Custom Ford Sierra Front Uprights

I had to enrol the skills of the ‘brother in law’ to TIG weld the new Ford Sierra based front uprights.

He’s done a cracking job 🙂

The upright has the same bolt spacing for the Mercedes S320 Brembo calipers as the removable steering arm assembly. Therefore uprights can be swapped from one side of the car to the other.


There have been a couple modifications to the design since I did the CAD. The dimensions are the same but once I built the assembly jig, I realised; that once the assembled upright was welded; I wouldn’t be able to get it from the jig.

I built the assembly jig around a standard Ford Sierra front upright (4×4 Cosworth) with mushroom adapters attached. A 4×4 upright uses a fatter strut and is therefore a different casting but all the dimensions are the same as it’s 2wd cousin.

As you can see from the pictures, there is still quite a bit of 3mm & 8mm steel plate boxing to add. In fact, each upright will get 2 pieces of 8mm boxing and 6 pieces of 3mm boxing. I’m not going to make CAD drawings, simply old fashioned paper templates. 2D drawings are somewhat tricky when making curved plates out of thick steel. Without this boxing; although they seem very solid; under heavy corning forces they will flex. The boxing will also make them look aesthetically a little more complete and less ‘hand fabricated’.

Once finished they should be visually ‘similar’ to a standard cast Ford Sierra front upright.

haynes-roadster-mushroom-adaptertapered-reamerI used a tapered reamer (1.5″/per foot) imported from America. I had trouble finding the correct one in the UK.

The top and bottom ball joint mounts were fabricated on the lathe from EN3B steel. The choice of steel was simple – I had some spare.


When I was planning on using the cast Sierra upright, there was a clearance problem between the front drive-shaft and the nut on the Austin Princess / Maxi ball joints.


However, with the new custom reamed top and bottom joints, I was able to recess the nuts. I now have a whopping 8mm of clearance.

Each upright has probably another good weekends worth of work in it before completion. I also need to machine new 5×112 bolt holes into the Mondeo ST220 discs, before I can actually bolt anything up.

The heat from the TIG welding may have distorted the round central section. If it has, the bearings may not press in. Signs are currently very good, with no obvious twisting, but tolerances are ‘in theory’ rather tight. Having said that, I have 8 Sierra uprights with nearly 0.3mm between the smallest and biggest.
fingers crossed

See also:

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