Damper mounting and lubrication

[peter_m7uk]

Hi, quick one about mounting coilspring dampers - My Hood has a set from Gaz, which I mounted over a decade ago and can't remember exactly what I did as it was a hell of a long build !!    Each one has a metal tube in an eye at the ends, where I *think* the bolt through the eye holds that tube absolutely solid so it doesn't move - Similar to mounting wishbones where the poly bush moves around the metal mounting tube, but the tube is also bolted on solid.  I don't think I put any grease on the bolt or bush back then..

The problem is that I now have squeaking and groaning from my suspension, so I e-mailed Gaz and they recommended using some red rubber grease lube.  I was told "Put it around the ends of the bush so it stops any friction on the brackets where the dampers are mounted & then also on the bolt that fits into the bush".  This is a bit different to my understanding, have I cocked up?!   Are the bolts through the damper eyes supposed to locate the tube but allow it to rotate around the bolt?   Or is the bush supposed to rotate around the tube like with poly suspension?

[IanS]

I have always been of the opinion that if a steel tube is expected to rotate on a bolt shaft it needs lubrication.

BUT I also think that the steel tube should be trapped to stop rotation in a rest position as rotation can wear the bolt weakening it a risking catastrophic failure as a tube over a bolt will not have the close tollerance fit required of a bearing thus allowing hammer action in the joint. The poly bush wearing will be progressive so should be caught in time to replace the bush.

I await other views.

 

[Jez Morton]

I believe the inner metal tube that the bolt passes through does not move it acts as a spacer in the bracket to stop the Bush being crushed. The Bush should be the only moving part between the damper and suspension bracket. Personally I grease every thing as this stops corrosion between the metal parts. If you have a bonded rubber Bush then the rubber forms part of the suspension and these need to tightened at ride height or you have tension in the rubber.

[peter_m7uk]

Thanks for your replies, Ian and Jez!   Is there a way to tell that the rubber is bonded, without talking the suspension apart and trying to turn the tube?  As you can see in the linked images, they appear to be "top hat" bushes where the tube can turn within the rubber. Maybe you'd want grease between the metal tube outer surface and the rubber inner surface? Or would you expect the rubber to be bonded hard to the tube and the "eyes" on the end of a damper? I don't think that's the case, but not really sure..

[IanS]

I cannot open the pictures.

As GAZ dampers I would be supprised if the rubber was bonded so grease between rubber and tube.