[Steering & Suspension] 'sem-deformable transverse beam'

[pjbw]

2014 Berlingo VTR diesel. 65,000 miles.
My transverse beam in the rear suspension has long been non-deformable.
I have just turned 80 years old and the road past my front gate has been 're-surfaced'.
It has three ridges at an angle and now even at walking speed it is neck snapping!
Is there any way this beam can be made deformable again ?

[jj9]

Hi,
The B9 has a beam rear axle with coil springs.

I imagine the beam will have been designed to incorporate an amount of torsional flex, hence Citroen marketing it as being semi-deformable.

I can't understand how your axle characteristics could change, was the ride of the vehicle a lot softer than it is now?

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[ffrenchie]

The description is "independent trailing arms with a semi-deformable transverse beam" It sounds like something may have seized on your trailing arms or your springs have broken. Do you load the car heavily at any time ? Drop something in there and see if it frees anything up

[jj9]

Yes, if you look at page 44 of the brochure in the link below they describe the suspension as "independent trailing arm rear suspension".

How can that be, it's a beam axle so that hardly qualifies the trailing arms which are part of the beam as being independent.


The rear axle on the M49 & M59 did have independent trailing arms.


https://www.justcitroen.co.uk/offers/bro...ispace.pdf


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[Matt Haigh]

I think the design of the torsion beam is intended to allow the separate trailing arms to move 'independently' with the connection between the arms acting like an anti-roll bar would on other suspension systems.

[jj9]

I get what you're saying Matt, but the trailing arms on the B9 axle aren't separate they're part of the beam, they are welded to it at each end.

In my opinion I think it's rather misleading of Citroen to describe the B9 rear axle as being "independent trailing arm rear suspension".

The fact that the beam between the trailing arms can Semi Deform (flex a little) doesn't in my book qualify the axle as having independent trailing arm suspension.

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[Matt Haigh]

I understand your point as well but in case of the Berlingo each each rear wheel is controlled by a separate (independent) spring which allows each wheel to rise and fall independently, the torsion-bar performs a number of functions in this set-up including that of an anti-roll bar.
If this is a misrepresentation then its one that could be levelled at several manufacturers.

[jj9]

Are you talking about the B9 axle or the M49 / M59?


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[jj9]

Forget my last post, I just read torsion bar and thought we were on crossed wires.

Yes, your description is I guess how Citroen would market it but in reality it's not true.

If Citroen market the rear axle on the B9 as having independent trailing arms and that is based on the flexibility of the beam that links them, it's very contradictory of them to then state that the beam also acts as an Anti roll bar, as in order to do that it would have to be rigid enough to inhibit independent movement . . . you can't have both.

So no matter how Citroen term it, it's not independent trailing arm suspension, it's a marketing ploy. 


The B9 Rear Axle.

   

[polar]

JJ is correct if its attached its not independent unless it is only attached by an anti roll bar.

Independent beam axle suspension goes back to the Cortina Mk3 and before that was also an independent suspension car that never was.