Differences between Mk1,2 and X7 steering racks

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leithant
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Re: Differences between Mk1,2 and X7 steering racks

Post by leithant »

white exec wrote:
17 Apr 2020, 22:41
I doubt very much that the swaged flange has any sealing function, except to hold the pipe firmly in position, and prevent any movement. The hydraulic sealing will be solely down to the green O-ring, sitting in the machined bore. This arrangement is pretty similar to the heater matrix pipes on XM/Xantia, which also feature a single O-ring and clamp plate.
I think that observation is on the money. Only question I would ask is does the end of the pipe push against that shoulder inside the casting? I would be surprised if the O-ring would handle the pressure from the PS!

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bobins
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Re: Differences between Mk1,2 and X7 steering racks

Post by bobins »

The tip (the open end) of the pipe doesn't sit against anything, the pipe isn't a tight fit in its hole, the flange / ring would normally be compressed (on first fitting) onto the stepped ring in the housing and that's what would hold the pipe firm in its socket.

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white exec
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Re: Differences between Mk1,2 and X7 steering racks

Post by white exec »

Thanks for posting those second photos, Bobs.
That, and your last post confirms that it's all down to the single O-ring, being of sufficient size to achieve a hydraulic seal.
Noted that the pipe is also a loose fit in the bore.
Just dreadful :( .

Would suggest, without major re-designing
1 - A slightly oversized O-ring *
2 - Look at sleeving the pipe in the bore, if space allows, to reduce movement. (Offcuts of aluminium venetian blinds can be of use, sometimes.) What is the gap?

* I couldn't spot that O-ring on Parts, to find its dimensions (which are usually listed).
Perhaps you or Marc can.

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bobins
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Re: Differences between Mk1,2 and X7 steering racks

Post by bobins »

The 'O' ring wasn't listed separately, but they did come free with when you bought a set power steering pipes :roll: The ones for earlier C5 did fit though as they were the right size !

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bobins
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Re: Differences between Mk1,2 and X7 steering racks

Post by bobins »

If you look on the photo of the housing, the red arrow points to a chamfer in the casting. The 'O' ring only just sits below this chamfer when the pipe is fully home - as in : the 'O' ring is less than 1mm below the chamfer :shock:
PS housing - own work
PS housing - own work

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bobins
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Re: Differences between Mk1,2 and X7 steering racks

Post by bobins »

white exec wrote:
18 Apr 2020, 12:23

That, and your last post confirms that it's all down to the single O-ring, being of sufficient size to achieve a hydraulic seal.
Noted that the pipe is also a loose fit in the bore.
I think that's the issue though - whilst the 'O' ring could possibly do with being a smidge bigger, unless the pipe is held firmly in its socket by the swaged ring compressing onto the steppd part in the casting - an 'O' ring seal will fail as the pipe can move in its socket. I tried many different sized 'O' rings to seal the pipe, but some would fail within a day or so, and some would last weeks - but the seal always failed in the end :(

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Paul-R
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Re: Differences between Mk1,2 and X7 steering racks

Post by Paul-R »

I reckon that if (big if!) you could engineer a second O-ring nearer to the end of the pipe that would be a nearly perfect solution.

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bobins
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Re: Differences between Mk1,2 and X7 steering racks

Post by bobins »

Agreed - but if you're going to remove the pipe to machine a groove to put a second 'O' ring on the pipe, you might as well replace the pipe with a new one :( There was a break point on one of the pipes somewhere near the front left wheel which meant replacing the pipe was ever-so-slightly less of a PITA than it was designed to be as you only needed to replace half the pipe. :roll:

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KennyW
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Re: Differences between Mk1,2 and X7 steering racks

Post by KennyW »

It's a shame we cannot use one of the bigger olive xantia seals ( 6.5mm and another size I can't remember the size possibly 9mm)from the Hydraulic pump, fit that over the pipe and fit into the Pinion. I did have some of these seals when I had to replace a seal on the pump.

Even flatten holding plate so it becomes flush with the Pinion housing.

Kenny