Assembling the STALKERV6 Bodywork
This afternoon began the process of fitting the Stalker bodywork. The body is comprised of both fiberglass components and aluminum panels. The fiberglass pieces delivered with the kit are some of the nicest quality I have ever seen in a kit. The gel coat is flawless and the chopped glass lay-up is very consistent.
The front fender assembly begins with the installation of the fender stays. These brackets attach at two locations on the spindle. I will eventually glass the fenders to the stays; this will require disassembly of the upper tie rods to remove the fenders, but since I don't anticipate the need to routinely remove them, I don't see this as a problem.
To establish a starting point, I taped two 3/4"x3/4" wood blocks to the wheels. Since the radius of the fenders did not exactly match the radius of the Falken 205/50-15 tires, I added a 1/4" shim to the front block. This gave me the fender profile that I wanted.
It is necessary to hand form the fenders stays. They are made of mild steel strap so hand forming is only mildly difficult. The fender brackets will need to be bent to where they look something like this. Forming was done with a combination of muscle, grunt, wood blocks, hand seamer and large pliers.
Fit and bend, fit and bend, fit and bend........
It is risky to show up at my shop when Stalkin' is taking place. Good Friend Dave arrived to check out the project and was promptly drafted to assist with the fender assembly.
Once the stays were formed, holes were drilled through the fenders and stays so clecoes could be inserted. Obviously, the cleco holes will be filled later.
The most difficult step of the process is getting right and left fender brackets to match. Getting one fender to look nice isn't too tough, but getting two fenders to look the same is a lot harder!
Most builders use resin to bond the fenders to the stays. It is necessary to disconnect the upper ball joint and brake line in order to remove a fender bracket once a fender is bonded to it. I considered modifying the fender stays to allow for easier removal; however, I ended up merely bolting the fenders to the stays with nice, round head carriage bolts. This allows the fenders to be easily removed without disturbing the fender brackets.
Besides, the bolts remind me of motorcycle fenders in the '60's and '70's.
The car is definitely taking on a Stalker look! About ninety minutes of work and the front fenders are marked off the list.
Update: Fabrication of Redesigned Fender Brackets
After #29 had accumulated about 900 miles, the right front fender bracket broke near the weld that attaches the fender strap to the vertical strut. Since considerable buffeting of the fenders in the slipstream at highway speeds had been observed, I was not totally surprised when the bracket fractured. Fortunately I had attached the fenders to the bracket with bolts, so removing the damaged fender was easily accomplished roadside. However, if the fenders had been bonded to the brackets as is "standard practice", the damaged fender and bracket could have been challenging or impossible to remove from the car with the limited set of tools carried in the car.
In an effort to avoid future problems with the brackets, and to reduce the buffeting of the fenders in the wind, I designed replacement brackets. These brackets are slightly heavier than the standard brackets, but I consider a little more unsprung weight to be an acceptable tradeoff if the new brackets prove to be troublefree and rigid.
(Original bracket on the right)
The new brackets are fabricated primarily from 1/2" cold rolled steel rod instead of the combination of thinwall steel tubing and 1/8" strap stock in the original units. The biggest change besides the heavier and stiffer material is the elimination of the straps at the fenders; these straps were no doubt utilized so each builder could fit the brackets to individual cars without resorting to welding. While the straps lend themselves to being shaped with simple tools, I think the aesthetics leave something to be desired and they are a source of potential problems due to the complex bends required. Even though not visible in the photo, the new brackets still have a brace at midspan of the vertical strut, but it bolts to the unit instead of being welded. The bolt plates on the new bows are 1/8" steel. I suppose some lightening holes could have been cut in the plates, but I am not that obsessed with eliminating weight. Even though I elected to bolt the fenders to the brackets, the bolt plates could be omitted if the fenders are to be glassed to the brackets.
The two solid struts are joined with a 1/8" steel angle at the ball joint nut instead of the 1/8" strap on the standard bracket. This lends stiffness and additional weld area to this critical assembly.
The new bracket assemblies were fabricated in place on the car so the fender could be located as close to the tire as possible. I also needed to accommodate the existing bolt holes in the fenders.
Shown here is the left bracket; a careful look will show the bolt-on brace from the vertical strut to the spindle. The bows were formed by bending them by hand in a large vice, no heat was required. A tight bend can be produced by slipping a pipe over the rod and using it as a "cheater bar" while bending the rod.
This is as close to the tire as the new fender bows can be located and still allow the wheel to be removed and installed with the fender in place. The bows were fabricated to keep them very close to the sidewalls of the tires for best appearance. However, at least 1/2" clearance between the lower bows and the sidewalls needs to be maintained so there will be no contact when the sidewall distorts during hard cornering.
Very small relief notches were required in the fender to allow the fenders to rest properly on the bolt plates. On the road the new brackets are very rigid and there is no movement of the fenders in the slipstream, even at imprudent speeds!
The original brackets may very well provide satisfactory service for many Stalker builders. The new design is merely my attempt to improve the appearance and durability of the fender brackets on #29, and I believe they deliver on both counts.
Update: #29 now has 4500 miles on the clock. The new fender brackets have been totally reliable with no indication of wear or fatigue.
As we begin the installation of the aluminum body panels, I thought it might be good to take a look at some tools that can make the job more enjoyable. Not everyone has an air compressor in the shop, but if you do, you can purchase some air tools at the local home improvement stores that will definitely make the metal work easier.
From left to right; aviation metal snips (come in left, right and straight flavors), air drill (spins much faster than electric or battery versions), clecos and pliers (probably have to be purchased from aviation supply house), hand seamers (be sure you grind a radius on the nose of the tool to prevent making too sharp a bend which could crack the metal), and a die grinder with a 2" ScotchBrite wheel (probably the most useful tool there is for deburring and shaping aluminum parts). The drill bit shown also has a drill stop installed which is a spring thingie that prevents you from ramming the drill chuck into the panel when the drill breaks through.
Here is another "must have" tool, the Unibit. Not only does this single bit neatly drill several different size holes, but it can nicely deburr holes as well.
The seat back trim lines were laid out from measurements taken from the chassis. It is important to remember that the chassis is not symmetrical; the passenger compartment is narrower than the driver's side. The transmission tunnel cutout is not "square"; it tapers inward toward the top. Be sure you use the top of the panel as the datum point since the bottom will be trimmed even with the floor! I also relieved the top corners to fit around the roll bar plates so the seat back will lie flush on the frame crossmember. Continue to trim and fit a little at a time; eventually the panel will drop into place.
It seems the hip panels are a concern for some builders, but I found that they could be inserted into the frame after only two minor cuts on two corners.
To mark for the first cut, put the panel in place as far as it will go and insure that it is plumb with the downtube on the chassis (left side of panel in this photo). On my car, the panel extended 5/8" past the forward edge of the downtube. With the panel in place, mark for the cutout that must be made in the bottom rear corner to clear the chassis crossmember. Remove the panel and transfer the mark forward the same amount as the panel extended past the downtube! Make the cut; the panel will now drop into place correctly vertically, but will still not push far enough to the rear due to interference with the top frame crossmember. Make sure the panel is plumb and mark for the cutout in the upper rear corner. Once again, transfer the mark the same amount forward as the panel extended past the downtube! Make the cut and the panel will now drop perfectly into place. It may be necessary to tweak the cutouts to allow for weld bead in the corners.
The diagonal tube on the seatback can now be marked on the panel along with the cockpit rail; make the cuts, and you are done. No cardboard patterns are necessary.
Here is the hand seamer in action forming the tabs on the aft end of the body side panels.
Detail of how the tabs are used on the end of the side panels to secure them to the aft chassis. Many of the body panels are delivered prebent and I have found the bends to be located very accurately.
As per Dennis's recommendation, I taped wood strips to the chassis longerons prior to bending the side panels. This avoids the kink at the cowl station of the chassis and allows the panel to form a smooth curve as it follows the longerons.
After the bending is done, remove the panel and wood strips, then reinstall. Begin at the aft end drilling holes about six inches apart, insert clecoes, and work toward the forward end of the panel. Another tap or two on the bump that pops up on the flange....and the side panels are done!
Turns out I am glad I got out of sequence with the panel fabrication. The instructions suggest doing the floorboards first, but now that the side panels are done first, I can butt the floor pans right up to the edges of the side panels and still have room for the fasteners.
Seat back, hip panels, and one side panels are now in place. I am waiting for the quick steer fittings so I can finish the assembly of the front suspension afterwhich the suspension will be removed from the chassis so the frame can be flipped over for the floorboards.