peter_m7uk
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| posted on 1/12/23 at 12:15 PM |
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Damper mounting and lubrication
Hi, quick one about mounting coilspring dampers - My Robin 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 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?
[Edited on 1/12/23 by peter_m7uk]
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adithorp
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| posted on 1/12/23 at 12:50 PM |
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Gaz voilovees come in 2 end varieties; Either rod ends or (as it sounds like yours are) metalastic bushes. On those the rubber is bonded to both the
outer and inner tube. There's no movement, just flex in the bush. Bolts should be tight but only done up with the car at ride height otherwise
you'll get too much twist in the bonded bush.
Lubeing the bush ends would stop any noise if it was touching the bracket; but if shouldn't touchn Lubeing the bolt only prevent corrosion.
Between bolt and tube.
You're squeek is more likely from the wishbone bushes... IMO
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Mr Whippy
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| posted on 1/12/23 at 01:14 PM |
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Could be a sign that the metelastic bush is knackered, a squirt of WD40 on the bush will probably silence it but would still need replaced.
They're are many websites you can order replacements once you have measured the sizes and they are very cheap, just a pest to replace without a
press, although most people just use a long bolt and washers to do so. On all designs, the crush tubes should be solidly mounted by the bolt, they
should never rotate. The bush should either deform or rotate about the tube.
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peter_m7uk
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| posted on 1/12/23 at 03:23 PM |
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quote:
Originally posted by adithorp
Gaz voilovees come in 2 end varieties; Either rod ends or (as it sounds like yours are) metalastic bushes. On those the rubber is bonded to both the
outer and inner tube. There's no movement, just flex in the bush. Bolts should be tight but only done up with the car at ride height otherwise
you'll get too much twist in the bonded bush.
Lubeing the bush ends would stop any noise if it was touching the bracket; but if shouldn't touchn Lubeing the bolt only prevent corrosion.
Between bolt and tube.
You're squeek is more likely from the wishbone bushes... IMO
Thanks, Adithorp. They are indeed the metalastic bushes. You've made me think now, back in the mists of time - I'm pretty sure that when I
tightened up the bolts it was in the lowest position with suspension most extended. The bushes are therefore being twisted quite a lot during travel
to the most compressed position... Probably doesn't do a lot for life of the rubbers, which is now over 15 years old, even if the car is very
low mileage.
The noise sounds part squeak, part metallic scraping! My concern is that possibly the dampers barrels/pistons have failed in some way and are
scraping internally? I will look at the bushes again - Maybe I could loosen the bolts off temporarily and apply some grease, to see if it makes any
difference. If not, I think they may go back to Gaz for a service. Cheers
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peter_m7uk
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| posted on 1/12/23 at 03:32 PM |
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quote:
Originally posted by Mr Whippy
Could be a sign that the metelastic bush is knackered, a squirt of WD40 on the bush will probably silence it but would still need replaced.
They're are many websites you can order replacements once you have measured the sizes and they are very cheap, just a pest to replace without a
press, although most people just use a long bolt and washers to do so. On all designs, the crush tubes should be solidly mounted by the bolt, they
should never rotate. The bush should either deform or rotate about the tube.
Thanks, Mr W. As I said to Adithorp, I'll see what happens when I loosen and grease them, how the noise changes. Hopefully that points to
whether the problem is the bushes, the damper unit, or bit of both! Out of interest, how does the "long bolt and washers" approach work?
It sounds like you'd have to clamp the outer tube on the damper ends so you can push the inner crush tube and rubber somehow? Good to know
that the crush tubes should always be solidly bolted in, I wasn't clear about that at all! Cheers
[Edited on 1/12/23 by peter_m7uk]
[Edited on 1/12/23 by peter_m7uk]
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peter_m7uk
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| posted on 1/12/23 at 03:47 PM |
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As an afterthought, what were Gaz trying to say about greasing?
"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"
That sounds like it could allow the crush tube to rotate on the bolt? Surely you *want* friction on the brackets and bolts so that the crush tube is
solidly mounted? Or does this allow for a tiny bit of movement?
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peter_m7uk
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| posted on 4/12/23 at 02:10 AM |
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Just to follow up on this, I had a look at the ends of my dampers to see how they're mounted and took the attached pics. I believe they are
"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.
 
Description
 
Damper Mount 2
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Mr Whippy
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| posted on 4/12/23 at 07:41 AM |
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That still looks like a mentalistic bush. if it was a top hat then the outer diameter of the bush would be the same as the metal housing. Only going
from the photo they look in good shape. I'd just make sure the bolts are done up tight. WD40 will stop the squeak and let you identify which bush
is the culprit.
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peter_m7uk
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| posted on 4/12/23 at 02:45 PM |
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I asked Gaz directly. They said that the inner tube is bonded to the rubber, but the rubber is not bonded to the "eye" on the end of the
damper. Therefore there must be some possibility for the rubber to rotate, also I don't think it would matter so much what position you tighten
up the bolt as the rubber could adjust. Thanks for the tip, Mr W, but I've read that WD40 can be bad for rubber?
My other thought is to use grease elsewhere on the units. The suspension noise sounds metallic, so I thought maybe some grease where the springs
touch the seats, also where the top seat "cup" touches the damper body. It seems like there could be a few metal-on-metal points. Anyone
got an opinion on that? Will it help? Or just attract dirt and dust?!
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adithorp
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| posted on 4/12/23 at 08:59 PM |
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Only use silicone grease or spray on rubber components.
Mineral based lubricants will damage them.
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peter_m7uk
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| posted on 27/12/23 at 12:50 AM |
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So in the end, I decided to just lubricate everything and see what happens. I removed both rear dampers, de-rusted the fitting eyes and bolts, then
greased everything and re-fitted! All noises have gone and I have my quiet suspension back  Maybe there will be a bit of movement in the crush
tubes, but never mind, it won't be much
[Edited on 27/12/23 by peter_m7uk]
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