Technical Need tips regarding complex suspension set up

[Jonathanhusbil]

Hi,

I have a Fiat Ducato MultiJet 100, 2.2D 2008. Total weight about 2.9 ton.

Front suspension: Original shock absorbers, Saschs (premium) and Lesjöfors springs (camper enforced + 20mm and about 30% stiffer).

Rear suspension: New single (original) leaf springs from lesjöfors + MAD helper springs 350 - 750kg. Original shock absorbers, AL-KO 204683.

Details for the shock absorbers:

Min. length (compressed): 293 mm

Max. length (extended): 444 mm

Stroke length: approx. 151 mm

Piston rod diameter: 15.8 mm

Weight: approx. 2.3 kg


The thing is that i feel that the rear suspension feels somewhat stiff and bouncy at the same time, on lower speeds. In large pot holes on fast speeds, everything is fine.

My guess, is that the rear shock absorbers now need to compromise for the +5cm increase in height the MAD helper springs provided. However, the Lesjöfors springs in front also raised it by 3cm in front and it works just fine with the normal shock absorbers there.

Anyways, i think my best bet is to try and find longer, or enforced rear shock absorbers. I still don't want them to be too stiff, however, as my campervan only weights about 2,8 - 2-9 ton fully. After all, iv'e even had air bags in the past with original shocks + the current al-ko ones and it was the same & even far worse compared to now with the helper springs. Still not perfect now, however. So the last thing to do is to 'upgrade' the shock absorbers in the rear. Maybe this has all the time been an issue, that i've had air bags or helper springs which have raised the campervan rear and despite buying new shock absorbers they were simply too short for the increased height?

I'm considering Bilstein B6 camper advanced shock absorbers. They are, however, the same height as my current just more stiff.

Perhaps KONI camper shock absorbers instead?

Or the finnish brand SV camper shock absorbers?

Or any other tips so i can increase the travel length of the shock absorbers? Preferrably not too expensive as ive already spent so much.

I understand my set up may be quite unique - I guess it can be compared to if anyone has mounted air bags, then discovered they needed to upgrade the rear shock absorbers as well due to the van having been raised, And, if anyone have gone a good result by doing this. In that case, with what shock absorbers?

 

[deejays]

First off, what a lot of people do not understand is that when uprating the front coil spring without fitting a matching damper, the Ducato top mount bush and bearing can be damaged by not only the lack of travel but also the increased rebound force of the spring causing the strut damper to "top-out" on its stops, transferring a large shock load to not only the damper, but also the top mount. There have been recorded cases of this happening. This occurs on the rebound stroke. If fitting stronger springs, then a matched damper will have lower damping valve ratings on the bump stroke and higher damping valve ratings on the rebound, and also a longer travel compared to the original damper. A good example of the correct way to do this is the ALKO uprated spring and damper package for the front.
As to the immediate issue you have with the rear suspension I suggest you contact a Bilstein specialist and give them the details of what you have done and what you require and they should be able to make a set of "special" dampers for you. This is what I did when I fitted supplementary airbags to the rear leaf suspension. Bilstein supplied me with longer travel, matched dampers for the spring/airbag combination.

 

[brokendonkey]

X250 Rear shocks | FIAT Ducato

Hi Team, Can you help me with a part number please? I have a X250 2007 3.0 camper van (van conversion). The rear shocks are tired, not leaking and are "topping" out when one of the rear wheels goes down into a pothole or big dip in the road surface. This then gives a big thump/bang as the axle...

www.fiatforum.com

this guy suggests that 3 lengths of shocks exist.