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My front suspension knock was ARB bushes even though my indy said there was nothing wrong with them. In the end I bought a new front ARB assy and got it fitted which fixed the probem.

May be something to consider?
 

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Discussion Starter #22
My front suspension knock was ARB bushes even though my indy said there was nothing wrong with them. In the end I bought a new front ARB assy and got it fitted which fixed the probem.

May be something to consider?
I only done the rear ARB and bushes so that's also worth considering, thanks
 

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Fruity,
My understanding:
The bushing rubber is what wears.
The rubber bushes fit over the steel crush tubes.
The rubber bush has no interaction with the bolt, only with the crush tube on which the rubber articulates.
The bolt clamps the steel crush tubes tightly to the aluminium casting (mount).
The crush tubes are clamped by the bolt, but the crush tubes are not prone to wear.

Note that when the bolt is properly tightened; the wishbone mounting relies for its' general stiffness / rigidity / strength upon the tensile strength of the bolt, but does not rely on the strength of the bolt in 'shear' (I say "strength", but 'rigidity / stiffness' is probably more important in this context). The bolt OD is 10mm, but the assembly as a whole has a lot more 'shear' stiffness than a 10mm bolt (which is only in 'single shear' mounting each side of the aluminium mount casting).

The 'shear' strength and rigidity of the mount assembly actually relies on the stiffness of the mount casting, and on the diameter of the tightly clamped crush tubes. The crush tubes have an OD of 22mm, and are in effect hugely more rigid than the bolt when fitted correctly (i.e. with a properly tight bolt). Because the crush tubes are very tightly clamped to the mount casting by the tensile loading of the bolt, they cannot move in any direction. Because they can't move they add very substantial rigidity to the mount assembly as a whole.

If the bolt does become loose then all of this nice rigidity will disappear, and the assembly becomes soley reliant on the relatively feeble shear stiffness of the 10mm bolt. The bolt probably won't break or even bend, but it will move and rattle (clearances) and may flex enough to cause significant camber and toe changes under load. The now loose crush tubes will no longer remain still as the suspension articulates, so given enough time (with the tubes rotating on the bolt) some wear will occur. There will probably be some wear on the bolt shank, on the ID of the crush tubes, and on the ID of the mount casting block hole.

But I still hold that the bolt won't loosen as a result of worn bushes or soft dampers etc. The bolt may well loosen as a result of the nut not being torqued tightly enough in the first place, or possibly as a result of a weakened nut stripping its' threads in use, as can happen with threads that have been thinned / weakened by repeated tightenings (especially common with softer steel nuts...).

All above = FWIW

Regards,
John.
 

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My vote is the ARB not being central, which allows one end to knock against the 'fork'. I had that after letting one side off the jack. I jacked it up and levered the ARB to be centred. It didn't stay like that for long because the ARB bushes were a bit worn.

The other thing is the driveshaft tripod bearing beginning to fail. That gave a harsh metallic rattle on mine. Grabbing the driveshaft just outboard of the gearbox, there should be no lateral movement, just in/out. a new driveshaft fixed that.
 

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Discussion Starter #25
My vote is the ARB not being central, which allows one end to knock against the 'fork'. I had that after letting one side off the jack. I jacked it up and levered the ARB to be centred. It didn't stay like that for long because the ARB bushes were a bit worn.

The other thing is the driveshaft tripod bearing beginning to fail. That gave a harsh metallic rattle on mine. Grabbing the driveshaft just outboard of the gearbox, there should be no lateral movement, just in/out. a new driveshaft fixed that.
Really hope it's something cheaper than that but again thanks for your comment, appreciated
 

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ARB not being central will show up as abrasion on forks or plastic end caps of ARB link rods.

I'm not sure whether the ARB or just the bushes were changed.

For my money, checking the ARB alignment (shouldn't be necessary if it still has both integrated washers at the outside of each ARB bush though) and if that doesn't provide a answer, perhaps a new bolt for top wish one pivot.

As I mentioned already, if the car ran with weakened dampers for some time, I think the likelihood of a worn bolt increases.

I just had to do that on red TS a few months ago as it just wouldn't quieten properly with old bolts. For the price of a bolt and nut and 3/4 hour labour, it makes reasonable sense taking a flier at that.
 

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Discussion Starter #27
ARB not being central will show up as abrasion on forks or plastic end caps of ARB link rods.

I'm not sure whether the ARB or just the bushes were changed.

For my money, checking the ARB alignment (shouldn't be necessary if it still has both integrated washers at the outside of each ARB bush though) and if that doesn't provide a answer, perhaps a new bolt for top wish one pivot.

As I mentioned already, if the car ran with weakened dampers for some time, I think the likelihood of a worn bolt increases.

I just had to do that on red TS a few months ago as it just wouldn't quieten properly with old bolts. For the price of a bolt and nut and 3/4 hour labour, it makes reasonable sense taking a flier at that.
Nothing seemed wrong with the top mount on that side when all the other work was done, so worn bushes n bolt replacement seems like a sensible precaution to do regardless, I'll ask for this to be done on the service too, thanks Fruity, you're the holy trinity, the man, the myth and the legend
 

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Discussion Starter #29
Just to be clear, you did not replace the front anti roll bar bushes ?
Sorry, I checked my receipts, full front ARB and bushes were replaced, up front it is literally sub frame (if applicable) and passenger side top mount that hasn't been done.
 
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