Castor Correction – by Bushes, Plates, Drop Boxes or replacement Drop Arms – for lifts over 50mm (2″).
For lifts below 50mm (2″) it is advisable but not mandatory. Generally 4WD vehicles will have less Castor Angle than the equivalent year 2WD, and most 4WD’s will benefit with extra Castor above standard.
There are various arguments for and against the differing ways of achieving improved Castor Angles. Briefly:
- If the radius arm bushes are already tired (commonly the case), then replacing them with 2.5 to 3degree Off-set Bushes, makes perfect sense (assuming you have to do the bushes anyway), but you require access to a press – to remove and fit the new bushes, and if you need a greater increase of Castor Angle than 3degrees, (for lifts above 3″), then you may have to replace both the Bushes and fit Castor Plates. Sold as a Kit
- The Castor Plates are easier for a DIY at home, as you dont have to remove the arms and press the bushes out or in. And the result is approx 5 degrees more Castor (compared to 3degrees with the bushes). Sold as a Kit
- (For Patrol ONLY) – Drop Boxes achieve the goal of greater castor but also have the advantage of putting the radius arms back to a more ‘normal’ geometry – ie horizontaly pushing forward, rather than ‘angling down’. This improves stability. When the arms are at a steep angle it can feel a bit like you are driving on ‘stilts’.
Also the rear T bushes on the arms allow articulation by compression of the bush, if it is already under compression due to the ‘steep’ angle, there will be reduced movement of the arms – particularly hanging down. Sold as a Kit
- Others do not like the Drop Boxes – because they hang down a bit and if you are sliding over rock ledges etc then this is a definite ‘hook-up’ point. They prefer the new longer Radius Arms which result in an equivalent amount of Castor with good geometry. Sold as a Pair (bushes extra)
So it depends on your budget and your use of the vehicle as to the best option to achieve greater Castor Angle.