Just replaced the rear tyres on my 2.9 TSI 4x4 which included the 4 wheel laser alignment check. As some forum members will know back in March this year I posted about the serious suspension misalignment cuased by a member of the motor trade driving my Karoq over a series of 30 mph limit speed bumps in excess of 40 mph. SO I was keen to check that my tracking and camber alignment were still correctly adjusted. Camber was within tolerance on all wheels, just the left rear tracking was right on the limit so I had that adjusted to be mid-way.

What I was puzzled by was the front caster, which is non adjustable. When I had new front tyres in Feb 26 caster was OK, when the suspension was re-aligned after the speed bump incident in March the caster was OK. Now 10 weeks and 2,000 miles later the caster on both front wheels is no longer within tolerance.

Overall mileage is only 15,000 which I feel is too low for the incorrect caster angles to be due to suspension component wear, and I have been very careful on speed bumps. On my previous car, VW Touran, which has a similar front suspension set up to the Karoq the front castor angle did change over time, but it was gradual over the 50k to 100k period, which was to be expected.

My concern is that the sudden change in caster angles might have been caused by the speed bump incident damaging s suspension bush, but its taken a while for it to become apparent.

I guess you are right.

As you say, caster is non-adjustable on the MQB platform. The angle of the MacPherson struts is primarily determined by the fixed geometry of the subframe, lower control arms, and top strut mounts. So something is either bent or worn. But since you know it was in spec after the car was abused and repaired and now it isn't, that suggests wear now occurring rapidly as a result of the earlier damage.

Someone who knows more than I do says it could be various things: lower control arm bushes, with the rear bush (the large one closer to the subframe) most susceptible to wear; the top mounts, which include a bearing that can start to disintegrate; and also ball joints, drop links, and subframe bushes. However, you already had the subframe dropped and re-fitted. I'm not sure which of the other items is most likely to mess up caster angle, but it does seem that a full suspension check is again needed. Many of these items, when worn, produce clunks, rattles, or creaks, which is a clear sign of a problem.

@mumpsim thanks for the comment. I’m going to speak to the dealer. I did wonder if it could be due to different equipment. KwikFit have the same laser alignment system as the dealer, plus first alignment was KwikFit and it agreed give or take a few minutes with dealer on caster.