Saturday, 22 November 2014

Anti-roll bars ARB

I have been trying to improve my track times in the Sylva J15. My impression is there is some over steer going into a corner that is not to my liking. One of the ways of controlling this is to fit front and rear ARB's and play about with them on a track. I have times on a dry day recorded on my RaceChrono app in my smart phone. All I need now is to try out these ARB's and plot the difference.


Unfortunately Sylva Autokits don't do an ARB for the J15, however Playskool do one for the Westfield that is a very useful starting point for the design. I copied the design of  the two alloy pivots from the Playskool parts on my Westfield modified of course to suit the Sylva. The drop links are standard 100mm x M8 parts from McGill Motorsport. The chassis attachment point braketry was a custom fabrication. It is bolted to the rear chassis rail and the (old) Roll bar attachment points near the top of the coil springs. I wanted something that was simple to adjust when finished as I don't know how much compensation to set the bars up for. The roll bar is fabricated out of seamless spring steel 3mm wall thickness 19,mm tube obtained from Blakes Metal Store and bent using a hydraulic former with a 1040mm curved right angle at both ends..

Adjustment points

Drop link ball joint to wishbone

Offside arrangement

Nearside arangement

ARB Bearing arrangement

Detail of drop link
Rear fully assembled


The front design is technically simpler than the rear (no custom extended mounts) but there is a lot of stuff to come off the car  including draining the radiator and removing the front clamshell. In my case the brackets mounting the radiator had to be remodelled to allow the ARB bar to pass between the upper chassis rail and the cooling fan. Also the alloy plate around the pivot point site had to be relieved using a dremmel and a chassis weld flattened. I used captive threaded studs welded from the rear to secure the pivot points, however bolts and spacers passing thu the chassis would have worked assuming they are long enough. The ARB bar shape has to take into account the relatively large steering angle change from lock to lock. The initial bend of the ARB was contacting the wheel on full lock so adjustment to the initial simple design was made. The bar is made of spring steel and ideally needs a hydraulic bender to implement.

General layout

Trial fitting the front
Radiator back in
I plan to base the initial settings based on an article and spreadsheet by "Keen tnkerer" on the WSCC site. I will be in contact with him shortly.


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