Replace rear coil springs on 2019 Y62 Ti patrol with HBMC

[PeterSv]

Hi all
I am having severe rear end sag towing my off-road caravan
I have fitted poly air bags and pumped up to maximum 30psi but rear still sags
I am looking at replacing the rear coils with heavier duty coils standard height or fit a 20-30mm lift possible without affecting the wheel alignment.
Can anyone tell me if this is possible and recommend a cost effective solution
Cheers Pete

[mudnut]

Please head over to the introductions and tell us a bit about yourself and your Patrol.

Are you experienced at towing? What is the towball weight of the trailer?

[PeterSv]

Hi l have done a lot of towing over the years and currently have a 3.5 tonne boat and the off-road caravan would be 3.2 tonne .
I would be guessing that the i ball weight would be close to 350kg when loaded
I have only just bought the caravan recently and have not put it over the weigh bridge. Attached is a photo of my rig
79784i

[mudnut]

You really need to measure the tow ball weight and what you are carrying on board before making decisions about mods.

[the evil twin]

X2 ^^^^

I had an MDC XT12 for 5 years and the ball weight was way more than it should have been when loaded (as is the case with a lot of vans). Once i rejigged what was loaded where and moved the spare wheel carrier out one pin hole it improved drastically.

If you have that much sag with polyairs at 30 PSI methinks the ball weight (or maybe whats in the back of the Vehicle if it is all heavy gear) is the first thing to sort out.

How does it sit with the boat and do you happen to know the ball weight of that?

FWIW... My S4 Y62 drops a tad with my boat (< 200Kg ball) and I don't have bags or WDH.

[PeterSv]

You really need to measure the tow ball weight and what you are carrying on board before making decisions about mods.

You are right. I will to go to a weighbridge check it out
Cheers
Pete

[PeterSv]

The boat sits OK . I am thinking it is a combination of a heavier tow ball weight , carrying over a 100kgs in the rear and possibly the boat weight on top. in the photo the front storage compartments were also loaded up with gear , 3 deep cycle batteries , 2 full 10kg gas bottles and 2 full jerry cans. I am thinking weight redistribution maybe the key.
Cheers
Pete

[the evil twin]

The boat sits OK . I am thinking it is a combination of a heavier tow ball weight , carrying over a 100kgs in the rear and possibly the boat weight on top. in the photo the front storage compartments were also loaded up with gear , 3 deep cycle batteries , 2 full 10kg gas bottles and 2 full jerry cans. I am thinking weight redistribution maybe the key.
Cheers
Pete

Yep... sounds like waay too much weight up front.

FWIW I operate on 5 to 7% trailer weight as ideal tow ball weight and ex-factory with the boot loaded and the tanks full my XT12 was closer to 15%.

The 10% ball weight "rule" oft quoted is american orientated with the massive trailers, tow vehicles and high speeds they do over there.

Euro/Pommy is more relevant to our speeds and vehicles IMHO and they work on more like 5%.

Interesting article here for anyone interested in real world testing etc.
https://www.outbacktravelaustralia.com.au/driving-towing-towing/towball-weight-and-trailer-stability