Although I haven't driven the car on track with the new front arb I don't have the feeling it will make the handling exactly how I would like it. In the movie where the Opel Speedster is behind me it's easy to see that the cossie is rolling quite a lot in corners. The 29 mm front arb is about 15% stiffer than the 28 mm so it should help a bit countering the roll. And with the stiffer front arb I can also run a stiffer rear arb while keeping the balance of the car the same, so that should help a little more.


But the rolling in itself is not that bad, once settled in the corner the grip is quite good. But when turning into corners the car really needs some time to settle. The car also feels a bit like it's not rolling horizontally, but more like the front dives a bit and the car is leaning a lot on the outside front tyre. i think you can also see it a bit on a screenshot from the movie.





With the lower ride height the front roll center is also lowered and I have the feeling that is at least partly the cause of the leaning on the outside front tyre. The lower roll centre will also cause more body roll and a less direct steering feel.


So it would be nice to get the roll centre back to where it originally was. One of the things I had been thinking of for a while was extending the pins on the TCA ball joints. So I've cut a TCA from a standard Sierra open to see how the ball joint is made and whether something can be done with that. On the bottom of the TCA there is some kind of 'lid' that is pressed closed. I've ground the edge off so I could see what's fitted inside. The steel pin has a metal ball at the bottom that is turning inside plastic bush using lots of grease.





While searching on the internet I found someone you replaces the standard ball joints in Escort mk1/mk2 arms with spherical bearings to make them last longer and also to be able to replace them, as I believe it is difficult to find Escort mk1/mk2 arms with good ball joints. The spherical bearings he uses are from SKF and have a 35 mm outer diameter. The outer diameter of the arm I ground open is just a bit more than 40 mm. So with a 35 mm bearing inside the wall thickness would only be about 2.5 mm, which I find a little small for such a thing.


Since the Cosworth arms are a bit different than standard Sierra arms I checked the diameter of the ball joint area on the Cosworth arms and those are 46 mm. With 46 mm there is a wall thickness of 5.5 mm left when the 35 mm bearing is fitted, so that should be fine. But I didn't have a set of worn Cosworth arms to use and I find it a shame to use orignal arms that are still good. After some checks I found that the arms from a Granada mk3 (Scorpio in Holland) also have the larger diameter of 46 mm.


I have cut a set of aftermarket Granada arms open. The ball joint and plastic bush in these arms was even smaller than the one in the 40 mm Sierra arm. That will explain why the ball joints on some aftermarket arms wear out much quicker than on OEM arms. But for what I have mind this doesn't matter anyway, there's just a little bit more meat to mill out.