18' Series My tow vehicle bounces while towing

[Lozza T]

Hi All,
I went to pick up my van yesterday from where it is being stored to take it home in preparation for the Christmas Holiday Trip.
It was only the 2nd time towing the new van but this time I was in the car on my own so I had no family distractions which meant I could really assess how my Triton tows the 2.2 ton (unladen) van.
One thing that is a little concerning is that there is a little bounce. It does not happen all the time. It is more prominent during cruising speed at around 80-90kms and is less noticeable if you are accelerating.
This will definitely annoy the 3 kids and wife during the 3.5hr trip to the Prom.

Theory 1:
Is the tow ball height critical? When I hook the van on, the Triton only drops about 10-15mm. I have upgraded the suspension with Iron Performance Foam Cell and raised the rear about 50mm so I am certain the suspension is fine. However, I think that the tow ball height may need to be raised. It appears that the van is not sitting level while hooked on the van and could possibly be raised 50mm - 100mm to get it closer to level. The fact that the van is sitting lower at the tow ball could this be contributing to the bounce? See photo.....



Therefore would the solution be to buy a new tow hitch that is adjustable to achieve the height required? Like this photo? From Supercheap Auto for $385

Theory 2:
My tyres need balancing. Currently booked in to be done on Tuesday.

Theory 3:
I simply need a weight distribution kit. Prices seem to be from $600 to $1200.
My spec plate on the van states that I have an 'empty ball weight' of 181kg. My Triton has a max towball download of 300kg. Should I be allowing for approx 225kg-250kg?

Does anyone else have a similar vehicle set up?
Any advice would be most appreciative.

 

[bigcol]

first thing
hook it up, and go to the servo and check the tyre pressure
then take it in for the balancing

in that picture - to me - it looks like the Van is level, but the Triton is bum sagging / nose too high
(it could be just the picture as well - so dont shoot me

YES I would suggest a WDH - I think anything over 2t should have one - irrespective of if it "feels" ok

 

[MickL]

Hi mate

I have the exact same car with ultimate suspension and am currently towing a star craft 17.58.3 so similar weight etc. I use a hayman reece WDH and my van feels fine behind the car. I'm not sure if upgrading suspension negates the need for a WDH but I personally wouldn't tow without one even with the suspension done as I think its more about getting the weight back onto the front wheels to assist with steering and braking etc.

Looking at your pic your van seems down at the front and the car seems down at the back and high at the front. Seeing the difference in mine after doing suspension I would say you would want to get the front of the van up a fair bit. One thing to think about is although you only added 50mm height with springs you may have added more when you take into account before the lift the sag in factory springs and weight from extras such as the canopy.... My car came up 90mm in the rear with a 2 inch lift.

I ended up changing the hitch on my WDH from the standard to the hitch that had 160mm adjustment and the van sits pretty much dead level now and seems to tow well.

 

[warren cook]

Hi All,
I went to pick up my van yesterday from where it is being stored to take it home in preparation for the Christmas Holiday Trip.
It was only the 2nd time towing the new van but this time I was in the car on my own so I had no family distractions which meant I could really assess how my Triton tows the 2.2 ton (unladen) van.
One thing that is a little concerning is that there is a little bounce. It does not happen all the time. It is more prominent during cruising speed at around 80-90kms and is less noticeable if you are accelerating.
This will definitely annoy the 3 kids and wife during the 3.5hr trip to the Prom.

Theory 1:
Is the tow ball height critical? When I hook the van on, the Triton only drops about 10-15mm. I have upgraded the suspension with Iron Performance Foam Cell and raised the rear about 50mm so I am certain the suspension is fine. However, I think that the tow ball height may need to be raised. It appears that the van is not sitting level while hooked on the van and could possibly be raised 50mm - 100mm to get it closer to level. The fact that the van is sitting lower at the tow ball could this be contributing to the bounce? See photo.....

View attachment 46659

Therefore would the solution be to buy a new tow hitch that is adjustable to achieve the height required? Like this photo? From Supercheap Auto for $385
View attachment 46662
Theory 2:
My tyres need balancing. Currently booked in to be done on Tuesday.

Theory 3:
I simply need a weight distribution kit. Prices seem to be from $600 to $1200.
My spec plate on the van states that I have an 'empty ball weight' of 181kg. My Triton has a max towball download of 300kg. Should I be allowing for approx 225kg-250kg?

Does anyone else have a similar vehicle set up?
Any advice would be most appreciative.

I would go theory 3 looking at the photo, back end of the truck is Deffo down and van leaning forward too. WDH will sort that straight away and will plant the front end down with force which will help reduce bounce also, not to mention better traction and breaking. It's well worth the money when you think how many $$$ your hauling along.

 

[Lozza T]

Will definitely get the tyres balanced bigcol
Thanks @MickL . Will look into WDH.
Which Hayman Reece WDH do you use? Is it the one rated 275kg?

 

[Tone]

Go with option 3. I'm towing with my second triton (Mq) had an Ml. and wouldn't tow van without a WDH, your triton looks quite low in the rear and this would make the setup so much better and safer.

 

[dagree]

The fact that the van is sitting lower at the tow ball could this be contributing to the bounce?

I think you answered your own question @Lozza T !

Don't want to sound repetitive but I also agree with @bigcol , @MickL , @warren cook and @Tone and go with option 3. If unsure about setting it up take it into a Hayman Reece dealer (If you go the HR option) and get them to set it up as required. It can be a bit hit or miss if you are not sure what is required and they will assist with providing the correct hitch during the process.... Might cost a few extra dollars but well worth it in the long run!

If not getting a WDH setup another option would be the adjustable hitch along with air bags to get the van and triton to within +/- 5mm level to original once hooked up...... But again suggesting to go the WDH when and where you can.

 

[dagree]

Forgot to mention.... Once the WDH system is setup paint the chain link that gets hooked up so you don't have to remember to count the links

 

[Drover]

As previously stated looks like a WDH is required, you will find an adjustable hitch like the pic is part of the deal...The WDH will stop the porpoising you are getting as you tow down the road.
To start off when unladen have your tug on flat ground and measure from centre of hub to bottom of guard at all four wheels, note down the heights then when you load up do it again this will give some base line figures........when you go to hook up your van, measure the height from ground to tow ball then see what the height is with the van hooked on, you will find the front of the tug will probably rise twice as much as the back dropped, when you hook up the WDH use the jockey wheel to raise the van about 75mm (this raise the back of tug as well and makes it easier to hook up chains) then hook up your chains and lower, adjust till you get the front of tug around the height it was before you hooked the van up.......once you have it the rig should be level..................your tug needs to sitting level before you hook up, if it's not then you have a loading problem.

A good rule of thumb is when the van is level and the tug is loaded, the height of the tow ball should be about 25mm higher than the van hitch before you hook up, usually means the load is good.

You can find some second hand WDH sets which make for a great saving.

To improve ride and carrying capacity of your tug springs and shocks need to be done, with upgraded springs and shocks then air bags can be fitted safely but putting them on the OE suspension seems to ask for trouble later on.

 

[Lozza T]

Thanks @warren cook @Tone @dagree @Drover.
Looks like the WDH option is the way to go.

 

[EDT82]

Yeah airbag it mate.. Reason being you can set the center line of gravity through the van and car..(more exact when weights change) Once kids and more load is put in car the rear will lower as in your pic. Causing the bunny hop affect..(to high and causes the front end of car down which can cause braking issues etc..)With air bags it's simple place load in car ( kids luggage fuel etc.) then place van onto tow hitch. The car will lower more.. Adjust airbags up till (as explained earlier post) the car and van level out. I always go just above level.. Hope it helps

 

[dagree]

Adjust airbags up till (as explained earlier post) the car and van level out.

Need to be careful about doing this while van is hooked up..... It is recommended not to inflate the air bags with the extra weight of a van or trailer attached to the vehicle. If doing so it is advisable to either unhook the van or at least take some weight off by raising the van (While still attached) by jacking it up with the jockey wheel.

 

[Bellbirdweb]

Yeah airbag it mate.. Reason being you can set the center line of gravity through the van and car..(more exact when weights change) Once kids and more load is put in car the rear will lower as in your pic. Causing the bunny hop affect..(to high and causes the front end of car down which can cause braking issues etc..)With air bags it's simple place load in car ( kids luggage fuel etc.) then place van onto tow hitch. The car will lower more.. Adjust airbags up till (as explained earlier post) the car and van level out. I always go just above level.. Hope it helps

You should not inflate the bags whilst they are under load.

I have the ability to inflate from within the cab and I have pressure gauges on each bag.

You should pump them up and then attach the van otherwise you might pop them.

 

[Dobbie]

Another check as absolutely no experience in this area.

Min of 5psi when not under load? As in, not towing?

Max of 40psi when need for load?

(I had my airbags installed earlier in the year, ARB, then sold the van so haven't used them as yet...but, hopefully soon...so want to check what the general consensus is)


and....do you use the gauge on the compressor or just a tyre gauge?

 

[bigcol]

Max of 40psi when need for load?

the amount needed for when loaded can vary

I have 12psi in the Patrol
and 15 in the Cruiser........

same van.....

 

[Dobbie]

Gee I'm glad I asked!

Thanks. I'd have blissfully pumped them up further before towing so I'll add extra very gently before I find the best for my setup.

And probably start around 10 as we'll be below 2 ton.....similar to your 16.49.

I'd hate to pop an airbag. It sounds uncomfortable.

 

[Bellbirdweb]

I'd hate to pop an airbag. It sounds uncomfortable.

If pain persists, see your medical professional

 

[Bellbirdweb]

Another check as absolutely no experience in this area.

Min of 5psi when not under load? As in, not towing?

Max of 40psi when need for load?

(I had my airbags installed earlier in the year, ARB, then sold the van so haven't used them as yet...but, hopefully soon...so want to check what the general consensus is)


and....do you use the gauge on the compressor or just a tyre gauge?

Yes 5psi when not loaded, I run mine at 20psi before attaching the van, which jumps up to 23-25 once I attach the van.

Mine are Polyair bags which have a maximum working pressure of 25psi.

According to the instructions I got when they were fitted, it states you should inflate them to 25psi, then attach the load, then reduce the pressure so that the load is level.

This is easy if you have controls in the cab, but quite difficult if you are doing it via the schrader valves, as I found they let the air out too fast and you end up going lower than you want, so I found it simpler just to find the pressure you like and inflate them to that and then attach the load.

 

[Drover]

I wouldn't fit airbags unless I had upgraded the suspension, pumping up the airbags when loaded to get things level means all that weight is concentrated on an area which isn't meant to be load bearing to that degree...................things can sometimes bend.

 

[G Daddy]

I run mine from 12psi to 22psi depending how much weight in the back of the Cruiser. Use a quality tyre gauge, air bags are tee to one inlet.