scratch built Mazzer roadster

Thanks. You don't understand, I'm actually pretending to spend some time in the house with the family. ;-)

 

This weekend I concentrated on sealing up small openings between aluminum panels and the chassis, bracing corners around the inspection openings at the tops of the foot boxes and insulating around the fire-wall area.

Some brief photo descriptions:

1) A partial sheet of 1" foil backed foam insulation board with a bunch of panel shapes laid out. I cut these out on a band saw. Lots of triangles on this car - I cut a lot more than seen here.

2) Some of the insulating panels have been glued into place here. In the upper most triangle space is the gas pedal shaft support that needed a seal against hot air blowing in. I made the seal out of two layers of foil backed fiberglass insulation cloth. A foam panel was glued over the top of that.

3,4) The upper portions of the foot boxes were insulated on the inside. I have aluminum corner braces flush riveted into the corners here and the heater hose end fitting screwed in place.

5) The upper portion of the fire wall and the front wall of the right foot well received insulation on the insides. The "no glue" labels are there since these insulating panels may still need to come out for component installations like windshield wipers, a dash support, etc.

6) The top of the right foot box. Measuring for and installing the insulation panels in here wasn't easy. There are more that are hidden from the camera so you can imagine what fun they were.
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I can tell you guys are really thrilled about insulation (which I'm still working on). The GAZ rear shocks with springs I ordered came in the other day with the UPS man, or at least I though they did. I ordered single adjustable shocks with adjustable ride height but when I opened the box I didn't see any threads on the shock bodies and knew right away I was in trouble. Called the supplier, straighted out the mistake (theirs), packed the shocks back up and waited for a call tag to arrive to ship them back. Of course the shocks I wanted they only had 2 of, so I have to wait about 2 weeks to get 4 correct rear GAZ shocks.

Today was better. The front Varishocks I ordered came in and, to my relief, were correct and so were the 250 lb springs. These shocks are have a single adjustment knob to adjust compression and rebound simultaneously. Twin adjusting knobs are available also but it's a street car. Single adjustable is good enough. Same with the urethane bushings. Spherical bearings are available but - it's a street car. I installed the springs on the shocks, along with a set of Energy Suspension bump stops, but installation on the car will have to wait a bit. I still need to do a preliminary suspension alignment before I put springs on the car. Right now ride height is perfectly maintained with the solid struts.
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The foam board panels will hopefully keep the foot-wells below 150*F. I installed the last few pieces this weekend and then had to make 8 more aluminum panels to hide the stuff where it shows. The panels are tiny and very thin so the weight penalty will be slight.

Yeah, unless you're using a stop-watch while doing multiple laps around a track it's going to be difficult to notice the difference in separate dampening and rebound adjustments. I installed the same brand (single adjustable) shocks on the 308, set the knobs at mid range and they feel fine that way on the road. I haven't messed with them any further. One of these days I do want to do some testing at the track but unless you have Roger Penske's budget you're going to run out of variables pretty quickly.

 

The foam board insulation panel installation is basically done at this point. I just finished cutting and installing foam panels along the sides of the car where the exhaust pipes will run and inside the transmission tunnel where I imagine it will get pretty hot also. I received a PM from one of you guys expressing concern about the flammability of the foam insulation. It doesn't burn like gasoline but it's not fire proof either. All the exposed foam insulation will be covered with aerospace, foil backed fiberglass insulation cloth for one more layer of protection against heat but also because the fiberglass is fire proof. Yes, fiberglass car bodies burn but that is because the glass fibers are only reinforcement for plastic resin which burns.
Fiberglass cloth is just spun and woven glass fibers. It's an open car and it will get a Halon fire system so fire shouldn't be any more of an issue than with most other cars.

Now I'm installing some (8) small aluminum panels (3003 "alloy" .037"-1mm thick ) here and there on the chassis to either hide the insulation or to block off remaining openings that could be sources of hot air into the passenger compartment. Some of the panels in the photo still have the protective paper on them others were cut from scrap that no longer had paper on it. These still need to be fitted, trimmed, filed, punched, etc before installing them. A couple of panels on the chassis had to be made in several pieces, with stepped lapping flanges, to allow installation in confined areas. The copper colored bullet shaped devices are Cleco temporary panel fasteners. They are very quickly installed and removed with special pliers and really aid in test fitting and assembly work.
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Photos 1 and 2
It's time to bolt the bigger body sections to the chassis but first I had to do some prep work like make sure the chassis and suspension are square (It would be a lot more difficult with the full body in place). One very important part of that was to make sure that the detachable rear sub-frame, which carries the differential, rear brakes and rear suspension was perfectly aligned with the center-line of the car.

The first step was to measure between the pick-up points of the front and rear suspension systems to find the exact center-line of the car. I had already done a lot of the preliminary work to establish the center-line while building the chassis. Plum-bobs were hung from the front and rear center points of the chassis and a string was stretched along the shop floor directly under the points of those 2 plum-bobs, establishing the chassis center-line just above the floor.

When the chassis was built, I made up 2 detachable lateral bars, with adjustable ends, that attach to the front and rear of the chassis. A String was run along each side of the car, between the afore mentioned removable bars. These 2 strings were adjusted to be parallel with each other and the center-line string via a plumb-bob at each bar end (each corner) to form a perfect box which was aligned with the chassis. Measurements were made from the string sides of the box and adjustments were made to the rear sub-frame and suspension to make it all nice and square to hopefully eliminate a lot of potential handling problems.

Photo 3
I also set the camber, caster and toe angles. The Quattroporte (Jaguar style) rear suspension uses the half-shafts as the upper control arms. Camber is adjusted by stacking shims behind the inboard U-joints. I still need to adjust bump-steer.

Photo 4
I got a little ahead of myself when I made the roll-bar braces earlier and forgot that I still needed to adjust the rear sub-frame, which the braces anchor to. After adjusting the sub-frame I had to cut the braces apart, cut new bolt eye tubes for the ends and prep the joints for re-welding.
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photo 5
New nuts for the rear suspension inner fulcrum shafts machined from 7/8" (22 mm) stainless hex rod and new stainless spacers for the upper mounts on the rear sub-frame cut from stainless tubing.

Photo 6
Front sub-fame bolted in place ready to accept the flip-up nose section. The whole nose pivots around the bolts at the front corners which carry bronze bushings and nylon washers. The aluminum panels mate to other panels in the nose to duct air to the engine air filters and the radiator which rides, almost horizontal, on the front sub-frame.

photo 7
Pip-pin latch at left rear corner of nose section (bonnet).

photos 8 and 9
Since the car is a spare time project, it's jammed, out of the way, into a back corner of the shop. It's time to get the rear body-work mounted but I'm sort of stuck until I can get some help turning the car around. In the mean time I needed something else to do so I machined these two pieces out of aluminum bar stock (6061 T6) to hold a boot around the U-joint in the steering shaft where it passes through the fire-wall. One piece (with the larger center hole and mounting screws) will bolt to the fire-wall and the other piece will ride on the lower steering shaft - the shaft will turn inside the center hole. The boot will be right over the left exhaust header pipes so I'm making it out of foil backed, fiber-glass insulation cloth. That's the plan anyway.
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Hey David,

Thanks for the compliments and for letting me know about the Thread of the Month thing. That's kind of cool! I had no idea.

Thanks for the input too. I hate the look of that exhaust wrap and it makes pipes rust but if I have to I'll do something like that. I should have built the header pipe extensions out of stainless. It would have minimized the rust problem and stainless holds heat in better than carbon steel tubing. I did have the headers JetHot coated and that should help.

The car does have large louvers in the fender aprons and there's a good sized gap between the fire-wall and the back of the bonnet for heat to escape. Hot air is also supposed to pass through the large transmission tunnel and exhaust out through multiple louvers at the back of the car in the low pressure area. I also installed 2 ducted fans in the bottom of the engine compartment for slow traffic situations. I did think about louvers near the back of the bonnet but was reluctant to do so thinking it might weaken the structure too much. This thing is a big experiment and I'm sure I'll be finding all sorts of things to up-grade and change once I get it on the road. My mother in-law still can't understand why anyone would build a car with no roof on it!

A couple of people have made the polished aluminum suggestion but it's a lot of work and I really think the car would look better painted.

 

I got to admit - I'm a little puzzled too. Were you having a bad night?

 

Time to check and adjust bump-steer.

For the uninitiated, bump-steer is a condition where a wheel self steers as the spring is compressed while passing over a bump or while cornering or braking. You can imagine that the car will be hard to control if the wheels toe outwards every time you brake hard for a turn. Having the wheels toeing IN under the same circumstances is not as bad as toeing OUT but it's still not desirable. Whether or not this condition exists can be measured and usually it can be adjusted away by raising or lowering the steering-rack or the tie-rod ends until the wheels stop self steering as they move up and down with suspension travel.

Since this car started with a bunch of components and a clean sheet of paper, it's important to check for,and measure for, bump steer and to adjust the condition away. The cross-member which the the steering rack attaches to was designed to adjust up and down in anticipation of having to deal with bump-steer.

I borrowed the bump-steer checking outfit shown in the photos. I don't like it as much as the one I used to own (I loaned it to someone and never got it back - note to self!) but it certainly does the job. Basically, a flat aluminum plate, with a piece of measuring tape attached to each end, is bolted to the hub, substituting for the wheel. Dial indicators touch the horizontal center-line of the plate with the suspension in a neutral (at ride height) position on a small bottle jack. The coil-over (or in this case the metal strut) is removed and the suspension is jacked up and down slowly while the dial indicators tell you if (and how much and in which direction) the plate steers. In my case the plate (wheel) was toeing out under suspension compression (bump) and the steering rack had to be shimmed upwards slightly. Adjusting away the self steering under bump is more important than under droop since under real world conditions, if the wheels are in droop, the car is coming of the ground and the tire doesn't have much traction to do any steering until you come back down anyway.

A good visual way of finding out if bump-steer in your car is at least minimal, is to check that the tie-rods are parallel with the lower control arms and of similar length. If they don't match like that, the tie rods and lower control arms will travel in different arcs and cause the wheels to change direction on their own.

The suspension geometry on the rear of this car will, by design, not have any serious bump-steer issues (or adjustments for it) but every car is different. Bump steer can happen on the rear suspension of some cars and the condition can be much worse, since you can't manually steer the rear end of the car. I've experienced body roll induced over-steer (roll over-steer) and it's not funny. When it first happens, and you spin the car repeatedly, you think you forgot how to drive fast.
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Thank you and me too. I hope to drive it this year. We'll see.

 

Got the bump-steer squared away so I finally came to the point where I could install the front shocks. I originally designed the chassis to accept a pair of racing Konis for the front but I later decided they're a little too rich for my blood and at that point I hadn't discovered VariShocks yet. I don't know, maybe they didn't even exist then.

Anyway, I had to make a few minor modifications to the varishocks to get them to fit. The upper bushings were just a little too wide for the chassis mount and I wasn't too eager to change the chassis. I disassembled the upper bushings, shortened the inner steel sleeve and the urethane bushing halves in a lathe. The urethane doesn't machine very well but if you're persistent.... eventually enough material was chewed off to where they were close to the correct thickness and then they were smoothed and finish sanded to size with 80 grit sand paper on a cast iron lapping table (any flat surface would have done the same job).
The bottom mount on the lower A-arm had the opposite problem. It was too wide so I lathe cut 4 Delrin plastic spacers to take up the extra space. I got the left front shock and spring mounted late today. Once the engine and other components are installed I'll have to set the ride-height and even out the corner weights of the car on scales.
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The front shocks are on the car now which is sitting back on the ground. The front end is sitting kind of high but that should settle once the weight of the engine, body, etc are installed.

By "squaring" the chassis and suspension I had to shim out the rear suspension sub-frame slightly which caused problems for the rear body section, part of which bolts to the back of the rear suspension sub-frame. Back when I was just beginning construction of the body, I kept telling myself to precision "square" the chassis and suspension before going too far but I didn't listen. So, now I had to make some modifications to the tail so it can go back on the car. The aluminum tail was riveted to some framework that also acts as a rear crash barrier. Since I earlier-on thought the chassis would be red, I sprayed the rear framework red before riveting the rear sheet-metal in place. To get the tail to fit I needed to modify the frame-work slightly but doing it without removal from the tail wasn't viable. Today I drilled out multiple stainless rivets, cut off one of the lower mounting bosses, prepped the end of the brace for, and made a new, mounting boss. Then the framework was mounted back into the tail but with Clecos this time to everything can be lined up on the back of the car to tack weld the new mounting boss in place. The tail sheet-metal will then have to be removed for proper welding access to the new mounting boss. After that the rear frame-work will be prepped and painted black to match the rest of the chassis and it'll be riveted back into the tail.

Without help, over this weekend, I couldn't move the car or the tail to continue the work so I decided to look for some other tasks to take care of.

The sheet aluminum door hinge covers had some redundant mounting holes in them so I TIG welded them shut, ground the welds smooth, and screwed the covers back onto the car. Now what?

The steel motor mount brackets that bolt directly to the engine block always seemed kind of agricultural in quality to me and much too heavy. Who cares if you're building a 4,000 plus lb. Quattroporte sedan right? I started trimming off the not needed pieces and drilling and boring some lightening holes. It probably won't save that much weight but It'll make me feel better to stream-line these clunky things a little.
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Thanks for saying that. BTW: When I was a kid the Mangusta was the Italian dream car just like the Countach was for eighties kids. You should change your Avatar to a shot with the engine covers closed and the front wheels dead ahead. It would look much better.

 

The new rear shocks and springs finally arrived today and I assembled them earlier tonight. Need to make up some sleeves for the upper bushings before installing the shocks. The 1/2" I.D. sleeves from the old Konis are about .003" too big in diameter to fit.
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