Wednesday, Aug 07, 2019 at 12:29
It's interesting to read through some of the States vehicle registration authorities requirements for GVM upgrades.
S.A.'s requirements are listed below, and they are clearly written and easily understood.
In the case of a GVM upgrade that increases the load rating of the rear axle, beyond the manufacturers original maximum load specification, the following applies in S.A. ... (LVES is Light Vehicle Engineering Signatory)
S.A. - Light vehicle mass re-rating
QUOTE:
"When the GVM upgrade exceeds the original manufacturer’s specified axle load capacity:
This will require an upgrade of the vehicle springs to a higher load rating than the standard springs.
The LVES will assess the suitability of the modified
suspension for the GVM proposed.
The LVES will address the structural adequacy of the vehicle at the higher GVM.
The LVES will address the braking performance at the higher GVM. This will likely require testing of the vehicle at laden mass.
The LVES will assess the axles and
suspension components to cope with the increased loadings beyond the OEM ratings. This will be likely to require detailed engineering analysis addressing stress and fatigue elements.
The LVES will assess the wheel and tyre loading requirements, and if these differ from the OEM tyre placard, then a new placard must be fitted to the vehicle replacing the OEM placard.
In addition to the above requirements, the following criteria may also be specified on the SOR depending on the modifications proposed:
Where the GVM increase is greater than 20%, evidence to confirm the braking system has been tested at a higher GVM including full brake
test report as required by Fact Sheet MR132 Brake system
test procedure, when loaded to the new GVM.
If the vehicle is fitted with any form of Electronic Stability control, evidence will be required that the system has not been affected by an increase in GVM.
A vehicle modified where the total lift (tyres plus
suspension plus body) is more than 50mm beyond the original manufacturer’s standard height will require a Lane Change
Test as required by Fact Sheet MR807."
END QUOTE.
Now, I'm of the opinion, that there's a lot of box-ticking going on here, with these authorised LVES's - much the same as building engineers, in the pocket of major builders, have been box-ticking dodgy new apartments in
Sydney and
Melbourne.
I cannot see where these vehicle engineers (LVES's) have the ability, or are doing the extensive and major testing required, to ensure that modified 4WD vehicle chassis' and axles, have the necessary durability to cope with substantial GVM upgrades.
It would seem to me to be pretty easy, as an engineer, once you acquired the necessary LVES qualification, to become a box ticker for the
suspension installers, without doing major durability testing.
The Govt is merely throwing responsibility onto the LVES's for any structural or durability problems that arise, and the LVES's can simply come back and say the vehicle was being abused.
There does not appear to be a robust enough system in place, whereby LVES's must provide documented strength testing, to back up what they are signing off on.
To my mind, any axle that is uprated in carrying capacity over the manufacturers original load limit, needs to be trussed in a substantial manner, to provide that extra strength and durability. I see no sign of any
suspension upgrade operators doing this.
Cheers, Ron.
AnswerID:
627096
Follow Up By: Member - John - Wednesday, Aug 07, 2019 at 14:37
Wednesday, Aug 07, 2019 at 14:37
Ron, just had my 2002 GU Patrol 4.8 GVM upgraded, the engineer did the brake
test fully loaded, also the rear axle was braced. As you say, "I see no sign of any
suspension upgrade operators doing this",
well ATOC in
Melbourne do and was required by the engineer. I have no idea how the other
suspension places get away with out bracing the diff. I also braced the front diff at the same time, just being prudent.
FollowupID:
901079
Follow Up By: RMD - Wednesday, Aug 07, 2019 at 17:14
Wednesday, Aug 07, 2019 at 17:14
I agree there is a lot of ticking going on and sure full testing and bracing isn't being considered.
The rear axle is simply a piece of steel tube used for a purpose. Lots of similar stressed steel tubes used in our society. Bigger ones on wind turbines fatigue and crack and the whizzy bit has a nasty accident. They are computer analysed for durability but not actually tested unless a giant does a fatigue
test. Rear axle tubes are subject to fatigue testing all their life, go past the limits and the result is obvious.
As
John mentioned above, bracing of the rear axle tube would be a basic requirement if the bearings are deemed to be ok for purpose and over design loads applied.
Someone above mentioned it rides
well and loves it, all good, but we aren't talking about the ride quality as it is a secondary consideration to the unit being able to carry more than designed. anything with longer travel, relatively compliant
suspension suspension for the load is a plus. My 6x4 trailer has done outback work but the
suspension and wheels are not as designed.
FollowupID:
901083