Front Suspension Modifications
The Mercedes Sprinter is currently the most popular cab/chassis used as a base for motorhomes in Australia. Some motorhome hire fleets are even 100% Mercedes, so this must tell us all something! It is very well finished and certainly has an excellent, world class, ground breaking motor. The Sprinter is an excellent compromise between a car like ride and a truck, and on motorways it is a delight to drive. It truly makes the solid front axle brigade, of old technology vehicles, seem positively prehistoric. However, everything in our view at least, isn't perfection if you happen to have a Luton Peak (cabover) motorhome. The photo below left shows what we feel is a potential problem with Mercedes Sprinters fitted with cab over beds (Luton Peak). We have looked at well over 100 vehicles and those without the Luton Peak have an acceptable 20/25mm of clearance between the bump stop and the wishbone. The photo shows the rubber bump stop touching the wishbone on a laden, but definitely not overloaded vehicle. This effectively means that the suspension travel is limited to the amount the rubber bump stops (suspension travel limiters) can compress. This lack of suspension travel is known in the trade as "push". This translates, according to the suspension experts, that when you hit a bump instead of the suspension absorbing the impact the vehicle "pushes" upwards. All the panel van types we have looked at have absolutely zero problems with lots of clearance. In an email Mercedes claim "For you information we have attached some information on the front suspension as fitted to your vehicle. It is important to note, the component you refer to as a bump stop is actually an auxiliary spring which is designed to be in contact with the suspension wishbone". We have dozens of photos of other vehicles without the Luton Peak, showing a good clearance. Like many others we are concerned at having to drive a vehicle with what feels like, the suspension "bottomed out". It certainly doesn't feel safe on cornering on corrugated/undulating surfaces, as it seems to hop sideways. Most unnerving!! Rather sadly Mercedes charged us $145.00 to tell us that in their view our vehicle was too heavy at the front - they weighed it, but the front axle was NOT over. The sad thing is they weighed it without any load behind the rear axles, so they got a completely wrong answer. In our case both outside bins are located behind (aft) the rear axle. We are extremely vehicle weight conscious, and as we have a free weigh bridge just 5 kms away, we ALWAYS weigh the vehicle before long trips. The photos below show on the right a Sprinter with 72,000 on the clock - note the huge clearance. It has no cabover. The shot on the left shows our current Sprinter with cabover at only 17,000 kms. The bump stop is resting on the wishbone. Mercedes seem to be having a bet each way - in practice the bump stop isn't on the wishbone, but they say in writing that it is designed to rest on the wishbone. We went with Mercedes because it was pointed out to us that they insist that any manufacturer fitting a body to their chassis have the design approved by Mercedes. This also appears in all manuals. If this happens in real life how has our present problem arisen? Their blurb reads in part "Precisely tuned suspension and damping properties are the prerequisites for excellent ride comfort irrespective of the load being carried". Our interpretation of this is they guarantee it will work well fully laden.
The Mercedes Viewpoint
So what does Mercedes have to say about this. Well we
don't get fobbed off easily, and apart from visits to dealers in NSW and Queensland,
there have been 28 emails. Sadly it is a complete stalemate as we write this.
Our current Winnebago was supposed to be the first unit fitted with "motorhome
suspension". Yes the rear suspension is really excellent and performs admirably
at full load. However the front is a huge disappointment. Rather oddly, Mercedes
will give us ZERO information on what the new suspension actually
entailed. After umpteen requests to Winnebago we eventually got a delivery slip
from Tynans Mercedes the selling dealer, stating that "MH suspension fitted".
Sorry, but this is all too vague for us. Mercedes are now not answering emails
and will not give us Germany contact details. They claim that "For
you information we have attached some information on the front suspension as fitted
to your vehicle. It is important to note, the component you refer to as a bump
stop is actually an auxiliary spring which is designed to be in contact with the
suspension wishbone." They enclosed a huge PDF file of a cross section
of the suspension. Interestingly the bump stop is NOT resting on
the wishbone. What bothers us is there are lots of vehicles out there with dual
torsion bars. Why is this? Mercedes will not comment on this either verbally or
in writing. We do 31 RV related websites,so we are indeed fortunate to have a
huge pool of technical people to call on for an opinion. All engineers shown our
vehicle feel that something is not quite right. Interestingly it is strongly rumoured
on several USA boards that the Sprinter is currently being revamped and this could
be the reason for the lack of interest maybe. One site even has a picture of the
2006 model. What we can't understand is why the suspension is not adjustable.
The old VWs had an easy adjustment. The best system to date would appear to be
the ratchets used on most Ivecos. They can even be adjusted without jacking with
a socket wrench.
Casino Village have started regular seminars for motorhomers and caravanners. So far there have been two talks on suspension. At the first one we raised our doubts about the suspension on Sprinters. After the seminar the presenter from Fulcrum inspected our vehicle and several others. We heard nothing more! Well at the next presentation some months later we learned that the chap had toddled off to Germany and had thoroughly researched the problem. It appears that there is a huge aftermarket in Germany. The local Fulcrum agents Carline Exhaust and Suspension then arranged for our vehicle to be measured - Andrew Boyd did this work. This showed that the front suspension was in fact down by 25mm. Their suspicion that the front spring was made of high tech plastic was confirmed. This meant that it cannot be reset as can be sometimes be effectively done with conventional springs.
This will be one of those continuing sagas. Fulcrum are currently looking at bringing the suspension aftermarket kits into Australia from Germany. We will keep you posted on how it all pans out. In the meantime if you have any suspension, muffler or cooling problems we have no hesitation in recommending Carline Exhaust and Suspension, 185 Walker Street, Casino - (02) 6662 6155 or mobile 0411 747 211.