<<Fixing the Angle Brackets>>

This section describes how the light-alloy brackets are stuck onto the chassis, initially using car body filler as an adhesive. This method makes it easy to get each bracket in exactly the right position - if you get one wrong, you simply knock it off and start again. To secure the brackets, you use pilot holes in them to drill through into the glass-fibre chassis, then fix them securely with machine screws.

The filler not only acts as a temporary adhesive, but also ensures that the brackets are securely bedded onto the surface of the chassis, and provides the opportunity for you to correct small distortions to the shape of the chassis that may have occurred during the moulding process.


The Front Wishbone Brackets

You need to mount a pair of the wishbone brackets 180mm apart on 8mm studding (threaded rod), as in the picture on the left. 180mm is the distance between the inside faces of the brackets. You will need two pieces of studding, four biggish washers, and eight nuts. Ensure the assembly remains flat when you tighten the nuts. I recommended you stick coloured PVC insulating tape on the faces of the brackets in contact with the chassis, so you can remove them easily and don't get unsightly filler oozing unevenly through the holes. You do not want to have a sticky surface facing outwards inside the cutout holes of the brackets either, so it is best to use two layers of tape, one of them only as wide as the holes, with their sticky sides together, on the area behind the holes. Trim off surplus tape with a sharp knife when you have backed the brackets.

Next, find some way to hold the chassis with one of the wishbone surfaces facing horizontally upwards, and rest the assembled pair of brackets on this surface, aligning the front corner of the bracket with that of the chassis. You may find that the wishbone surface of the chassis is not absolutely flat, due to distortion of the chassis during the moulding process. The amount is not likely to be more than 1mm or so, but it is still a good idea to correct it. Use a biggish try square (left) to determine which end of which bracket needs to be raised in order to make the plane of the wishbone assembly rectilinear to the floor. When you have identified this, use small squares of adhesive tape on the back of the bracket (right) to raise it up by the required amount.

If you have some fine sandpaper or emery you should lightly abrade the surface of the chassis where the brackets will make contact. This will remove traces of release agent and help the filler adhere. It also helps to fix masking tape where you do not want the filler to stick. Next you should mix some filler and stick the assembly to the surface, checking its squareness again as before. It is more important to get filler around the mounting holes than in the centre of the bracket. You need to ensure that the assembly is not skewed on the surface. If you don't trust your eyes to do this, measure at the front and back by hooking a tape measure under the floor, as in the shot on the right. At six inches, the height of the chassis is roughly equal to the length of the brackets, and you want the bottom mounting holes of the brackets to be as close to the floor of the chassis as you can comfortably get them (right). Press down to exclude excess filler when you have got it right.

The other pair of front wishbone brackets is attached in a similar manner to the first, except that you should also check that they are the same distance forward on the chassis as the first pair you stuck on. Providing you have made both brackets the same shape, you can do this by laying a ruler across the front, as in the picture on the left.

When both pairs of brackets are attached, and you are satisfied they are in the correct place, you can drill the mounting holes through into the chassis, then secure them with machine screws. You need 8mm screws in the lower end of the front angles; the other three screws on each side are 6mm. You will probably need countersunk head screws as the clearance between the head and the inner ends of the wishbones is tight, especially around the 8mm screw. I recommend you use stainless washers and nyloc locknuts inside the chassis to secure the brackets.

 

The Rear Brackets

The rear brackets are attached in a broadly similar way to the previous section. Instead of using studding to separate the lower end of the brackets, you can use the rear arm itself, including a thinnish stainless washer on each side between the bush and the angle bracket. Use 8mm studding at the top, with the nuts adjusted so that the brackets are parallel. Again, you should hold the chassis so that the face you want to attach the brackets to is horizontal (left). You should again check that there is sufficient movement in the hinge, so that the rear wheel will be able to come round and touch the floor, when the rear arm is folded (right).

The outer faces of the brackets will be slightly wider than the chassis. The height of the brackets on the rear face of the chassis should be as high up as is consistent with folding. You should find (left) that the bottoms of the heads of the countersunk pivot screws are around the same level as the floor. You can file a little bit off the appropriate part of the bottom rear corner of the chassis in order to achieve sufficient folding, if necessary.

 

The Boom Brackets

To do the best possible job here, you need to check that the boom goes on straight. I suggest you do this in the following way. First of all, support the chassis so that the attachment face of the boom brackets is horizontal. Now get something with flat sides that is dead straight and about as long as the boom and chassis combined. In the picture, I have used a light-alloy section 1"x1/4". Somehow, fix this truly parallel to the sides of the chassis. In the pictures on the left, I have used a couple of engineering blocks, and bungees. Make sure the elastics are near the packing blocks and therefore not pulling the reference crooked.

If you have not done so already, get four 6mm socket screws and nuts - you don't need washers here - and fix the boom tube between its pair of carbon-fibre clamps. As you tighten the screws, ensure that the distance between the ends of the studs is the same on both sides. Then place the assembly on the horizontal front face of the chassis.

You can now measure the distance from the reference at the top and bottom of the boom (left). Use the same technique as before, small squares of tape on the back of the brackets, to align the boom tube straight. When you have done this, you can bond the brackets to the chassis in the same way as before.

 


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