Difference between hydractive/non hydractive strut tops

[Dommo]

Hi all.

I've got a perfect condition non hydractive strut top in my garage, and I'm not convinced the strut tops I have bought are 100% as the car makes a strange vibrating noise that can be felt throughout the car, and the steering wheel, and almost anything front suspension related. I can film the noise later on today as it does it all the time when you steer to a certain point, even when stationary.

So I was wondering if there is a difference between hydractive and non hydractive strut tops, apart from the thread size entering the strut top. Could I alter the thread size with a drill and tap (or is it a die?)?

Or if this is a common problem, what are the things to check? I've checked the power steering ram and it moves a little but not loads.

Thanks. Dom.

[DHallworth]

Non hydractive stut tops have a tiny 3.5mm feed pipe whereas the hydractive ones have a big one as thick as your thumb.

Not sure if the strut diameter is different or not.

I wouldn't think you could change the size as the hole at the back will vary depending on the size of the pipe. Also the flare on the ends of the pipes will be very different too.

You'd need a matching strut top to do it really.

David.

[CitroJim]

Apart from the pipe hole, I have a feeling Hydractive strut tops may allow a different castor angle although I may be confusing that with the rare non-PAS Xantia tops.

Strut diameters are the same and personally, I see no reason why a competent engineering firm should not be able to bore out and retap the pipe holes to suit hydractive pipes.

The castor angle question needs checking though.

[Dommo]

Well my brother (handily) is a mechanical engineer, so if anyone could do it, he could. I was just not sure if something else internally is different.

You'd assume the non hydractive ones would have more castor due to leaning more than hydractive ones, however the hydractive ones are more 'sporty' and may have more castor for that reason.. It's hard to say!

How would I go about checking the castor angle?

[addo]

At the risk of sounding argumentative, I can't see any reason for PSA changing the castor angle.

A manufacture isn't likely to make those kind of assumptions (about how a car will be driven) based on it having a slightly wider range of suspension controllability. If it were changed, you'd expect "knock on" effects like different tyre wear patterns.

Having not had a Hydractive car, I don't know the pipe end details, other than to say it almost certainly needs reworking on a mill. Setup (fixtures and clamping) would take a few minutes but a skilled machinist wouldn't get a migraine doing the job.

[davoxx]

So did anyone have a go at this?

[CitroJim]

So did anyone have a go at this?

Have a word with Chris570

[xmexclusive]

On XM strut heads the pipe entry has been successfully enlarged to take 10mm pipe.
I supplied the new non hydractive head and Dean got the engineering work done.
The suspension angles between hydractive and non-hydractive are altered by using different angled brackets for the front wishbone.

John

[Deanxm]

yes as John said ive done it, Fred the head drilled it out and fired a thread in for a drink, i would have a bash myself but not on a nos strut top.

D

[Mandrake]

The castor angle on a Xantia is different between power steering models and non power steering models, according to this:

Hard to believe there were ever any non power assisted steering models of the Xantia, but there you are!

As far as I know there are no differences in castor angle between hydractive and non hydractive models, however as well as the feed pipe diameter being different I seem to remember that the taper at the top of the strut shaft where it enters the strut top is at a different angle between hydractive and non hydractive units, thus making it impossible to mate a non hydractive strut top to a hydractive strut and vica versa. Unfortunately I no longer have access to the Citroen service manuals (from which the above scan was taken) to confirm this.

[CitroJim]

Hard to believe there were ever any non power assisted steering models of the Xantia, but there you are!

You can tell the driver of such a car. Has arms like Popeye...

[citroenxm]

I know of someone else who has sucessfully drilled a 3.5mm feed head to larger hydractive for a VSX.. with GREAT sucess! The tops are identical - and being an alloys structure drill easilly...

In hindsight, this points that we do NOT need to keep actual VSX tops for re manufacture, but any number of 3.5mm feed tops will do for either models of cars..

[Dommo]

Hard to believe there were ever any non power assisted steering models of the Xantia, but there you are!

You can tell the driver of such a car. Has arms like Popeye...

And empty cans of spinach on the back seat