I have not given up, dont worry, I have just been very busy and not been able to spend much time on the Arachnid, but hopefully I am over the worst, and normal service will resume! Another area that came out of the Brands test was that the car was physically quite hard to steer! It quickly became obvious when we looked at it that the original suspension had a scrub radius of over 5 inchs!!!! So we spent a bit of time redesigning the suspension to sort it all out. We put the figures into our software and have come up with a new arrangement that reduces the scrub radius to effectively nothing. It also allows for longer wishbones, which maintains camber in roll a little better and we have tweaked the roll centres etc etc.
This has meant that we have had to do some welding, with the obvious issues with painting etc, and cutting of the ally panels. However, I have a plan for the winter to go over all the car and reduce weight, I just want to prove these parts before drawing them up in CAD and get them machined in ally, such as the new rockers.. Below you can see the new upper pickup points and the axis for the rocker.
Here you can see the paper mock up of the rocker. We dew all the suspension from paper to check clearances before committing to steel for these prototype bits.
This modification does require a modification to the front hubs. To move the pick up point it was easier to machine the upright flat and bolt on this new art, which also includes a bracket to mount the steering to, to put it into double sheer.
Here you can see the original upright after machined.
And here it is all built up. It looks a little messy but again, once it all work I will draw up a much stiffer upright and get it machined.
Below is the jig for the upper wishbones. They are identical left and right, which means only one spare. This one is only migged up, for speed, but is more than strong enough!
Here is the upper wishbone with the rosejoints screwed in.
Unfortunately it does mean new offsets for the front wheels. Below is the original offset, the inner and outer rims are almost the same width.
Here are the new rims. The outer rim is the smallest that BBS makes, at half an inch.
The new suspension has been designed around using rockers and pushrods. This keeps the dampers out of the airflow and also allows for simpler rideheight adjustment, as well as allowing for different damper movement ratios via different rocker pickups. I decided to make the rocker have a proper bearing, unlike some I have seen without! The shaft on the right goes through the two bearings in the rocker and is slightly, 1mm, longer which means I can clamp it up hard and the bearings will still rotate nicely.
I then set about making the sideplates for the rocker. These are designed to give the damper 1:1 movement to wheel movement. At the moment they are made from 2mm thick steel plate, but hopefully not for too long!
This is the final shape, a little more aesthetically pleasing.
I then bolted them together with some spacers ready to tack in the bearing housing.
Here you can see the rocker in situ with the lower wishbone. I have not yet assembled the rockers up with the bearings though, as they are only tacked together and the final welding would most likely destroy the bearings. Once the dampers return, which should be Monday, I can check it all does what the computer says it will before welding it all together.
Here are the new steering arm and push rod. The steering arm is actually the longer one and this time I remembered to machine on some flats!!!
Here are the wishbones and hub all assembled
Another shot here. you can see that the upright is now all well within the wheel
Tags: Suspension
