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Post Info TOPIC: rear suspension overload


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rear suspension overload


Hi. I tow a Jayco Journey 17.55-8 with a Triton. Towball mass is about 140kg and tub load about 150kg. Total van mass 2100 kg. Total Triton mass 2300 kg. I noticed on a recent trip that, when coupled up, the Triton rear springs change from convex to concave. The rig tows easily and I have never experienced any sway. The advice to rectify the problem seems to be driven by the product that is being offered. There are three solutions: 1.Additional spring blade(s)  2.Airbags  3.Tow hitch Weight Distribution System. I am not too keen on the additional spring blades because they  would make for a stiff ride whenever I am not towing. Any thoughts/advive would be appreciated.

Regards Bosrob



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sounds like you need to reset or replace your springs
cheers
bkaze

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Increasing rear spring stiffness without doing similar to the front risks a reduction in the designed-in understeer which can have a serious destabilising effect on the vehicle in any emergency situation.
Cheers,
Peter

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nbosrob wrote:

Hi. I tow a Jayco Journey 17.55-8 with a Triton. Towball mass is about 140kg and tub load about 150kg. Total van mass 2100 kg. Total Triton mass 2300 kg. I noticed on a recent trip that, when coupled up, the Triton rear springs change from convex to concave. The rig tows easily and I have never experienced any sway. The advice to rectify the problem seems to be driven by the product that is being offered. There are three solutions: 1.Additional spring blade(s)  2.Airbags  3.Tow hitch Weight Distribution System. I am not too keen on the additional spring blades because they  would make for a stiff ride whenever I am not towing. Any thoughts/advive would be appreciated. 

Regards Bosrob


 Hi Alan....Because of its big TBO (towball overhang,or distance from rear axle to hitch point) the Triton is notorious for bent chassis...think bananas....seriously! Google Bent Tritons or some such and you will see what I am saying.And should never fit airbags to a car that has leaf springs,as you get point loading in the wrong place,which helps to bend the chassis.Airbags do little except make the car look pretty.You are also well below the generally recognised towball weight of 10%,or around 200kg in your case,so you seem to have big problems. As suggested,replacing your springs with a heavier set seems to be the first thing to do,but as Peter says,you must do the front springs as well.And I believe that maximum rear axle load on the Triton is only 1840kg..... more fun.Good luck with your car,and please keep us in the picture.Cheers.



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I agree with the comments regarding the airbags, particularly on the Triton, for all the reasons mentioned. However, I do not necessarily concur with the comments regarding the springs. Yes you can go overboard and change the handling of the vehicle in a detrimental way if the rear springs are set at too high a rate You can set up the rear springs so they are stiff enough for the load you are imposing on them without endangering the cars handling. If it is done properly you can have it set so that without load, the car handles close to normal and without changing the front. Talk to a specialist suspension company like Pedders who do various packages depending on what you are wanting to do. I would stay away from many of the after market 4wd accessories stores who seem only interested in selling you their latest 2 inch lift kit rather than properly approaching the problem.

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Greg 1 wrote:

I agree with the comments regarding the airbags, particularly on the Triton, for all the reasons mentioned. However, I do not necessarily concur with the comments regarding the springs. Yes you can go overboard and change the handling of the vehicle in a detrimental way if the rear springs are set at too high a rate You can set up the rear springs so they are stiff enough for the load you are imposing on them without endangering the cars handling. If it is done properly you can have it set so that without load, the car handles close to normal and without changing the front. Talk to a specialist suspension company like Pedders who do various packages depending on what you are wanting to do. I would stay away from many of the after market 4wd accessories stores who seem only interested in selling you their latest 2 inch lift kit rather than properly approaching the problem.


 Hi Greg...you are,of course,correct in what you say,but I was simply trying to make things easy for Alan. Pedders?...not for me,but certainly a better bet than the aftermarket 4wd shops.What Alan must not do is think that a WDH will help him,as all a WDH does is increase his TBO,increasing his weight problems,as well as promoting instability issues.A WDH does not change ball weight,but simply creates what is effectively a stiff-arm from the front axle,through the hitch point,to the vans axle group. All fine and dandy on a flat surface,but can you even imagine the enormous stresses imposed on the chassis when you drive through dips in the road,and even into some servos,and all the weight is on only two sets of wheels? Cheers.



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post deleted 



-- Edited by AndyCap100 on Monday 1st of July 2019 11:40:27 AM



-- Edited by AndyCap100 on Monday 1st of July 2019 11:51:58 AM

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HI
Goto a place that offers standard height rear springs in differing load ratings at least 3 variations . Job done

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Peter,

Under normal circumstances I would agree about the springs but the Triton is a lightweight with unusually weak rear springs. The suspension is completely inappropriate for a vehicle intended for commercial use, which is why you only ever see them tail way down, even with a fairly light load.



-- Edited by Mr Fuse on Monday 1st of July 2019 12:39:42 PM

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In my opinion the Triton, for any purpose needs heavier rear springs. They don't have to be so stiff as to materially affect your comfort. I would back those with air bags. Just make sure you follow the relevant instructions and always beep a little air in the bags, or risk damaging them.

I'm still in the process of setting up our new tug (Navara) and haven't done the suspension yet but on our previous rig (Pajero) I used a combination of heavy duty springs all around, due to the extra weight of the stuff fitted to the vehicle, and air bags. 5PSI for normal daily use without additional load and 35PSI when towing. That kept the rear height within about 10mm and we never noticed a loss of comfort.



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Hi all. Thanks for the prompt responses and good advice. Glad that the WDH and airbag solutions seem to be generally discarded. I am going to shop around at a few suspension specialists - not many here in Mandurah so will look to the north. Will report back re options when I am done. B rgds



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Sorry, I didn't realise that you are in WA too. Try WA Suspensions if you are not keen on Pedders. They have a good reputation and I know a few who have used them in the past. Stay away from airbags on a leaf sprung vehicle. As stated, they place a large point load right where the chassis is not designed to take it and they act as a rising rate spring over bumps as they compress. They are fine on coil sprung vehicles as they are normally placed where the load is imposed on the spring saddles as in the case of the aforementioned Pajero, and the chassis is designed for load at that point. Contrary to some opinions, WDH's are very good, but not for the purpose that you are wanting them for. Over the years, people started calling them load levellers and trying to use them for correcting poorly laden rigs. Used for what they were originally purposed, that is to place some load back on the front wheels to improve steering and braking, they do very well but must be set up properly. Half the rigs I see on the road have them adjusted up way too far and then you are into the realm of issues that yobarr has indicated above

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Thanks Greg. That makes a lot of sense to me and I will check out WA Suspension and also see what Pedders have to say. I am not going away for a month or so I have time to source a supplier that best suits my needs. rgds Alan



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bosrob wilinson suspensions in bayswater may be worth a look at as well they have been around for years and seem to be well regarded


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boab wrote:

bosrob wilinson suspensions in bayswater may be worth a look at as well they have been around for years and seem to be well regarded


I am from SA, but I thought Bayswater was a suburb of Melbourne.

If so, may be a bit far from WA to have a look. 



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ok so why say you would check out wa suspensions or are they in melbourne as well as perth


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boab wrote:

ok so why say you would check out wa suspensions or are they in melbourne as well as perth


 Sorry if you misunderstood me.

I believe the original poster is from Mandurah in WA, so Bayswater may be a bit far to go.

 



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Bayswater, WA 6053
cheers
blaze

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blaze wrote:

Bayswater, WA 6053
cheers
blaze


 Thanks for that. I stand corrected.



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Often another leaf at the bottom ? Not full length .. It allows std type ride but stops low ride,so it has progressive ride . Firmer springs require firmer shocks also .. Trouble is all these tug vehicles are a little on the light side ? Maybe consider LR / MR. licence ? Far better vehicle ?? Weight and size is the issue !!

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This reply may be a bit late, there is a very highly regarded pedders shop in Mandurah.

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Hi all

Pedders offered new rear springs with a 150kg loading either side ($1450) Using 300kg ($1750) per side would obviously give a very hard ride when not loaded. Another option was a single additional blade on the bottom ($950). WA Suspension suggested airbags for $950. In response to my question re point loading he said one only needs to pump them up to the vehiche unloaded height. If more than that, air bags then assume the role of the spring system and therein lies the danger. I must assume he is correct? By the way, I found Mandurah Pedders to be pretty on the ball with my questions. rgds bosrob



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bosrob wrote:

Hi all

Pedders offered new rear springs with a 150kg loading either side ($1450) Using 300kg ($1750) per side would obviously give a very hard ride when not loaded. Another option was a single additional blade on the bottom ($950). WA Suspension suggested airbags for $950. In response to my question re point loading he said one only needs to pump them up to the vehiche unloaded height. If more than that, air bags then assume the role of the spring system and therein lies the danger. I must assume he is correct? By the way, I found Mandurah Pedders to be pretty on the ball with my questions. rgds bosrob


Some truth there,,, my Firestone airbags give 40lbs or 18kg of support per 1lb of air pressure,,, ie as load applied you get the suspension effect,,, so at say 10lbs pressure I get 400lb or 180 kg of support progressively as air bag is compressed.

There is NO MYSTERY HERE,,, use as required,, and yes you do get a small lift effect.

I use about 6-8lbs of air in LC79 series ute 3,700kg GVM,,, never had a problem in 10 years since fitted.

Obvious problem if you pump up to 90psi you are asking for trouble.

Most common misconception is airbags are made to raise vehicle to compensate for load,,,, not so.



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oBaz421 wrote:

I use about 6-8lbs of air in LC79 series ute 3,700kg GVM,,, never had a problem in 10 years since fitted.

Obvious problem if you pump up to 90psi you are asking for trouble.

Most common misconception is airbags are made to raise vehicle to compensate for load,,,, not so.


Hi Barry.... Whilst it is great to see that you have had good experience with airbags in your 79,I wonder why you would even consider them necessary? I too have 3760kg GVM 79 and can tow a 3500kg ATM van right on GCM of 6800kg....no airbags. I can run 1350kg on the steer,2300kg on the rear axle and 3150kg GTM for GCM of 6800kg....all legal,all safe,with the car almost 16% heavier than the van,and both the car and van dead level.With a chassis barely half as thick as the chassis on a 79,there is no way you would ever put airbags in a Triton.Again,I suggest the OP Google Bent chassis,Triton,and he could then spend a day looking at pictures that may help him understand that Airbags and Tritons are not good mates.....Cheers

As an aside,140kg towball weight is too low for a 2100kg ATM van.

 



-- Edited by yobarr on Monday 8th of July 2019 07:14:14 PM

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I concur. There is no way in hell I would consider airbags on a leaf sprung vehicle and particularly most of the dual cabs on the market. Broken chassis are not just limited to the Triton, and airbags feature prominently in many of the sad tales of woe.

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Peter_n_Margaret wrote:

Increasing rear spring stiffness without doing similar to the front risks a reduction in the designed-in understeer which can have a serious destabilising effect on the vehicle in any emergency situation.
Cheers,
Peter


We still need to drive to conditions . You cant drive with a van on the back like you would with out either . Btw stiffening suspension promotes tighter roll and it will break out or skid if pushed . But your still driving like a idiot to get that far . loaded and unloaded weight makes a difference also . Trouble is if you have to be told ? Some just DONT have experience, retire . But a 4WD and Van and go !  Never done anything like this before !!  Its not as easy as it is on TV !  Like the Castle . Its the feeling , seat of the pants when driving !! Some are just steerers . 



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