towing van/susp upgrade?

Submitted: Tuesday, Jan 24, 2006 at 17:01
ThreadID: 30063 Views:2598 Replies:5 FollowUps:7
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I keep getting told that my 98 L/Cruiser 100 needs a suspension upgrade (not as a result of inspection, just "advice") and better shocks. Now, I've seen it often enough on here so there's obviously room for improvement on the standard factory stuff. I use the car for a moderate amount of moderate off-roading, or more likely dirt roading when I'm trying to get to kayaking or fishing spots and towing my 17 ft van (1600/1700 kg loaded). I use four ride bars and the thing looks pretty level to me. OK the car dips a little bit, and I mean a little bit at the back but tows fine. I've also been told to go for the Hayman Reese setup, but again I'm wondering if it's really necessary. You've got to be a bit picky to see any "dip" at the back. I think it tows fine, but I thought black & white TV was fine before colour came out. I'd be glad to hear from experience.
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Reply By: gaz4 - Tuesday, Jan 24, 2006 at 17:33

Tuesday, Jan 24, 2006 at 17:33
Steve

The thing that decides whether you need to do something about the towing setup isn't whether the L/C looks like it's dipping at the back, it's whether the front is higher with the van on (with the 4 bars connected) than it is with the van off. If the front's higher, then you've lost load from the front axle and therefore steering contact for the front wheels - potentially dangerous. The reason this happens is that the ball weight of the van is well behind the rear axle, and the vehicle tends to pivot around the rear axle when the weight is applied, lifting the front. Think of pushing down on the handles of a wheelbarrow - the front wheel will have less weight on it.

To check this out, find a level place where you can put the L/C and the van; measure the distance front the top of the front wheel arch to the ground with the van disconnected. Then connect the van and the 4 bars and measure the distance again. If it is more than about 10mm or so greater than before (ideally it should be the same or less than before), then you've lost enough weight on the front axle to need something stronger than the 4 bar setup - they are usually only able to cope with about 110kg ball weight and my guess would be that your van is probably 150kg+ on the ball. In that case, I'd suggest using a HR weight distributing hitch - although in really rough terrain you'd need to take the bars off, they don't have enough articulation. But at least you're travelling slowly in those areas so the loss of front wheel weight isn't as serious.

Suspension modifications have no effect on the transfer of weight from the front wheels caused by loading up the towball - they are useful for raising the overall clearance and/or coping with extra load put into the L/C but they can't affect the weight transfer issue.

Hope this helps, or at least provides some food for thought.

Gaz.
AnswerID: 150590

Follow Up By: Steve - Tuesday, Jan 24, 2006 at 17:44

Tuesday, Jan 24, 2006 at 17:44
cheers Gaz. I haven't checked that.

So what you're saying is if the weight is evenly distributed around the 4 wheels there is no need for susp or shocks upgrade? It does make sense and of course ringing Pedders etc, they'll only tell me what they want to tell me.
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FollowupID: 404093

Follow Up By: Member - toohey - Tuesday, Jan 24, 2006 at 19:21

Tuesday, Jan 24, 2006 at 19:21
g'day steve
try packing the van distributing the weight of the stuff you take a bit more to the rear(over the axle)even if you pack it in boxes on the floor,less tow ball weight,hope this helps.
cheerts toohey.
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FollowupID: 404117

Follow Up By: Steve - Tuesday, Jan 24, 2006 at 20:05

Tuesday, Jan 24, 2006 at 20:05
yeah toohey, I do consciously try not to put too much on the towbar although at the same time make sure it's slightly front-heavy. Bit of a balancing act. Must admit I've never gone to the trouble of weighing it - bit of a fiddly excercise - perhaps I should.
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FollowupID: 404134

Follow Up By: Member - toohey - Tuesday, Jan 24, 2006 at 21:56

Tuesday, Jan 24, 2006 at 21:56
steve something else worth considering, fill your water tank most likely it's fitted around about the axle, gives a lower centre of gravity, better stability, most of em' are 65lt so bugger all weight,
cheers toohey
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Reply By: Sand Man (SA) - Tuesday, Jan 24, 2006 at 18:00

Tuesday, Jan 24, 2006 at 18:00
Steve,

Forget towing for the moment.

An upgrade to factory suspension will have you believing you have a new truck.
It will handle and ride noticeably better around town as well as off road.
In addition, a modest lift of 50mm will give you that little bit of extra clearance.

You can achieve this in stages if finance is an issue.

First of all put in a new set of shock absorbers. Something like 41mm gas filled, adjustable OME's, or similar. (Forgive me for mentioning a brand, I'm not necessarily promoting them)
This will give you an immediate improvement in ride and may be all that you desire.
You will even wonder why you hadn't done it before.

If you wish to give more clearance you can then replace your springs with beefier ones and increase the ride height moderately at the same time.

Now include the towing scenario. If your rear suspension feels as if it still drops a little, you can improve this in two ways.
1. Use torsion bars (is this what you mean by ride bars?)
2. Install a set of Polyair Airbags to the rear.

The shock absorbers at least will provide you with the biggest improvement and due to the larger diameter will provide better damping and less fading because they will not overheat as much. You will be looking for corrugated tracks to try them out.
Bill


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AnswerID: 150595

Follow Up By: Steve - Tuesday, Jan 24, 2006 at 18:08

Tuesday, Jan 24, 2006 at 18:08
thanks guys. I'm learning.

btw, cant afford any "lift" in the car because I use my roof rack a lot and I have less than 10mm clearance to get in the garage.
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FollowupID: 404095

Reply By: Rob from Cairns Offroad Training & Tours - Tuesday, Jan 24, 2006 at 19:43

Tuesday, Jan 24, 2006 at 19:43
I just sent my front Bilsteins away to be rebuilt as they had lost their damping after 60 k klms and put the OEs back on. Unbelievable even the stuffed Billys were better than origional. As you guys may have realised from previous posts I am not big on unnecessary accessories. Good suspension under a 3 ton truck is necessary. Cheers Rob
AnswerID: 150620

Follow Up By: Steve - Tuesday, Jan 24, 2006 at 20:06

Tuesday, Jan 24, 2006 at 20:06
yeah, right.
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FollowupID: 404135

Reply By: Muzzgit (WA) - Wednesday, Jan 25, 2006 at 02:47

Wednesday, Jan 25, 2006 at 02:47
Jayco actually recommend puting as much as you can in the car, not the caravan. Anything that is put in the caravan should be central, above the axle.
AnswerID: 150726

Reply By: gaz4 - Wednesday, Jan 25, 2006 at 10:33

Wednesday, Jan 25, 2006 at 10:33
Hi Steve

You've probably guessed by now that this particular issue can arouse quite a few varied responses. Without wanting to go on and on about the various ways of dealing with trailer ball weight, there are a couple of things to bear in mind:

1. for towing stability, the accepted 'rule of thumb' is that 10% of the trailer's loaded weight should be on the towball. So it's OK to adjust ball weight by shifting load, so long as you keep around 10% on the ball;

2. for safety you need to ensure that you don't reduce the road contact of your front wheels, and the measuring approach I described in the first response is the way to do that.

Outside those two principles, anything you do to improve the suspension of the tow vehicle can only be good, but provided it's in good condition it will be OK for towing. My feeling is that for towing, better shocks particularly would be worthwhile - a heavy van on the back tends to make the tow vehicle move up and down more, and this means the shocks are working hard.

One other thing to keep an eye on is the Gross Combined Mass (GCM) of your rig - it's the all-up loaded weight of your L/C (including driver, passengers, fuel and luggage etc) and caravan, and to keep within the law it should not exceed the rating for GCM of your L/C - insurance companies love to find issues like this to avoid payouts in the case of a mishap.

Cheers

Gaz
AnswerID: 150767

Follow Up By: Steve - Wednesday, Jan 25, 2006 at 11:31

Wednesday, Jan 25, 2006 at 11:31
cheers Gaz. i am aware of those other issues but I'm a bit behind the door with shocks/suspension effects. I think I'd need to bring the pet elephant with us to exceed the GCM;) as the van's tare weight is just over 1100kgs and I put as much as poss in the back of the car, which is possibly one of the reasons for it being a little bit low in that area. Think I might lash out on some decent shocks before out winter trip thru W.Qld and maybe later, some poly airbags on the back at least. btw, the car is coming up for 130,000ks and as far as I can see the existing shocks have no branded name on them so I assume they're the factory ones. I bought the car with 112,000 ks on it from an old bloke who used it to take his wife shopping in it, so it hasn't had too much bouncing around until I bought it just over a year ago. Since then it's main wear and tear would be it's towing trips. So if they are the orig shocks, it wouldn't do any harm to renew I suppose. Is there such a thing as an average useful lifespan for shocks?

Regarding insurance payouts, I blew a tyre on the old van at 95kph which dumped one side onto the road after shearing off the wheel studs and rolling off into the bush. The van was written off in a borderline case, in the end mainly due to the fact they couldn't get replacement parts. No questions were asked about condition of tyres or load.
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FollowupID: 404323

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