BT Stiffening Plate Review

I would like to thank all of you that have commented and voiced your opinions about our BT Tech stiffening plate.

When I first produced this part almost a year ago, (geez time goes by too fast) there was a lot of data that I posted including a complete FEA analysis on our plate compared to the stock plate. The analysis showed that the BT Tech plate was over 1600 percent stiffer than the OEM factory plate!! What this translates to when attaching it to the car is an increase in torsional and compressive rigidity to the unibody structure. The differences in which our plate makes on the car is significant and felt by most that have installed it that are in "tune" to what their car feels like.

For those that have put our plate next to the factory OEM plate will notice a few things. Not only is our machined plate thicker and engineered to be a lot stiffer it is also over an inch deeper than the factory plate. In fact the differences in the depth necessitated the need for me to design reliefs into the plate so there was adequate clearance for the unibody where it increases in height.

I can understand that there are those that want an absolute numerical value placed on our part in terms of the amount of improvement it will make. Unfortunately the amount of resources in time and money this would take is not practical; especially when you consider the low quantity produced and cost of this part.

I can tell you that it is made to aerospace quality standards and starts as billet 6061-T6 aluminum. It is fully CNC machined on a 4 axis mill, checked and double checked for accuracy and then Type III hard anodized. In fact the shop that makes this part is a major supplier to companies such as Boeing, Lockheed/Martin and dozens of other defense/aerospace contractors.

The bottom line is that our stiffening plate works and for the amount of engineering and quality that goes into it I truly believe that it is money well spent.


Thanks!!

Brian
BT Tech
305-652-3115

 

Please excuse unattributed quotes from many folks...

Indeed. I've never been convinced by pontificators, except myself of course.

I hadn't read this in any of the other threads. Good to know. Maybe Brian should add this bit of info to the sales page. Might help quell skeptics like me. Better still would be a little diagram showing how the plate works. I've read several "chassis stiffening" guides for other cars and most of them deal with connecting structures nearer to the wheels or reinforcing the frame front to back and side to side as well as diagonally.

Yes, my engineer friend and I noticed that the plate (looking at the pictures) is "wider" than the stock plate and that the corners appear to be machined to fit ridges in the unibody frame. The additional width would certainly impart more front to back rigidity, but would it be significant compared to normal body rigidity?

Let's see if we can describe this in terms of a piece of paper. Imagine a single 8x11" sheet of paper with a line down the middle (11" line).
I would say:
1) Agreed, the plate has no effect on vertical movement of the entire sheet of paper.
2) The plate has little to no effect in dampening movement of the separate sides front to back. Imagine putting your hands on the paper one on each side of the line and pushing one hand forward and one back. Since the paper is not cut on the line, the entire front back motion would have to overcome the paper's strength down the entire center line. The plate would contribute only in a very minor way to that strength down the center compared to the paper itself. Basically the two bolt holes on the plate would contribute little compared with the strength of the unibody chassis down the center. No help there.

Now we are getting somewhere.
Since the plate is bolted on with the longest piece ACROSS the car, not longest front to back I'd say:
3) That the plate does very little to stiffen the car front wheels to back wheels. On a piece of paper lift up on the top 8.5" edge or the bottom 8.5" edge and it bends in the middle. But since the car unibody appears to be shapped with numerous "groves or valleys" from front to back flexing of the body from front bumper to back bumper should be minimal. Take your piece of paper and fold it in 1" strips like a fan to fan yourself when it is hot. Notice that the paper becomes extremely stiff because of the peaks and valleys. Same on the unibody of the car. That is, if you pick up the middle of the front bumper, the car won't sag in the middle at the back of the driver's seat because there are structural ridges down the length of the car. And, even if it did sag by some miniscule amount, the BT plate would not do anything to stop it. Even with it's greater width. Why? Because the bolts are so close together in the middle of the plate, not on the corners. It would help prevent lift in the middle; for example, if you were strong enough to lift the car in the air by putting your hand on the BT stiffening plate, the front and rear wheels wouldn't droop down as much because the wider corners of the plate would push against the frame ever so slightly more than the narrow stock plate. BUT! Lift would be very unusual in real world driving so the BT plate does little to nothing here.

4) Diagonal. Getting to the heart of the matter. If you were to lift the driver's front wheel, would the plate help prevent diagonal sag in the middle of the car? I would say a little. The body appears to be designed to be rigid front to back, and the plate is not really designed or positioned to help front to back. But using the paper fan from above, lift the "driver's front" corner of the paper. Notice that the passenger front corner also lifts, as does the driver rear corner, but not the passenger rear corner. Here we see that the ridges of the fan (unibody) are "splaying out." The worst splay is side to side in the front, the next worst is on the same side as the lift point but in the back. Why less lift in the back? The ridges of the fan keep the body stiff front to back and offset some of the left right stresses. But again, lifting a single wheel would cause sag not lift in the middle and the plate wouldn't stop sag (front to back). The plate will help in preventing sag from right to left (still talking diagonal stresses), but the front back ridges of the body probably do just as much. But if lifting only a single wheel or wheels on oposite corners, I would think that a plate in the center of the car would be much less useful than three, one between the two front wheels and a separate plate between the two back wheels, plus one in the middle. I guess that's why people seem to be looking for more reinforcement in the suspension (usually side to side support).

5) Stress across the car, driver to passenger. In my opinion, here we have the most significant impact. Clearly the car body is stiff from front to back. You can see in the fan example. And diagonally, it appears somewhat stiff as well. Now lift your paper where the door post would be in the middle of the car on the driver's side. Which wheels lift? You got it, driver front and driver rear, equally. The passenger wheels stay put. Why? You don't have a stiffening plate! When you lift on the one side, the fan truly splays out along one of the front to back ridges (or valley). Putting a reinforcing strut across that ridge or valley will absolutely stiffen the car (paper) side to side. The strongest stiffening factor will be at the point where the plate is installed, between driver and passenger seats. Any side to side forces would be lessened by a plate across the bottom of the car. Hmm, that would certainly make it handle better than no plate in a crosswind, no?

The real question remains, since both plates are strongest from driver to passenger side (or vise versa), is the BT plate stronger than the cheaper stamped Toyota metal plate. It would seem so, but in this case does stronger matter? Would not the frame of the car itself bend at the bolt points before either of the two plates broke? Clearly the body bolt holes would break before the BT plate. The factory plate? I don't know.

Please note that I have NEVER doubted that the BT plate is higher quality than the stock Toyota plate. That is obvious to me and should be to everyone.

Now the real question, how can we measure the differences between the two plates on the car without spending thousands of dollars?

How about this (all you engineers speak up). What if you lift the car at one of the corners with the included jack? Like you were changing a tire? The stiffer the body across the car, the fewer turns it would take to get a second wheel off the ground? Not really off the ground, but above some threshold.

Raising and lowering the driver's front wheel would we not see:
Without any plate...slight rise in passenger front and driver rear?
With a plate...more rise in passenger front and driver rear given the equivalent height of driver front wheel off the ground as without any plate?
The stiffer the chassis the higher other two wheels would be off the ground, no? Which plate would be better installed on the car? Could we measure the difference? Engineers, speak up. Would that tell us which plate allows for less body flex? Cost for this kind of test would be negligible (the cost of the BT plate), but would it be accurate enough?

 

<div class='quotetop'>QUOTE(BT Tech @ Apr 12 2006, 11:20 PM) [snapback]238946[/snapback]</div>

As has been said here before, static analysis of a component, whether its a brace, strut, shock, whatever gives very little insight into dyamic handling. Even "stiffer is better" is not always necessarily true. And when you throw in cost/benefit considerations, it gets even harder. That's why they have test tracks. Would somebody like to donate their car for a consumer reports style evasive maneuvar tip test before and after?

 

<div class='quotetop'>QUOTE(pocketpenguin @ Apr 12 2006, 11:58 PM) [snapback]238968[/snapback]</div>

A couple of things. I don't think static measurements of deflections say anything useful about the handling. Or rather I should say I don't have enough knowledge or experience to draw a conclusion. Consider a short history of bicycle frames: the old lightweight steel alloy frames were quite flexible, almost whippy. Along came TIG welded aluminium and truly stiff frames which were said to transmit more energy to road rather than twisting the steel. Lots of bike tests with jigs to measure frame stiffness. Unfortunately, it transmitted the road energy to your nice person quite well as well. It was realized that you wanted flexibility in the longitudinal direction but torsional stiffness in the bottom bracket and elsewhere. Lots of fancy brackets were developed but they didn't really get it right until carbon fiber allowed the designers to locally engineer the stiffness even making it different on different axes.

So lets measure what we say is happening rather than something else and then wave hands. Go to a stadium or arena parking lot on sunday morning and run laps around light poles at higher and higher speeds until you drift, skid or chicken out. If you're a good driver (and who here would admit to not being such) you should get some repeatability. Repeat with the other plate. Make it blind (the brace selection, not the driving), double blind or whatever. Report to the forum.

Legal disclaimer: Don't do this. I'm kidding. It's parody. A thought experiment. Buckle up and wear a helmet. If you do this and mess up you or your car, take some responsibility and don't sue me, the moderators, forum owner or web server.

 

Damnit! I still can't wipe the grin off my face when I drive my Prius now. It handles the turns beautifully since I've had the BT plate installed. I'm a handling freak and was sorely disappointed by the Prius' cornering performance vs my old Nissan Sentra Spec-V.

My Spec-V had it all. Power, looks, handling. I used to drive out from the city about 45 min to get to a 5km stretch of twisty mountain, and carve the hell out of road a few times. I had intimate knowledge of that car's characteristics and knew how it would respond to certain conditions.

Everything about the Prius was great except for the entertainment system, and the handling. It doesn't have a lot of high end power, but for me, it's all about the low-end kick which the Prius provides aplenty. Curves that I could take at 60km/h in the old car were difficult for the Prius to navigate at half the speed.

For a $160 investment, I bought the BT plate that spawned all these threads about it. Based on how my other car was setup, I figured anything that could stiffen up the body should help it out. It was a night and day difference. I could take those sharp curves a lot quicker now, and the Prius grabs the road nicely and understeer was greatly reduced. Roads that I would easily understeer no longer had that problem. It's like a new car. I can't wait for my Sportivo and Tom's to arrive to further enhance the ride.

I would highly recommend you buy this. Once you install it, you will be kicking yourself for not getting it sooner (I know I am). If you don't want it, I'll buy it off you (for a small discount, of course ). My cousin has a Prius, and I wouldn't mind hooking him up with this little gem. His car is the American doppleganger of mine

 

<div class='quotetop'>QUOTE(Presto @ Apr 13 2006, 12:46 AM) [snapback]238983[/snapback]</div>

"a lot quicker"? Don't leave us hanging! What is the carving speed of the BT enabled Prius?

<div class='quotetop'>QUOTE(pocketpenguin @ Apr 12 2006, 11:58 PM) [snapback]238968[/snapback]</div>

Am I the only one playing with corrugated paper tonight?

If you hang the "front axle" over the edge of the table and rock the front wheels out of phase, the rear wheels will also rock out of phase with each other and its corresponding front wheel. Its a vibration mode. There's lots of them. The "unibody" has very little torsional stiffness on this axis. Indeed, the purpose of the suspension is to decouple the wheel motion from the rest of the car to prevent this kind of rocking. Put a brace across the body (I layed a pen knife on it). The rear wheel twisting was greatly reduced unless the brace was placed at the table edge.

What does all this mean? Not much except statics are different than dynamics. Run through a slalom at low speed and nothing much happens. At high speed the car will rock severely if its underdamped and skid if its overdamped. But if you are at that right speed the suspension will match the forces and the car will seem to be on rails. Who would have thought that from measuring the static deflection of different suspensions.

(note: sorry if this gets posted twice. some strangess occurred and I seem to have lost the first post)

 

I am also sitting on the fence on the purchase of PT plate. I have read so many positive feedbacks on the BT plate. To me, it must be working because placebo effect is not this powerful. As someone have said, I haven't found a negative review yet.

In automobile, engineers talk about torsional and bending rigidity. The BT plate definitely affects the torsional rigidity (twisting diagonal corners), not bending (front to rear). Torsional rigidity improvement helps cornering and improve suspension control over rough surface. It would also help side-wind situation as well.

In fact, I was thinking that someone (or me when I get it someday) could do a scientific measurement on the torsional deformation by comparing the following three cases. In every case, measure the the height of the rear-right tire off ground after jacking up the rear-left and front-right (same points in all cases) to fixed height. Since Prius has heavy front (59/41 f/r), the front-left tire will remain touching the ground. If a vehicle has higher torsional rigidity, the distance of the rear-right tire off ground will be larger (less deformation).
(1) w/o any plate (OEM or BT)
(2) w/ OEM plate
(3) w/ BT plate

I am expecting the result would be (3)>(2)>(1). This would be a great science project for my son, but he is only 5.... :lol:

 

<div class='quotetop'>QUOTE(RonH @ Apr 12 2006, 11:47 PM) [snapback]238991[/snapback]</div>

I would say, I can comfortably go from 50-100% faster around the usual curves now. There's a fairly nice curve that's has a speed limit of 30 km/h. Pre-BT plate, I could probably go up to 40 km/h before i feel the initial tugs of understeer, if it's wet, i'll go a bit slower. Now, in the BT plate age, that same curve can be executed at 70-75km/h. There's a sharper curve on the highway on-ramp that's marked as 30km/h. 30km/h is the absolute limit that the stock Prius could handle... now it's 50-55km/h.

Seriously, if you're on the fence. Buy it. Try it. If you really don't like it, PM me, and I'll buy it off you (provided someone else hasn't sold it to me already)

 

<div class='quotetop'>QUOTE(ceric @ Apr 12 2006, 11:56 PM) [snapback]238997[/snapback]</div>

I'm really on the fence too. I did read where someone removed the OEM plate, didn't install any plate and then took their wife for a ride. The wife was told the BT plate was installed and she thought the ride was much better. Then the BT plate was installed, but she was told the original plate was re-installed to show the difference. She thought it was looser. Granted that's just one test.

Frankly I don't have any problems with the handling right now. My commute is residential, freeway and winding hilly roads. I might see an improvement, but I don't think I'll notice it. But that's me, for my normal driving. I know this would be different for others, as we drive on different roads, at different speeds and in different weather. I'm NOT saying it doesn't work and it's all placebo, but it may not work for me. And since my wife needs new tires, $160 would go better in that direction.

 

Yep, I read that too. darrelldd's website. I thought that 'blind' test could be replicated for all the significant others/spouses/etc. before the plate is installed and after. Simply telling someone that something's new and improved can influence their reaction.

I put snow tires on this past winter. My significant other drove it soon after and reported that the handling was mushy and the noise was higher. She did not know I had put snow tires on. She has been known to notice car noises and such from her previous cars that I could never hear...then something would go wrong with the car. She's in tune with what is 'normal' and knows when things aren't. YMMV.

 

This upgrade is not for the passenger, though. I don't expect passengers to feel the handling difference since they don't have a grip on the wheel nor control of the pedals. My friend could tell the difference as a passenger, but we cruise the same roads and turns all the time and he is aware of the speed limitations of the various curves.

I'm more than willing and serious that if there's anyone on the fence wanting to take the plunge, I will offer to buy the plate from you (discounted) if you're not satisfied with the BT plate.

 

<div class='quotetop'>QUOTE(Presto @ Apr 13 2006, 09:07 AM) [snapback]239131[/snapback]</div>

The place where I read it merely said "She took a drive," so I don't know if it was her at the controls or not. But since it's not for the passenger and if I have no problems with it, my need isn't as great as with others.

 

I love all the pseudo-engineering talk from those who have never experienced the plate, trying to discount the experience of those who have it. Its like the scientist who proved mathematically that a bumblebee couldn't fly. This whole thread has turned ridiculous, IMHO.

Either get the plate, or don't. (Just look at "mods" in the signature of those who balk at the idea of parting with $160 for an upgrade that makes their car WORK better and drive safer. Amazing.)

 

<div class='quotetop'>QUOTE(aaf709 @ Apr 13 2006, 09:17 AM) [snapback]239141[/snapback]</div>

She drove the car, and she is the one with the most miles behind the wheel of the Prius to date. Please note that while I do have that info on the web page, I have never mentioned it, or posted a pointer to it publicly. I have no intention of opening my door to a mob of torch and pitchfork toting townspeople holding a rope.


<div class='quotetop'>QUOTE(jbarnhart @ Apr 13 2006, 10:11 AM) [snapback]239189[/snapback]</div>

Indeed it has. It would seem that everybody's experience is discounted except for those in the majority. What of the actual engineers who have the plate installed? I've already gotten in trouble for taking one of these many "review" threads off topic... and it seems that this one which has stayed ON topic is still bothering you. Seems you'd be happier to just avoid any of these threads since the plate works perfectly for you, and any questioning discussion seems to annoy you.

Seriously. Be happy.

 

<div class='quotetop'>QUOTE(darelldd @ Apr 13 2006, 11:16 AM) [snapback]239227[/snapback]</div>

My apologies. You notice that I didn't mention where I read it (didn't even include a link) and said that it was only one comment. I felt it was an honest opinion and should be included with other honest opinions.

Maybe I'll get one. With this many positive comments it must do some good, but it isn't one of those "gotta have items" for me.

Pax

 

<div class='quotetop'>QUOTE(darelldd @ Apr 13 2006, 02:16 PM) [snapback]239227[/snapback]</div>

Yes, but what about a mob of LED flashlight and soldiering iron toting townspeople holding some electrical wire?

 

<div class='quotetop'>QUOTE(darelldd @ Apr 13 2006, 11:16 AM) [snapback]239227[/snapback]</div>

And so far, yours is the only opinion in this minority. At least I have not seen any other "neutral" opinions on the plate. The comments I find ridiculous are not "experience" but "speculation".
<div class='quotetop'>QUOTE(darelldd @ Apr 13 2006, 11:16 AM) [snapback]239227[/snapback]</div>

There are many engineers who have Priuses. I'm sure I'm not the only one who also has a BT plate.
<div class='quotetop'>QUOTE(darelldd @ Apr 13 2006, 11:16 AM) [snapback]239227[/snapback]</div>

Questioning doesn't bother me. Grand theories about how the plate doesn't work, from those who have never seen one, bother me. Nothing in my rant indicated you either directly or indirectly. Don't go all Carly Simon on me! ("I'll bet you think this song is about you...")

 

<div class='quotetop'>QUOTE(koa @ Apr 13 2006, 12:40 PM) [snapback]239336[/snapback]</div>

Those guys are invited in for a frothy mug of beer.


<div class='quotetop'>QUOTE(jbarnhart @ Apr 13 2006, 01:08 PM) [snapback]239352[/snapback]</div>

I actually had no intention of posting my neutral opinion on PC, so if I hadn't been outed, you likely would still have not seen it. There are other similar opinions out there that are not expressed publicly.

I agree. And I've heard just as many positive specualtions from the folks who don't own the plate. Doesn't make it right or wrong. Speculation is just human nature. What it sounded like to me, was that you were having problems not with the likes of me... but with the folks who were skeptical, and wanted some additional information. I'm a BIG fan of skepticism. Being a skeptic is not the same as making speculation comments.

No worries there. I've always know that you have a fond place for me in your heart.

And here I go again, dragging things off-topic! I'll stop here.

 

Well, like other posts, my last post about the difference the installation of the BT plate made to handling the car is not scientific. I am a scientist, not an engineer though, and can only add my opinion and observations to the transformation the installation of the BT plate made to handling of my Prius. Note, I had over 3000 miles on the Prius when the BT plate was installed and I knew how it originally handled in strong cross winds, on rough roads (lots of those in NM!), and around hairpin turns. The installation of the BT plate increased my handling ability of the Prius, I've lost the white knuckles and claw-like sitff hands that occurred in pre-BT plate driving in strong cross winds; like another poster said, I have noticed a significant decrease in vibration of the car on rough roads, on any roads for that matter, and in strong cross winds (maybe explaining somewhat the slight increase in mpg due to the decrease in the vibration?); and, it really does hug those hairpin turns nicer and at higher speeds. Lastly, I did notice an immediate difference in how the car handled and where the car centered when I drove it out of the dealership. I'm pretty darned sensitive to these things and, prior to the Prius, I had driven heavy 4x4 SUVs for 15 years.

IMHO, for the first 3000 miles pre-BT plate I imagined the car sort of lightly driving above the road bouncing/vibrating along with any little roughness in the road bed. After BT plate installation the Prius felt more "substantial," the car felt "heavier" toward the back, more centered, more stable, less "light" and bouncy, and I stopped feeling every little bump in the road.

Would changing the tires cause this as one poster suggested? Maybe, but I figure I'm going to get as much wear out of the OEM Integrities as I can and use that tire warranty before I get a new set of any type of tire.

So, yes, all observations and the best $$ I could have spent. I loved my Prius pre-BT plate, but now I love it even more.

 

<div class='quotetop'>QUOTE(gilahiker @ Apr 13 2006, 01:49 PM) [snapback]239381[/snapback]</div>

I'm still on stock tires. I'm wearing them out a lot faster now that I have the plate installed. 34,000km so far and I've almost owned the Prius for a year. I'll definitely be changing the tires before winter. What's this tire warranty you are talking about? If i wear it out before the year is out will Toyota give me a new set?