Seems as if the car loses alot of rigidy whenever I put the top down. Does this happen to all verts? Are there any hard numbers from the factory as to the specs of a vert with the top up and down? I have added just about every stiffening device they make for a vert but it still feels loose when the top is down. With the top up, the car feels like a rock. Even a good condition secondary road causes the car to shudder, or vibrate kinda. Maybe something is broke; but if everything works fine with the top up, I'm guessing it has to do with the roof. Any ideas?

 

You tried foam in the frame? supposed to help. What do you have done?
Sean Cathcart
-not much help on verts....

 

I get some cowel (sp?) shake over RR tracks and poor roads, but overall it's pretty solid. Any car will lose some rigidity with the top down. Supra targas exhibit similar behavior and have more metal in place. I'm actually impressed with the rigidity of the RX7 with the top down. I can still corner pretty hard without flex problems, which is saying something.

Have you driven other cars with the tops down/off? That will tell you if your car is OK. The only things I can think of off-hand that drastically affects the feeling of "rigidity" in a top-down 7 are wheels out of balance or previous accidents the car had which may have affected body or frame integrity.

 

Mazdatrix strut tower bar with engine and firewall supports

Kirk racing roll bar

Cusco lower a-arm bar

Ground control coil-overs

Tokico non adjustables

Suspension techniques front and rear sway bars

Mazdatrix adjustable end links front and rear

Mazdatrix adjustable camber link

That's what I got!

 

http://www.geocities.com/dorifto/urethane.html
might be worth a shot...
Sean

 

If the tires were out of balance the vibration would occur with the top up or down right? And the only accident the car has been in was hitting a deer which only effected the cosmetics. It has been aligned with no problems other than the rear camber which was corrected with the adjustable link. I'm thinking that it must just be the way convertibles are with the top down. This is my first convertible car, so some of this stuff is new to me. Some factory specs on rigidy would be nice; somebody must have this info.

Thanks!

 

That foam stuff sounds interesting. I remember ReTed posting about it before. But where do you find the stuff? And is filling the door sills the only place to use this? Couldn't you fill in the frame rails under the car? And on that web page; they spell it "rigidity" is this correct? That word just seems hard to say.

 

Under the panals in the back...I was considering adding custom "monkey type bars". They are NOT the ones you see that look like a custom roll bar.

I know someone that had installed them in AE86's... I had drove it, it was totally solid...like a skate board.

I will explain.

These are chromemolly bars that are flatten at each end. Then a hole is drill though the ends to bolt on to the chassis. This is done in a cross sectional fashion. I wish I had some pics. I do not get the same sound as you do when my top is down...but, I do notice some additional flex.

Once I have the money...I will be looking for this guy. He had bought one of my AE86's in the past and I know he still autocrosses...

 

It is rigidity, and you got me on where to get the foam. try with Ted.
I doubt it is the wheels balancing, that would be affected all the time, top up or down.

 

http://www.itwfoamseal.com/auto_aftermarket.htm

 

Mine flexes a bit, I don't have any of the extra rigidity pieces. I haven't noticed a difference top up/down though, so maybe the aftermarket stuff you have is accentuating the difference.

 

There are two types of foam - The high expansion polyurethanes (and Urea/Formaldehyde) that are primarily SEALANTS , they are NOT very strong and don't add much rigidity, and the much stronger structural foams, mostly and or Epoxy based - these are what you want to use for stiffining a car. Try MARINE stores they general carry structural foam products. I think WEST SYSTEMS makes a two part Polyester structural foam.

 

why don't you try a rear strut bar? you prob feel the flex most there because that's the least stiff part of your car now, you have one in the front not the rear with the top up you won't feel it as much because you have the extra support fron the top with it down you feel it a lot more because there is nothing to hold it any more. you don't need it as much on a hard top because much better structure actual metal holding it together.

just my opinion

james

 

http://www.rx7hotpage.com/mycar3.htm
I wish that I could get the above roll bar but will probably buy the Kirk bar this summer.

Add more to the roll bar. 4 point vs 6 or more should be better.

I would like to foam my convertible but would like to find a shop with some experience with it. SportCompactCar was happy with that 300z that they foamed.

 

It's probably just normal then, from what you've said. I know when my wheels were out of balance, the car shook 10 times more when the top was down. It was noticeable with the top up, but way way worse down.

The foam is awesome. My buddy used it on a 300ZX frame with great results - very solid car!

 

so you are saying the car is stiffer when the "cloth" roof is up??... I highy doubt it.

 

The body is actually stiffer with the roof up.

Hidden in the "cloth top" is a full roll bar simular to the one in the mercedes SL cars. When the targa its locked in place and the top is up the frame is slightly tighter.

Thats what makes the cars so heavy. Its not like a Miata or Fiat 128/spider.