BT Tech Stiffening plate

Hi Allande,

First some comments on the experimental methodology.

In the picture, the car appears to still have some force on the tires (on the ramps). For the test to be believable by skeptics, the jack stands have to be the apparent sole means of support. Were they?

Did the car actually sag 1.3 inches from the level condition when the jack stand was removed? Or is this a relative position made between at a constant condition between the variation in the plate / no plate? I am unclear on that after reading your April 22 measurement comments.

I would like to see the initial level measurement, and the sag measurement , and the differences all put into a spread sheet. You should also include these measurements for the supported corners in all the load conditions for completeness.

Did you use a water level to set level ? What datum's did you use? How are you sure the chosen datums are designed to be at the same level? You might need to get some screw jacks like in the SAE paper to get proper level. For a first pass the top of the wheel arches might be assumed to be designed to be at the same height. But for aero, or styling, they may not be.

One way around this problem is to add weight in the unsupported corner and measure the additional sag. After measuring the unloaded unsuported sag, add 50 pounds of load in the unsupported corner. Measure the additional sag. This will give you a third data point. If the first two data points are inline with the second data points, your initial point is probably accurate. The sag versus load line should be straight between the three points. The degree of crookedness of the line is a good indication of measurement uncertainty. Ignoring the first point altogether and using the slope between the unloaded and loaded points is a better method.

You may want to load the opposite corner by at least the amount of weight you add, and in a manner that it cannot slip off. This way the car will not rotate (and possibly come off) the other two jack stands.

A professional methodology would be to measure 4 to 10 increasing loads. This way the straightness of the load line can be more accurately accesed.

An upward modulus measurement should be made too. That is 4 to 10 points at increasing upward force. For this you will need the attachments to the ground that will resist tension and being yanked out of the floor, as well as compression.

In driving conditions there are forces that are sideways (cornering) and axial (braking). So do a horizontal push/pull in the sideways and inline directions test as well.

My opinion is that your test is good first effort, but its hardly complete. And its not going to be sufficient to say the plate is not doing anything.

Finally, your standard deviation is 8 times as big as the difference. So, your test results says its equally probable for the BT plate to have had a .04 inch improvement as it could have had a .05 inch degradation. The .01 difference could easily be experimental error. Hell, its 8 times less than your noise.

Which beg's the question " Why would Toyota have put a plate in this location, if there is statistically no difference? ". If the BT Tech plate had no difference then no plate, then the standard plate will have no difference either.

Because the load you chose puts the plate in a buckling condition with the roof in the tensile condition to counter it. Here is my hypothesis: Since the roof did not change between your tests, you saw statistically no difference. No, or very little load was being put on the plate in your test. As the Miata is a roadster, this test makes allot of sense for a Miata. Not so much for a sedan.

The next step should be to get a force gauge, and put it under a jack, and lift on the corner.

 

<div class='quotetop'>QUOTE(daniel @ Apr 23 2007, 04:56 PM) [snapback]428705[/snapback]</div>

Especialy fundamentalist religions - they have the one true testament. Everyone else is a heretic!

 

<div class='quotetop'>QUOTE(donee @ Apr 23 2007, 05:29 PM) [snapback]428741[/snapback]</div>

Hi donee

This has been a lot more work and a lot more unpleasant than I imagined it would be. I respect your approach to discussion and your thoughtfulness. I take you seriously. You are more than a worthy adversary.

As I reported, the net sag from neutral to the average total flex without any plate installed was 4.1 inches. Of course, that was only negative sag. There would be equal positive upward sag which would actually double the universe for the proportion of the effect (if any) of the BT Plate. I could have caused that but saw no reason to do that.

I didn't use a water level, but I had the concrete floor laid and there is a 2% slope in the direction of the front of the car for drainage of the garage. The floor is quite even as demonstrated by the pattern of water when it does get wet. The jack stands were new, identical, and set to identical levels. They were never moved during the test to retain consistency. There was only one jack stand which had any chance of being touched during the test and its location was marked with tape and photographed. I carefully swept the floor to be sure that no accidental objects intervened to affect measurements.

I know that you looked at my earlier work and that you are a serious thinker when it comes to matters like this. A lot of what you suggest would be more significant if there had been any indication that the BT plate had an impact on the stiffness of the chassis, but there was none, not ANY outside of a range of normal variation. (It is one thing to speak of theoretical POSSIBILITIES and another to speak of realistic PROBABILITIES)

As for the reason to put the ramps under the front tires as a back up support, I had my personal safety in mind for that. When the right rear of the car was unweighted without that back up support, the car posed on jack stands at an angle which frightened me. So when I did the test, there were jack stands holding the car in position, but the ramps prevented the car from assuming a dangerous angle. So, there had to be some weight remaining on the right front wheel, but not much. This could have influenced the measurement of the total amount of chassis flex but I did not focus much on that. What I focused on was the comparison of the amount of chassis flex at its extreme both with and without the BT plate which was what you read in my report. This is the index of chassis stiffness. This is what did not change.

Perhaps I was not clear enough in my report. In the interests of consistencey and accuracy I set a fixed point on the larger carpenter's square to measure from. That point was arbrtrary and has no meaning other than consistency. All meaurements started there. The smaller square moved with each measurement and always touched the mark on the fender. The measurements were from the fixed point to the bottom of the smaller movable square which represented the most recent measurement. The total chassis flex at each measurement differed slightly as the measurements differed slightly but was about 4.1". I gave that in my report.

I did not approach this as though I was the only one who would ever do this test. Too many people had said that I could make the test come out to look any way I want to, so I depended not on my skill to make it look good but rather on the possibility that others would repeat the test and see the results for themselves. I could have shown photos of the floor jack and the calipers at each measurement. I could have made spreadsheets as you menationed, but they would have all been called forgeries. I could have even moved the jack stands a little here and there to get the effect that I wanted. I HAD to depend on the possibility that others would do the test.

The basic point is that the conditions for measurement both with and without the BT plate were identical. I took great care to be sure of that and it took three iterations to get there. If the BT plate made a difference in chassis stiffness, it would have shown.

This test was sensitive enough that in one iteration, I accidentally moved just one jack stand a fraction of an inch horizontally and it showed a difference of measurement in the the body flex of almost an inch. What are the chances that I could have forced a coincidence of measurements as close as I reported?

As I said the real test is in the repeating of the test.

Why would Toyota put the OEM device where they did? When I asked the company, I was told that they put it there to stiffen the floor for the traction battery (and I presume any loads in the back seat and the rear of the car in combination with that). Nothing was said about handling of the car or stiffening the chassis. As you know I found that the OEM device had no chassis stiffening effect.

Brian speaks about adding plates to a Corvette. It has no roof but it does have a frame. It is quite a different car than a Prius just as is a Miata or a Porche. But chassis stiffness is still an issue. If no or little load was being put on the plate because of my test as you opined, it isn't being done in the real world either because mine is a valid test of chassis stiffness. The roof is there 24/7.

You say the BT plate could have had a .04 improvement (at the outside exteme of my test). That would have been a 1% improvement in chassis stiffness if it were true. This is possible, but very unlikely. If it were true, it would be insignificant when a 30% improvement is in the range of what is considerend to be needed for a positive effect.

donee, there is no question that a very stiff chassis does not sag when supported at just three corners. The less stiff, the more sag. This is measureable. I measured that. This is not complicated. I suggest that you do a test yourself. You have the BT plate. You have the tools. Come up with some measurements the hard way like I did. Demonstrate that the numbers I reported are out of line if they are. It won't cost you anything. It won't take more than a few hours. You have my respect, support and good wishes.

Go for it and all the best!

 

Hi Allande,

My point is that the any claim that plate made things worse is inconsistent with the data. As the difference measured is in the measurement noise. .04 inch improvement was written in the same sentance with .05 inch degradation.

Here is my concept of what you did was that you measured with the chasis supported at 4 corners, removed the jack stand, and let one corner sag, and then remeasured. And the 1.3 inch was the difference between the supported reference datum, and the unsuported reference datum. Is this correct? How was the 4.1 inches measured ?

I have avoided reading the other comments in detail. Some people are criticising you, I could care less. You are trying to quantize things, which is good. I am only trying to provide my experience in engineering measurement as an aide to your effort. But, I am an amateur when it comes to this type of mechanical measurement. And as an amateur do not take what I write as anything more than an opinion of an amateur.

As with most experimental endevours, the experiment brings up a question. As no change was seen, why is there a plate? Could the car be driven without the plate? If we take your conclusion at face value the answer is yes. Does that seem right to you?

 

<div class='quotetop'>QUOTE(daniel @ Apr 23 2007, 06:56 PM) [snapback]428705[/snapback]</div>

I know its a stuggle accepting things on faith if you've never done it and had it pan out to the positive.... maybe you had faith in the wrong things?... sorry.. but it happens to us all...., but have you none at all in your fellow man when there is such an overwhelming testimony?

I have discovered we tend to judge by ourselves and when its hardest to trust others, its often because we would not trust ourselves if the shoes were on the other foot.

Not believing the testimony of so many can be counted as wise caution, but it can also be counted as not seeing the obvious and refusing to see at all?

I understand that there are throngs of people out there that follow the wrong things... stupid goofy rock stars, soap oprah queens, Oprah!.... LOL! and such... so I totally understand the caution of going by mere words of others on seemingly empty words following a lost cause or idol..

But you also have to consider some merit as to "who" is saying this?
Are you refusing the words of pure stangers or people you have heard long enough that you should trust by now?

No, you are refusing the words of ladies and gentlemen you have gotten to know for some "years" out here on PC... one of which is Evan who is not only a moderator but is required to make decisions at work than can kill or heal folks, there are many other out here that carry similiar levels of responsibility and do it well......yet you reserve your judgement and formulate conclusions that inspite of all of this overwhelming testimony of "credible" witnesses and friends that you could still be getting decieved into wasting 165.00 bucks and 10 minutes worth of work?

Herein lies to point of contention as its an insult to "everyone" that "thinks" the plate does something to have someone merely stand up and discount it with a stroke of ration or one test in a garage.

So be it, the money was not that much to me, and I was willing to risk it in light so many postive reviews and I have no regrets.

This seemingly "unrational" lack of trust and ability to not believe in anything without proof tends to make one consider looking inward rather than outward.

My point is, can't you guys admit you could be missing something?

Sometimes doing a complicated test that shows negative could actually throw you off the truth if its wrong as we trust in the test more than the results.

If this plate was indeed an afterthought by Toyota, it would make sense that determining its need was not obvious even by the Toyota engineers.

 

<div class='quotetop'>QUOTE(Allannde @ Apr 23 2007, 10:57 PM) [snapback]428881[/snapback]</div>

Here is the heart of the matter: A very stiff chassis does not sag at all. The Prius chassis with no plate sags about 4 inches. With the OEM plate it sags the same. With the BT Plate it sags the same.

Therefore, neither the OEM plate nor the BT Plate stiffens the chassis by a measureable amount. And since a 30% improvement in stiffness would be needed in order for there to be a significant improvement in handling, the BT Plate does not improve handling by stiffening the chassis.

<div class='quotetop'>QUOTE(donee @ Apr 24 2007, 03:42 AM) [snapback]428911[/snapback]</div>

Allan does not claim that. He claims there is no difference. He claims that he could not feel any difference after a very long road trip with the BT Plate, driving aggressively, and he claims he measured no diference.

<div class='quotetop'>QUOTE(donee @ Apr 24 2007, 03:42 AM) [snapback]428911[/snapback]</div>

Allan has answered this question already several times: The OEM plate is there to help support the weight of the batteries:

<div class='quotetop'>QUOTE(Allannde @ Apr 23 2007, 10:57 PM) [snapback]428881[/snapback]</div>

I think Allan chose the wrong word above. I think he meant to say that the OEM plate strengthens, rather than stiffens the floor. Note that the weight of the battery puts a tensile stress on the OEM plate, not a compressive stress. A very flimsey plate can easily support a tensile stress.

<div class='quotetop'>QUOTE(windstrings @ Apr 24 2007, 06:15 AM) [snapback]428935[/snapback]</div>

On the contrary: It is easy to close your mind and simply believe what some "authority" tells you. The hard thing is to use your brain, think for yourself, and come to a rational conclusion based on the evidence. Galileo looked through his telescope and saw the heavens as they are. People who took the Ptolemaic system on faith refused to look, because they believed that faith is more authoritative than physical evidence.

Faith refuses to accept reality when new information becomes available. The scientific outlook allows its view of reality to be constantly refined by the available data.

Courage in the face of adversity is admirable. Obstinate faith is not.

 

Wow... I have been gone a month - and you guys have really been at it. Allande, I am glad you did the test.

Let me pipe in with a couple of technical comments:

- The existing plate by Toyota provides zero, or a negligible amount, of torsional stiffness. This is evident by its design. However, it does an excellent job as a strap to keep the bell housing from opening up. Allande, Toyota gave you the right answer - what they were saying was that as the car was bouncing up and down on the road, the weight of the batteries flexed (spread open) the bell housing. The existing strap keeps the housing from spreading.

- The BT plate, in addition to being a good strap, has torsional stiffness - which helps the car chassis become stiffer. The question is to what degree and is it enough to make it worthwhile.

By the way, the test you conducted is a valid measure of torsional stiffness of the entire frame. For those of you who questioned at what points on the car the test should be conducted; the answer is precisely at the axle points. Ultimately, it is the wheels and the connection points on the chassis that control how the car behaves.

With the test conducted, we should have seen some improvement - and as you indicated - it should have been significantly better than the 0.08 deviation that you found. Bottom line is that as of now, the conclusion is that the BT plate provides minimal improvement in torsional stiffness. (But by its very nature, it has to provide some).

There is one improvement to the test procedure itself: The test really should be done with the car at load capacity (or slightly less than load)... and should not be done in an empty condition. I know that would be a hassle, but you can apply 100 lb sand bags in each front and back position along with another 100 lbs in the back. This 500 lb load would deflect the car significantly (especially in the back) and would truly measure the "envelope" as you indicated.

 

<div class='quotetop'>QUOTE(donee @ Apr 24 2007, 02:42 AM) [snapback]428911[/snapback]</div>

Hi donee

To answer your last question first. YES. I have done it extensively and with vigor. The Prius was clearly designed to be adequate in all anticipated conditions without anything mounted there. Only after some extrordinary happening later, did they discover the need to add the OEM device, which they did with the usual Toyota extra degree of caution. Toyota designed the degree of chassis stiffness into the chassis which they intended. They NEVER would have designed a mounting such as this with the intent of adding chassis stiffness. The only similarity with this and other cars with such a plate (such as a Corvette) is that these other cars have FRAMES on which to mount such a plate. Such frames ARE connected to the suspension which is why those plates work and this plate does not.

I explained the method of measurement in my original report and again in my last reply to you. Read it again. I did not explain how I reached the 4.1 inch number so I will now:

The way I measured the total flex which I reported was to return the car to neutral and set the right rear on a support of exactly the same height as the one on the left rear and then measure the height at the same point on the right rear fender. I then subtracted the distance from the average low flexpoint (with no plate mounted at that point) to the fixed point of measurement so what I was getting was the actual movement of flex in the car only. My measurements were to three decimal places. I rounded them to only two places for reporting.

Finally, I did not report any negative effect of the BT plate. What I said was that if one does not use care in such a test, it may APPEAR to produce such a result. I went ahead with more care and the test produced the result that the BT plate had no effect on stiffening the chassis of my car.

The initial question to which you refer was simple. "Does the BT plate stiffen the chassis of the Prius as claimed"

It did not.

Is there some other explaination for what is reported about the BT plate? Possibly. But I own one and I have driven almost 1300 miles with it mounted on my car in all imaginable conditions trying to discover for myself what these things are. It remains a mystery for me.

I just can not understand how people can have such a high regard for the Prius generally and assume that in the case of this OEM device the Toyota engineers would have made such a HUGH blunder. The problem is that the OEM device has NOTHING to do with chassis stiffness and everything to do with strengthening the floor of the car as they name they gave it implys ("The Front Floor Brace"). The fact that the bolts have only 17 foot pounds of torque and attach to low carbon, stamped sheet metal attests to that. The fact that despite reading this site (they do, you know) they have made no changes to the OEM device in four years, also attests to that.

I hope that you find that responsive.

Allan

 

<div class='quotetop'>QUOTE(Les Gas @ Apr 21 2007, 11:59 PM) [snapback]427661[/snapback]</div>

jumping in here very late...

I noticed a definite improvement in handling and tracking immediately after I had the BT brace installed. Therefore, I'm not willing to go through the trouble of removing it to see what it's like without a brace. I've already done my comparison: OEM brace v.s. BT brace, and feel I can extrapolate from that what I would expect from removing the brace... as others in my situation could, too.

 

<div class='quotetop'>QUOTE(daniel @ Apr 24 2007, 10:17 AM) [snapback]429001[/snapback]</div>

yea.. that would be my brain as I notice it works......

Did you turn yours off when to did your test drive?... but I think I remember, your one of the ones who never bought it in the first place.

I guess all fields have their doubting Thomas's.

 

I have been reading these BT plate discussions for close to a year now and although I have responded to a number of posts I feel it is time that I put my mechanical engineering degree that I earned back in the 60’s to good use.

I worked for a company in Michigan that specialized in designing high strength steel and structural components for all of the big 3 automakers (back then at least) One of our jobs at the time was to measure the strength of the frame of a certain Ford vehicle, (which one I don’t remember.) The methodology used at that time was for us to take this frame to a company that specialized in taking these measurements and that is all they did. This company had a special fixture for attaching the frame to a Rota table concrete structure and then measuring the deflection of the frame at over 240 points along the frame. We would then make our modifications and the test would repeat, often taking 6-8 hrs per test In this time, the frame would be rotated at different angles to simulate loading. It was imperative that the frame was mounted in this fashion. At all of the measuring points, we were able to measure the results in .0001â€! These tests were often very expensive and even the auto manufacturers often balked at the bills they got for executing these tests.

I have read Alan’s data and although I give him a lot of credit for going through all of this to conduct his own tests, I am sorry to have to say but the methodology is completely wrong and subject to many errors and inconsistent results. When you are measuring a chassis, frame or a uni-body structure, you can not have the wheels or any other compression type devices coming in contact with the ground to achieve accurate results. This is why when we tested the frames we had to bring the car to the facility and the cars actual frame/body was bolted to the concrete barriers. This was done so that there were no outside forces like the tires, springs, shocks and struts that compress and expand making any measurements suspect at best. In addition, the testing should be done on 3 axis that can induce loads to the structure, none of this was done in Alans test.

It is my opinion that Toyota added the brace in that location because they knew there was significant flex occurring in the latter portion of the vehicle’s structure. To say it was there because there was a battery sitting on top of it is horse manure.

The company I worked for later went on to do testing for race car sponsors and it was imperative that they had the best/stiffest chassis so that the cars of that day could withstand the 1+ G turns of that era. In order to test these chassis’ with a degree of precision, we built a device that we called a twist fixture and would attach this to the chassis but again we would attach the fixture to concrete and the actual fixture would suspend the chassis in order to get accurate measurements. What was great about this fixture is that we could simply lower one side using a type of tie-rod end to lower or raise the chassis with great precision and measure the deflection at number of points along the chassis. The fixture was also able to be rotated so that additional forces could be placed during the measurement process and documented.

To sum all of what I have just written here are my findings:

The test by Allan although well meaning was conducted incorrectly and the results in his own admission showed inconsistencies. He also conducted no tests of the effect of compression while measuring the amount of deflection anywhere on the body under amy type of load. The methods used for measuring were not proven to be scienfiically accurate and the person (Alan) in this case is not known to be proficient in using scientific meausring tools (un-calibrated) with an unknown degree of accuracy.

A vehicle in motion is also affected by outside forces such as road surfaces, gravitational loads (g-forces) and aerodynamic forces which put additional loads, (sometime great amounts) on the vehicles body. Having a part that stiffens the body would counteract these effects to an extent. The more stiffening the part provides, the greater the result will enhance the differences the driver feels.

I never claimed to be a race car driver but there is no doubt in my scientific mind that the BT plate is providing a stiffening effect on the body of the car. This would explain why the car feels more stable to me when driving it. What is in question is the amount of stiffening that the BT plate provides and I personally do not have the inclination or financial ability to dive into that.

Best,

Ken Stewart

 

<div class='quotetop'>QUOTE(Ken Stewart @ Apr 24 2007, 08:53 AM) [snapback]429069[/snapback]</div>

Hi Ken

Thank you for recognizing my hard work and sincere purpose. I found that I had a different reading of your comments after the third time through. Careful (i.e. scientific) observations seldom include absolutes or pejoratives.

I stand by my report and its references.

My photgraphs show my measuring tools and what I did can be replicated by you or anyone else if you question my application of those tools. The basic point is the comparison of BT plate and no plate. Other variables fade into insignificance under the circumstances. I was not measureing pricise degrees of chassis stiffness at many points as you may have done once. I was trying to detect ANY evidence at one point.

You can contact Toyota as I did and you will get the same answer I did. The OEM device is not regarding chassis stiffening.

If you think I found the incorrect answer, show me what you have found the correct answer to be.

I put some sweat, research and a little money behind my words. Are you up to that?

 

<div class='quotetop'>QUOTE(windstrings @ Apr 24 2007, 03:11 PM) [snapback]429173[/snapback]</div>

I'm just curious has Brian performed this test? What scientific evidence does he have to back up his statements?

 

<div class='quotetop'>QUOTE(windstrings @ Apr 24 2007, 11:11 AM) [snapback]429173[/snapback]</div>

Hello Windstrings

In fact I did just that vigorously, many times. I could not tell the difference from the OEM device.

I am not a bit frightened to leave the OEM device off. But the factory put it on, so it probably doesn't hurt to have it. Of all of the factory engineers to trust, I place the Toyota engineers at the top!

 

<div class='quotetop'>QUOTE(Ken Stewart @ Apr 24 2007, 08:53 AM) [snapback]429069[/snapback]</div>

Very professorial, however, the tests you dealt with in the 60's were trying to measure the torsional effects on the individual members of the chassis. Here, we are just trying to understand the extent of the overall stiffening of the chassis - we don't care about any of the subsets. Allanne was looking for large changes that would be consistent with the large number of people in this forum that say the plate had an immediate effect on performance. So, we are looking for 1/2" to 1" reduction in deflection - an amount that a typical driver would sense on the road; and not microscopic changes that are less than 0.01"

Maybe, Allanne does not have the best tools in the industry or an extensive certification on how to use a yardstick... but I don't think we are looking for that type of precision. It is my engineering opinion that his test is appropriate for the understanding that we seek.

 

<div class='quotetop'>QUOTE(Allannde @ Apr 24 2007, 02:54 PM) [snapback]429215[/snapback]</div>

Indeed, they have engineered an amazing car!... I'm still not used to it as it facinates me everytime I drive it...
My expertise is not as an engineer and I have no proof at all other than I feel the difference.
Maybe I have decieved myself and fallen prey to mass hypnosis... if so, I'm satisfied and happy in my bliss and I was glad to spend a mere 165.00 buck to make my 30000.00 car drive better!

I wish we could figure out a way to at least show a difference in the stock plate and not, then we would be on the right track to see if the there is a difference in the BT Plate and the stock.
So far, the main difference other than what it does to the car is the fact that I cannot begin to bend it as I can the stock and its quite a beautiful piece of machined art!

I know guys to spend serious money dolling up thier guns, cars, bikes etc with parts that do nothing functional, except to add class.

Unfortunately this part is not visible for all the world to see and admire... but nevertheless, I'm glad I have mine and I have said in the past and still stick by it.... "I would not sell mine for 500.00 each if I knew I could not replace them for cheaper".

Alan, it seems you first responded on this thread way back on about post # 91 as you made a solid 1/8" steel plate and tried and found to no effect?

I'm wondering, if you already went to the trouble to make a plate of 1/8" steel and were not happy with it, why did you buy the BT Plate?
Did you think it would be different and more support than 1/8" steel, or was it to make a point?
You did test in your garage back then too and now the impression is being given that you are doing something fresh.

I'm perplexed if you didn't like the plate back then, why is this still an issue with you?

I have reviewed that "many" people have responded to your posts and proclaimed thier positive results to no avail.

If you don't believe it works or will not believe.... it seems its driving you nuts that you can't reproduce the reason it works and therefore are out to prove everyone else is wrong?

I want to be reasoanable and get along with you if I can, so maybe you can help me some here.

Based on the extensive history of your feelings, yet your adamance at proving its nothing, it makes me feel like your just enjoying being the contender rather than being reasonable.

Asking people to do test more complex than what you have already done is not really reasonable just to satisfy your skepticism, is it?

You have still not responded as to why your feelings are so strong against so many credible witnesses.

 

Hi Daniel et al,

I though I read this in Allande's comments:

"
The BT plate finally arrived after the slowest trip across the land that I have ever witnessed. It, however was FREE. I immediately installed it according to instructions and left on a 1200 mile trip which included curvy mountain roads, freeways, and high speed driving which I did as vigorously as I dared. I came home and repeated the chassis stiffness test which had given strange results (it appeared that the BT plate had weakened the chassis which did not seem possible) so I knew that I must be even more careful. "


Which seemed to me to indicate that he was saying that the BT Tech plate made things worse.

 

I earned my M.E. degree in 1966 and went on to work for more companies than I care to remember. The company where I designed strucural reinforcements was the same one where we did the tests on vehicle structures. I worked there from 1978-1989 so we worked on everything from full frames to unibody structured automobiles. While at this company we had many major corporate customers includng the Big 3, Honda, Nissan and Porsche to name a few.

In response to your post, you are never going to see a deflection of 1/2-1"! A 1" deflection is huge and would be indicitive of either a very poorly designed body or something that was in the process of structural fatique/failure.

Often at times when we made changes to a cars frame/body the associated change would show a deflection differential of less than .02" which sounds like a very minor amount but when measured at the contact patch of where the tire meets, this improvement can translate to a tremdous increase in overall TR! This is why I mentioned earlier that not only does the structure have to be secured in such a way but the accuracy of the measurements must be calibrated to a known standard and the person taking such measurements must be qualified to do so.

Things have changed drastically in the automotive world and manufacturers typically rely upon resonant frequency measurements where the vehicle structure is placed in anechoic chamber and the point at which the structure begins to resonate is a definitive test to know the actual stiffness of the product they are testing. The higher the resonant frequency the stiffer the body and vice versa. These tests can also be conducted on high speed computers using complex software where it can detect to a great deal of precision what the resonant frequency of the structure will be. Often times the manufacturers will still test the structure for confirmation but computers have saved engineers a vast amount of time and at the same time money.

As I mentioned previously I think it is great that someone went through the effort to conduct this test however I feel it is my duty as a M.E. to point out the flaws on how the test was performed and that the results whether they were positive for the BT plate or negative against it serves no real purpose other than to say that someone actually did a test.

What I can appreciate about the plate is its simplicity and overall quality. The machining of this part is first rate and I am honestly suprised that they are able to offer it as inexpensively as they do.

In response to Allans post inviting me to do further testing, I will leave that to you younger guys. I really do not feel the need to test something that I already know works as I have a lot more important things to do like relaxing out by my pool.

Best

Ken Stewart


<div class='quotetop'>QUOTE(John in LB @ Apr 24 2007, 04:38 PM) [snapback]429258[/snapback]</div>

 

<div class='quotetop'>QUOTE(donee @ Apr 24 2007, 04:08 PM) [snapback]429385[/snapback]</div>

Hi donee

May I speak for myself?

That was poorly said. I apologise for that. Let me paraphrase myself.

" The BT plate took a long time getting here. When it got here I mounted it according to the instructions and set out on a trip......... While I was away, I thought about why I got strange results in my testing before I left. It then occured to me that the reason I got strange results was that I had not been careful enough. When I got home, I repeated the tests being more careful this time." Please don't make a meaning which was never there. Do you always write clearly. I wish that I did.

Incidentally the trip was succesful in that it resulted in the purchase of an EV which will be a fun new toy.

May I now respond to WS

I appreciate your gesture toward conciliation. I know that is difficult for you as strongly as you feel. There are people in this world, me included, who are guided by evidence rather than the opinion of others. That leads to rather different behavior. When you drive down the road, you are also guided by evidence. You do not drive where the road SHOULD BE. You look to see where it IS. That is acting on evidence. But you draw a line where I don't. I don't wish to argue or compare the difference. It just is. You have every right to your way and I have every right to mine.

It sounds to me like you are saying that if 100 people get together and vote that the sun should come up an hour late that the cosmos should bend and cause the sun to come up an hour late. That is the line I am talking about. People of free will are not guided by the vote of others. They are guided by the evidence which is persuasive which sometimes includes the opinions of others and sometimes does not.

If you notice, Windstrings, I do not call you names or question your sanity. I do not verbally beat you over the head. That is called acceptance of you the way that you are. And your job is to accept me the way that I am.

That is it.

You have my best wishes for your efforts.