Most of the time, my steering is fine at all speeds and all road geometry. Just occasionally, it will go through a phase of sudden over-steer at 15-20mph around a constant bend - roundabouts are the worst. Just cruising round the roundabout without moving the steering wheel, and suddenly, some additional steering kicks in and the wheel moves a bit. No problem at any other speed/condition. This occurs for a few days and then goes away for weeks. No problems currently (well not up till a week ago when the autobox went).

 

Wierd!!!! Any ideas?

i dont know what it is but my manual does that too. not very often but occasionally. i presumed it to be something to do with the hicas having a moment so i've ignored it. i always thought the hicas has a speed crossover point where it works at low speed but switches off after X-MPH. so then i thought i must be crossing that point, causing the hicas to work or stop working depending if im slowing down or speeding up.

the other thing i used to get (due to a dodgy de-limiter, now sorted by a JD'd ECU) was that at 100mph on the speedo, the clock would drop to 0 and the lighter steering and hicas would start working. NOT big, clever or funny at that speed. almost makes it pointless de-limiting because the car becomes so nervous you cant really use it past 100mph.

HTH but if anyone knows for sure what happens can you let me know, please.

thanks.

si.

Faulty HICAS perhaps?

just had another thought. what about the de-limiter thingy? would that slow the speed sensor signal by a tiny ammount therefore confusing the hicas?

i'd love to know why it does it.

si.

My Z is a non-turbo convertible. Not even sure that it's got HICAS!! All I do know is that when it misbehaves, it scares the c*^p out of the missus!!!

most likely one or both of the steering rack bushings have gone.

Nah - rack bushes cheched out OK

> Nah - rack bushes cheched out OK

 

out of interest , did you check them using the following procedure:

Put the car on a lift (4 posts, as it's important the car still sits on it's wheels)

And while having a helper turn the steering wheel from side to side, you check from under the car for any movement of the steeringrack. (there shouldn't be any)

If the rack moves, be it even very slightly: replace rack bushings.