Reply With QuoteHave you had your wheels balanced, an out of balanced wheel can show up in funny ways.
cheers
blaze
Hi
Got a new Dunbier trailer under the 6.2m HH. All is good, except when I tow it down the coast it gets up a real vibration when towing it along the concrete part of the highway between about Yatala and Helensvale. Doesn't seem to matter what speed 90-110 and there is no detectable vibration on the bitumen sections at the same speed.
Its not a wheel out of balance vibration, but the vibration seems to occur at the towball, and the whole back of the car vibrates up and down at a lower frequency than the wheels rotating.
Changing the springs would be one rather expensive solution, but I wonder whether changing the winch post and changing the balance of the boat on the trailer would make a difference.
Any thoughts
Whichway
Have you had your wheels balanced, an out of balanced wheel can show up in funny ways.
cheers
blaze
That particular section of concrete road isn't all that smooth is it?
I know what you mean, I feel the vibes too, don't have any probs at the hitch though. Seems worse in the northbound lanes.
What sort of weight do you have on the hitch? dual axle?
Does the trailer tow well, no fish tailing?
Mine's at the upper end of the allowable hitch weight and tows straight as a die, I moved the axle forward 80mm from it's original position (single axle), may even need to come forward further. Your situation might be the reverse?
I have a Dunbier also, not that the brand is the cause, they don't always come set up right for each boat and usually need some tinkering.
regards
Or how old or the tyres...might be starting to delaminate.
A balance may or may not show this up.
The smooth concrete will make the delamination more pronounced because of the smoooth surface.
When I bought my seajay the trailer axle stub bolts were not central to the stub. Probably a few mm out and a close look clearly showed the rim did not spin centrally on the axle. Surprising actually as I've never seen it before, or perhaps never took much notice of something like that.
Dealer was very happy to exchange the wheel stub in a flash.
Made a difference.
Steve
On thinking more about this problem Gelsec could quite possibly be on a winner.
The up and down oscillations (really slow vibrations) could be caused by the joins in the concrete.
A movement of the axle and job might be done.
It's not a side ways movement is it Whichway??
I remember the old concrete road from Murwillumbah to Tweed in the old days and dad's old '64 Chev used to take 4 hours to stop rocking after the trip. We had to loose our sea legs before we could do anything each time after the trip.
Whichway, I know I bring this up all the time, but what tyre pressure you running. Too tight and your trailer won't obsorb the vibration, just transfer it to the tow ball.
Maybe drop it a tad and let the side walls of the tyre take some of the vibration.
It could even be the tred pattern of the actual wheels conflicting with that rough sort of road on the highway.
I mean its a great highway now but it isn't the smoothest of rides compared to say a bitumen road.
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Show me the Snapper!
I don't know who you could speak to but it maybe a harmonic vibration.
Old Peugeot 505 wagons had this problem and Peugeot solved the problem by placing 2 varying size rubber blocks that hung off the tailshaft mount and removed the vibration harmonics that would occur at 100km/h.
Also do you have another set of wheels of a different rolling diameter you could try as this would change the range of the vibration.
Good luck
be gentle with tyre pressure changes. you don't need much, just a few psi can have a huge change. I run mine at 35psi(max stated on sidewall) with no probs. anyless than 32psi and the sidewalls flex too much. The flex is a vital part of the suspension setup, I'd say half the (boat on) travel in the suspension is tyre wall flex. Thats why the thing bounces around wildly if you take the trailer for a drive without the boat on. without the weight, the tyre won't flex much and the trailer (which most are just sprung without any shock absorbers) will bounce like a rubber ball.
Multi spring suspensions are partially damped by the friction between the spring leaves. A lot of smaller boat trailers have the single leaf setup which means no damping at all.
cheers, roo.
I'm with 4x4Frog on this one, concrete roads are cast in relatively small sections with expansion joints that can set up a vibration at the right speed. Both my trailers, (9inch and 13inch wheels) will set a harmonic on concrete roads. The worst section I've found is the extension of Bermuda Dr, between Reedy Creek Rd and the highway on the Southern Gold Coast. I've taken to going the long way around when towing - it sets the whole rear of the car bucking and I don't like the idea of the drawbar flexing like that, nevermind the poor old boat riding on top.
i had a prob with a car float that that use to bouce the back of the car in a hypnotic rythem (good for making people car sick) only on the freeway to sydney concrete
had to modify the trailer to move more wieght to the downward force on the tow bar
as the trailer was hiting the the ridges and the wieght was being lifted of the tow ball then settling again
i dont know if this has any reference to your prob but as stated trailers arnt made specfic so a adjustment may be required
i think gelsec is on the money
all the best
gone fishing
I would be a little careful about too much of a drop in tyre pressure. The new trailer will be plated and will specify the pressure for the tyres Dunbier fitted. As you probably know too much tyre flex is going to heat and over time degrade the tyre perhaps even to the stage eventually when there could be a. failure.
That said I know that stretch of road, Bermuda from Reedy Creek to the M1 is a sad case and my trailer sure doesn't like it either but with the weight on the trailer I'm still sticking to the plated pressures and putting ing up with it.
Will be very interested to hear if there is a sure fire solution that won't risk a blow out on a later trip down the road.
Cheers
Chimo
What could go wrong.......................
I think Whichway may have answered his own question . It may only be that section of the roadway that is like that . Try driving over these roads in a truck and you will soon realize that tey are not all the same even though they may look the same. Theres a piece off concrete road south off Brunswick that the contractor should have been made to rip up.
mickc
Hi
Thanks for all of the thoughts.
I rang Dunbier - they suggested tyre pressure should be 35 psi minimum, which I checked one wheel and it was so I will check the rest also.
They also suggested that I check the little screw at the front of the towing hitch with the trailer on the car and check it was tight. I undid the lock nut and it was only finger tight. So I was able to tighten it quite a few turns. I could still get the trailer on and off fairly easily so it's not too tight. If this is the problem, I never would have picked it, because it doesn't sound like a rattle which is what I would have expected if the towing hitch was loose. We'll see tomorrow
Whichway.
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