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A Special Builder's Notes

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The Special Builder's Breakfast Club

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20 December 2020

Piece By Piece.

It was easy to forget that in dealing with a nearly 70 year-old chassis, there were bound to be inaccuracies that would need to be accommodated in the new subframe. Overall, the diagonals of the main chassis were within ⅛". However, I reported that a couple of the chassis lugs had to be replaced as they were completely oval and throwing everything out of kilter. After assembling and disassembling the subframe a zillion times, making small adjustments to the chassis as I went, it was time to start the assembly for real.

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There are 16 captive nuts on the subframe, fortunately all of them ¼ BSF so I needed only drill and tap one length of bar. With the spacers tacked in place - there was no requirement to weld them all round as with the bolt inserted, they weren't going to go anywhere. In any case, it was awkward enough trying to get the TIG torch in the confined space as it was.

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The doubler on the bottom tray was secured by an autogenous weld along the seam.

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The trickiest bit was tacking in place the spacers on the tower's outer plate. The plate and bolts had to be in situ before welding and getting the torch and filler rod in the space was only just possible - the worst being the two lower spacers when I had to lie on the floor to get at them. The auto-darkening helmet, seeing the fluorescent ceiling lights, would go black, effectively blinding me.

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With one tower completed, the second didn't get any easier. The larger of the two captive nut plates had to be cut off and repositioned as the spacer had somehow shifted. It transpired that another of the chassis lugs was not properly aligned. The simplest remedy was to lever it into place, being careful not to distort the end plate.

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I was going to slip along to Chumley and get him to turn down a piece of chrome-moly bar I had in store which I could then insert and pull the lug round into line. Too late! He'd broken up for the hols so I had to get the steady out and use the Myford. Taking a deeper cut with tipped tools seems to work better than a lighter touch.

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The lug needed only tweaking, but it still bent the end of the bar. I think that whatever had caused the two offside lugs to deform, the load had transferred to the nearside and levered this lug too.

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Offering up the steering rack revealed a mistake I'd made in the initial stages of drawing up the subframe - the look on its face says it all. I don't know why I didn't check at the time the alignment of the rack mounts. So, the lower captive nut plates had to come out again to be filled and redrilled and welded, this time with the rack in place.

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There's still a way to go and it hasn't exactly been a piece cake.

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Talking of which, a parcel arrived from Big Sister.

 

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