Incorrect spelling may be hindering the search for secondhand parts. Not all sites use fuzzy logic in their searches.
@maxiboy Look what I found, at least the driver's seat has the bit you want. https://www.ebay.co.uk/i/254709284992?chn=ps
Make a cast of the original splined section in something like plaster or even wax or plasticine. Line a section of aluminium tube with JB weld or similar, use the cast former to make the male splines. Given the requirements from the original post, that's how I'd do it. If it needs welding, make the weld first. If the OEM part is plastic, JB weld or any resin/epoxy will be strong enough. Super easy to do too.
I would copy the external spline in steel, make a new adjuster knob from Delrin and wobble-broach the spline into the hole.
yes they are but they wont sell the knob without the seats the cheapest on ebay currently is 350 and 60 quid postage the ones you linked arent correct only car i can find with them fitted is the gta of which onkly 245 currently exist breakers want btween 350 and 700 for a seat with knob depending on condition.. going to try plastic printing a few and see if i can get the dimensions right
tried searching part numbers correct spellings and incorrect spellimgs just in case.. down a part search on part finder and visited local scrap yards.. its a pretty rare item see above
If you’re going Delrin, you could melt the existing/copy spline into a suitably sized tube of it. The OP wants aluminium so they can use a pre made knob. I ran into that technique making large internal threads In Delrin. Doesn’t need to be red hot, with a large enough heated part, 200C would do it.
I'd just get a smooth bore knob that fits, or bore it out, & shove a grub screw or two through the side to lock it in place.
I think that you're all over-complicating it. A piece of ally tube and a small round file with a bit of patience would be all that's needed.
