The curse has struck again

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lexi
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Re: The curse has struck again

Post by lexi »

I had a right few goes at getting the pressure screw slackened off on donk 03 plate. ...........nope. Rocol freeze spray and a touch of heat too.

Filberton
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Re: The curse has struck again

Post by Filberton »

Many thanks Kenny, I have searches out with a couple of suppliers as recommended in this forum so will look up your Glasgow guy for a quote. Most now seem to go for “we’ll refurbish yours” as few seem to hold these racks stock. They say they are like gold dust as folk who can’t wait take them as soon as they have one.

Needless to say, all those suppliers I have spoken to are, shall we say....are less than complimentary for the Citroen design!

I now just regard it as an expendable item....cam belt, Eolys, air con condenser, brake discs, steering rack...then start again ☹️☹️ But having bough the car second hand I have more than saved on depreciation and the comfort is worth the extra. (I now expect around £1000 pa repair bill which all said and done is not too bad for 12 years old and 170k miles (and I still get 48mpg, whisper quiet and comfort) 😄😄

So again, thanks guys for the help and advice 👍👍

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KennyW
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Re: The curse has struck again

Post by KennyW »

Lexi,

Did you get it off, I've had similar problems with the bleed screws on brake calipers, all with different outcomes, even enlarged the hole and re-threaded.

Kenny

lexi
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Re: The curse has struck again

Post by lexi »

KennyW wrote:
13 May 2020, 20:09
Lexi,

Did you get it off, I've had similar problems with the bleed screws on brake calipers, all with different outcomes, even enlarged the hole and re-threaded.

Kenny
No. Last year I was going to do a whole strip of back end for new suspension and the rear arm bearings. I put the job off with the bleed screw seized and the clunking from rear arm bearings has stopped for last 10 months. This car is moted till Nov and ATM I think that will be last of it. Still goes good and that is 5 years out of it. I must be due another car I think.

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ksanturion10
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Re: The curse has struck again

Post by ksanturion10 »

white exec wrote:
01 May 2020, 06:40
Not quite sure what you are recommending there, ksanturion ↑
Regarding the dimensions, maybe 8,2x1,8 and 9,3(9,4)x1,8 would be more optimal, as you won't expand too much the o-ring over the groove. But those would be more hard to find than 8x2 and 9x2.
Regarding the choosen material I think its obvious, in hotter countries -15 deg C is not that common as in colder climates. Either go for the special -35 deg C Viton compound or NBR standard compound +100 deg C to -30 deg C (special comp. +120 to -50). Don't believe you could get +100 deg C at the steering rack in normal conditions.

P.S.: its quite possible that in UK (western EU) you are only sold the special Viton compound, but I doubt it :-D

BR
Martin

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white exec
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Re: The curse has struck again

Post by white exec »

I really don't understand why you are suggesting even smaller cross-sections of O-ring. The originals were a loose enough fit in the groove and bore, so going smaller is only going make the joint even more prone to leakage.

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ksanturion10
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Re: The curse has struck again

Post by ksanturion10 »

You have:
12.16 - 9.45 = 2.71, 2.71/2 = 1.36 mm groove depth (GD) -> from my table (:D) for GD 1.3 (1.4) -> fi 1.8 mm (fi 1.9 mm) o-ring thickness;
11.16 - 8.3 = 2.86, 2.86/2 = 1.43 mm groove depth (GD) -> from my table for GD 1.4 -> fi 1.9 mm o-ring thickness - made mistake in the previous post;
As I said, compensating for the diameter of the groove with thicker section diameter is not optimal, as you are introducing more prestretching of the o-ring, which you actually need for the compression set, which is doing the job. Optimal would be to have those thicknesess, but with the stated internal diameters for the o-rings. I'm citing a producer data, which could make you think twice :D.
BUT as a whole, 8x2 and 9x2, should be perfect in this application.

BR
Martin

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white exec
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Re: The curse has struck again

Post by white exec »

Taking the just the first one, space to be filled by the O-ring = 1.355mm x 2.45mm = 3.32mm²
r² = A/π = 1.056mm
∴ r = 1.0276mm
∴ d = 2.06mm

O-rings provide best seal when compressed - and constricted in all directions so that they don't just alter shape and then become loose - so next commercial size up (in Polymax Viton listing) is 2.2mm thickness.
A 2mm ring will not fill the space.
2mm was also the O.E. size iirc, which we know can eventually leak.
Citroen also have a habit of under-sizing their O-rings in various instances, as already noted.

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ksanturion10
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Re: The curse has struck again

Post by ksanturion10 »

According to the literature I'm using, filling the whole groove (slot) is recommended only for vacuum applications. For example at injectors manifold side.
The leakages could probably be due to lower temperatures, at which the material can't provide adequate "compression flexability" (made this up :D).
Or if a rupture occured during installation due to over sizing ;)

BR
Martin

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xantia_v6
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Re: The curse has struck again

Post by xantia_v6 »

I agree that in most circumstances it is recommended that there is some lateral clearance for an o-ring, see for example https://mykin.com/oring-groove-design (note that they are working in inches!). Having no clearance makes it more likely that the o-ring will get pinched or twisted during assembly.

The problem is that in some applications, PSA seem to have used an o-ring with too small a cross section, such that sealing is unreliable if there is the slightest misalignment or any hardening of the o-ring. If you can get a fatter o-ring to fit without damage during assembly, it is unlikely that it will start leaking later.

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white exec
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Re: The curse has struck again

Post by white exec »

Agree about avoiding any scuffing or damage while fitting, so the ring and joint should be lubricated with something appropriate.
In practice, on an installation not tackled before, I tend to lay in two or three sizes of ring, and select the best and snuggest fit.
In the case above, there is also the unfortunate 0.105mm gap between pipe and bore, which would allow the ring to spread very slightliy up and down it.
An interesting discussion!

Filberton
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Re: The curse has struck again

Post by Filberton »

Hi guys,
I know you like closure so I thought I’d report back. Many thanks to Kenny and to others on the forum for advice. Thanks also for the detailed disassembly notes etc. All of which were a great help. Really Appreciated 👍👍

Well, last month I said I was expecting to find I needed a replacement steering rack and a bill of over £1,000 but I was wrong. When we got the old girl up on the ramp it turned out the problem was a slight weep from the spindle on the rack but also a split in the low pressure pipe. (Both would be MOT failures later in the year for me) To add to that, we also found a knackered CV joint and dodgy gear box oil whilst we were under there but the good news is the whole lot (new LP pipe, reconditioned rack, complete drive shaft and gearbox oil change) was a touch under £700 with the majority being For parts (plus a good indie mechanic) 😀😀

My findings.

The CV joint was knocking slightly but it was so corroded it would not split so the complete drive shaft was changed. The oil that leaked out when the shaft was removed I think came from the Torey Canyon so we drained and refilled the gearbox. It is not a service item so was probably the first change in 12 years and 170,000 miles!!

The LP steering pipe was split so we had to get a new one from the main dealer but it was only £72 so not as bad as expected. This was replaced 5 years ago for a similar split right at the end where it connects to the rack. Not sure why it split, was it fatigue in flexing or was it galvanic corrosion. One might ask who designed an aluminium pipe to go into a steel rack, to then add rubber/plastic insulators at all support brackets but not at the end. Surely designers know by now what happens when aluminium and steel are connected together!
I am not sure I will ever replace it again but it was annoying, and having to buy a whole pipe when just the end 50mm failed made it worse, especially when it is in parts with flexible bits in it anyway.
I do wonder whether, being an LP pipe if one could cut the pipe and put in a further flexible piece and just replace the end 100mm or so? I further wonder what would happen if that aluminium end could be replaced in brass or plastic From that last flexible bit if it would stop the galvanic action?

As for the rack it’s self, I tried Glasgow Power Steering but they had neither racks or seals in stock and did not know that they would get any in. Likewise SSL at Wakefield. And the same story at Kelly Bray in Cornwall however Len at Kelly Bray was most helpful in what to look for, how to do the job etc. We chatted and he said they no longer work on C5x7 racks because of the poor manufacture Quality by ZF for Citroen and they were getting too many back on warranty or otherwise their refurbishment would be too expensive compared to the competition however he explained to do a good job in most cases he would recommend re-chrome plating the rack, reworking the pinion, turning it down and fitting over size seals etc. But this work would put his prices out of market. I include this comment as these racks are becoming scarce and finding a reconditioned one with any life left in it is difficult and new ones costing well over £1,000. Whilst Kelly Bray would not “price match” To £250 with warranty I got the impression that they might do any rack for a price and negotiate a warranty.
As I needed an exchange (my motor taking up all the garage space as my indie only has one ramp) I could not go further with Len on that approach but I mention Kelly Bray as they were most helpful even though they got no business so, for any power steering rack problems, (any car not just C5 or Citroen’s) they might be able to offer a service and if they can't they may know a man who can! 😂

In my case I eventually had to get a reconditioned exchange rack from Andrew Page with a 12 month warranty (£250) It seemed ok and if it follows the same as my last, it may last 5years and 60,000 miles but even better, with lessons learnt from the forum, plenty of marine grease, maybe a protective sleeve it might even see the car out.

So all in all, reconditioned rack £250, new drive shaft £100, new LP pipe £75, oils, bits and bobs and 5 hrs labour came to a tad under £700.

For 170,000 miles and 12 years old I can’t complain. 😀😀

Mike

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Re: The curse has struck again

Post by jgra1 »

thanks Mike..

I am soon to remove my rack and will look into (also, I think white exec's) thoughts into re-sleeving the shaft after I guess it's been turned down..

John

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white exec
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Re: The curse has struck again

Post by white exec »

Some interesting detail there, Mike, not least the professional opinion on the rack. Does look like more than one design flaw, at the end of it all, both inconvenient and expensive.
If the LP pipe is only subject to low (return) pressure, I can't see why the pipe shouldn't be repaired with a suitable length of plastic. No idea about pressure there, but likely considerable flow.

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KennyW
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Re: The curse has struck again

Post by KennyW »

I think we shall run out of repairable racks and end having our own racks reconditioned to a personal level ie pinion shaft turned until cleaned up, oversize seal inserted on shaft along with other modifications as per Mike's post.
But this will cost and maybe too expensive for some people.
SWMBO is interested in the C5 Aircross but my concerns are the rack and the electric/electronic suspension. Is the rack the same design but modified using improved materials or new design. The reviews all state there is issue with rack driving feel.
I'm waiting to see how this C5 progresses with age and what problems appear.

Kenny