Haynes Roadster Mushroom Adaptors

I’m using Ford Sierra 4×4 front uprights. But here lies a problem……

The standard Haynes Roadster / Locost and indeed many other kit cars use Ford Sierra 2wd uprights (I’m 4×4). The upright is normally fitted to the bottom of the suspension strut but in order to change it’s usage to double A arm type suspension, the common practise is to use a  mushroom adaptor. Some of these adaptors have the hole for the ball joint in the centre and some have them off-centre. The reason for a off-centre hole is to allow adjustment of camber and caster. The adaptor is rotated within the upright and the length of the top arm is adjusted accordingly. Some of the adaptors have the hole for the ball-joint at an angle, to help keep the ball joint running closer to it’s central position.

Ford Sierra Upright Adapter

These are commonly available at reasonable prices from many suppliers. I bought some thinking they would be perfect for my needs, however when they arrived they were far too small.

The standard 2wd Ford Sierra strut has a diameter of 45.25mm, however my 4×4 Ford Sierra uprights were designed to fit 50.25mm struts. Hence why my shop bought 2wd ones, simply dropped through the 4×4 upright. My suspension design dictated I use adaptors with off centre holes. With my limited machinery, I would either have to use a local machine shop to make some ‘specials’, or I could adapt the ones I had bought. I had imported a special / expensive custom made reamer for the job, but I decided to take the ‘cheat’ option. I sleeved the ones I had, then TIG welded my sleeves to the shop bought adaptors. When I had the special ‘1.5 inches per foot’ (7.15°) reamer made, I found that the English specialists were twice the price of the US ones. Even with import duties it works out £80 cheaper. I could find endless metric ones off the shelf, but imperial ones were thin on the ground. Maybe if I was in the trade I’d know someone, but I’m not. Some forum sites say you can use hand reamers but these sites should ignored, as I bought several recommended reamers, measured them and found they were in fact all 7°.

Making the Sierra Upright Mushroom Adapters

I made some top hat or mushroom shaped sleeves for the adaptors to sit in. These, with the aid of a suitably large mallet, were slid over the shop bought adaptors.

The brother in law Mark then stepped in with his TIG welding skills to weld the two parts together.

Mark TIG welding

Now, the clever ones of you out there will spot that these adaptors make the ball joint sit 1.5mm higher than the shop bought ones. To compensate for this, I’m using Austin Ambassador ball joints and not Austin Maxi. I much prefer the neat look of these -plus they are shorter.

Austin Ambassador ball joints

Once all of this was done, it would have been almost as quick to have made my own from scratch and if I was asked, this is what I would recommend, but this is another job ticked off my still growing ‘job list’.