Hi everyone , having had 3 RR Sports to date (all with the suspension KNOCK) issue !!

I now need another RR Spt , and am concerned about buying due to this KNOCK from the suspension , i was told that if i bought a PRE 06 car , then they do not come ARM thus should have NO issues....

Is that true ?? Please advise

ARC or Dynamic response was fitted from Job1 RRS on V8SC and optional fit on V6D if the sport pack was fitted. It was also fitted standard on V8D when that came in more recently.

So if you dont want Dynamic response then pick a old V6D without the sport pack. - This does'nt mean it won't knock though it just might be quiet enough for you to not notice. There is much poor information around concerning the knock issue on RRS, the biggest mis-understanding is that it is caused by the DR system. There are two distinct and completely unrelated types of knock. If it is the knock when you turn the wheel side to side then it is inherent in the design, if its when you go over drain covers and broken road surfaces then there are now some good fixes available (mass dampers & new ball joints). Which knock did your last ones have? - Personally i'd put up with the inherent knocking to get the massive handling benefit of DR but everyone to their own (mine doesnt knock anymore after being recently fixed)!

For the knock when driving in a straight line - Vehicles without DR tend to knock at a much lower level because the noise transmission paths are different. Disco, X5, Cayenne and Q7 also knock but at a much lower level becasue they are better at isolating suspension impulses (they are less stiff).


In case your intersted, heres some background on the inherent knock i've posted before :

The knock which is inherent in the system is the one where you turn the wheel left to right quickly, sometimes referred to as a "water hammer" sound. This is caused by the hydraulic directional valves openning with high pressure one side of it and lower pressure the other. Basicially these two different pressure heads slap against each other as their trying to make their mind up which direction to flow, this is why its inherent in the design, the architecture of system means these pressure heads cannot be equalised before the valve is openned.

Right then, because this is a laws of nature thing the knock happens on all vehicles whether they are new, old or inbetween. the reason why on some vehicles it is loud and sometimes it can not be heard or from new its good and then gets worse with age is all to do with noise transmission.

Every vehicle that comes out the factory has different noise transmission paths for all noise generators due to tolerances and environmental effects. Take the RRS body - it sits on elastomeric mounts, the position of which will be different car to car due to dimensional tolerancing. The mounting position affects the "pre-load" on the mounts which effects the mount stiffness, this will effect the noise transmission path. Elastomeric components change stiffness with age also which again changes the noise transmission over time, temperature also changes the noise transmission - generally cold market cars suffer badly from noises. And really confusingly - the noise transmission path can change direction completely if a certain element changes stiffness for any of the above reasons.

In terms of this particular knock, the problem with isolating it from the driver is that the DR system is connected by stiff elements to multiple points on the chassis frame due to the pipework, this means that when the valve block creates the knock the noise is transmitted at high energy levels all over the chassis frame making it incredibly difficult to absorb.

The "other knock" is also noise transmission related deduced from the fact that LR are fitting a mass to the body mount area which will make the mounting on the chassis resonate at a different frequency. Trust me, i'm an Engineer!

Many thanks for the detailed reply , my other RR Sports the knock was to be fair between 5 - 30 mph and going over uneven road surfaces.

Just purchased a 08 TDV6 S , and not sure if it has ARC or Dynamic response , being an S model may be it does not have these extra bits as standard ?

Any info welcome

If it has 20" wheels then check and see if it has the extra hydraulic oil tank under the bonnet that the ARM needs, if it has that then somebody paid for the Sport pack (I could think of better extras to put on an S!). According to my 2006MY brochure it should also have Brembo front brake calipers and Bixenons if it has the DP or Sport pack. As you say you don't have the Bi-Xenons then it is highly unlikely you have the fancy systems! 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW

Car came with the standard 18inch alloys , and has no xenons , so i guess no sport pack and no ARM system so may be no knocking from the suspension ?

 2020 Pangea Green 1st Edition D240 New Defender 110 is here and loving it
2018 Melting Silver Mini Countryman PHEV - soon to be replaced
2015MY Corris Grey SDv6 HSE Dynamic, the best car I have ever owned, totally reliable only a cou0le of rattles in 3 years, now no longer in my care
Also in my garage is a 1996 TDi300 Defender 90 County HT made into a fake CSW