Bouncing when towing

Hi All,

I've had D4's since Jan 2010 but haven't towed anything of much weight until recently. Previously I was aware of clunk noises and movement which I assumed were just due to the (loose) connecting metal parts of chassis-LR kit-tongue and ball to trailer hitch. Other than that no issue.

I recently hired a twin axel (leaf sprung) Jayco Expanda that weighed about 2 T loaded. I'd changed wheels to my GOE 18s with 285/60/18 Cooper LTZs as I didn't trust the OEM Wranglers on gravel roads. I ran (according to my monitors) at 40 front and 45 back once everything warmed up ... those temps stayed stable regardless of surface or speed. It bounced quite a bit on anything but the best tar surface and my car has only done 40,000Klms ....so I'm not thinking shocks or air springs. It didn't affect the handling at all but was just a different feel to the car unloaded .... which I would have expected.

If that's not supposed to be happening, I'd say the van weight distribution or van suspension system is the issue. I guess unless you own the van you haven't got the option to experiment. At low ks I doubt it's the D4.

Kev.

I tow an AOR Matrix, which has a ball weight of over 250kg and the van is typically around 2300kg. My Disco late 2014 HSE has just clocked up 50k. Bought new, its towed the van less than 10k.

But I have noticed a sort of bouncing. It only happens on concrete roads. I presume its a sort of frequency of the way they pour the concrete roads. As soon as the concrete road goes, the bounce stops. It doesn't happen with every concrete road ... but I think concrete roads seem to have regular patterns of ridges or panels of flat and then another panel of flat - maybe the frequency is defined by a load of concrete. I don't know how they pour concrete roads.

But it shows that a Disco can get a sort of oscillation when towing. Speed doesn't seem to change the oscillation much either - but I have not really tested that.

I don't have LLams but if I did, I would play with the heights to see if that would make a difference - maybe lower the vehicle a bit ...

AOR say you need weight on the tow bar to ensure safe towing. 180kg on a 2500kg van doesn't fit AOR's formula - but I don't think the van is the cause, since mine sort of oscillates on several concrete roads.

If its happening on bitumen roads, I would be quite annoyed. Maybe tyre pressures would help, but somehow I doubt it.

I'm going to put a roo bar on my D4 - that might change the issue on concrete roads - but once again, I doubt it.

This may be totally off target, but are your trailer brakes working OK? If not, the trailer could be pushing the vehicle.

Quote:

---

Originally Posted by DiscoMick

This may be totally off target, but are your trailer brakes working OK? If not, the trailer could be pushing the vehicle.

---

Wouldn't that only occur if you were braking but not in the cruise?

Whilst it could be Disco related I'd be investigating the Jayco suspension with interest. Literature outlines this van has 'new' Jtech designed suspension. Is it any good / why invent something to solve what exactly; when there are plenty of existing solutions?

I guess you could try using a mates tow vehicle and see what the van does. It's also interesting following vans, as you get quite a different perspective for whats going on.

Its just another trailing arm setup,, but with a new name,, [bighmmm]

Hi

I have a 2011 D4SE and use it to tow a 3.05 tonne 24 foot full size dual axel van. have been around Australia through the middle and even on the boat to 6 weeks in Tassie. I often use the airbag lowering and raising to hitch and un hitch which often gets looks and comments. I also tow a 14 foot dual axle car trailer on a regular basis.
Even after 270,000KM I don't see a problem with my shocks and haven't experienced any bouncing.
we do have a hefty ball weight often 300kg weighed at a weighing station. I do try to run 10% ball weight. it is industry standard.

perhaps before spending money on shocks it would be worthwhile loading u the front of the van. maybe a couple of drums of water on the a frame?????.... in a safe manner of course

just a thought. good luck

cheers
will

Have been towing for quite a few years with both my old D4 and my current one ( 2013 with now 130,000 Km on the clock ) a double Jet Ski trailer with 2 x Ski's, a Jayco Swan ( with J Tech ) and now a 22 ft Jayco Starcraft ( with J Tech )

never had the bounce thing, I do get the occasionally sway with the big Starcraft if you overcook a corner by going to quick ( my fault, not the D4 or Caravan ), I would be seriously looking at how your weight in the van is loaded, I doubt very much it would be your D4.

I tow with standard D4 towing pack, my ball weight is around 250Kg with my new van, I haven't had it weighed yet fully loaded, but I suspect it will be something around 3.2 ton plus.

good luck
jack

Quote:

---

Originally Posted by wcody01

Hi

. I do try to run 10% ball weight. it is industry standard.

cheers
will

---

Yep,, the Caravan Industry standard,,

what does my mate have on his tag line??,,

tell a big lie, tell it often, advertise the **** out of it, and people will believe it,,


remember,, they dont build these things to tow---
they build them to make the centrefold of "Home Beautifull"
and then they just bolt 4 wheels on anywhere--
( oh yes they do-- to adhere to your 10 thing,,)

I'd love to read your Technical papers for 10%,,

Love to..

and the worse thing about the stupid 10% rule?
They dont tell you its the MAXIMUM !!!!

no one EVER-ANYWHERE say 12% is ok,,