Suspension Spring Assistors

[Joseph_5097700]

After some advice.

Tow with a Hyundai Santa Fe and am thinking of adding spring assistors to the rear suspension. Looking at Grayston or MAD springs but there is about £20 difference between the two (Graystons are cheaper). Has anybody used spring assistors and any thoughts on the makers of them?

Thanks in advance.

 

[Tony A.]

Joseph,

Are you fitting spring assistors to compensate for the low nose weight of the Santa Fe ie. 80kg, if so I would say its a mistake, and advise you to load the van correctly to meet the 80kgs limit.

Tony A.

 

[RogerL]

Firstly check that your caravan's noseweight is correct.

Ideally it should be 7% of the caravan's MTPLM but it must NEVER exceed any of the limits set for - the car noseweight, the towbar noseweight (which may be less than the car's limit) or the caravan hitch.

Secondly check that your Santa Fe suspension isn't faulty - broken springs and worn dampers need fixing, not hiding the symptons.

Suspension assisters are normally only needed on softly sprung saloons - most estate-type vehicles normally have stiffer suspension to cope with their expected loads.

If you really need assisters, go for the MAD - they're proper additional springs, not Heath-Robinson blocks like the Grayston. The MAD units are well-engineered and they work - they may cause the car to ride a little tail-high when unladen but the comfort level isn't noticeably changed.

 

[Guest]

One has to take care with any device that is basically a modification to the car. Firstly, unless informed and approved, it will invalidate your insurance and also some of them can alter the handling of the vehicle when solo to quite an extent. Lifting the rear end will effect the braking characteristics. I would suggest getting approval from the manufacturer before fitting any third party device. The device manufacturer will tell you they are fine, but they are not liable for any adverse effects you may experience, you are.

 

[sparkes]

Joseph

I have the MAD air system in the back of the discovery to keep the rear at a level stance when towing. I informed the insurance company who stated that unless the mod is to increase the speed it did not matter as it will have been designed CE standards.

These allow the ride height and stiffness to be adjusted for towing and then the car returned to standard when not towing. Its the best of both worlds and you can pick how much you want them to stiffen up.

Worth every penny,

 

[jacky3]

if you load your van to the max mptlm, ie 1200 kgs it should be 7%of that figure(not exceeding the manufacturers tow ball weight)

7% is actually 7% of what the caravan weighs at that particular time,your caravan could weigh different everytime you pack it,therefore it will not be a constant figure

 

[CliveV]

I would have thought that unless you are towing something truly unusual, then uprated shocks (De-Carbon Gas Shock Absorbers are my favourite) and possibly uprated springs would be a better idea than anything that is an "add-on".

An add on gives an insurance assesser the oportunity to invalidate a claim if it could be proved that the handling may have been compromised. Uprated springs and Shocks should still be on your record with your insurance company but better quality componants would not cause a problem whereas an "add-on" system gives them the opportunity.

Always try to fit Manufacturers upgraded parts rather than bits from "Halfords" or whatever.

The air assist bags Steve mentions are great but the handling and towing on my Discovery was transformed by fitting Gas Shocks - nothing else. The rubber blocks (Grayston) make the springs deform in an odd way and put strain on a particular section of the spring rather than the compression being taken up over the whole thing.

 

[Lutz]

if you load your van to the max mptlm, ie 1200 kgs it should be 7%of that figure(not exceeding the manufacturers tow ball weight)

7% is actually 7% of what the caravan weighs at that particular time,your caravan could weigh different everytime you pack it,therefore it will not be a constant figure

I wouldn't agree with you there, Klarky (see my response of a couple of minutes ago under 'Towcars').

 

[Lutz]

There should be no need for spring assistors specifically for towing as the rear axle load must never exceed the maximum tested and specified by the car manufacturer, regardless of whether the car is fully laden solo or towing.

 

[sparkes]

Surly the maximun axle load has little to do with the suspension used. Manufacturers set their suspension so that a car loaded with driver and passenger are comfortable. If they where to set the suspension so that it was right with a full load then it would be too hard for a single driver on his own.

Assisting the suspension can recover this comfort without having to live with a softer suspension due to the fact the car is full and you have 100kg of tow ball load.

Many manufacturers offer harder suspension if you ask them. I would say it is safer to assist the suspension than to leave it in a bouncy unstable manner that many seem to think is OK

From the MAD site

Suspension is designed to offer optimum comfort when the car is carrying a driver and one or two passengers so, when all the seats are occupied and the boot is loaded, the original suspension is working at the limit of its capabilities. Add towing a trailer or caravan and the car can feel overwhelmed. The result can be reduced ride comfort, poor handling and loss of traction on front wheel drive cars, not to mention a nose up, tail down stance on the road.

 

[Lutz]

I'm not questioning your comments regarding comfort, Steve, but if a manufacturer quotes a maximum rear axle load, then the car must be fit for use at that load without the need for modifications to the suspension. If it isn't there would be a case for recourse against the manufacturer.

 

[Lutz]

Surly the maximun axle load has little to do with the suspension used. Manufacturers set their suspension so that a car loaded with driver and passenger are comfortable. If they where to set the suspension so that it was right with a full load then it would be too hard for a single driver on his own.

Assisting the suspension can recover this comfort without having to live with a softer suspension due to the fact the car is full and you have 100kg of tow ball load.

Many manufacturers offer harder suspension if you ask them. I would say it is safer to assist the suspension than to leave it in a bouncy unstable manner that many seem to think is OK

From the MAD site

Suspension is designed to offer optimum comfort when the car is carrying a driver and one or two passengers so, when all the seats are occupied and the boot is loaded, the original suspension is working at the limit of its capabilities. Add towing a trailer or caravan and the car can feel overwhelmed. The result can be reduced ride comfort, poor handling and loss of traction on front wheel drive cars, not to mention a nose up, tail down stance on the road.

The statement made by MAD, quote: "Add towing a trailer or caravan ...." is incorrect. One cannot add the noseweight to a car which is already on the limit of its GVW. Hence, towing a caravan has nothing to do with maximum suspension loads. The same would apply if the car was solo but fully laden.

 

[sparkes]

lutz

I don't disagree, but the manufacturer has to make a call. if the suspension is good for normal use then its deflection and ability to work at optimum will be changed at max axle load.

My comment was to point out that this deflection and comfort can be corrected with assisters without going over the axle load. I can tow my van without going over or near any of the safety margins, it just does it with comfort and less deflection with the air bags in the springs. On my MG, I had to add some as when it was fully loaded the stabiliser would leave groves in every speed hump. Thats down to the fact its very low before I added a van, not the fact it was overloaded at all

Steve

 

[sparkes]

The statement made by MAD, quote: "Add towing a trailer or caravan ...." is incorrect. One cannot add the noseweight to a car which is already on the limit of its GVW. Hence, towing a caravan has nothing to do with maximum suspension loads. The same would apply if the car was solo but fully laden.

Lutz

I understand what you are saying, but many cars can be loaded with people and luggage to a point that deflects the suspension without going near the GVW.

MAD have not stated that the vehicle is near or on its GVW in the statement so it's not incorrect. But I will agree it misses out some important facts that most people will not consider

Steve

 

[Joseph_5097700]

Thanks very much for all the comment - most welcome.

Just to clarify about the Graystons. It was their springs that I was looking at fitting rather than the rubber blocks.

As far as I am aware I don't have a problem with my cars suspension. As with a lot of 4x4 without self levelling the rear end sags so I was thinking about giving it some help when towing as I am aiming to keep the car for a number of years and want to look after it. Yes it has a 5 year warranty but this does not cover wear and tear.

 

[clivea]

hi,

I use MAD spring assisters ona SAAB 9000 and they have left the solo ride unaffected but the car is less susceptible to pitching when the van is being towed. I never considered them as aids to increase loading or noseweight etc, soley to damp out the nose pitching caused by the van.