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Suspension for a Dandy Five.

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petethebeer

Posts : 19
Join date : 2013-08-26
Location : Somerset

Suspension for a Dandy Five.

Post by petethebeer on Fri 22 Aug 2014, 9:42 pm

Hello,

Our Dandy Five desperately needs new suspension. The wheels are almost touching the arches when stationary!

I've read various threads on here with people upgrading to 750kg units and I wondered whether this might be a good idea. What I wondered though is does this put the chassis under more stress, since presumably being underweight for a given suspension rating would give a stiffer ride (less shock absorbtion)? Hopefully there are a few people reading this who have taken either route and can give me an idea of the pros and cons.

The other, related (at least in terms of how and when to fix it), problem we have is that the chassis has sagged away from the support points of the suspension and the A-frame, giving the floor a definite hump, and making the lowest sliding doors of the kitchen unit very stiff. The hump is most pronounced from the middle to the back of the trailer, which I think makes sense as this is the largest unsupported section, and very slight from side to side. Actually I think it's only the front the has the side to side bend. I'm fairly sure this has happened as a result of the knackered suspension (It was this low when we bought it, and for who knows how long before that) transferring every shock of the road directly to the trailer, but I suppose it's also possible that someone hit a speed bump too fast. My proposed fix for this is to mount the new suspension via full trailer length beams of box section, stiffening and hopefully straightening the chassis, and bringing us up to modern towing height at the same time. I would work out the details with whoever I got to do the work, as I realise the new beams might want tying in with the a-frame which would make it more involved. As an idea though, does it sound workable?

The reason I mention this in the same post as asking which suspension to use is this: We are about to move back up to Scotland. Once there this is just the sort of job that my Dad is good at, whereas down here it could quickly get expensive! If upgrading to the higher rated suspension doesn't sound like that big an advantage I would probably have new suspension of the original rating fitted before driving up and then get dad to help with the other work over the winter. If we were upgrading to 750kg then I understand that some welding is required anyway (as the mounting plates don't match) in which case I would probably swallow the expense and get the whole lot done at once.

This is a fully insulated five with underfloor heating and not much rust, in good condition apart from this, and which we got for a good price. That's why I'm willing to perservere with what might be fairly severe structural problems, the rest is in good nick.

Any advice anyone can give will be much appreciated.

Thanks
Pete
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: Suspension for a Dandy Five.

Post by Tow Itch on Sat 23 Aug 2014, 3:53 pm

The standard advice is that Ian (Riva Dandy Sales) has always said that the Dandy Chassis was good for 750Kg suspension. As the length of the arms differ from the 500Kg units the mounting points do need relocating. This has been covered before.
As for your concern about higher rated suspension putting greater stress upon the chassis of the Dandy. I can see your point that the mass of the Dandy then represents a lower percentage of the mass that the suspension was designed for however lets look at other cases. A normal trailer pulled by a car has only a small percentage of its maximum weight when unloaded. Maybe these are more rigid than a Dandy? When Dandys were first produced the 4 had an unladen mass of 250Kg  which is 50% of the weight the suspension was designed to cope with. If you have a 5 with an awning then by the time you have loaded a few bits and pieces into it you will be very near, at or over 500Kg. I've never run my Designer onto a weighbridge to confirm this but I'm reasonably confident from what others have reported. So that is running at 66% before addressing the extra weight of the new suspension or steel added.    
In your case though it's addressing what is wrong first. Other than Dandys where the frame has rusted I've limited experience of Dandys that are out of true.
Caz Numbers (Caz1960) did have a concern about if her 6 was out of true but I think it was addressed by re mounting the bed hinges and it was the beds that had slipped out of true not the tub of the Dandy.
A Dandy that was used for European travelling over a variety of road surfaces ended up giving up and the floor buckled.
Myself Cazz (Not the above one) and Wayne looked a Dandy where the frame had distorted. I can't remember if it had rusted through or it had distorted following an accident. The seller had made up a new frame using thicker walled tubing. The Dandy frame is made from a non standard thin walled tube.

I've encountered damp floors that have been springy but never encountered what sounds like a frame that has become banana shaped. I've got a feeling that a fair amount of time will be spent by your Dad working out where the chassis has bent and how to straighten things.
Phoenix has the greatest experience of frame reconstruction but in his case he knew the Dandy to be rotten. Your problem (or your fathers) might be minimising what he deconstructs to find out what is bent.

If you could keep us up to date on this I'm sure many will be interested and it could end up being a reference piece for others.

The other, related (at least in terms of how and when to fix it), problem we have is that the chassis has sagged away from the support points of the suspension and the A-frame, giving the floor a definite hump, and making the lowest sliding doors of the kitchen unit very stiff. The hump is most pronounced from the middle to the back of the trailer, which I think makes sense as this is the largest unsupported section, and very slight from side to side. Actually I think it's only the front the has the side to side bend. I'm fairly sure this has happened as a result of the knackered suspension (It was this low when we bought it, and for who knows how long before that) transferring every shock of the road directly to the trailer, but I suppose it's also possible that someone hit a speed bump too fast
We do have lots of experience of sagged suspension. I think this is a red herring. users are getting by with less than 2" of clearance. Apparently not only does the suspension sag with age it can stiffen up too. I have a 1970s 4 that bounces here there and everywhere. I was most concerned about until speaking to one of the more helpful bods from Indespension. He wasn't bothered at all. Witness marks from the tyres in the wheel arches would be the time to worry.
The hump is most pronounced from the middle to the back of the trailer, which I think makes sense as this is the largest unsupported section, and very slight from side to side
Why is the rear unsupported? The strength comes from the box structure of the frame. The individual tubes are relatively weak. It the 2' whatever between the top and bottom tube that give the chassis its strength.

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I tend to think a rail(s) have rusted through or weld(s) have snapped.

Anyone else?

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On further reflection looking at the base section. I do wonder if something on the lower side has rusted through oo an upper weld has let go and the frame has broken it's back at the axle.
Most curious at what you find.

petethebeer

Posts : 19
Join date : 2013-08-26
Location : Somerset

Re: Suspension for a Dandy Five.

Post by petethebeer on Sun 24 Aug 2014, 9:22 am

Thanks Towitch,

Sounds like 750kg should be fine then.

I got it jacked up this morning, and had a proper look. Mystery solved, but not in a good way! On both sides, the main lengthwise tube that passes under the suspension unit is snapped all the way through, right behind the mounting plate for the suspension. Before getting it jacked up I just couldn't get a view of this, because it really is low on the suspension. My head just didn't fit under the trailer (I do have a big head). All of the rest of the framework is solid, so I perhaps this was caused by an impact rather than by rust.

There are a few people locally who I can ask about this job: a good blacksmith who specialises in security gates (lots of box section!) and has been quite happy to do some fairly odd jobs for me in the past, our regular car mechanic, and a place specialising in trailer and caravan repair- but I suspect they will refuse to weld that close to the wooden floor, which leaves me with having to strip the whole thing. I guess I’ll have to get some quotes and see if this is something we can even afford to fix. I don’t think driving it to Scotland in this condition is an option, and I don’t have much spare time between now and the move.

Another technical question , and apologies if this has already been covered: Assuming we persevere with this, what size of box section would we need to bring us up to modern towing height (combined with 750kg suspension)?

I’ll try to get a photo of the damage later. Currently none of our cameras are cooperating.

Thanks for your help.
Pete
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: Suspension for a Dandy Five.

Post by Tow Itch on Sun 24 Aug 2014, 4:25 pm

Sorry to be so close to the truth. I'd still be curious has anything let go on the top rail unless at the fracture on the bottom rail there were signs of it pancaking. i.e. the broken ends were compressing together.

I'd severely doubt it would tear itself apart on the trip but I presume you would like a temporary repair.

My initial thought is that two pieces of square section tube could temporarily splint the length of the trailer.

Issues: because of the A frame these cant be full length. Not only are we welding metals of different thicknesses but the rails on the Dandy are so thin I doubt we could grind small stitch welds or even tack welds out without damaging the tube.
I'd still look at a temporary repair but I think the splints may have to stay in place. If I had a few strong mates I'd look at flipping the Dandy (as Heat rises) and welding the splints on after applying force to straighten up the Dandy. Accepting that the splints may have to be cut out if the Dandy wasn't exactly straight.

Why not speak to the blacksmith, he will be a better welder than I am. Maybe he has no problem in welding in situ and damping off the wood also might see no problem in cutting out the splints when in Scotland if not straight. Though jacking up the front and rear to straighten out as he best can. It all depends how he sees the job. I'm depending on your blacksmith being a blacksmith and not just some egit knocking up gates or ask the garage but I've seen good garage welders and purveyors of what looked like pigeon poo my last choice would be the caravan repair centre as it's purely a welding job.

You sound sold on a Dandy and so if your dad has time and ability the cheapest fix is properly sorting it together.

There was some post on how high to raise I'll search it out after you resolve to go up north as it might take some time.
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Phoenix
Dandy Expert

Posts : 1435
Join date : 2011-09-07
Location : South Norfolk.

Re: Suspension for a Dandy Five.

Post by Phoenix on Fri 29 Aug 2014, 1:16 am

As a temporary  fix to get you to Scotland Mr Itch's idea of a splint could work.

Tow Itch wrote:Issues: because of the A frame these cant be full length.

Not sure if the A frame would be a problem with yours, Looking at Phoenix's pictures it wouldn't be on her as the A frame doesn't reach the outer chassis rails. Dylan is down the warehouse at the moment so would have to look when we are down there next.

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I would be tempted to weld a short piece of box section on either end of the outer rail that has broken and 2 more either side of the suspension unit. These would all have to be as deep as the suspension units. Then jack up either end to try and get it somewhere near straight, then weld a length of box to them.

A simple way of supporting it if you are worried about getting it to Scotland and your Dads to fix (Mr Itch likes our simple fixes). So long as you are not worried about your floor covering, get a couple of bits of 4" x 2" the length of the trailer put them on the inside of the Dandy either side where convenient . Drill holes through them, the floor and possibly the one from end cross rail or a piece of box section or 4" x 2" bracing the last 2 cross rails and bolt them together. This should stop it breaking its back on your trip up there.

petethebeer

Posts : 19
Join date : 2013-08-26
Location : Somerset

Re: Suspension for a Dandy Five.

Post by petethebeer on Tue 02 Sep 2014, 12:07 pm

Thanks Pheonix and Towitch for your advice and suggestions.

Yes our A-frame is like your's Pheonix, in that it stops short of the side bar. I went to see the blacksmith on Thursday, before ordering the suspension units: He is happy to do it, and isn't even charging all that much. We're going with full length rails underneath with a joining axle in the middle, shifted forward 29mm to accomodate the longer suspension arms. If he can re-route the gas line for the heater using what's there he will, otherwise he'll disconnect for us to sort later.

As you both say, the trailer probably would have made it up to Scotland as it is. What I maybe hadn't made clear though is just how low the old suspension was. After our last trip I realised that the left wheel was actually in constant contact with the arch! Really I think we were lucky it didn't either burst or burn the trailer. I think it was a combination of low suspension with the arch being pulled down by the bend in the trailer. Unloaded I can squeeze my finger tips in there, but not past the first knuckle. So I will be much happier to have it fixed before driving up. Also it's worth getting it done while I'm still near this blacksmith, since I know he's good, and since I already have a lot of other favours to ask of my dad this winter! He's already given up half of his house for us and then once I'm up we have to build a new workshop for me to work in. I suspect I'm going to owe him a lot of boat repairs over the coming years!

The suspension arrived yesterday, so I dropped the trailer round today and if all goes well I should have it back on Thursday. I'll let you know how it goes. I have some "before" photos which I will put up alongside the "after" ones, assuming all goes to plan.

Thanks
Pete
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: Suspension for a Dandy Five.

Post by Tow Itch on Tue 02 Sep 2014, 6:43 pm

Wondered where you had got the 29mm figure from hoping desperately it wasn't from here [You must be registered and logged in to see this link.] as the figure provided is incorrect. Then looked at my own maths which was also wrong. [You must be registered and logged in to see this link.] Did you take the 29mm from John or was it given by Indespension or others?

petethebeer

Posts : 19
Join date : 2013-08-26
Location : Somerset

Re: Suspension for a Dandy Five.

Post by petethebeer on Wed 03 Sep 2014, 9:41 am

Yes I got it from John, in the second thread you linked. Someone else mentioned 28mm a few posts before him as well.

Is this well out? Work should be starting around 1pm today. If we're not sure of the right number we can probably get close by looking at the units. I'll check back here before work starts.

Thanks
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: Suspension for a Dandy Five.

Post by Tow Itch on Wed 03 Sep 2014, 4:53 pm

Sorry to post late. John has practically used 29mm and it worked for him.
We are only talking about 6mm difference which actually gets less as both units are loaded. Just me dotting i's and crossing t's after seeing that my own maths were wrong and then wondering where you got your figure from.

petethebeer

Posts : 19
Join date : 2013-08-26
Location : Somerset

Re: Suspension for a Dandy Five.

Post by petethebeer on Thu 04 Sep 2014, 12:13 pm

Well the job's all done, and I'm delighted with it!

Before and after pictures of the ride height:
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Here's the original break in the frame (this was the same on each side):
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And here's the new suspension and H-shaped subframe:
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The new subframe runs the full length, and is 40mm*60mm section, so the trailer is stronger than it has ever been. The little angled struts you can see are to support the outer section forward of the arch, which had sagged after that weld had gone. As you might see from the photo 29mm offset has left us a little forward of a central position within the arch, although not drastically. The blacksmith has left the priming and painting to me to keep the cost down. The plan is to prime the new work right away, but then leave the underseal until I do the rest of the frame this winter. As you can see the brake cables aren't connected yet: the cables for the old brakes have a different end, so I need to get some new cables. I also need to pad the gas pipe where it passes through the notch in the axle. The trailer now tows slightly nose down unloaded, so should be about flat with every thing in it. The bed legs are still long enough on the level, we'll have to try camping on a slope though and see what happens. Our awning will probably need the height extending too, and we'll definitely need to start carrying a step!

In total the blacksmith only charged me £125 for the work and materials, which is a lot less than I had feared. I can pass on his details, if anyone in the southwest would be interested.

Also, I've kept the parts of the old Brakes and suspension, just in case anyone on here might have a use for them. Anyone?

Thanks for your help! I should have got some knobbly tyres for offroad!
Pete
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Phoenix
Dandy Expert

Posts : 1435
Join date : 2011-09-07
Location : South Norfolk.

Re: Suspension for a Dandy Five.

Post by Phoenix on Thu 04 Sep 2014, 7:24 pm

Looks good, a job well done.

It will give you better ground clearance for your heater too.

Don't leave painting that steel too long, if it gets damp over night you will get surface rust appearing.
I had to get the new panels for my car put into primer as they where and they where stored in a dry warehouse.

petethebeer

Posts : 19
Join date : 2013-08-26
Location : Somerset

Re: Suspension for a Dandy Five.

Post by petethebeer on Fri 05 Sep 2014, 9:23 pm

Will get the primer on asap! Luckily we have a heatwave just now.

The heater was part of the reason I went for 60mm section rather than 50mm (the example I found on here used 50mm). That and the fact that one of my favourite festivals is at the end of several miles of Forestry Commission tracks! I might even be able to tackle those single lane speed bumps now. You never know...
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: Suspension for a Dandy Five.

Post by Tow Itch on Sun 07 Sep 2014, 6:28 pm

The new subframe runs the full length, and is 40mm*60mm section, so the trailer is stronger than it has ever been.
I can't say I'm entirely certain of that if there were damage to any point of what is a space frame chassis other than the bottom rail. Then again why should there be any other damage.
It certainly looks the business and £125 was very reasonable.

As you might see from the photo 29mm offset has left us a little forward of a central position within the arch, although not drastically.
I think the original wheels may have been slightly forward of centre. Don't forget yours will move slightly back once fully loaded or are you already fully loaded?

Also, I've kept the parts of the old Brakes and suspension, just in case anyone on here might have a use for them. Anyone?
Please do keep at least the drums and shoes. Pre 1990 Knott parts are a fortune if available. You could do someone a great favour and make a few pounds on those parts.

As you can see the brake cables aren't connected yet: the cables for the old brakes have a different end, so I need to get some new cables.
Is that just a change in the Knott ends or are the brakes Al-KO ones? Cant quite see from the pictures of the backs.

Makes me realise how little I know for while I can weld reasonably OK I would have no idea on specifying beam size nor on the difference in using the cheaper welded tube or the slightly more expensive cold drawn tube.

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