Targa people, would you be interested in...

[speed]

I'll give my .02 on this...

1) I have the first Weezl wing... you can notice a BIG difference with it. I can jack the car up, and it'll lift the whole side up. Going around off camber corners, the car doesn't squeek and feels much more together.

2) I'm really worried about the strength of this bar. The four corners have no connection other than the center point. That centerpoint is the center of rotation for the car anyways, and without the other points being linked together... i don't see how it'll do much. Steel still flexes and bends. Yea, it'll probably be better than nothing, but I think it could be better engineered. The center bracing should be on all 4 sides, not just 2, and the tabs should be solid peices all the way across linking the monting points on multiple planes, not just the one.


And like suprahero said... When pete was making the weezl wings, the reception was huge. He had to GIVE the last one away as a ROTM prize. Don't expect them to sell like hotcakes, sadly

 

[Facime]

Why does everyone ignore subframe connectors? They'd let you eliminate the shimmy, AND keep the top completely open!

right up front, Im NOT a structural engineer but let me see if my laymans brain can inject some logic here.


The reason a targa top shimmies when you take the top off is because you have disconnected the "top of the pyramid". Imagine if you will the following demonstration:

Take a 2 dimentional flat sheet of sheet metal roughly the shape of a supra (as if you are looking down from above, a rectangle roughly). Now pick that up and bend it in the middle and from corner to corner. Not very stiff, lots of flex. Ok now using some thin strips of the same sheet metal, lay them on edge from corner to corner, crossing in the middle. If you pick that up you WILL notice a great inprovement in end to end rigidity but you will still have some and you will still be able to twist flex it quite a bit. This is roughly what subframe braces do. Finally, using the same strips erect a pyramid shape going from corner to corner and meeting at the top in the middle. Now pick that up and you will find that the torsional flex is gone.

No matter how much bracing you do to the subframe you will always only have a 2 dimentional connection from corner to corner with the top of the car removed. A targa brace simply reconnects the corners of the car at the top of the pyramid.

Another way to visualize whats happening is take a shoe box and take the top off. Flex it around a bit. Now take the lid and slip it over the bottom of the box, try again. Now put the lid back on the top and do the same thing...It doesnt take a structural engineer to see whats going on.



As for the OP, that brace looks nice and simple and "should" do the job. My only concerns looking at it from my standpoint is that with the front and rear ends not tied together all the stresses will be transfered to shearing force at the mount bolts, rather than compression back into the front or rear half of the car. In a hard enough collision my guess is that the bolts will shear off and the top of the car will collapse as though there isnt anything there at all. For removing "targa shimmy" it should be strong enough though.

As for demand, I see enough people ask about targa braces from time to time that if its cheap enough I think you could sell them. As Jay said, buyers tend to vanish in the fog when it comes time to put up or shut up. My advice if do a feeler, count the number of people that say they will buy one and divide by two. That should give you a manufacturing quantity.

 

[ExileMFG]

right up front, Im NOT a structural engineer but let me see if my laymans brain can inject some logic here.


The reason a targa top shimmies when you take the top off is because you have disconnected the "top of the pyramid". Imagine if you will the following demonstration:

Take a 2 dimentional flat sheet of sheet metal roughly the shape of a supra (as if you are looking down from above, a rectangle roughly). Now pick that up and bend it in the middle and from corner to corner. Not very stiff, lots of flex. Ok now using some thin strips of the same sheet metal, lay them on edge from corner to corner, crossing in the middle. If you pick that up you WILL notice a great inprovement in end to end rigidity but you will still have some and you will still be able to twist flex it quite a bit. This is roughly what subframe braces do. Finally, using the same strips erect a pyramid shape going from corner to corner and meeting at the top in the middle. Now pick that up and you will find that the torsional flex is gone.

No matter how much bracing you do to the subframe you will always only have a 2 dimentional connection from corner to corner with the top of the car removed. A targa brace simply reconnects the corners of the car at the top of the pyramid.

Another way to visualize whats happening is take a shoe box and take the top off. Flex it around a bit. Now take the lid and slip it over the bottom of the box, try again. Now put the lid back on the top and do the same thing...It doesnt take a structural engineer to see whats going on.



As for the OP, that brace looks nice and simple and "should" do the job. My only concerns looking at it from my standpoint is that with the front and rear ends not tied together all the stresses will be transfered to shearing force at the mount bolts, rather than compression back into the front or rear half of the car. In a hard enough collision my guess is that the bolts will shear off and the top of the car will collapse as though there isnt anything there at all. For removing "targa shimmy" it should be strong enough though.

As for demand, I see enough people ask about targa braces from time to time that if its cheap enough I think you could sell them. As Jay said, buyers tend to vanish in the fog when it comes time to put up or shut up. My advice if do a feeler, count the number of people that say they will buy one and divide by two. That should give you a manufacturing quantity.

Thank you for the advice in quantity. The picture Zerocool put up is a MK3 targa brace we came up with. We welded in the dimple die plates in the middle for two reasons.
1. Most importantly strength, dimple dies add a tremendous amount of strength to plate steel.
2. It adds a nice look to finish off the brace.
As you said, the brace is to rid targa cars of "shimmy" with the top off. It's not a roll cage by any stretch of the imagination which would protect against a collision.

 

[T-MA71]

I would love that. Any pics of it on the car?

 

[ExileMFG]

I would love that. Any pics of it on the car?

I will post up some pics this week installed.

 

[Guyana00]

I'd like to see pictures of it as well installed.

I think that on one hand, subframe connectors sound like a good idea for people with modest power who use their supras for spirited driving and/or daily driving or something along those lines. The bonus is the aesthetics factor, having the targa look like it was intended to

On the ther hand, if you're going to be throwing the car into corners or anything, then a brace would probably do better. Then again....if this is their intended use then they could leave the top on or drive a hardtop.

This is just my opinion, and although I appreciate the effort I agree with the majority of concerns about rigidity and the design concept.

 

[americanjebus]

Ummm...NO. Not true.
I have a set of Weezle Wings myself. There is a noticeable difference in chassis flex with the brace installed vs top off with nothing.

These look like a good alternative.

Not talking performance, just in terms of how gay it would be.

 

[jdub]

Not talking performance, just in terms of how gay it would be.

You can't be serious...or, are you one of the types on here that puts looks before function?

Most of us like running the car without a top on a nice spring day. If I can minimize chassis flex (i.e. targa shimmy) and still enjoy the car with no top, then why the heck not.

And, if you're saying I'm gay...those are fighting words in my house

 

[Mr.PFloyd]

I am still waiting for someone to make one that can stay on the car at all times. As in you can bolt the roof on it....

 

[Supra469]

I would love that. Any pics of it on the car?

I would like to see it on the car also too. :biglaugh:

 

[Doward]

stuff

One huge glaring flaw - nobody makes subframe connectors out of sheet metal

Having ridden in an '01 Camaro SS T-Top both before and after subframes, they are a tremendous improvement. Obviously, the tightest would be subframes + targa brace, but subframes will still tighten up the unibody construction!

 

[IJ.]

Boxing the Seat mount rails then closing in the Trans tunnel with an X brace that intersects the seat mount boxes would have more effect on torsional ridgidity than any of the "connector solutions" I've seen tried here.

It needs to something 3d not on a single flat plane.

 

[sneakypete]

so i assume this brace would have to be installed every time you take the top off?
-pete

 

[supradjza80]

I think the car would look extremely goofy with that on the roof. I would say you should just keep your top on if you want the car to be more rigid. I personally do not think the shimmy is that bad, it is noticeable but i doubt anyone pushes their car hard enough with the top off to know the difference. I would much rather go top on with the windows down than have that over my head with the roof off.

on another note, I second the notion that there is no reason that bracing underneath the car cannot fix the shimmy problem. I believe in the fourth gens a lot of people use underbody bracing to alleviate any of the targa off shimmy. Think of a gen 1 miata compared to an s2000, it isn't just about what part of the "trapezoid" is connected to each other, whats really important for an open top car is the shape and structural rigidity of the cars backbone.

 

[Satan]

I have a couple of the WeezL wings (1st and 2nd Gen) and the only thing I can think of that would be better, is if you could design and make it to fit with the targa on. Lance has one and it's nice to be able to pull into a stop, and throw the targa back on (hold by a bolt or two). Gives a much less inviting feel for a would be snatch-and-grab.

And yes, I bought extras to make it worthwhile for everone else. I also have the original targa bars which are more effective tahn one would think. Dang, I need to sell of some of this extra stuff ;-)

 

[Facime]

One huge glaring flaw - nobody makes subframe connectors out of sheet metal

Having ridden in an '01 Camaro SS T-Top both before and after subframes, they are a tremendous improvement. Obviously, the tightest would be subframes + targa brace, but subframes will still tighten up the unibody construction!

LOL, of course they dont make subframes out of sheetmetal...nothing gets by you man! I see the point of the experiment was lost on you.

and please tell me you realize that a t-top is not a targa and dont have the same dynamics at all. I didnt say subframe connectors dont do anything, I said they dont solve the problem. They certainly help, and in regards to many other aspects of the car including launch and suspension tie in they are certainly something worth developing...but THEY WILL NOT do what a targa brace (or leaving the top in for that matter) will do.

But, Ive said what I wanted to say, if you want to debate the benefits and drawbacks of both options I would be happy to, but its inappropriate in this guys thread.


PS. Satan, Im sure you could sell one of those pretty easily, I have people ask all the time if I will make more. I wont. My experience making parts for the mk3 community was less than spectacular. I hope nothing less than great success for the OP and their designs.

 

[Clint]

Thank you all for the feed back id like to let this thread go for a day or two more and get more feed back from as many members as possable.

ExileMFG and I are working on getting this brace bolted onto a MKIII and see how it looks and feels.

We futher hope to make more custom supra parts for the community and hopefully have a more variety of custom fabricated parts to display at the SILV09 event stay tuned.

 

[shenronzero]

i have the titan harness bar which does the same thing... could we get a pic of what it looks like with it on and how much would it be?

 

[ExileMFG]

I don't want to post prices in fear of the moderating staff getting upset. I know I am not allowed to sell anything yet, still waiting on pm's from mod's to get setup into the misc vendor forum. It is exciting to get this level of feedback though. Thanks everyone.

ExileMFG

 

[Doward]

LOL, of course they dont make subframes out of sheetmetal...nothing gets by you man! I see the point of the experiment was lost on you.

and please tell me you realize that a t-top is not a targa and dont have the same dynamics at all.

The dynamics are much more similar between a t-top (which stands for targa top, btw) and the Supra's targa top. Picture the twisting created over bumps between the front passenger and rear driver's wheels. Note also that the thin strip the Camaro has between the 2 separate T-tops will twist right on that axis. The Camaro has superior rigidity at any Y axis plane, but has no difference in the X axis.

I'll PM you tomorrow and we can discuss it more - the wife wants my attention, sorry guys!