Suspension Leak, Gaiter looks loose

[demag]

I took the car to an indie today and he got it on the ramp.

It looks to me like the cylinder gaiter is clamped onto the cylinder with the correct gaiter clamp. However the small end that I assume fits to the rod or swivelling ball (?) somehow is just loose and floating about. So although I'm losing lhm I should imagine if the gaiter was clamped at both ends the fluid would return to tank.

The indie said there should be no fluid there anyway only air, but I thought it was normal for the cylinders to leak and the lhm returned to the tank. The ride height looks the same on both sides so the cylinder must be doing its job.

What does the team think? Do I need a new cylinder or not? Or just a new gaiter?
Or does it simply need refixing?

Thanks.

[techmanagain]

It would appear that when the gaiter was disturbed some time previously, that it was not correctly located on the pushrod. If it had been, I don't think there would have been any leak as the shape of the piston rod would seal the small end when the wire rod-retaining clip was fitted.
There will always be some fluid leaking past the piston as it wears; that is why there is a drainage pipe fitted which exits into the large rear axle transverse tube.
This is a virtual copy of the CX rear axle assembly, as are the brakes.

[noz]

Hi demag,

As techman says the last person to assemble the gaiter and rod did not push the gaiter over the end of the rod correctly. If that means that the bits have been dismantled during the cars lifetime then its a very easy thing to put right. Lower the suspension down to the lowest setting and depressurise in the normal way. Lift the car body until the rear wheels are dangling under their own weight. Next, pull out the spring steel clip which holds the rod into the swinging arm. The rod will come free at this point and you'll be able to push the rubber gaiter over the end of the rod. Push the rod back into the hole in the swinging arm and replace the spring clip. Job done.

As you will notice there are two tubes coming from the gaiter. If you were to disassembe the whole thing you would see that there are two rubber o-rings in the strut which seal the pressure against the piston. The first of the plastic leak-off tubes is located between these two o-rings. If the first o-ring passes slightly (which they are designed to do for lubrication purposes) then the fluid is stopped by the second o-ring. The trapped fluid is therefore pushed out of the annular gap and into the tube from where it is returned to the LHM tank.

The second of the two tubes simply vents the concertina part of the gaiter. As the wheel rises and falls in the wheel arch then the gaiter is pushed and pulled like an accordian. As it does so the volume of air changes within it so air is sucked into and blown out of the tube which is then routed to a hole in the circular crossmember as techman says. In theory no fluid should ever come out of the second tube.

And now to blow the theory out the window - My silver 2.5TD has bad leaks in both back struts such that fluid pours out of the circular crossmember at the ends. Its getting in there via the second of the two tubes, one at each side. The reason that there is fluid getting past the second o-ring is that the bores in the struts are so badly worn that they are oval in shape rather than circular. It surprised me slightly but not all of the forces in the strut are axial. There is some side thrust which results in wear of the sidewalls of the cylinder. The piston is stainless but the bores are aluminium so the aluminium wears preferentially.

Hope you're still awake after all of that !!

Cheers

noz

[demag]

Yes thanks both.

Next dumb question

How does the small end of the gaiter fit on the rod, is it simply a push fit or is there some sort of clip holding it?

Thanks.

[DerekW]

Noz,

Thank you for once again adding to my store of knowledge.

[noz]

Hi demag,

The rubber just pushes over the 'swivel' end and locates in the recess. When the rod is secured in the swinging arm the rubber is trapped between the two metal surfaces. The only thing which should be showing past the rubber is approx 5mm of parallel sided cylinder approx 15mm in diameter. The tapered and recessed parts should be hidden from view.

Hi Derek,

Glad I could help. The whole point of club-xm is to share knowledge for the benefit of all. If everyone had everyone else's knowledge can you imagine how well all those XM's would be running out there?

Cheers

noz