independent suspension failure on Windsor Rapid

Submitted: Tuesday, Mar 27, 2012 at 22:55
ThreadID: 92827 Views:11119 Replies:5 FollowUps:15
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We have a 2005 Windsor Rapid 472 with independent suspension on a Preston Chassis, and have loved this van so far on our trip around Oz.
But our stay in Tassie has been inadvertently extended due to a breakdown where the suspension suffered a major failure. The trailing arm has cracked completely through on one side near the gusset plate welds, and has begun to do so on the other. Also, the mounts on the chassis have also cracked and come away from the chassis. This has caused both wheels to have negative camber.
Just wondering whether anyone else has had a similar experience with their independent suspension, and what repair was made. Preston Chassis were not overly helpful except to say that their new design was better.
I am inclined to go back to a single axle, mainly for the cost but also for the obvious strength benefits. Does anyone want to talk me out of this decision
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Reply By: GT Campers - Wednesday, Mar 28, 2012 at 10:18

Wednesday, Mar 28, 2012 at 10:18
Fit quality leaf springs and a simple, solid axle. This will be the easiest option (from a cost and labour point of view) and more than likely substantially improve the towing performance of the van, as well as its durability. Independent suspension is a WOTAM on a trailer. It introduces all sorts of problems when used in a trailer situation - such as you have discovered - for absolutley no towing/performance benefit
AnswerID: 481593

Follow Up By: Member - gooble - Wednesday, Mar 28, 2012 at 23:00

Wednesday, Mar 28, 2012 at 23:00
Thanks for your followup, I have to agree with you. I was duped in to thinking that IS is better.
FollowupID: 757016

Follow Up By: Barry 2 - Thursday, Mar 29, 2012 at 01:09

Thursday, Mar 29, 2012 at 01:09
At the risk of appearing to high jack the post !!
I read with interest your reply to Gooble's unfortunate problems.( Hope he finds a cost effective solution to get back on the road )
" Independent suspension is a WOTAM on a trailer "
I am in the process of pounding the pavement in the pursuit of designing a small " Off Road " caravan ( around 14ft ) and thought that Independant suspension was the way to go to combat the zillion of Klm's I intend to do on outback corrugated roads ??
I would appreciate your thoughts.

FollowupID: 757018

Follow Up By: Member - Wamuranman - Thursday, Mar 29, 2012 at 09:04

Thursday, Mar 29, 2012 at 09:04
Yes I'd like for information as well. I have just ordered a new van with trailing arm coil independent suspension (with 8 Gabriel h/d shock absorbers) because my lengthy research identified as this is the most suitable for corrugations. I have a friend with a PhD in mechanical engineering who supports the view that shock absorbers are essential to handle the pounding a chasis/van gets from corrugations.
Gooble, can you post a picture of the damaged suspension?
Was it possible your van was overloaded at any time in use?
WAs it leaf spring or coil independent suspension?
What brand of independent suspension was it?
I am just interested to add to my knowledge base, thats all.

Hope all goes well for you in the new set up

FollowupID: 757028

Follow Up By: Member - gooble - Thursday, Mar 29, 2012 at 11:03

Thursday, Mar 29, 2012 at 11:03
I want there to be discussion on independent suspension, as I think that it is falsely promoted to be a more robust system for rough roads. Wamuranman, I was led to believe the same...
The failure has obviously been caused by cyclic loading. There are cracks forming on both the trailing arms around where their are welds for the reinforcing plates, and the mounts to the chassis where the trailing arms attach.
This suspension system was manufactured by but is no longer used by Preston apparently, it was coupled with leaf springs and shock absorber. The system looks robust
We have had the van only 6 months and 15000kms, and taken it on a few dirt and rough roads, but not many with long corrugations. Tyre pressures have always been adjusted accordingly, as has speed. We have had the van weighed in, and we are on par with GVM. We are unsure of the previous history regarding this or it's use, and didn't really inspect the suspension that closely when we bought it.
I am just putting it out there to people to do this check, especially if it is an off-road van as previous owners would have obviously bought it to go off-road.

FollowupID: 757043

Follow Up By: Member - gooble - Thursday, Mar 29, 2012 at 11:06

Thursday, Mar 29, 2012 at 11:06
Image Could Not Be Found
FollowupID: 757044

Follow Up By: Member - Wamuranman - Thursday, Mar 29, 2012 at 11:59

Thursday, Mar 29, 2012 at 11:59
Thanks gooble - thats helpful to understand what has happened.
I agree these are relevant issues that need to be discussed so that all can make informed decisions.
Can you explain in simple terms what you mean by cyclic loading?
FollowupID: 757045

Follow Up By: Member - gooble - Thursday, Mar 29, 2012 at 12:54

Thursday, Mar 29, 2012 at 12:54
if I can put it this way, repeated force on a part or member of a part not too dissimilar to breaking a wire coat hanger by bending back and forward repeatedly until it snaps.
It refers to material fatigue, in this case steel as a result of fluctuating load over time.
Looking at the photo, there is a large distance from the wheel hub back to where the mounts are, causing a significant twisting in the arms. Repeat this twisting thousands of times...
FollowupID: 757046

Reply By: splits - Wednesday, Mar 28, 2012 at 18:24

Wednesday, Mar 28, 2012 at 18:24
It might be worth talking to something like the Dept of Fair Trading or the Motor Trading Association. There has been some discussion recently on Sydney talk back radio about warranty claims after the manufacturer's warranty has expired. It was said very few people are aware of this. It is based on an expectation of service or similar words to that. In other words if it is reasonable to expect a part to last a certain time and it fails well before it then apparently it is legally possible to make a claim and have it repaired under warranty.

Your van's suspension should fall into that category. A car's suspension for example may wear out many rubber bushes and ball joints over its lifetime but the arms and their mounting points should not break. Your problem sounds like a design fault so even though the van is seven years old, you may still have a claim. I would be definitely be looking into it.
AnswerID: 481646

Follow Up By: Member - gooble - Wednesday, Mar 28, 2012 at 22:51

Wednesday, Mar 28, 2012 at 22:51
I do thank you for this advice, I will definitely look into it. We have to keep on moving, and a warranty process would probably take too long unfortunately.
FollowupID: 757015

Follow Up By: PJR (NSW) - Friday, Mar 30, 2012 at 09:46

Friday, Mar 30, 2012 at 09:46
You may have a problem with warranty.

As you stated "We are unsure of the previous history regarding this or it's use" then it would be a bit hard to be able to say that it was never used in a manner for which it was not designed to be used.

FollowupID: 757144

Reply By: Member - gooble - Wednesday, Mar 28, 2012 at 23:06

Wednesday, Mar 28, 2012 at 23:06
We have decided to opt for a solid axle modification by removing and using the original stub axle and hub assembly, welding them onto a solid axle with a new set of springs, longer u bolts and the existing shockers.

If anyone out there is looking at buying a used van with independent suspension, please check the suspension system for wear and cracking. It is obvious, now the components have been removed, that cyclic loads over time have taken their toll on the suspension and chassis.
AnswerID: 481690

Follow Up By: GT Campers - Wednesday, Mar 28, 2012 at 23:26

Wednesday, Mar 28, 2012 at 23:26
Glad you have found your way out of this problem.. may I suggest it may be easier to simply fit a straight axle - with welding/labour etc it should be cheaper and is guaranteed to be straight. Axles (bare) are cheap

Ensure you get Aussie made springs that are matched to the weight of the van

FollowupID: 757017

Reply By: GT Campers - Thursday, Mar 29, 2012 at 13:54

Thursday, Mar 29, 2012 at 13:54
did someone say EIGHT shock absorbers? Are you SERIOUS? Have you ever seen a semi trailer or tourist coach - even those used in remote areas - with eight dampers?

So why would it be a good idea under a caravan?
AnswerID: 481732

Follow Up By: Member - Keith Berg - Thursday, Mar 29, 2012 at 15:21

Thursday, Mar 29, 2012 at 15:21

It might be worth giving the parts a really good clean and crack testing them. You can buy a red dye from welding supply shops, which you spray on and then wipe off with a rag. The dye stays in any cracks that you can't see. Then you spray on a chalky coating, which makes the cracks show up.

Once you're aware of the extent of the cracking, which almost always goes further than you can see, a good engineering shop should be able to grind the cracks out, repair them and then weld on some serious reinforcing to stop it happening again.

No point in chucking the whole suspension out if it can be fixed cheaply.
FollowupID: 757055

Follow Up By: Member - gooble - Friday, Mar 30, 2012 at 00:00

Friday, Mar 30, 2012 at 00:00
Thanks Keith for this information, but the member has cracked completely through, I would not trust any sort of repair. The part shown in the photo is from the opposite side, (photographed for part identification purposes), we had troubles removing the offending part due to twisting of bolts etc.
Since I have seen the extent of cracking, I no longer trust this system of suspension (at least on a single axle).
We have to weigh up the overall cost regarding this, not just of repair. We are a fair way from Hobart, so towing and accomodation while the repairs are being made have been factored in.
FollowupID: 757117

Follow Up By: Member - Keith Berg - Friday, Mar 30, 2012 at 08:36

Friday, Mar 30, 2012 at 08:36
Good call. If the failure is that catastrophic and in evidence on both sides, it's probably a basic design fault. If the goods are not reasonably fit for their intended purpose or not of merchantable quality, you do have a legal claim on the manufacturer. If the thing had let go completely the consequences could be tragic. I'd keep the parts and demand fair compensation from the manufacturer.
Good luck.
FollowupID: 757135

Reply By: ChrisE - Thursday, Mar 29, 2012 at 21:08

Thursday, Mar 29, 2012 at 21:08
GTCampers - sounds like you are biased, is that the sales pitch you use? Our local cars have used IRS for a few years now, wouldn't be using for no benefit. Even new 4bys are going that way. Same benefit in a trailer, doesn't upset the whole trailer if one wheel hits a hole, etc. After having my van now with independent suspension wouldn't go back.

8 shockers totally reasonable, probably a tandem with 2 shocks per wheel. Less chance of cooking them as they do half the work.

Gooble, unfortunately for you it is a bad design and the maker didn't know what they are doing. For starters the friction in between the leaves in a leaf spring set acts as a shock absorber so there are no need for the them in a leaf spring set (this is what my van has). Sounds like the cracks are from stresses caused by the welds. At first clance anyone thinks they can weld up a trailer, but if you don't know what you are doing, it is easy to weld in the wrong spot and induce stress fractures. Like has been suggested I would be getting someone who knows what they are doing to fix and reinforce what you have.

And no I don't sell anything!

AnswerID: 481794

Follow Up By: Member - gooble - Friday, Mar 30, 2012 at 00:16

Friday, Mar 30, 2012 at 00:16
ChrisE, not sure what you are trying to say here. First you say that IS is a great design but mine was not.
The cracks that developed are not from welding stress, they are from metal fatigue resulting from cyclic loading. Preston Chassis make for so many caravan manufacturers, I would have thought they were a reputable company if they are still being used. I have no complaints about the design and make quality of the rest of the van and chassis, just that the IS system has some short comings in this case.
Since I started this topic, I have learnt that IS is not the solution for off-road proofing a caravan, and that if people are looking into buying a 2nd hand van, consider a thorough inspection of the suspension if it is IS.
FollowupID: 757118

Follow Up By: GT Campers - Friday, Mar 30, 2012 at 08:56

Friday, Mar 30, 2012 at 08:56
No not so much biased, experienced...this suspension tech, to me, is kindy stuff.

Unfortunately to many others its'a very stressful, expensive mystery.

Yes you are correct about many cars having independent suspension - all my road, race and tow cars for the last two decades have had indy at at least one end; most of them at both - however the geometry, layout and fabrication quality of suspension under just about every Indy-sprung trailer in Oz is DEPLORABLE.

I offer Exhibit A (the pic in this thread): if that was installed under a new motor vehicle/tow car there would be public outrage so why should we accept it under our caravans/trailers? It's a pile of ****. I know 16 year old kids who are already designing and fabricating product better than that and in this age of CAD etc, for any manufacturer to offer us a suspension arm of such pathetic geometry (ie: there is none) and rudimentary third-world dirt-floor quality is a DISGRACE.

Only one or two manufacturers here do a truly acceptable quality of indy suspension and by that I mean well-considerd geometry, quality of construction, serviceability and appropriate spring rate. And even then, if the tow car has one or two live axles... what is the point? A trailer will always follow its's not racing at Bathurst. Understeer and oversteer and zero-offset steering geometry and toe-in under brakes and camber gain on bump and handling balance front to rear are non-issues with a trailer.

I almost laugh when I see the big bushwacker style caravans - without exception, they bounce and shake thier tow cars on their indy super-duper trailing arm suspension and splimteen shocks... the tyres are flexing yet the suspension is not. Nothing moves. And that is on-road! I have never, never yet seen one of these with effective suspension, yet they cost seriously good money. Even some of these companies' own demo videos (intended, no doubt, to impress us...?) only show 2-3 inches of travel, at best, with wheels lifted off the ground.

I stand by my statement - Indy suspension under any trailer or caravan is a waste of time and money.

Appropriate spring rate and adequate suspension travel is FAR MORE IMPORTANT than if the suspension is beam or indy - and beam actually offers better geometry (among other things) than 99 percent of indy designs.

I certainly hope Gooble gets back on the road ASAP - the best way is with a beam axle and two new leaf springs. That's little more than four welds, two hours' labour and maybe $1000-1500 in new components. Throw everything else in the bin out the back.

With nice supple springs matched to the weight of the caravan and no crook geometry, Gooble's van will tow/track and handle better than it EVER has.

FollowupID: 757138

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