Air Bags for 200 series

Submitted: Monday, Jan 21, 2013 at 13:25
ThreadID: 100104 Views:1980 Replies:3 FollowUps:1
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Hi all
I have heard of putting air backs in the rear of the 200 cruiser to help with the soft rear end. One guy has just put them in and says it has taken out the body roll and he no longer uses his weight distibution bars towing his 2.6 tonne van, 28ft long, ball weight 260- 300kgs. My question being as anyone else heard of doing this and are there any safety concerns. I would still use my bars, but sounds the way to stop the sag.
Regards
Richard
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Reply By: RobAck - Monday, Jan 21, 2013 at 18:38

Monday, Jan 21, 2013 at 18:38
If you are talking about using something along the lines of a poly air bag they are a spring helper and have no other role. All they are is an adjustable bump stop.

If you mean replacing the rear springs with an adjustable airbag that is a different story but still not the answer

Put simply all springs do is maintain height and shock absorbers or more correctly dampers deal with the pitch and yaw or more correctly bump and rebound of the vehicle which is what causes the wallowing feeling, along with improved sway bars

If you do this then the vehicle will remain "stiff" at all times as the suspension is fixed at its configuration

There is considerable information regarding the benefits of weight distribution hitches and one key issue that is not understood is they actually move the down ball weight forward, which is their role, to the front wheels so the towing weight is more evenly distributed across the towing vehicle for improved safety

RobA
AnswerID: 503087

Reply By: Kyle H - Monday, Jan 21, 2013 at 19:58

Monday, Jan 21, 2013 at 19:58
I have Firestone airbags on my 200 series that I purchased from the Michigan Spring company delivered for $160 a couple of years ago.
They are for levelling your truck when you put extra weight in it. They are by no means a substitute for a WDH particularly towing a heavy van.
Basically you load the truck then pump the rear airbags up to the normal drive height, then you connect the van and WDH which should be tensioned to give again the normal ride height.
AnswerID: 503094

Reply By: splits - Monday, Jan 21, 2013 at 23:48

Monday, Jan 21, 2013 at 23:48
Richard

The golden rule with suspensions is don't change anything unless you fully understand how it works in the first place and what your changes are going to do to it. A 4wd owner may see his rear end way down too low so he goes ahead with alterations while totally focused on getting it back up again. Once he has achieved that he thinks the problem has been solved but what, if any, other problems has he created? He most likely hasn't a clue and is not even aware that it might be possible to create any adverse effects.

A basic rule with suspension design is if you want one end of the car to slide more than the other in corners then you transfer more weight to the outside wheel by stiffening the springs or sway bar. As you increase the weight on the outside tyre, you reduce its traction. That is why they reach a certain point then let go and slide.

Car manufacturers almost always set up the suspension to under steer meaning the front runs out wider in corners than the wheels are actually pointing. The rear sliding out first (over steer) is much more hair raising for the average driver so they rarely design them that way.. Having both ends the same (neutral steering) makes the car more twitchy and needing constant movement of the steering wheel to keep it straight. This can make it tiring to drive.

If you stiffen the rear end with air bags without doing the same to the front, you will most likely change it from an under steering car to neutral steering or even over steering. This can be potentially dangerous when you have hundreds of kilos of weight sitting on a tow ball that is located about a metre behind the axle. In addition to that is the weight of whatever you have in the back of the car. That is a long heavy tail to wag on a car that may now want to slide out rear end first.

That man you mentioned says he has eliminated a lot of body roll. I am not surprised because that is not hard to do. A couple of blocks of wood between the axle and chassis would have done the same thing but what has he done to its handling? Knowing what has happened is even more critical when you consider he has a 28 foot van tagging along behind. It will have a hell of a lot of weight a long way in front of and behind the axles and that will swing the ends around like a pendulum in the right conditions.

The only thing controlling all that energy will be the car's grip on the road and it may not have very much at the back.

Use a WDH on your car. They are levers, not springs. They stick out the back like wheel barrow handles and transfer weight to the front suspension as they lift the rear. Toyota recommends using them above a certain tow ball weight in the handbook of my car. The book in your 200 series will say the same thing.
AnswerID: 503119

Follow Up By: 410 - Tuesday, Jan 22, 2013 at 07:02

Tuesday, Jan 22, 2013 at 07:02
Thankyou to all, that answers my question and i will not change a thing, just try and get another link on my WDH.
Richard
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FollowupID: 779733

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