C5 X7 Steering Rack - Again!

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xantia_v6
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Re: C5 X7 Steering Rack - Again!

Post by xantia_v6 » 11 Jun 2018, 20:46

bobins wrote:
11 Jun 2018, 19:34
I couldn't resist any longer - so I set about taking my old spare leaking rack apart to see what I could see. And the result is... inconclusive.

Image
Looking at that, I am fairly sure that the seal comes out and goes in from the top, no need to disturb the bearing (and maybe no need to dismantle the rack).

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Re: C5 X7 Steering Rack - Again!

Post by bobins » 11 Jun 2018, 20:54

'fraid not :( there's a 2-3mm lip on the casting and the seal sits under that. If it wasd a flexible seal then it'd be possible to put it in from the top, but it's a classic rigid oil seal so can't be persuaded into place from the top :cry:

I've got the housing sitting next to me here so if anyone wants better photos then I'll dig out the grown up camera and take some better shots. :-D

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Re: C5 X7 Steering Rack - Again!

Post by xantia_v6 » 11 Jun 2018, 21:27

OK, assuming that it is a steel bearing in an aluminium housing, it should be easy to remove the bearing by heating the assembly to about 150 degrees C and let differential expansion do the work.

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Re: C5 X7 Steering Rack - Again!

Post by bobins » 11 Jun 2018, 21:33

OK, that'll be gas mark two and a half and don't tell the Mrs :) I'll give it a go tomorrow. By the way, what temperature do oil seals melt at ? :wink:

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Re: C5 X7 Steering Rack - Again!

Post by Stickyfinger » 11 Jun 2018, 21:36

That lug is a pain in the backside being there.........is it a solid lump ?

I see that lump as the ideal fixing point for a gator...I have a plan forming in my little bit of grey matter.

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Re: C5 X7 Steering Rack - Again!

Post by bobins » 11 Jun 2018, 21:48

Yep - a solid lump, but with a drilling all the way through to take the stud.
As an additional note, the top of the casting is only just parallel to the sides i.e. it'd be a little bit of a pain to get a positive fix of some form of cover onto the casting and use something like a jubilee clip to hold it on - the more you tightened the jubilee clip, the more the whole lot would want to slip off the top of the casting.

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Re: C5 X7 Steering Rack - Again!

Post by xantia_v6 » 11 Jun 2018, 21:51

bobins wrote:
11 Jun 2018, 21:33
OK, that'll be gas mark two and a half and don't tell the Mrs :) I'll give it a go tomorrow. By the way, what temperature do oil seals melt at ? :wink:

Oil seals should be OK well above that temperature as engine oil gets hotter in some engines.

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Re: C5 X7 Steering Rack - Again!

Post by Sloppysod » 11 Jun 2018, 21:53

Delugging the rack is a good idea, however, you can, I did, fit the boot over the lug and secure with a tie wrap and left the top to sit snug over the floor boot.
I also agree that leaving it without a tie-wrap could leave it open to the environment, but then again it may well help to let air circulate and keep it all dry, it's a personal choice and we will not know which is best for a few years (if ever).
The problem with corrosion is that to stop it you need to completely remove it so sanding down and painting, like most refurbished racks, is only a short time measure, so the Lithuanian guy who turned his spigot probably helped the situation, providing he removed ALL the corrosion and retreated afterwards.
I am not sure about the double seal mod, if the rack is allowed to corrode then surely it will eventually wear out both seals, again only time will tell.

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Re: C5 X7 Steering Rack - Again!

Post by bobins » 11 Jun 2018, 22:02

Sloppysod wrote:
11 Jun 2018, 21:53

I am not sure about the double seal mod, if the rack is allowed to corrode then surely it will eventually wear out both seals, again only time will tell.



I think there may be an element of 'red herring' with the double seal mod. I think it's nothing more than an R23 seal instead of an R21 seal. OK, so an R23 seal has double the seals (!) but there's only about 4-5mm between the two lips and, as you say, they'll both wear out soon enough if the shaft rusts.

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Re: C5 X7 Steering Rack - Again!

Post by white exec » 11 Jun 2018, 22:19

Looking at several of the photos of the lump and the pinion casting, I wonder whether it might be possible to just slice off the outboard end of the lump - by a 'vertical' sawcut made parallel to the pinion shaft - so a modest diameter gaiter can be slid over the remains of the lump, and properly clamped on to the curved 'waist' below the lump.

Some more photos of the lump and its environs, from all angles, would help.

I see no advantage at all in not greasing the pinion shaft, and encasing it in a properly sealed gaiter. If weather can't get in, there will be no rusting. The part of the pinion shaft below the seal (inside the rack) is made, presumably, of the same steel, and that doesn't rust. (I'm amazed that a chunk of steel capable of being worm-cut, and presumably case-hardened, can suffer such appalling and destructive corrosion.)

All this is, perhaps, one for John on club-xm; his professional expertise was partly in metallurgy.

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Re: C5 X7 Steering Rack - Again!

Post by Stickyfinger » 11 Jun 2018, 22:37

As was mine....mostly materials used inside the human body mind you. :)

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Re: C5 X7 Steering Rack - Again!

Post by xantia_v6 » 12 Jun 2018, 10:31

white exec wrote:
11 Jun 2018, 22:19
(I'm amazed that a chunk of steel capable of being worm-cut, and presumably case-hardened, can suffer such appalling and destructive corrosion.)

A minor technical point, but this piece of steel does not have the pinion teeth cut into it. The shaft is made up of two pieces joined by the torsion spring.

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Re: C5 X7 Steering Rack - Again!

Post by wurlycorner » 12 Jun 2018, 12:11

Yep, they will only have case hardened where the teeth are cut.

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Re: C5 X7 Steering Rack - Again!

Post by white exec » 12 Jun 2018, 12:31

OK, thanks; didn't realise that the shaft was a two-part assembly with springing.
Can the parts be separated?

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Re: C5 X7 Steering Rack - Again!

Post by xantia_v6 » 12 Jun 2018, 12:38

white exec wrote:
12 Jun 2018, 12:31
OK, thanks; didn't realise that the shaft was a two-part assembly with springing.
Can the parts be separated?

I expect so, but it would upset the calibration of the pinion valve, so not a diy excercise.