| The front end consists of two unequal A arms.
Mine are slightly longer that the standard book size, by approximately
40mm longer. I decided to make a jig that was adjustable in length.
Fully closed the jig will make standard book length arms, whilst when
extended it can make arms up to 700mm long if anyone wanted a clubbie about
2m wide. |
| Lower Arm Here is the jig with a test piece of 25mm by 2
wall CDS tubing in place. Note the pivot tubes in position at the
right hand side of the jig and the bent tube in it's housing to the left.
The jig will also have a dowel to pin the upper steel plate into position.
The lower ball joint will be fixed to this plate as will the shockie bracket. |
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| Upper suspension Arm Ignore the upper part of the
photograph i.e. the top of the tube.
The lower part is in position. The threaded sleave is in position
placed in its housing as well. This offset of 20mm is to engineer 5 deg
of front caster into the geometry. |
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| My top arm pivots are Rose Joints. I'm showing the
threaded sleaves here that allow for the Rose Joints to be fitted.
They are welded around the tube and plug welded as well.
The caster can be increased by lengthening the front rose joint and
shortening the rear. Camber is adjusted via the outer ball joint itself. |
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| Jig closed in the book chassis width. The Jig is
adjustable in length. Here it will make 340mm length arms. From
the centre of the ball joint to the centre of the pivot tubes. |
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| Jig open to what ever length you want. |
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| Jig MK II You can see the Solid Steel Bar here that will
ensure the Pivot tubes are exactly in line. Also shown is the
Stainless Steel brackets to ensure that fix the above stated bar is held
firmly into the jig, and another set that will hold the lower A arm legs
equidistant from centre. |
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| Top arm Thread I ended up routing 2 slots in the jig
to accept this mandrel. It sits inside the thread sleave and aligns
the treaded bush with much greater accuracy than before. Also it
allows much easier access to weld the actual joint. |
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| The Ply Template Shown is the Ply template for the 3mm
steel plate. The bolt holes centres have 1mm holes with piano wire
coming out of the jig to line everything up (see above picture). Once
the plate is welded to the tube I will drill these out to size. The
square hole is used to position the shocker bracket to the steel plate.
The large diameter hole is for the ball joint. The round plug has a
1mm hole in the centre to align the 40mm large hole. |
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| Hydraulic Tubing was bent on a mandrel. I first rammed
a plug of paper into one end, filled with dry sand and capped the other end.
Very little shrinkage in OD is evident after bending. Cool. |
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| Using the Jig. |
| Lower Arms
Lower arm tube in jig.
3mm steel plate is positioned on
the 3 1mm pins you can see in the first photo. |
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| You can see the pins here. Then place the ply jig onto the
same pins. |
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| This allows the shocker bracket to be positioned and tacked
into place. The ply can be removed and the bracket fully welded. |
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| After making the first A arm I used
the tube itself to make this template. Don't completely trust it
you should always finally fit the suspension tubes to the pivot tubes. Cut
2mm ish away from the line.
Then File with a good Rat tail or round file. Test and
file......... Test and file....... Test and file...... :-)
Take your time, it needs to be right.
 
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| Hack saw the excess material.
Note the soft aluminium jaws in my vice so the material isn't damaged.
Second shot shows the Birds mouth. It need to be perfect, so take your
time.
 
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| A arms fitted to the pivot tubes.
Note also the steel bar in the pivot tubes.
This steel bar is fitted to both the pivot tubes, thus ensuring alignment.
The second shot shows the 5mm plate also bird mouthed to the A arm and
will be welded to the 3mm steel plate.
 
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| You can really see the 5mm plate here.
It is positioned between the ball joint and
shock absorber bracket. Second shot shows the 3mm steel plate in
position, bird
mouths on the pivot tubes and the steel alignment bar in-between the pivot
tubes.
 
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| All in place including Shock absorber
bracket. See the stainless clips at the pivot ends
to align the ends of the A arms. The tubes will be G clamped to the
jig to ensure there
is no movement.
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| Once it is all welded the holes are drilled out for the
lower ball joint bolts. |
Picture to come. |
| Upper Arms
Ends of the tubes are fitted with steel threaded plugs.
They are vee ground and have plug weld holes drilled.
Fitting the pivot tubes is a very time consuming activity.
It MUST be right. no gaps at all. Hand file is the Go.
Show is the upper arms with bird mouths hand filed. You can start
with a hacksaw and grinder however be very careful not to go within 1mm of
your wanted line. You should finish these off with a hand file. |
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| Jig Mark 2 I didn't like the possibility of inaccuracy in
the original jig. This one is adjustable lengthways via nuts on the
tie rod.
Obviously the ROD ends and Tie ROD ends would be replaced with bolts for
the purpose of welding the arm pieces together.
You can see I will have to remake the upper suspension arm tubes as these
ones unfortunately no longer fit. |
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| Here it is all finished. With bolts, all thread and
machined nuts all in place. New tubes were bent and it's off to the
welders. My engineer wants this professionally TIG welded. Fair
enough. It takes one hell of a lot of load. Getting closer to
one massive go cart now. I'll be able to to assemble all the
suspension when I get this back. Then I'll play with the steering
rack. No bump steer through the shocker movement is the aim. |
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| Mk 2 escort rack ready for a bit of tender loving care.
I have ordered extensions from "Formula Motor Sport" in Brisbane to fix bump steer issues. |
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| Mk 2 escort rod ends on special at super cheap for $20 for
2. Always keep and eye out for a special. |
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| This is the Lower Front Ball Joint I decided to use. I
liked the fact that the flange was substantial and it has 3 mounting holes.
It is also greaseable. Wow, don't see that often any more. It is a BJ
94. It's for a XA - XF Falcon. On the shelf for $19 each however it pays to
ask. I picked these two up for $30 for the pair.
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| It certainly has taken a while however here is the finished
product. Just have to paint it and machine up some bolt spacers for
the upper arms. Might even replace the screwdrivers for bolts to. |
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