blueovalz

Great news! Glad to see this project still moving forward. Keep picture coming though.

AND, the other shoe drops!

I went as wide and deep as was possible (keeping the front to rear dimension as short as was possible) on my cell while still trying to maintain a 15+ gallon capacity. As was mentioned in the "sister string" about the Rusty Old Datsun, I also ramped the bottom of my cell upward as it goes back toward the rear (a 3" difference). In addition to this (and not readily visible), the rear deck on my Z (the 240 anyway, but I'm sure it's true with all of them) is angle upward slightly as it goes rearward and is in the same plane as the top of my cell. These two factors aid in keeping fuel forward at the pick-ups near the front of the cell. This obviously has it's advantages and disadvantages. The advantages are that the center of gravity of the fuel is kept closer to the axle, aesthetically the end of the cell (and the fuel fittings)is no longer visible behind the valance panel, and some amount of airflow advantages could be argued. BUT, the disadvantages are the required increased baffling to keep the fuel forward under acceleration, and the "custom" design required, as all (the ones I've seen) aftermarket cells are flat bottomed. All in all, I had the local sheetmetal shop build my 17 gallon cell to these requirements for about $250. It is .060" walls with a .125" top (which is now the rear deck surface) and brackets welded on the sides to allow the tank to be dropped in place into a frame similar to the tubes used previous photos.

Glad to see you back again.

The tech person I spoke with today at Billet Specialties said that even though they do not powder coat any of their wheels, they do not see any problems with this being done. I posed some of the above information to him and he maintained that this would not be a problem with their wheels. I then contacted my local powder coater, and he has, at specific customer requests, reduced the temp to about 370º for this reason and is aware of the above concerns. So, now I'm wondering if I should continue my quest to powder coat the center section of my wheels, or use a conversion coating and paint them myself? Being the center section is so deeply inset into the rim, I hardly see future chipping as an issue.

Somebody hi-jacked Johnc's user name!

bar size is a function of what kind of stress you'll put on the bar. A 1/2" tube can hold a ton of weight if it were strictly compressive forces. A flexible cable could do the same for tension loads. Get my point? Properly triangulated structures rely on this principal, and this is why I rely on it as well. It allows lightweight aluminum tubing when no shear loading is present. In your case, if you evaluate what you've done, and see no significant shearing, then it won't make any real difference on the size of the tubing. A string quite a while back (and it was quite an argument on this point) about a "bent" strut tower tube brace brought up this point that a structure of straight tubes connected at common points, will be very strong, AND light in relation to the small size tubing used. Look at the Birdcage Masarati for example. Yes, it was a complicated structure, but it was very rigid. In regards to recommending a size for you tubing? I'd rather not go there being I cannot see the car and what you are planning to do. Any time the "connections" (the points of the various triangles in the structure) of the tubes start getting separated, it's wise to up the size of the tube. This is because the forces of tension and compression start becoming lost in the other forces of shear and twist as the points become more and more distant.

In reference to your photoshoped photo, will you have any room to bring the two "side bars" (that connect to the towers) inward as they go forward, so that they can create a triangle over the front of the engine (or would this cause problems with access to parts and pieces?)? For example: ______ __/__

I can't remember where I got it, but it (I think I cut it out of a small piece of sheet) made it the same size as the white nylon type of washer used by the fuel cell (about 1 1/2" in diameter).

I do not consider anything forward of the strut towers as "structural". This opinion is based on the following argument specific to what I’ve done on my car: The strut tower location is where the suspension forces are impressed into the unibody (the sway bar is another location for impressed stresses, but it is in close proximity to the tower’s base, on a boxed steel support, and considered to impart negligible forces forward to the core support), and if these points are reinforced directly (as they are with the multi-point strut tower bracing I use), then there should be no movement forward of these points (core support area), because there is nothing forward of these points placing significant stresses onto the unibody. If the unibody IS flexing at points this far forward (at the core support area), then using the engine bay’s side sheet metal shape to counter these forces is, in my opinion, an ineffective use of the bracing you want to use. In essence, the bars you are placing across the sides of the front bay area will flex at the point of the welds (OEM sheet metal in particular) and no matter how big a tube you use, the flex area will not change or diminish. This is why the OEM core support used sheet steel (in the same plane as the support to distribute this loading along its entire height) on both sides of the radiator to provide a rigid box (gusseted for lack of a better term). One might argue that engine torque is another source of concern in distorting the (un-reinforced) core support area, and this is a viable argument (even with a simple single strut bar support), which is another reason why I chose to solidly mount the motor to the unibody using multiple points of attachment as well as tubes attaching the motor to the strut towers. BUT, again, simply attaching a bar(s) between the sides of the front bay (as I have done on my car as well) will not keep this core support’s “rectangle†from flexing at it’s corners. My success in using the small ¾†tubing to support my radiator is only because of the bracing done further back at the towers. Too many horror stories of cracked radiators due to weak core supports affected my modifications further back toward the strut towers. From what I can see from you photos, I would say you've got some room to triangulate the tubes behind the IC. One tube would be good, two tubes (an X connecting the two cross-tubes) would be great. Doing this would allow smaller (lighter) tubes because you'd now be dealing with tension/compression forces on these tubes instead of shear forces at the welds at the ends where they meet the OEM sheet metal.

Okay, so that explains the bodywork! Took the expertise of an outside group of Zcar.com clones to bring this to light, and all this time I though Dan was being honest with us, his own brethren. I'm hurt!

I had the same problem with mine. I eventually put a softer (fuel safe) thin rubber-like washer between the white nylon ones and the cell material. This stopped it.

I'm a bit confused as well, but would like to help you out if you'd provide more information or photos.

Nice job Rufus. If you get a chance, post a picture of the overall car in reference to this new "hatch". I'd like to see how the quarters, riding up into the pillar, appear from a more distant view.

Most all aftermarket MCs have a bolt pattern VERY close to the OEM pattern (perhaps off by 1/16" or so). I used a Girling, but the Tilton has the same bolt pattern as well, and their web site may have all the dimensions on it.

Yep, with my high force RAM pressure plate, I kept the size of the MC at 3/4". Anything larger tended to flex the firewall, but a lighter duty plate may allow a larger MC than this.

I my memory is correct, 1.2 to 1.3 Gs was not unachievable in the old Sharp racing Zs.

One of my good friends had the exact same thing happen to him (he can tell you exactly how many years, months, and days since it happened on any day you ask him) a few years back. Sad, very sad as it has changed their (his and his wife) lives in the worst way.

I'd verify the differential gearing first by counting the revolutions of the propeller shaft (or drive shaft) verses the half shafts. Propeller/Half shaft is the ratio that you want. If only one half shaft is turning when you turn the driveshaft, then this will cause the rotating half shaft to spin twice as many times (single track diff) as it would if both half shafts are spinning (LSD), so your 3.9/1 would look like a 7.8/1 if you don't correct it, but this would be obvious when you see it. Then you'll know the final drive ratio and be able to verify the acuracy of the tach when you plug in tire rotations per mile, and test it in say, a 1:1 gear to make it easier (4th gear on most manual transmissions), at a specific speed. Most speed verses rpm tables will give you the information you'll need for this.

I'd put this question in the "personal preference" catagory. I've seen the hole in the hood for the air cleaner style, but still prefer it covered up with a well done cover. If you want to see the air cleaner move, then perhaps a "shaker" type of scoop would meet your needs.

I'd say you are fine with what you've got on your list. The radiator size is still up in the air though, but a descent sized 3 row should handle what you are planning on.

Yes, it is blue but I've no idea about his history with the car. It's got the usual wide 914 flairs.

Went driving today with a close friend of mine who owns a highly modified 914-six cylinder (has a 3.6L 911 motor in it). He used to do some PCA racing, but only does local Solo events now. Anyway, we headed out of town on a twisty, curvy, roller coaster type of country road today with him in the lead (he does this route regularly and I felt more comfortable with him in the lead). After some prior discussion, it was found that our cars are more similar than expected. Weight is within 100lbs of each other, same final gear drive, and roughly same horsepower. What gave him a big edge was the Toyo RA1 tires verses my hard as rock Comp T/As. Anyway, it was a blast listening to his car pull out of every sweeping turn. The course was a dream set-up of 20 miles (each way, there and back) of left/right switchbacks with speeds from 125 in the valley straights, down to 20 for some of the tighter curves. The highlight was a 400 foot ascent full of constant left-right turns at nearly full throttle (for him). Even though I could outpull him in the straights, he was way ahead of the game on the corners. I guess it's time for some serious rubber! I've got to say it and I know I'll get flamed for it, but 11 second runs are no match for a 1 hour drive like this. It's been such a long time since I've had some real fun with this car that it's almost as good as the first day I drove it.

I always end up spending 60% or more than planned whenever I get involved in a project like this. I ran SuperTrapps and liked them (I had the smaller diameter ones) but these 5" may become a problem with low riding inclines (dragging). Mounts, oil pan, and steering linkage are the 3 main concerns with the SBF, but none are really bad problems. I'd go closer to the 2K+ to complete your project.

My HTOB is the McLeod slip on. The manufacturer uses O-rings to make the fit snug onto the input shaft housing. One thing to note here is to make sure the adjustment is on the far end (fully extended range) of the operating "window", especially if using a long style (or similar finger type) pressure plate (and may be applicable to a diaphame type as well). This is because the fingers move inboard toward the bearing as the clutch disc gets thinner due to wear. I initially adjusted it on the short side of the window wanting to stay in the mid-range of the threaded sleeve. Then, after the clutch wore a bit, the fingers moved inward toward the bearing, which then eventually butted up against the "at rest" stop. This resulted in having constant pressure on the pressure plate (on the fingers), and a slipping clutch. I consequently re-adjusted the threaded sleeve (threading the bearing back toward the engine block) so that future wear on the clutch disc would still allow a bit of margin between the minimum (at rest) setting, and where the clutch fingers would be with the clutch completely wore out. This is a self adjusting bearing just like brake calipers are self adjusting. I did have an issue with leaking banjo fittings, but a simple replacement of the tiny O-rings fixed that. I also had the pressure plate wear through the lining of the braided SS lines as well (which was my fault for not insuring sufficient clearance away from the spinning pressure plate). This was too resolved and I've not had trouble with it for 4 years now.