ok.. its MOT / NCT test time again and you guessed it! failed.

60% imbalance on rear suspension...
how is that possible on an air suspension?
I thought that type of failure was associated with gas shock and spring type suspension?

I certainly haven't noticed any unusual feeling driving on twisty roads or high speed corners. 60% imbalance is pretty high... would expect to notice that while driving.

anyone got any ideas... or had this fault before? Are there any settings that should be engaged before this type of test?

results of test are shown below.
Suspension
test Nearside Offside
Front Axle 40Mm 35Mm
Rear Axle 40Mm 103Mm

Last edited by MGO on Mon May 27 2013 7:42pm. Edited 1 time in total

Doesn't 60% imbalance usually refer to braking efficiency? One side at the rear is braking 60% less than the other. 2008 MY Java Black TDV8 HSE

In this case it is suspension response.
If it was a standard spring and strut setup id just do both shocks... but in this case im not sure. if the airbag was leaky. id expect to see some lean on one corner after a few hours off.

Exactly how is that 60% figure derived? Was it with engine running and suspension at normal height? Don't have any other ideas but am sure someone with more knowledge will be along soon  2008 MY Java Black TDV8 HSE

it is basically the suspension response at each corner to a excitation input from a test pad under the wheel.
Does the UK MOT check for performance of the suspension on each corner?

No, UK MOT doesn't test suspension like that. Like this site? Buy some RRSPORT goodies to show your support!

its probably the response rate of the Shock absorber itself.

I know mine havent failed, but it is a much bumpier ride than it used to be. I have a set of rears to go on, but not got round to a set of fronts yet.

You will be amazed at the difference a set of shocks makes.

Another friend of mine in Ireland had many suspension issues, one of his shocks was partially siezing.

Replaced for KoniFSD shocks and apparently much better than even the new OEM ones. Bodsys Brake Bible
Software Updates Contact me
RRS Timed Heat/Remote kits - Contact me
BAS Engine Re-maps/ EGR Blank EuIII and EuIV
Clock On The Dash/ SNOTM /3Flash / BT Update /Service Reset/Error Codes read\ Gearbox Reset
See it HERE

What does the car sit like is it level measure from the centre of the wheel hubs to the top of the wheel arch on each corner and post your results.

Flack

in the US at the moment but will measure when I get back.
FYI it doesn't settle overnight or sit lower on one corner. I've read all the suspension fault postings here and my RRS doesn't display any of those faults/symptoms.

Are sure it's not a 60% imbalance across the axel something like that I'm an mot tester and the brake test regulations in the uk anyway have recently changed could be due to your brakes on the back not pulling evenly as in one side may be getting a reading of say 500 and the other side reads 350 therefore would fail on an imbalance across an axel hopes this helps some.

left rear airbag replaced. retested... no imbalance.
very strange given that the car didn't sit down or settle as is expected if airbag is faulty.

I think I have the same fault with mine, how much did this repair set you back and was it a main dealer job ?

had to get done with main dealer as I was away and the wife wasn't going to do it! ha ha
parts were 450...fitting was 90 euro all plus VAT
its a simple enough job as long as you know which one is faulty.
if I was doing it myself at the time I would have replaced both.