How stiff is your VR or convertable Z car?

[74660z]

Hello

I am a new poster here. (although I thought I registered and posted a few years back, but cannot figure out my screen name.)

 

Anyway, I am re-restoring my 260 and seriously considering a roadster of some sort. I have looked around, but not seen much comment about how rigid the car is w/o it's roof. Obviously it needs re-enforcement. And there are alot of different posts about it. But, none seem to comment on the rigidity of the finished product.

 

I plan to start by doing a full frame rail, like (I think) Pete Paraska did. Then re-enforced rockers, tied to the strut towers.

 

Anybody with a driver care to share their experiences? Does the windshield shake worse than an MGB?

 

Any input or direction would be appreciated.

 

Eric

 

(I wasn't sure if I should post here or brake/chassis forum. I figured I'd find more topless owners here.)

[SHO-Z]

Here is my write up on doing one. I do not have any lateral stability problem. The car lacks torsional stability, I can feel it flex on hard turning. I need to add an "X" brace tied to the 1x2 tube stock that I installed. Heck I have not put 500 miles on the car since I finished it 2 years ago and in mosty somewhere to stack stuff on in the garage anymore.

 

This conversion was done similar to the Z Therapy conversion. I collected through the internet and several Kit Car Magazine articles my plan of attack on the conversion. First I would not do this to a real clean Z, there are enough ones out there with minimal rust and body damage around.

 

This is a general summery of how I constructed my project.

 

Step One

Sit down with a couple of beers and think this project out, once you get to Step Two there is no turning back.

Remove the entire interior from the doors back and the head liner.

Jack the z up level and put the stands on the suspension points. Evan though the car is still a coupe I wanted to make sure that when I added the reinforcement the car was still square.

Install the 2” x 1” x 1/8” tube stock under the car, behind the seats and through the floor. The use of a protractor square helps in laying out the angle cuts. I added additional welded tabs tying the tube stock into the existing uni-body frame rails. This does limit the seat travel for some one well over 6 ft. Evan with this there is still some torsional deflection in the car. I am planning in installing an X brace between the frame rails to elevate the problem. After doing this conversion I do not believe anyone who says that no reinforcement is required.

 

Remove the rear hatch and side rear windows,

 

Step Two

Now comes the lump in your stomach.

 

Layout a line about 1-1/2” back from the top of the windshield. Then another line from the back corner each of the rear windows to the around 2” from the back of the car.

 

I used both a sawsall and a 4” grinder with a thin wheel to do the cutting.

 

Basically cut on the lines lines, some blocking is required to keep things from binding.

 

Once the top is removed cut the top again just off of where the top and the hatch hinges box section. Trim all of the excess metal from the sides of the hatch area. Remembering to leave enough metal to weld too.

 

I set hatch hinge box section directly over the rear strut towers, leaving just enough room to get a box end wrench on the strut nuts. This will get you the length of the trunk and a hard point for the rear shape of the Z. This is the first section of the car that I welded in place. Welding the box section onto the strut towers is like adding a strut brace and I feel really helps stiffen the car. At this point the edges of the trunk were basically installed. This gives a basic arch across the back of the car.

 

I cut out cardboard templates of all of the three sections that need to be filled in. Two for each side and one for behind the driver compartment. I used 10 gauge sheet steel for my added body work. This is trial and error situation but with the cardboard templates it just takes time. I added ¼” angle iron around the rear lip of the driver’s compartment for stiffness. The radius was bent around a piece of plywood after I heated the angle iron.

 

After all of the basic sheet metal was installed and welded in I fabricated and installed a piece of sheet steel for the bulkhead between the driver’s compartment and the trunk. On both the lower lip I installed ¼” angle and one across the center. The upper end had extended 1” tabs every 5” that were bent over. Holes drilled through the sheet metal behind the driver’s compartment were used to weld the upper end of the trunk bulkhead in place. The rear hatch was cut and shortened in the widow section. I used a 1x2 piece of wood inside of each side to align the hatch and welded it back together. The widow section was filled with sheet steel from the original top with and added angle iron brace from below. The latch end of the hatch lid needs to be modified to clear the back edge off truck. I used a remote trunk latch from a Lancer mounted under the drivers seat.

 

On the windshield header I cut slots about every inch or so with a grinder. These are bent down and tack welded to the windshield frame. Square cut and cap off the ends of the windshield posts. This gives a flat top to the windshield and will make fitting a soft too easier.

 

This will basically finish all of the metal work. Now comes the pain of the body work. Looking back if I did this again I would use some of the new fillers with glass in it. One trick I did learn is using a long board sander to flatten and shape the trunk. I used a 2x12 that I cut to fit long board sander paper, glued on some old rubber sheet that I had and just stapled the sandpaper to end ends. It worked great flatting and smoothing the trunk and large surfaces.

 

I have a top frame for a TR7 convertible that I need to modify to fit my Z. The design that I used does not allow for the top to be folded down. John Washington makes a fiberglass top that could probably be modified to work.

 

Seat belts are from an Acura Integra, 3 point using bolt points on the inside body panel.

 

This is the basics for building z convertible.

 

Lessons learned:

 

I would fiberglass the rear trunk lid instead of adding the steel window filler section, I was never happy about how this worked out.

Use fiber filled body filler and less Bondo.

Start with a Z that was in a little better shape than I had, found more rust around the rear edge of the hatch on both sides.

Use a quality MIG welder. The one I used was borrowed and I fought the thing from day one. One weld would be great the next looked like ♥♥♥♥.

Maybe I should have had a few more beers put my money into more HP, GTO kit, instead of no top.

Trial fit everything at least two the three times to avoid mistakes.

Do not hit a truck tire carcass on the freeway on your first day out, it can do a number on the front fender if hit just right.

 

Would I do it again, I really do not know.

 

This is a good exercise in

 

Look at my photos

http://album.hybridz.org/showgallery.php?cat=500&ppuser=8660

Edited March 24, 2009 by SHO-Z
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[VinhZXT]

I have an 8 points cage and can still feel the flex. Here is a test I did to test for flexing. Jack the car right in front of the rear tires and check the gaps at the doors. With my cage in the gaps made very little change.

You can see pictures of my re-enforcement cage on this page http://www.cardomain.com/ride/768663/5

GL.

 

PS. I recently saw a convertible Z for sale on ebay and it didn't have any reenforcement. I wonder who bought it.

[attworth]

Somewhat unrelated, But I know that when I jack the front of my car up, opening the hood is not an easy task due to flexing in the body.

[74660z]

Thanks for the responses. I am pretty sure I can get the car strong enough, even if I have to tie the front and rear struts together and weld the doors shut.

 

Most of the advice offered seems to be ZX's, not Z's. Very similar, but I don't think close enough for comparison here. (Nice car BTW, Vinh).

 

Sho-Z, you said you've barely driven the car. Bored with it or issues driving it?

 

I was mostly wondering about cowl shake and windshield vibrations. Is the windshield frame rigid enough without the roof, as I am clueless how to stabilize it w/o a roll cage attached to it. (I'd rather have no doors than supports above the belt line. The roads suck around here (charleston sc)...like four wheeling on pavement. It won't be a daily driver, but it's not worth doing if it's annoying to drive.

 

Eric

[SHO-Z]

Right now I am thinking about selling it, have a bad back and is no longer fun to work on. There is some added shaking in the hood area that could be corrected with a 3 way strut brace. There is no problem with the windshield, it is heck for stout, no flexing at all. I tied the rear struts together when I used the roof section for the trunk. If you look in my photos I used what is in the drawing to stiffen the chassis.

 

If your 260 is a clean small bumper, keep the top on. If it is a semi abused large bumper 260 get a marker out and a 6 pack and start cutting after you install the reinforcement.

 

Have fun either way!

[VinhZXT]

I am with Sho-Z also. Lot of squeaking around the hood area. No problem with the windshield. I also tied the rear strut towers together. I have no problem with the rear. Only the front I can feel flexing if I drive one wheel on a speed bump. The Z should be better since it is shorter at the front compare to the ZX. So with the triangulate strut tower re-enforcement you should be good. I will re-enforce the front of my ZX in a few years when I rebuild it.