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It's a big fan
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Discussion Starter · #1 ·
Found it at last – Front Suspension Rattle

Since the ZS was about 6 months old I’ve been getting the occasional knocking noise when accelerating off a roundabout, originally it only happened if the wheels went over a bump or lost traction on a metal grid but it has slowly become more frequent until I was hearing noises almost every time I drove it. I’ve looked for the cause many times, checked all the bolts, replaced the dampers by Bilstein ones, the damper mounting bushes with Superflex ones, the springs by XPower ones, the anti-roll bar bushes by Superflex ones, checked for the subframe too close to body issue but never found the cause :(


However over the weekend I replace the lower wishbone rear mounting bushes (the big one under the drivers feet) with Superflex versions and found an issue with the fit of the crush tubes over the end of the wishbone arm. The arm itself has a diameter of 28.02 mm, the original bush crush tubes have an inside diameter of 28.4 mm and the Superflex crush tubes an inside diameter of 27.96 mm. So the original bushes have nearly half a mm of rattle room while the Superflex ones wont fit :confused:


Putting the original bush back on without the nut and trying to rattle it by hand does produce a rattle that sounds very like the one I’ve been hearing but not as loud but of course one hand power is a lot less than that bush normally experiences , it takes nearly all the acceleration and braking forces between the front wheels and body – I guess the equivalent of maybe 200bhp on each bush during heavy braking, the rest of the front suspension takes the side forces but very little of the acceleration/braking force.


So I sanded out the inside of one of the Superflex crush tubes until it was a perfect fit (probably a lot better than if it had fitted in the first place) and went for a drive. There was still a very definite rattle on rough ground, but only from one side. I replaced the other side and all the rattles disappeared J It also feels rather nicer to drive, as though the engine is connected to the body a lot more firmly and the engine even sounds nicer although I can’t work out why that should be, maybe that is just the nice weather and having the windows down J


Normally a crush tube should be locked (crushed) into place by the nut but in this case I don’t think that single nut is able to overcome the amount of force passing through the bush.


So if anyone wants a reasonably cheap improvement to their ZS, a new set of lower wishbone rear mount bushes is definitely recommended.


A rough fitting guide as a warning:


1. Remove the bolt from the bottom of the anti roll bar drop link to free up the lower wishbone.


2. Remove the bolt attaching the damper fork to the lower wishbone to allow the wishbone to drop down a little extra and give enough room to get the bush off its end.


3. Remove the two small bolts holding the anti roll bar to body bush, one of the bolts goes into the rear bush mount preventing its removal.


4. Remove the nut from the end of the lower wishbone rear fork.


5. Remove the three large bolts holding the bush mount to the body (under the drivers right foot), you might need an impact wrench for these – the 3 M14 100Nm bolts give an idea of the forces this bush takes!


6. Slide the bush together with its mount off the lower wishbone.


7. Extract the bush from its mount. There is no metal shell on this one, I just used a long bolt, nut, some washers and a socket wrench to pull it out, plus you need something to form a gap to pull it into. Came out easy.


8. Pull the new bush into the mount, again I just used a nut, bolt and socket wrench – easy.

9. Slide the crush tube into the centre of the bush.

10. Reassemble everything using a torque wrench – you don’t want the wheel falling off. With a bit of luck your crush tube will fit on the end of the wishbone arm, if not it may take you some time to get it to fit, but at least you can get a tight, rattle free fit!
 

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YELLOW PERIL
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Re: Found it at last – Front Suspension Rattle

I'm getting a few knocks and rattles that wernt there when I bought it.

Just have to turn the radio up a bit, till its time to check the bushes.

Least have some idea what to look for now.

Ta.

:wave:
 

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It's a big fan
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Discussion Starter · #3 ·
Re: Found it at last – Front Suspension Rattle

I'm getting a few knocks and rattles that wernt there when I bought it.

Just have to turn the radio up a bit, till its time to check the bushes.

Least have some idea what to look for now.

Ta.

:wave:
The rubber bushes soften with use and the knocks slowly get worse. I wont guarantee that your knocks are from the same place but these bushes do seem one of the most likely causes and I reckon these particular ones are worth changing to polyurethane ones anyway for the improvement in ride quality. It's hard to tell if their causing knocks without actually replacing them though, my old ones look fine but the new ones are much better.

I'm tempted to have a go at the rear trailing arm bushes next which seem to be the ones that actualy fail first, don't think they are quite so easy to change though...
 

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YELLOW PERIL
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Re: Found it at last – Front Suspension Rattle

Are those the ones that rust in, heard horror stories about trying to get them out.
 

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Re: Found it at last – Front Suspension Rattle

It's true the trailing arm bushes can be a nightmare, I remember burning out the rubber part, and having to cut through the metal shell of the bush to remove them, the next time they went the local garage got the job.

I'm sure if you removed the arms and took them along with new bushes your local garage they would press out the old ones and fit the new for not much £, if you decide to poly them you'll need to salvage the metal shells off the old bushes as the poly ones don't come with the metal outer part.
 

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YELLOW PERIL
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2,407 Posts
Re: Found it at last – Front Suspension Rattle

Nearest I've got was the front suspension on my MGB GT's, had the use of a 30 ton press at work that made it a doodle.

Now no workshop, so your garage idea sounds good to me.

:wave:
 

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It's a big fan
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Discussion Starter · #7 ·
Re: Found it at last – Front Suspension Rattle

...if you decide to poly them you'll need to salvage the metal shells off the old bushes as the poly ones don't come with the metal outer part.
That was my plan, but since you need to keep the metal bits, do you actually need to remove the shells at all? Can you just burn out all the rubber and then push the new bush into place?

I'm also wondering how the centre metal part stays in place when the poly bush is used :confused:
 

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Discussion Starter · #9 ·

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Re: Found it at last – Front Suspension Rattle

Pretty brutal, certainly no going back once you start.
 
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