OME is not always a guide to what is suitable and good for stated purpose (and implied use!), as (say) problems with diesel engines and in fitting towbars to some vehicles have indicated. After denying any problems existed despite many proved examples of failure, one vehicle manufacturer 'fixed' its modern diesel engine by raising the fill level mark on the engine oil dipstick!

Cynics say that some vehicle manufacturers can be cheaper by having the public do the QA for them.

A vehicle purchase is often the second highest expenditure of many ordinary folk. It pays to err on the side of caution. Maybe that includes loading the vehicle under spec limits and doing the same with unit to be towed.

That is where posters like Kiwi-as do us all a service, reminding us to stay withing the hopeful limits of manufacturers who are trying to make profits in a highly competitive world.

In modern sedans, in stress areas they are made of high tensile for strength [obviously] but also weight saving..
Also helps create crumple zones .. These Ute style cabs are much like convertible cars.. With out the roof there's NO box section for support..

This tech has not crossed over to light trucks yet !!
All the stress is on the chassis rails.. Seen double axle utes which not only look much better !! Drive way better also..
Spreading weight way better.. Trouble is people want the total package off the showroom floor !! Its not going to happen..

-- Edited by Aus-Kiwi on Sunday 3rd of November 2013 11:08:11 AM

Too often people are not advised HOW to use air-bags.  I don't recommend their use on a leaf sprung car but if you have them and use them properly then there shouldn't be too much problem.

How often have you heard people say " I loaded my car, hooked up the van then pumped up the airbags, the mudflaps raised 3" from the ground".

WRONG!.  The weight is now being carried almost completely by the bags in that weaker area between the spring shackles.

The correct way is to inflate the bags prior to loading, to the point that the car just STARTS to lift.  Stop!  Enough air.

Now when you load the car and fit the van the weight is evenly spread between 3 points.  

If the sagging is now excessive then fit stronger springs.

To those that suggest that today's cars & 4x4s are not built strong enough, remember the old saying, "any engineer can build a bridge, the best engineer is the one that builds the bridge to do the expected job with the LEAST materials".

Cheers Neil

 

KevKim37 wrote:

---

I have a Toyota LC79 2004 series ute which from new was fitted with Poly Air Bags/Std Rear Springs/HD Tough Dog shocks and loaded from 5000kms on with a GVM of 3.76T. I was running 80 to 90 psi  in the Air Bags towing a 3.4T van until 4yrs later when unloading the ute and dropping the air out of the Airbags the Std springs were bending backwards from failure. So officially upgraded suspension to 3.76T GVM and now only run about 30 to 40psi with new springs. 

This vehicle has done numerous trips off road before the GVM upgrade loaded to approx 3.5 to 3.6 tonne driven to road conditions at the time and yes at times have unexpectedly had it airborne a few times with a good whack from the wife to slow down (luv the dirt driving). The chassis on this vehicle shows no sign whatsoever of bending, cracking or deformation of any type and has done 103000kms and still on the road fully loaded towing our home on wheels.

These D/Cab type vehicles are definitely not designed to carry some of the loads one sees on them, designed as they are without the ability to place most of the heavy loads forward of the "Rear Axle". My brother who is a mechanic off many years at a Nth Qld Toyota dealer has told me of numerous d/cab utes arriving back from Cape York with busted rear axles, housings, bearings and chassis in different brands of vehicles. Most of these vehicles have large canopies fitted with all the good camping gear,some boats on top, and some towing camper trailers ie carrying more weight than what used to be carried or should be. 

Cheers Kev.

---

 Hi Kev

we upgraded springs (sold the Tojo ones from new) all round and new HD shocks and had GVM increased to 3.7 tonnes in 2006 and fitted the Firestones in 2009.

As you know we have a substantial chasis under the LC79 so we wouldn't expect any problems, would we.

Likewise we drive to conditions and with van are right on the GCM also.

We've never needed more than 15 psi in the bags to give us the ride and suspension we need for the weight.

About 122000 k on the clock.

Did you read my post of 31/10 on this thread?

-- Edited by Baz421 on Wednesday 6th of November 2013 09:06:20 PM