Having experienced an A-frame failure, thankfully at low speed, it’s important to take care during the A-frame fitting.

A-frame snapped from poor install

It’s a bit difficult to see from the only image I have, but there were insufficient washers installed and the A-frame snapped, because it was being pulled apart by the bolts. I suppose it could have been just one of those things when you own an ex-race car.

The A-frame fixings are a mixture of metric and imperial bolts. The bolts attaching the A-frame the chassis are metric and the bolt that attaches the A-frame to the De Dion is imperial.

Be careful when installing the A-frame (and the rear anti-roll bar) with the wiring in this area, you don’t want to squeeze or pinch them during the install.

I start by holding the A-frame on the chassis by just passing the metric bolt through the chassis and A-frame.

Get the A frame the right way up

It’s really important to get the A-frame the right way up. The pivot points should be above the frame. At this stage I don’t fit any washers or nuts to these metric bolts; they are just there to hold the A-frame in place.

Now I fitted the imperial bolt into the A-frame / De Dion tube. As usual, I applied a little copper grease. This bolt can take a bit of alignment, but I didn’t need the pin punches. Don’t forget the nylon washers. Once the bolt was started I did have to wind the bolt through the hole, until there was enough thread clear to get the nut installed. For this job you will need a thin-walled 3/4” deep socket to get to the nyloc nut. If the socket-wall is too thick it gets caught on the A-frame.

The new manual only states fit washers where required. The old manual advises ”normal” is three washers are fitted one side, and four on the other, which is the same as my 360R. I measured the gaps and found I could fit six washers easily and seven with a push, so that’s what I went with.

As usual, one side was a little more tricky to get aligned than the other, so that’s the side I started with. Aligning these washers needed my selection of pin punches, and even a tap (and I mean a tap) with the dead-blow hammer on the bolt for that final push.

With four washers on the left-hand-side and three on the right, the set square showed exactly the same measurements each side. You should be able to get it within 1mm difference between the chassis tube and the De Dion tube ear mount.

With the A-frame installed I could now raise the car on the De Dion tube, so the rear suspension could take the weight of the chassis. As this stage I was able to torque all the rear suspension components installed so far.

Tools used

  • Dead-blow hammer
  • 19mm Semi Deep 3/8” drive socket
  • 19mm 3/8” drive socket
  • 3/4” Deep 3/8” drive socket (thin walled)
  • 3/4” 3/8” drive socket (thin walled)
  • 3/8” drive ratchet x 2
  • 3/8” drive extension
  • Selection of pin punches
  • Set square