Monday, September 13, 2010

Frame head

The frame head is the primary location for most of the front suspension/steering mounting points and, if this assembly is rotten then the car's handling will be unpredictable and dangerous. The base tends to suffer from rot long before the top section. Because the cost of a replacement frame head assembly is almost as much as that of a new chassis assembly complete with
framehead, repair is an attractive alternative. This is far from an easy task and would normally only be undertaken during a full body-off restoration. Access to a spot welder is almost vital.
Strip the car to a bare chassis, then clean off the top of the frame head to check that it is passable before turning the chassis upside down. It is as well to pull the fuel pipe out of the spine before you begin cutting steel.
Clean off the lips of the two halves so that you can see the spot welds, centre punch then drill these out, taking care not to drill through the lip of the top pressing. Split the join as you progress. Cut across both sides of the track control arm pressing, drill out the spot welds holding this to the frame head lower pressing, grind away any MiG or gas weld you find and finally prise off the pressing.
The repair panel should have captive nuts for the anti-roll bar fixings, intended to replace the two internally threaded rods per side of the upper frame head pressing. If possible, clean, re-tap and use the original fixings, and grind off the captive nuts on the repair panel. The original fixings spread the loadings from the anti-roll bar between both pressings of the frame head, whereas the captive nuts on the repair panel place all of the strain on the repair panel itself if they have to be used.
Clean up the inside of the top frame head pressing and apply a good rust-proofing primer, then offer the lower pressing into position and bolt it down as shown in the photographs. It would be possible to plug or seam weld the two panels together, but strength here is so vital that the author would urge the use of a spot welder, even if it has to be hired for the day.

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