450-h shock knocking rear

[hondansxr]

hi 2008 450 h i put it in sport mode suspension , and it was banging on the rear o/s  are these standard shocks or different due to the sport mode or would i be better off putting a set of adjustable coilovers on 🙂. cheers p

[Farqui]

Mine has sport mode and the top of each shock has an electric motor that adjusts the damping. This motor twists on, so might yours be loose? Or not seated properly?

You'll need to unclip the boot lining to get to the rears, a 2 minute job.

The sport adjustable dampers are more expensive, circa £240 each.

[OldTrout]

Paul,

Your post reads as if there is no banging in normal mode. Is this the case?

As Lee says, in sport mode a motor twists a shaft which runs down the middle of the main damper shaft. This shaft alters the damping. In sport mode the damping is heavier.

John

[hondansxr]

i thinkit accentuates it in sport mode .

[hondansxr]

yes banging is in normal or sport  mode

[Farqui]

Are you certain that the cause is the damper?

Have you checked the damper is solidly mounted top and bottom? It could just be a worn bush.

Are the rear anti roll bar bushes and drop links all okay?

The multi-link rear suspension has many parts that could cause knocking.

[hondansxr]

hi yes i had it on a ramp thursday the bushes have no play in them .i would call it a BANGING as opposed to knocking

the odd thing is you cannot move the back end when you press down on the rear quarter it SOLID , is that correct. cheers

[Farqui]

Good, eliminating worn bushes is good.

Sport mode will firm up the rear but i haven't tried bouncing it so can't say how firm is firm.

Does it bounce more when the dampers are set to normal?

Is the rear ride height similar to the front?

[hondansxr]

only tried bouncing on norm , it solid .

looks slightly down on the rear right , had a new one n/s fitted by lexus  in june (by prev owner)

[Farqui]

Ah okay, so maybe the other side needs replacing now?

Would be good to hear from someone who's had a damper fail properly (not just a dealer saying its leaking). They might be able to say if the dampers lock up?

Were the dampers dry or oily?

[hondansxr]

hi yes the one banging is dry !

if it has locked up can it be unlocked !

[Farqui]

Is the electronic adjuster seated properly?

Maybe twist is off and have someone switch to/from Sport mode. The motor should rotate each time. Remember to reseat the adjuster in the same setting from which it was removed? I vaguely recall that it's supposed to be in Normal mode to remove.

[Farqui]

Maybe compare the position of the adjuster with the other/quiet side?

You could adjust the damper manually if you can get something down inside to rotate the mechanism yourself.

[Britprius]

It is quite possible to get a knocking or banging noise from the shock it's self.

In the bottom of the shock tube is a free floating piston with nitrogen under pressure at about 500 psi beneath it pushing it upwards. Above it is a second piston attached to the top rod. The piston has adjustable restriction valves in it to allow oil to pass through under control. This piston is in the oil above the floating piston putting the oil under pressure, and moves up, and down as the suspension moves.The oil is under pressure to stop bubbles forming affecting the oil flow through the piston valves and to allow for the different volume in the rod piston chamber as the rod move in and out of it.

Normally the rod piston works in an area well above the floating piston being held down by the oil above it. Over time oil is lost through the top seal, and this space is taken up by the floating piston rising keeping the oil under pressure. When enough oil has escaped the floating piston rises to the point where when the suspension is under compression after hitting a bump the piston connected to the rod can move down and hit the floating piston giving rise to the knock or bang.

John.

[hondansxr]

HI MANY thanks for the input , i bit the bullet and ordered a new shock, when the guys took the adjuster off the top it was leaking from the top .. 

it now drives superb ... would still like the car a little lower so if another one goes ill be going that route .. 

on a foot note WOW I LOVE THIS CAR  ........talk about wolf in sheeps , more like a t rex in a baby chick lol 

 the wife get 33.9 mpg when she uses it and i get a HOOT  when i drive it ... best of both as they say .

[KayCee]

well done Paul glad you have sorted it

[Britprius]

Happy you got it sorted. The seal on the adjuster shaft leaking does only show under the actuator motor covers so is difficult to see until these are removed. This area is not as prone to leakage as the main rod seal as it is in a relatively clean environment.

I get over 40 mpg in my 2007 GS450H on country roads with no dual carriageways or motorways, and I do not drive for economy. I think on a motorway I would be getting close to 50 mpg.

John. 

[hondansxr]

hi britprius   my wife uses it mainly and get 34.8 mpg  dont think she has mastered the off throttle bit yet .. ... 50 thats brill .