motor home air suppesinon

[donemyheadin]

i have a 2015 autotrail 634 apache was thinking of fitting the dunlop air ride suppesinon kit is it any good and will it cut the bad noise down any help on this matter would be greatly appreciated thanks

[Tracker]

I fitted the Dunlop system to a 2009 Cheyenne 640 as part of uprating the payload and it did soften the ride a bit but as expected made no difference to any noise levels, not that I ever expected it to.

Can you clarify what you mean by 'bad noise'?

My kit came from Marcle leisure and was very easy to fit myself.

[Keithl]

I have also fitted a Dunlop system and, like Tracker, also from Marcle Leisure but I fitted to improve handling and I can't say it made any difference to noise. The only other difference is our AT is on a MB Sprinter chassis and not a Fiat.

 

As a question to try and understand your 'bad noise' what tyre pressures are you running at?

 

Keith.

 

PS And welcome to the forum.

[Derek Uzzell]

Auto-Trail’s website indicates that a 2015 Apache 634 will be built on a Fiat Ducato ‘light’ chassis with 3800mm wheelbase. The model’s maximum gross weight will be 3500kg (or optionally 3650kg) and the mass in running order is given as 3235kg. The vehicle’s overall height is 3.10m and its overall length is 7.09m. From those data, the Apache 634 is built on the same Ducato ‘light’ chassis as my Rapido 640F, except the Apache is higher, longer and heavier when ‘empty’. There is one other difference (and this may be significant) - my Rapido has 215/70 R15CP tyres whereas the Apache has 225/75 R16CP tyres.

 

If the “bad noise” relates to rattles from the oven, furniture, etc. then merely fitting ‘semi-air’ suspension to the rear axle is more likely to make matters worse than improve things. There should be substantial air-gaps between the Apache’s rear axle and the bump-stops above the axle (there certainly is with my Rapido) and inserting air-bellows into the air-gaps will just firm up the rear springing.

 

Keith mentions tyre pressures. I don’t know offhand whether Auto-Trail specifies the tyre pressures that should be used for an Apache 634, but the Ducato Handbook will advise for 225/75 R16CP tyres that the front and rear tyres should be inflated to 5.5bar (80psi).

 

A (relatively) light motorhome based on a current-model Ducato chassis-cab and fitted with 225/75 R16CP tyres inflated to 5.5bar will inevitably have a firm ride and it should be anticipated that anything inside the vehicle that can rattle, creak or squeak will.

[Rayjsj]

Derek, I thought that the Bump stops were part of the suspension on Fiat Chassis ? Wasn't there a case of a Sevel based motorhome failing its MOT, as the tester wasn't aware of the fact? It is a bit of a hard ride though, and I would think that air doughnuts would be a bit softer than the bumpstops.

[Derek Uzzell]

It used to be the case with certain Ducato (and Transit) chassis that the ‘bump-stops’ were actually ’spring assisters’ and an integral part of the vehicle’s rear suspension. As these ‘bump-stops’ reached all the way from the chassis to the spring/axle, some motohomes were being failed by MOT testers. (See following link)

 

http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Ducato-X250-rear-leaf-springs-MOT-issues/23529/

 

But Transit-based motorhomes using Ford’s camping-car chassis and motorhomes based on the current X290 camping-car chassis have ‘genuine’ bump-stops (with an air gap between the spring/axle and the end of the bump stop) and the bump-stop should only come into play when the motorhome is so heavily loaded that the axle’s upwards movement causes it to impact on the bump-stop.

 

As there should normally be an air-gap between the bump-stop and the spring/axle, removing the bump-stop and replacing it with an air-bellows must firm up the rear springing, as any air-bellows is going to be more resistant to axle movement than air.

 

If donemyheadin’s Apache currently has no (or very little) air-gap between the bump-stop and the spring/axle then fitting semi-air suspension should help, but otherwise not.

[747]

Check the tyre pressures first. It is not uncommon for vans to leave the Dealerships with 80 psi (5.5 Bar) in all tyres.

 

Maybe someone can tell you the pressures that should be more appropriate.

[Derek Uzzell]

As I said in my posting of 9 February 2016 5:40 PM above, the Owner Handbook for a 2015-model Fiat Ducato advises that 225/75 R16CP tyres (which a 2015 Apache 634 apparently has) be inflated to 5.5bar (80psi) for front and rear tyres. (That’s why motorhome dealerships inflate the tyres to that pressure - it’s not from bloody-mindedness!)

 

Unless Auto-Trail recommends different inflation pressures, reducing the pressures below 5.5bar will be contrary to Fiat’s advice. Weighing the Apache 634 to establish its ‘fully loaded’ axle-weights might well permit the 5.5bar pressures to be safely adjusted downwards, but if the tyres are made by Michelin (as is quite likely given the size) and advice about reduced pressures is sought from Michelin based on weighbridge-measured axle-loadings, Michelin will advise 5.5bar for rear-axle tyres irrespective of the axle-loading. (This is what the ETRTO mandates and Michelin sticks rigidly to that organisation’s guidance.) Michelin will advise on an inflation-pressure appropriate for their tyres when these are fitted to a motorhome’s front axle and weighbridge-measured axle-loadings are provided, but not for rear tyres.

 

What this boils down to is that, if a motorhome is fitted with Michelin ‘camping-car’ tyres (as 225/16 R16CP tyres are) and running these at 5.5bar results in a harsh ride and a good deal of noise in the motorhome’s interior (which is a fair bet will be the case) the motorhome owner must be prepared to ignore Michelin’s advice if he/she decides to address the ride/noise problem by using lower rear-tyre pressures.

 

(I don’t know if 2015 Auto-Trail motorhomes have a TPMS system, but if so that would be another thing to bear in mind if tyre-pressures are to be reduced significantly from the Ducato Owner Handbook’s recommendations.)