Rear wheel carrier and Drawers should I up rate suspension

Submitted: Friday, May 31, 2013 at 21:50
ThreadID: 102527 Views:1784 Replies:7 FollowUps:3
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Hi I am looking at putting a rear wheel carrier and some draws into the back of my 04 model hilux and am wondering with the extra weight of these items should i also then put heavy duty leafs under for the wieght????
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Reply By: Member - Rosco from way back - Friday, May 31, 2013 at 21:58

Friday, May 31, 2013 at 21:58
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.
AnswerID: 512291

Reply By: Idler Chris - Friday, May 31, 2013 at 23:07

Friday, May 31, 2013 at 23:07
Yes .
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Reply By: Member - John - Saturday, Jun 01, 2013 at 08:10

Saturday, Jun 01, 2013 at 08:10
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.
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Follow Up By: locked hilux - Saturday, Jun 01, 2013 at 17:16

Saturday, Jun 01, 2013 at 17:16
how on earth do auxillary springs work is that like air bags?? the hilux is only leafs, have looked at air bags but think better leafs maybe better
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Reply By: SDG - Saturday, Jun 01, 2013 at 12:13

Saturday, Jun 01, 2013 at 12:13
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.
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Reply By: Member - John - Saturday, Jun 01, 2013 at 22:49

Saturday, Jun 01, 2013 at 22:49
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.
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Reply By: splits - Saturday, Jun 01, 2013 at 23:17

Saturday, Jun 01, 2013 at 23:17
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.
AnswerID: 512348

Follow Up By: locked hilux - Sunday, Jun 02, 2013 at 21:23

Sunday, Jun 02, 2013 at 21:23
Can you tell me then what is the wieght that can go over the rear wheels of a 04 Hilux?? is it able to be improved or not??. I know it is about 700 or 900 kg over the rear. have had close to that springs ok but have used 2 sets of shocks since 04. I wonder what is the best why to carry the weight have looked at draws as they are right between wheels and well the tow bar and rear wheel carrier are just to get the extra tyre out of the back. how much would that stuff wieght loaded, only have standard r16 tyres LT of course though. am on foam cell shocks now and as stated great when loaded but rough when not.
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Follow Up By: splits - Sunday, Jun 02, 2013 at 23:16

Sunday, Jun 02, 2013 at 23:16
What I wrote applies to someone who has weighed down the back of their car with too much weight so they start changing the suspension to compensate. That is when you can run into major problems with handling and reliability. If you change anything on a car, it will affect something else and it may not be for the better. If yours looks ok with your intended load then no problems, there is no need to worry about changing anything.

My handbook lists the maximum rear axle weight as 1570 kg and the front as 1180. That gives a total weight of 2750 but the insurance papers state the GVM is 2500 kg. That makes sense when you weigh the car. It comes in at 1610 kg stock standard with no accessories and a genuine Toyota aluminium tray. If you remove the tray it would be somewhere under 1500 kg. It is supposed to be a one ton ute so if you added around one ton (including the tray, driver and passengers and a full fuel tank) it would weigh 2500 kg.

The weight of my wife and I plus a tow bar and few other odds and ends takes the car up to around 1850 meaning I can put another 650 on the tray. I have only done that once on a short trip around town and the stock suspension looked fine as I would expect seeing it has been designed to carry that weight. I have had it sitting on top of Big Red in the Simpson with an all up weight of 2390 and it performed perfectly. The shocks are stock and the factory fitted rears are still there and going well. Tyres are stock 205 x 16 LT.

As for improving the weight carrying capacity: yes some people do that but the Outback repair centres make a lot of money fixing cracked or bent chassis, cracked diff housings, broken wheel studs and collapsed wheel bearings so that is up to you. My theory is if your car won't carry your intended load then buy one that will.

I hope this gives you some idea of how yours will go. Obviously a dual cab won't carry as much as a single out the back but it will take a lot more in the cabin. The axle loads and GVM are most likely the same.
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Reply By: Member - DingoBlue(WA) - Sunday, Jun 02, 2013 at 22:44

Sunday, Jun 02, 2013 at 22:44
Drawers and leaves!!!
Rather a bottle in front of me than a frontal lobotomy!

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