I bought a couple of replacement rear threaded shackle plates. Unfortunately Britpart was all I could find.

I am not happy with the quality of these. The threads in both holes are not parallel with the surface of the plate. In fact they are off by a substantial amount.

Does anyone know anything about the material these are made from?

Britpart can make them, and a supplier can then sell them for £1.29 a piece. From this, I would think that the material is probably standard mild steel.

If so, I have access to some strips of 10 and 12mm thick flat bar and a set of 9/16" UNF taps. I had considered making them originally, but I didn't think it was worth the effort if I could buy them for £1.29 each.

I wouldn't bother shaping them into the figure-of-8 shape, It would just be a strip of flat bar with two holes in it.

Thanks for any info.

Try using an automatic centre pop on your originals then the same again on the Britpart crap if both mild steel will get same size pop mark.

The ductile strength of mild steel should be OK. If I make things like motorcycle wheel spindles or girder fork pivots I use EN16T this is a nice tough general purpose steel. Not easy to obtain in flat sections though. Being a tight arse I have just made a 9/16 20tpi tap to clear a damaged thread! Happy daze.

When I had my Series I made mine from 1/2" x 3" bright strip, drilled and tapped using a small pillar drill to keep everything square.

Thanks for the replies.

Oldseadog said:

drilled and tapped using a small pillar drill to keep everything square.

Click to expand...

This is exactly how I would do it. I would also tack weld the two pieces of flat strip together in a stack, along with a drilled, un-threaded plate on top. I would first use a 14mm drill to spot onto the plates to centre the drill, then drill and tap for 9/16" UNF. All of this can be done in one go while clamped into a drill vice. Once the plates are drilled and tapped, simply grind away the tack welds to separate them.

4140 carbon steel would be a good choice

Having just done mine, genuine LR ones are not much better than you describe. Quite a rough bit of steel, but the threads did appear to be straight. It's probably a mild steel punching.
Got mine from Dunsfold, about £8 each I think.