!)

The observation worth repeating is that structural integrity of the Prius in-toto is not dictated solely by torsional (twisting) forces; tensional and compressive forces are also at play. Until such time that we can examine (and / or model) the frame-suspension as a whole, speculation is free for all…The MEM types would say: bond few strain gauges on the plate and stress the body (corner lift, body roll, etc…) and the truth will vector out

 

<div class='quotetop'>QUOTE(darelldd @ Aug 4 2006, 10:15 PM) [snapback]298049[/snapback]</div>

That's the first time I've seen someone say it made things worse.

This may have been discussed and I missed it, but does anyone know if replacing the original plate with the one in question here would have any effect on the warranty?

Last thing I'd want to do would be to void my warranty!

 

Nothing you can do to the car can legally void your warranty - if it doesn't break anything.Mini FAQ: Are you nuts? Doesn't modifying your expensive, irreplaceable vehicle void your warranty?

From my Rav4EV mod page:

Mini FAQ: Are you nuts? Doesn't modifying your expensive, irreplaceable vehicle void your warranty?
A: No fair, that's two questions. Modifying any vehicle does NOT automatically void your warranty, though I hear this all the time. Check the Federal Trade Commission website. the Magnuson-Moss Act is what answers this question. A car maker can refuse to repair under warranty any item found to have been damaged by "aftermarket" products or repairs, but they cannot void the warranty just because you had work done by "non-Toyota" people or have aftermarket products installed. If they cannot prove that an item or repair caused the damage, they remain obligated to their warranty. An example: I add a Manzanita conductive charger, and the next week my steering pump fails. That steering pump is still covered, though I've quite obviously modified the vehicle in important ways.

 

I installed the stiffening plate but before I did, I drove the car for about 500 miles and over specific country roads to test ho wit handled. I then drove ona specific highway including trying to go as fast as I could on the on and off ramps as I wanted to test body roll. At highway speed of 70 + MPH the car felt like the rear was wiggling, adding the higher tire pressure helped but did not eliminate it.

After installing the stiffening plate, I drove the same roads again.

RESULTS: The stiffening plate has a definite positive effect on the Prius as I was able to drive the roads faster with a better ride, better handling and the most noticable was the on and off ramp body roll is gone and in fact I can now accellerate in these turns. I can now drive at over 80 MPH and the car tracts smooth and straight.

One negative aspect and this only happens on rare occasions and that is the traction control light comes on if I hit a little dip in a road when driving a bit fast. I am assuming the body isn't flexing as it used to hence the problem.

SUMMARY: IN my opinion the plate significanly improved the overall handling characteristics of the Prius and so far is one of the best investments I have made. Quite honestly without this modification I don't think I would have kept the car. I know have 8,000 miles on it with not ONE problem.

 

<div class='quotetop'>QUOTE(BVISAILMAN @ Aug 30 2006, 08:29 AM) [snapback]311521[/snapback]</div>

I have not install the BT plate on my 2005, but I still experience what you have there. I even try the max speed of 106MPH, the car tracks straight and smooth. Just this morning, there's light rain and I'm driving on uneven road. The traction control kicks in when I go over bumps. So I don't know if part of what you are seeing are due to the plate.

I am not saying that the BT plate is useless. I'll believe it when someone do a blind test like darell did. http://www.darelldd.com/ev/prius_stiffening_plate.htm
Quotes from his website

 

ScottY - You are starting to sound like a zealot.

Every time someone puts up a positive note, you have to bash the BT plate again. You don't believe anecdotes, unless they criticize the plate, then you take them for gospel. Just decide for yourself not to try the plate, and leave others alone. The only thing of less value than anecdotal evidence is opinion without benefit of any personal experience with the product. Try not to make it your personal mission to prevent anyone from buying the plate.

Give it a rest.

 

jbarnhart, please avoid making personal attacks on this issue. I just want some facts here, not feelings.

Actually, this is my first post "bashing" the BT plate, if you want to called it that. I read MANY posts on this issue, and all the "positive" result come from how the driver feels. From darell's test, the result produced also come from how the driver feels, but it is a negative result.

Like I said, all it takes to convince me is a blind test like what darell did. But no one was able to produce it with a positive result. The only blind test I'm aware of produces a negative result.

I don't have an issue that you guys are buying it, and I don't run around screaming, "DON'T BUY THE BT PLATE!" I never call you guys names because you guys bought the plate. In my reply to BVISAILMAN above, I just want to point out that I can reproduce the conditions he/she described without the BT plate installed on my car. So I really don't understand why you guys have such a big reaction when someone demands some facts about the plate. oh well.... I guess I better shut up from now on. :mellow:

 

ScottY, I strongly recommend you do NOT buy or install the BT Tech stiffening plate. I have one. I am among the MANY who can feel it's beneficial effects. Darelldd has one. He is one of the FEW who don't feel it is beneficial. I think his "blind test" speaks more to his realtionship with his wife than to the benefits of the tested part. She was probably just trying to please him.

You won't get "facts" without million dollar testing. You reject overwhelming anecdotal evidence. The BT Tech plate is not for you. You would always feel you had wasted your money. Forget the plate and get interested in a different mod. Don't feel you have to shut up, just stop beating the dead horse.

 

<div class='quotetop'>QUOTE(Bill Merchant @ Aug 30 2006, 10:51 PM) [snapback]312027[/snapback]</div>

Double-blind tests cost a million dollars? I think it'll cost less for Toyota to just build it into the Prius at the factory, if it was even an issue. I find it amazing that data-driven Prius owner's can-testdo-anything attitude changes here.

Some of us will continue to point out that most of the "positive" responses are incomplete due to NOT testing, or feeling, the OEM plate after the BT plate in a proper double-blind.

If you bought the BT plate and it did "something" for you, great! But bashing people who disagree for pointing out that 'incomplete "overwhelming anecdotal evidence" does not equal a rigorous scientific theory with the assumption that all the BT drivers, except one, have accurate SOTP meters' just lowers your credibility.

anecdotal: based on personal observation, case study reports, or random investigations rather than systematic scientific evaluation

Personally, I've driven 50K miles on the stock plate and regularly pull 0.7Gs+ (measured) on turns. I gained the same improvements BVISAILMAN talks about with upgraded tires, or ... folding down the back seat, without worrying about wiggling nor tracking so far, and my POV is just as valid.

She was probably just trying to please him. is just as anecdotal.

 

<div class='quotetop'>QUOTE(NuShrike @ Aug 31 2006, 12:29 AM) [snapback]312043[/snapback]</div>

I quite agree. I never suggested otherwise. I never bashed anyone.

Less heat!

 

<div class='quotetop'>QUOTE(Bill Merchant @ Aug 31 2006, 12:35 AM) [snapback]312047[/snapback]</div>

I didn't mean you, and I'm sorry if you felt implied. I was trying to be generalized about anyone.