Tuesday, March 24, 2009




The rear body work was re-fitted to the car early this evening but I'm not happy with they way it aligns with the rear sub-frame (red). I'll have to make some more alterations to the way the rear sub-fame attaches to the rear suspension cage. It's the old "two steps forward, one step backwards" routine but we'll get this problem resolved. As soon as I'm happy with the way the tail fits, I'll install the doors to get the cowl, doors, rocker panels (outer sills) and tail all lined up and work the remaining high and low spots out of the aluminum skin. The nose will have to be refitted also. After that we can start getting the body ready for paint, which should be exiting.


I also finished carving up the motor mount brackets. The first photo of these, which I posted about a week ago, showed them already considerably pared down from original. They should weigh less than half of what they weighed originally. The left mount held several accessories, such as the AC compressor, on the Quattroporte donor car. I still need it to help anchor one device so I couldn't chop it up as much as I would have liked but it's way smaller and lighter now.

Sunday, March 22, 2009

More on rear shocks and springs

The new rear shocks and springs are on the car now. It wasn't a quick
1, 2, 3 operation (when is anything ever simple?). The shocks came with
5/8" I.D. bushings so I had to make sleeves to fit the 1/2" upper shock
bolts. The old Konis had sleeves in them too but they didn't fit the
GAZ shocks. The shaft that mounts the lower shock eyes has a 16mm O.D.
so the lower 5/8" I.D. bushings had to be reamed a few thousands to
fit. The adjustable threaded spring perches were left low on the shocks
for now while the car is light with no engine, trans, much of the body,
etc. I also had to make spacer rings for the outer radius arm rod-end
bearings so they would fit snugly in the clevises attached to the rear
up-rights. I couldn't finalize the installation of the radius arms
until the new shocks were installed due to mechanical interference.

After the rear suspension work was done I installed the rear sub-frame
so I could tighten the upper shock bolts and the inner fulcrum shafts
for the lower control arms, which the rear sub-frame attaches to.
Attaching the front and rear sub-frames with the already existing front
and rear suspension hardware seemed like an elegant solution when I came
up with the idea but it does complicate assembly of the car with so many
fasteners doing double or triple duty.

As I said before, the rear sub-frame is red because I originally planned
to paint the whole chassis red. When I'm finished fitting the tail
section (rear body-work) I'll remove, sand and paint the rear sub-frame
black (urethane enamel) along with the roll-bar braces.

Since a slight adjustment had to be made to the rear sub-frame I wanted
to make sure the fuel tank still fit on it's mounts and it does. I
bought this tank from Summit or Jegs a while ago and modified it to
fit. I may have mentioned it before but the aluminum cylinder at the
right lower front of the fuel tank is the fuel surge tank. As long as
there is enough fuel left to keep the cylinder full (about a gallon),
the fuel pick-up will never suck air like it would in the bigger tank.

I also made and installed a bracket to hold the brake-line T-fitting to
the rear suspension cage. I used a piece of 304 stainless sheet so I
wouldn't have to paint it.

The motor mounts received a bunch more "lightening" holes and trimming
today. Tomorrow I'll try to finish them up with some more sawing and
grinding.

Friday, March 20, 2009

rear shocks and springs


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.

Sunday, March 15, 2009

some other tasks











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.

front shocks





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.

Wednesday, March 11, 2009

bump steer



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.

Sunday, March 8, 2009

some machine work






photo 1) 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 2) 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 3) Pip-pin latch at left rear corner of nose section (bonnet).

photos 4 and 5) 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.

chassis alignment, camber/caster/toe angles





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.