Sunday, 22 June 2008

New front anti-roll bar

I bought an uprated ARB for ‘t Kreng earlier this year but didn’t find time to fit it. This was mainly due to the fact that the DHC was used for Le Carrera and as such, that car was at home and ‘t Kreng was temporarily put in storage so I didn’t have the opportunity to work on the car.
Last Friday I brought ‘t Kreng back home to get her ready for next month’s MOT. Before starting on its service I had a go at installing the uprated ARB. But before removing the original ARB I first took some measurements, to help me with adjusting the suspension afterwards (the anti- roll bar also acts as tie rods and thus influences the castor angle of the uprights).

The new ARB is (again) from Down Under (Selbys/Whiteline # WHIBLF91). With a diameter of 24 mm, compared to 19 mm for the original one, it's quite a lot thicker and stiffer (actual roll stiffness increased by 155 %). Luckily it came with new polyurethane bushes to go inside the mounting saddles. The original clamps had to be widened a bit as did the dished washers that hold the end bushes.

Putting the new ARB under the car turned out to be rather straight forward. I used two trolley jacks for this, one under each strut so the car's weight is supported completely on the struts, thus maximizing the distance between the mounting holes for the ARB. As a result the ARB slipped easily into the holes of the track control arms.
Actually it went in so easily that I should have been warned at this stage! Even mounting the ARB to the front sub frame turned out to be pretty straightforward, also thanks to a ratchet strap and a spray-paint can.

The problems started when I checked the castor measurements. With the original ARB the measurements I took were 288mm on both sides. But I couldn’t get it under 310 mm, as a result of which the wheels were sitting far too much to the front of the wheel arches.
After some measurement comparisons between the old and the new ARB I found out that the “track-rod ends” on the new one were approximately 10mm shorter then on the original ARB.
So off with the ARB this morning to put some spacers between ARB and TCA. This brought the “measurement” down to 295mm, being 7mm more than the original set up. As a result the castor angle has gone up slightly to approximately 3,5°, still well within the given tolerances.

Only have to see how the car is handling now. In theory a heavier front ARB lessens oversteer, due to the fact that a front ARB increases rear end grip. Hope to get some time this week to see how she behaves now.

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