550 suspension woes

I'm looking for advice help in fixing up the suspension on my 550 stx. when I bought it the guy had just put a TJM 2inch lift kit on with constant load springs on the front and medium springs on the back. As I don't carry a load ride was harsh and was only good if you carry tools etc in the back. The front was making a noise and decided to check it out so got the guys at Climax suspension in Singleton to have a look.
It turns out TJM newcastle put a sleeve on the strut to get the 2inch lift but it also had the effect of putting to much strain on the top shock mounts and shock shaft creating excess wear making the shocks useless and needing new shock mounts.
Climax suggested a tappered front spring giving 40mm lift up front taking into consideration the front alloy bullbar and softer leaf springs at the back, great I thought this will fix my problem, in go the king springs and off I drive but after about 4 months the front springs have sagged and I've gone back to a harsh ride again.
Is there anyone who has a 550 STX with a 2inch lift that runs around with no load and are happy with their suspension or am I asking to much out of the 550

Tks in advance
Brad
Currently living in the upper hunter valley

Hi Brad,

My 550 has Lovell Struts and Dobinson Coils up front, the rear Has Blue Max 5 +2 with Bilstein Shocks. Genuine 40mm of Lift and a very comfortable Ride. Get in Touch with Zordo. Zordo will help you get the lift and the Comfort.

Cheers

Saggy said:

Hi Brad,

My 550 has Lovell Struts and Dobinson Coils up front, the rear Has Blue Max 5 +2 with Bilstein Shocks. Genuine 40mm of Lift and a very comfortable Ride. Get in Touch with Zordo. Zordo will help you get the lift and the Comfort.

Cheers

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Tks Saggy yeh Zordos name keeps coming up in this forum

Why not go back to standard ? Standard is best.

TomAu said:

Why not go back to standard ? Standard is best.

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For a boat anchor lol.

Once you get the front springs set properly you can forget about that end of the car because the load is fairly constant. I'm not sure I'd have gone tapered or dual-rate coils on the front, I'd just get a decent set of springs to take the load.

Problem with the front end of the D40 is the travel limits imposed by the upper control arms and the angle on the CV. Your upward suspension movement should be restricted to about 45mm - mine's set at 43mm (ARB's Old Man Emu Dakara HD springs, but I have a steel bar + winch up front). You can resolve the limitation with new UCAs (I think Superior Engineering do a set, from memory somewhere around the $1K mark) and if you're trying to make sure your CVs last, you can drop the front diff too.

Up the back is a different kettle of fish. I don't think any of us should be using single-rate simple leaf springs if we're changing loads. Leaf springs are great at not only supporting the car but spreading the load across the chassis at the rear, but they're terrible if they're not rated correctly for the load. Factory leaves are nearly flat and provide a nice, soft ride that makes the Navara feel like a normal car. Load carrying capacity is near zero - and the leaves sag so quickly it's silly. Two bags of cement in the back and you're hitting bump stops.

Upgrade the springs to something not flat or inverted and you've got the structural support you need but a major increase in ride stiffness where bumps just hammer the tail of the car upwards.

Inbetween sit the dual rate leaf spring packs. Again, ARB solved my problem with OME Dakar springs. Under a light load, long leaves that sit almost (not quite) flat give the car a nice smooth and responsive ride. Add some weight and the rear settles onto the additional leaves which give the tail the support it needs with the extra weight. My car does prefer more weight than less - but I chose a heavier leaf pack. You can choose a lighter pack that gives an even better ride when empty and still handles some (not as much) load when carrying stuff.

Shocks are something else. For normal city driving there's not a lot of variation in the shocks, really. They all dampen the up-down motion which is what they're supposed to do. It's when you take them off-road onto corrugations and the like that the good shocks shine and the not-so-good really let you know about their inability to handle. It comes down to what a shock does and how it deals with it.

Shock absorbers are really "motion dampeners". They stop the car from bouncing. They do this by having a shaft inside an oil-filled cylinder that has a plate with holes (valving) that the oil has to squeeze through. The action of squeezing (compressing) the oil causes the oil to heat up, making it thinner, and transfers that heat to the internal components. Plastic components quickly give way, followed by light alloys etc etc. The smaller (narrower) the chamber, the faster it heats up and the slower it can shed that heat.

Enter some basic engineering. Make the shock wider, with stronger components = problem solved. It will naturally hold more oil so there's more fluid to handle the heat and a greater surface area to shed that heat. Any shock with a chamber diameter below 40mm just doesn't cut it when you've got a couple of tonne of ute slamming the axle around on the road.

That's where Tough Dog make their mark on the market. 41mm of chamber and they can handle a lot of abuse. Old Man Emu saw this and went a little better - 43mm (this is what I'm currently using). Neither of these come close to the massive 57mm bore of the ShockWerx shocks from Seldom Seen Engineering (my next shocks when the OMEs fail).

The 550 is well supported (haha!) with options for different suspension but you do have to look at what you're doing with it. For us, we go from lightly loaded around town to carrying fridge + generator + 100L of extra diesel + caravan when touring. Dual rate springs and big bore shocks were the only answer for us, hopefully this helps you find an answer for yours.

happy john said:

For a boat anchor lol.

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+1 factory shocks are just bad the sooner you get rid of them the better.
it all comes down on how you want to use the truck. if you just use it to cruise around town and highways just get 4 bilsteins shocks and suspension is perfect, if you carry weights and offroad use uprated springs.

What Old.Tony said - however if you're going to get after market upper control arms go with the ones from Performance Suspension in QLD. They are about $650, adjustable and awesome.

If you're after a 50 mm lift, the guys at Outback Armour can supply a 'true 50 mm lift' which involves replacing the upper control arms. Otherwise, all the major brands will really only be around the 35-40 mm mark up front.

If you want more than 50 mm and don't want to diff drop, then the max you'll be able to go it 100 mm before the front CV angle says no. Plethora of options available, just up to you which way you want to go.

I hav a dobbinson kit in my 550 and haven't had any issues up front. Only issue is mine sagged in the rear so I hav now put 2 10mm Packers under each side lifting it up 20mm and sits nice now. Wen it was put in I measured it before and after and got 45mm all round.