Rear wheel carrier and Drawers should I up rate suspension

I'd suggest you try it first, but if the L/C 70 series is anything to go by, you will be sorely disappointed and in need of an upgrade.

Yes .

G'day, maybe look at fitting auxillary coils in the rear rather than heavy duty leaves. Much better ride when unloaded and also spreads the load over three points rather than two. Not sure where you are, but Fred's, http://www.freds4wd.com.au/comfort.html, does Qld and some NSW and Outback Suspension, http://www.outbacksuspension.com.au/, in Croydon do Victoria. Maybe worth looking at.

Sorry, can't seem to embed the links.

My old GQ had drawers, dual wheels, and a long range. According to a suspension place when I queried about springs, he said I had standards in it, which were doing a good job, and did not need to upgrade to anything heavier.

Hi, did you have a look at the links? The auxillary coils are fitted between the axle and the chassis, very similar to an air bag, these coils give a very flexible ride and use the leafs as axle locators.

If you have the rear end of a car dragging on the ground then you have a weight distribution problem and changing the suspension design is never a good way to go. You will get the back up again with heavier springs but they will shake your teeth out when empty and, unless you make the same changes to the front as well, you will change the rear weight transfer in corners and most likely make the car prone to going into sudden oversteer if you go into a corner a little too fast.

You may also change the brake performance. The linkage operated proportioning valve on the rear will reduce the pressure to the rear brakes when the car is unloaded or lightly loaded in order to prevent rear wheel lockup. With heavier springs you will have the car sitting up high with reduced brake pressure but with a lot of weight hanging off the back needing higher pressure to help you stop.

I am assuming this car is a dual cab. These cars are so easy to incorrectly load because many people tend to forget they have been designed to carry five heavy people in the front and a weight in the rear that is less than the people. You can't put one or two average size people in the front and take it up to GVM by putting the rest of the weight it is capable of carrying in the rear tub.

If your car is anything like my 03 single cab Lux then the handbook will tell you to use a WDH if you put 90 or more kgs on the tow ball. You are not towing but the weight of your wheels and carrier, plus the draws and whatever you put in them, could be placing 90 kg or more a similar distance behind the axle only this time you can't use a WDH to transfer some of it back to the front. The car is now outside its design limits and it is the fault of the owner, not "crappy" stock suspension as some people will tell you.

Whatever you do, try and avoid putting anything between the axle and the chassis, particularly an air bag. Some people have fitted a coil spring in there. At least it is a linear spring and will keep compressing until the axle reaches the bump rubber but it is still risky. An air bag is exponential. It hardens as it compresses and can become like a rock on severe bumps if its pressure is high enough. This means all that mass you have hanging off the back around 1200 mm behind the axle will slam down with a force far higher that its static weight whenever the wheels drop into a depression in the road. The end of your chassis, that is now sitting up on a progressively hardening air bag and getting reduced support from the springs, will be flexing up and down like a plank with someone bouncing on the end of it. If is just a matter of time until you suffer chassis damage in a situation like that.

Drawers and leaves!!!