Silent droplinks in the sunshine

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isisalar
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Silent droplinks in the sunshine

Post by isisalar »

Having replaced all the suspect spheres on the HDI there are two remaining jobs outstanding on the body side of things, namely the droplinks and the P bushes.
I've really been enjoying the ride now the hydractive is all working as it should. I was delighted today to find the ride had improved even further and after a while I realised that the droplinks were virtually silent, since fitting the new front spheres they've been very noisy. I can only surmise that this is due to the heat over the last few days, car temp. reading today 34 degrees. Is this possible? Could a little expansion make such a difference to their performance and in turn to the suspension?
Anyway droplinks have just gone straight to the top of the to do list, a subtle ride difference but very noticeable, at least to me.
I dread to think what the temp. of the LHM tank would be in these sort of conditions, could that have any bearing on things?
Cheers guys
J reg 1.9d auto BX first Citroen
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Re: Silent droplinks in the sunshine

Post by CitroJim »

isisalar wrote: I dread to think what the temp. of the LHM tank would be in these sort of conditions, could that have any bearing on things?
It could Paul. See my reply to cc101 earlier...

I noticed my Activa was softer than normal this afternoon...
Jim

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Mandrake
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Re: Silent droplinks in the sunshine

Post by Mandrake »

I'm going to play devils advocate here Paul, and suggest that temperature has no effect on how noisy droplinks are, and that if they have gone quiet for no real reason that the droplinks are in fact not faulty, or at least aren't causing the noise you could hear.

I'm not sure if I've seen anyone else propose this theory before but I believe that Hydractive models can sometimes suffer from what I'd call "phantom droplink knocking", which is a sound that is just like knocking droplinks over broken surfaces, and is felt as a harsh vibration through the body as well but is in fact a vibration that is transmitted from the large strut top hydraulic hoses into the front wings where they clamp onto the inner wing (Just where the steel pipe joins the flexible pipe) or by touching against the body further down.

The cause for this seems to be - tada - air in the hydraulic lines, possibly exacerbated if the pipes are not clamped securely in their mounts on the wings. I was seeing a lot of this "phantom droplink knock" especially on the front left of my Xantia and since the hydraulic tank pipe mod its all but gone - none at all on the right now and only a very slight effect on the left. Interestingly the right hand side pipe is securely clamped in position, while the left hand pipe has slipped out of the clamp, which can lead to the steel pipe that runs under the battery moving out of position and resting against the bodywork - thus transmitting hydraulic shock-waves directly into the bodywork.

Where the air fits into the equation is that large amounts of air bubbles cause a violent oscillation in the oil flow when you hit a broken surface, that oscillation vibrates the pipe against the bodywork if its not mounted and located correctly. By the way my droplinks were replaced about a year ago and no difference was noted in the noise before or after at the time. (However if your droplinks are worn, then the oscillation caused by air can rattle the loose droplink joints even more than usual making them seem worse)

My previous Xantia had the same phantom knocking noise on both sides at the front quite badly despite brand new lemforder droplinks, it greatly lessened when I did that U-tube pipe modification on it, but it never entirely went away. On that car BOTH of the pipes were not securely mounted to the wings because someone before I owned it had lost the round spacers that normally space the bracket away from the panel and just screwed the clamp against the wing with self tappers! #-o

So if you replace your drop links and the knocking is still there and you think the other balljoints are ok, carefully check the pipes where they clamp to the wings to make sure they're secure and lined up, and if necessary lift the battery and tray out to check the steel pipe that runs from there to the hydractive regulator near the radiator is sitting properly in its plastic clips and not touching the bodywork. Same for the pipe on the other side. Then do the pipe mod ;)
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
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isisalar
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Re: Silent droplinks in the sunshine

Post by isisalar »

That's a very interesting theory Simon and something I'll certainly check out when I'm doing the new pipe and the mod. Studying this yesterday it would appear that the heat is certainly a factor in how noisy they are, or appear to be. I did at one time have silent droplinks together with slightly harsh suspension though. The symptom when doing a bounce test on the front is that it feels hard when trying to push the wing down, a bit more effort seems to free it off and it's then nice and soft with perfect damping until it's left to settle for a few seconds, it's then the same as before. I would say it takes about 3 times more effort to get it moving than to keep it moving.
The improvements in suspension seem to be related to how hot the LHM tank has got while the car has been parked, car temp 33/4 degrees, undertray in place, underbonnet insulation in place, the LHM must be close to boiling point and this may well purge out most of the air in the tank giving the temporary ride improvement. Heating elements for tanks?
Droplinks or otherwise the heat is certainly related to this noise, I drove to a job yesterday, 33 degrees, silence, return journey 28 degrees, noisy. 30 degrees seems to be where the noise starts diminishing.
I'll certainly do the mod and the new pipe before the droplinks are replaced so it'll be interesting to see the results.
Cheers
Paul
J reg 1.9d auto BX first Citroen
M reg 1.9d auto Xantia lx
N reg 1.9 td Xantia VSX Estate
T reg 2.0HDI Xantia Exclusive Estate Present car
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Re: Silent droplinks in the sunshine

Post by Mandrake »

isisalar wrote:That's a very interesting theory Simon and something I'll certainly check out when I'm doing the new pipe and the mod. Studying this yesterday it would appear that the heat is certainly a factor in how noisy they are, or appear to be.
Heat can certainly affect the noise that you're hearing, what I'm suggesting is that the slack in the drop links, if any, won't be changing with temperature. Something else in the suspension is changing that is affecting how much you hear it or its something else entirely like I'm suggesting with the pipe rattling on the bodywork.

My previous Xantia was in New Zealand and exposed to much higher temperatures on a regular basis and there was a clear correlation between ride quality and temperature on that car - it always got worse when the weather was stinking hot and rode best in cold weather. That was with brand new drop links. The "phantom knock" that I refer to got much worse in hot weather too, and sometimes went away in cold weather. In hindsight I believe what was changing was air leaks in the hydraulic system were getting worse with high temperature due to swelling of poorly sealing rubber hoses. I had a lot of problems with air bubbles circulating into the tank and through to the pump in that car and never really got it under control despite a lot of time and effort expended, although I was able to make a big improvement.
The symptom when doing a bounce test on the front is that it feels hard when trying to push the wing down, a bit more effort seems to free it off and it's then nice and soft with perfect damping until it's left to settle for a few seconds, it's then the same as before. I would say it takes about 3 times more effort to get it moving than to keep it moving.
I'm assuming the engine is idling during the bounce test ? It sounds a bit like your front struts are binding. You didn't jack the wheels off the ground and then lower it back onto the ground and do the bounce test without rolling the car forward or back by any chance ? Or roll the car into place with the suspension up or down then adjust it to normal height without rolling it again ? If you do either of these even good struts will bind around the normal ride height position due to the geometry changing the wheel track.

To test the struts for binding you need to have the car at normal ride height then let it roll/drive forward or back a bit to release any side thrust on the struts. If it still seems to bind they might need lubricating, or the strut shaft could have bad surface wear or pitting at the position where the top bronze bush rests against the shaft - if you lift the suspension right up you may see something like this on the shaft:

http://homepages.igrin.co.nz/simon/imag ... strut1.jpg" onclick="window.open(this.href);return false;
http://homepages.igrin.co.nz/simon/imag ... strut2.jpg" onclick="window.open(this.href);return false;
http://homepages.igrin.co.nz/simon/imag ... strut3.jpg" onclick="window.open(this.href);return false;

This is from my previous Xantia and you can see that the surface hardening has been worn through in places which can cause it to bind slightly at the normal ride height where the worn patch rests against the top bush. When you consider that this bush takes all the side thrust from the car when cornering and runs dry by design, its not surprising to see the shaft can wear.
The improvements in suspension seem to be related to how hot the LHM tank has got while the car has been parked, car temp 33/4 degrees, undertray in place, underbonnet insulation in place, the LHM must be close to boiling point and this may well purge out most of the air in the tank giving the temporary ride improvement. Heating elements for tanks?
I very much doubt the LHM is near boiling point :lol: It will boil at a far higher temperature than water and wouldn't be getting hot enough to boil water anyway.
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
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Northern_Mike

Re: Silent droplinks in the sunshine

Post by Northern_Mike »

isisalar wrote: the LHM must be close to boiling point and this l
Tell me, how is the weather on the surface of Venus these days? Does your Xantia cope well....

I believe the boiling point of LHM is around 350c..

http://www.totaloil.com.au/Pages/content/NT0000C6E6.pdf" onclick="window.open(this.href);return false;

Nor, does it appear, that a few degrees temperature variance has any effect on it at all. It *might* have an effect on some other component, but it won't be the fluid. Don't forget, the pump is warm all the time, whatever the weather..
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Re: Silent droplinks in the sunshine

Post by SaabC5 »

It is entirely possible. Saab 9-5's suffer from creaking front subframe bushes. In winter they groan like grandads bones over speed humps/bumps, in hot weather they mysteriously go silent when the rubber expands.
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isisalar
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Re: Silent droplinks in the sunshine

Post by isisalar »

Since the last post I've been paying a great deal of attention to this noise and I don't think it is exclusively temp. related. I've not had the ultra soft ride again since and the noise comes and goes.
I replaced the tank to pump pipe with a length of suitable 1/2" and a short length of 3/8" hose from Pirtek cost £20. The 1/2" is marked as 12.7mm ID the original is marked 12.3mm ID at the tank end, the 3/8" is I think 9mm and is a perfect fit on the pump spigot. They were unable to supply a suitable reducer though so I had to use an old plastic one I had handy. Did the 10min mod but was still getting crashy ride and lots of bubbles in the tank. I diagnosed this as the hose still leaking so returned to Pirtek for another try at getting a reducer. The only thing they had available cost £20 and weighed about 1/2 lb, I had discovered that the pipe from the tank didn't need any elbows and can be routed alongside the air filter and across the top of the rad, and then to the pump with no kinks. There's even a suitable hook on the top of the rad to tuck it under. The join is in this section to the pump so a heavy fitting is a definite no no.
They reluctantly admitted that one of their neighbours might be able to help so I went to visit these people:-
http://www.hopespare.com/" onclick="window.open(this.href);return false;
They were able to supply the perfect item for £7, a proper brass and ally job all screwed together and sealed up with PTFE tape, perfect barbed spigots. I wasn't happy with the tank end connection either and was going to build up the spigot with amalgam tape but wasn't sure how this would react with LHM. They advised PTFE for this. These guys were very helpful and provide a service very useful to Citroen owners, eg they can provide repair sections for LHM metal pipes, or make up a new one. Bookmark them!
Re did the connections and fingers crossed after a week the ride is still good and the brakes are getting better. The ride is firmer than during the two ultra soft episodes but drain covers are no longer like potholes. I checked the bubble situation yesterday, much better, on low a slight surface bubble layer appears after about a minute and is gone in 5.
I've delayed getting the brakes bled since the LHM replaced the Hydraflush, not wanting to put a LHM/bubble mix in the lines which are presently full of a Hydraflush/bubble mix. Can anyone advise how long it will take to get the bubbles out of the system enough to bleed the brakes?
Getting there.
Cheers
Paul
J reg 1.9d auto BX first Citroen
M reg 1.9d auto Xantia lx
N reg 1.9 td Xantia VSX Estate
T reg 2.0HDI Xantia Exclusive Estate Present car
M reg 106 diesel red
L reg 106 diesel white
02 Saxo 1.1i desire wife's present car(sadly now very ill cambelt gone- Doh)
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Mandrake
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Re: Silent droplinks in the sunshine

Post by Mandrake »

Is PTFE tape mineral oil safe ? I'm not sure that it is...
Simon

1997 Xantia S1 3.0 V6 Auto Exclusive in Silex Grey
2016 Nissan Leaf Tekna 30kWh in White

2011 Peugeot Ion Full Electric in Silver
1977 G Special 1129cc LHD
1978 CX 2400
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Re: Silent droplinks in the sunshine

Post by lexi »

It goes gooey the PTFE
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