HP suspension height mod. debate

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Thunderbird

HP suspension height mod. debate

Post by Thunderbird »

What will I win and lose on lowering the suspension 5cm and on raising it 5cm?
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AndersDK
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Post by AndersDK »

You will loose much of the suspension travel - feels like you hit the rubber stops all the time.
Just try set the suspension low or high ... [}:)]
Jon

Post by Jon »

Thunderbird, if this is reference to your previous post, (recharging spheres) please note that a crazy fool got on the forum ( X_Auntie, now deleted) and when I went to do an edit, unfortunately, I hit the trash can icon by mistake, and deleted that whole post. For which I apologise to all.
My mistake.
Dave Bamber
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Post by Dave Bamber »

It’s such a shame the previous post was deleted as it contained some very useful comments and opinions.
alan s
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Post by alan s »

By the sounds of the title, I suspect we might be getting close to the truth behind the dodgy ride referred to in the 'lost post' (no pun intended...much! [:D][:D]
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Post by citronut »

if you dont like the ride of you hydraulic citroen perhaps you should get a fiesta or mini metro,crindge crindge shuder shuder regards malcolm
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Post by ActivaV6uk »

Yeah the old one was a good thread, but accidents happen as we all know.
The rule of thumb I was told with modding suspension height is that the lower arms can only be taken until they are level with the sub frame, other wise you will damage the drive shafts over time and the ride quality will be affected. If I was going to do this, as Jon has rightly done I would alter the spheres to suit so that the suspension can’t be bottomed out easily.
Andy
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Post by Jim_Reaper »

Thunderpants matey, from purely a ride point of view if the Citroen is not to your taste why not go for a classic like the BLMC Landcrab.
Very easy maintainaence on the suspension - if you have the tools we are talking maximum of a couple of quid every year for fluid.
Plus in the UK a car like this would attract classic insurance and free road tax.
I woud be interested to find ut more about how Jon lowered / firmed up the ride on his BX - mine is still running estate spheres all round (its a saloon) but seems comfy enough, just a bit wallowy into bends. Its up for an MOT very soon, so will see what the tester thinks of the spheres.
What exactly are you looking for ride wise from your Xantia? This might help us establish what route you want to take with the car.
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim_Reaper</i>

Thunderpants matey, from purely a ride point of view if the Citroen is not to your taste why not go for a classic like the BLMC Landcrab.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
[:D]
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
I woud be interested to find ut more about how Jon lowered / firmed up the ride on his BX - mine is still running estate spheres all round (its a saloon) but seems comfy enough, just a bit wallowy into bends. Its up for an MOT very soon, so will see what the tester thinks of the spheres.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Often the estate spheres for the back will give a SOFTER ride on a saloon than the normal saloon ones, as they probably have a higher gas pressure in them. (Not sure on the BX, but the Xantia has 30 bars for 2.0 saloons and 40 bars for estates)
As far as wallowing is concerned, thats mainly affected by the diameter of the bypass hole in the damper valve (although also influenced by gas pressure) - too large a hole will give a soft but wallowy/floaty ride, too small a hole will give a firm ride with good damping but the ride will be a bit rumbly and will not be the "magic carpet" ride some Citroen owners probably expect. (It will ride just as well over large bumps, such as judder bumps, but not over very small irregularities, or manhole covers etc)
We just recently reduced the bypass hole on the front spheres of my Dad's Xantia from the standard 1.5mm to 1.2mm and the wallowing that it was doing is completely gone now, in fact I find the damping control excellent. Ride is just *slightly* more rumbly on harsh surfaces, and not quite the magic carpet ride, but it is still excellent compared to conventional suspension cars, and the vehicle feels a lot more stable.
Roll in light to moderate cornering is also reduced a lot, (although I'm not entirely sure why, as it should only slow the roll reaction, not the amount of roll, in theory) as is side to side rocking on irregular surfaces.
Reducing the hole is tricky though, we got a friend with a good miniature lathe to machine and drill a tiny brass terminal into the shape of a hollow rivet that was an interference (hammer tap) fit into the original hole. The head of the "rivet" also helps hold it in, as the oil pressure has more surface area to press it in than it does to press it out.
Not a 5 minute Sunday job though [;)]
You wouldn't think that a tiny change in a tiny hole would have such a profound effect on the overall handling and feel of the car, but it does...
The following page has a nice chart of BX sphere gas pressures and damper valve bypass hole bores:
http://www.tramontana.co.hu/citroen/sus ... spens.html
Regards,
Simon
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Post by jeremy »

I had wondered about trying to tinker with the sphere damping hole and had wondered about brazing the original closed and carefully re-drilling close by.
How much influence do you think the small LHM feed pipe has as on non-hydractive cars there is no restriction and so some fluid must be transferred in roll?
Jeremy
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Post by Mandrake »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jeremy</i>

I had wondered about trying to tinker with the sphere damping hole and had wondered about brazing the original closed and carefully re-drilling close by.
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I would be very wary of doing that on a gassed sphere. Although you might get away with it, there is no telling whether the flame or the indirect heat from the flame could burst the diaphram and send 400cc of high pressure gas your way [:0]
It's likely that the centre rivet section (with the hole in it) is fairly well bonded to the damper valve and therefore the sphere body - making the sphere act as a big heatsink. It would therefore probably take a lot of heat to get it up to the temperature where it would braze.
I considered doing something similar with solder, and shied away from it for the same reasons of heat damage...(and the heatsinking effect would probably make it impossible to get it up to temperature even with a fairly large iron)
Another risk would be drilling right into the diaphram by mistake. Although there is quite a clearance between the damper valve and the diaphram button (about 20mm) the consequences of puncturing it are pretty severe.
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">
How much influence do you think the small LHM feed pipe has as on non-hydractive cars there is no restriction and so some fluid must be transferred in roll?
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Thats a very good question, and one that I don't have an answer to, even though I've given it a lot of thought over the years.
Because of the cross piping, in theory a plain hydropneumatic system minus the rollbar would have NO roll resistance, and relies entirely on the rollbar for any roll stiffness. But because the pipes are deliberately very small, (a similar size to the damper bypass holes) and quite long, I guess they would limit the crossflow a lot, but not entirely.
I was just thinking the other day that a nice mod for older hydropneumatic models would be to retrofit a ball crossflow blocking valve like the one used in hydractive 2, and I can see no reason why it couldn't be added to an existing system in place of the T junction between the height corrector and left and right suspension cylinders, and reduce roll with no significant downsides or ride degredation.
Unfortunately the crossflow valve in the hydractive 2 models is (as far as I know) simply one part of the hydractive block and not a seperate unit, making it impractical to fit unless you wanted to machine your own copy of the crossflow valve.
Whether it would make a difference is unproven too - it might not be necessary with the small diameter crosspipes, whereas with hydractive 2 the cross pipes are very large so there definately WOULD be a large cross transfer of oil in roll if the valve wasn't there...
Tweaking the diameter of the damper valve bypass hole (on a non-hydractive model) is definately a worthwhile exercise though if you want tighter handling, less roll, and less/no wallowing, and you're willing to sacrifice a small amount of ride smoothness.
Regards,
Simon
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Post by zorgman »

i tried the lowering trick on my xantia by keeping the lever slightly down by hand after first marked the settings ie hieght per mark, dont bother the ride was bloody awfull, anyhow i liked the landcrab me and a girl had lots of fun in them as the seats went down and made a full size bed ahh the memories
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