Lowered springs and low profile tyres probably, in combination with a poor weld.
Lowered springs and low profile tyres probably, in combination with a poor weld.
That's scary! We may all be driving around with something like that and not know. Time-bomb!
Vans.... This is the 2nd time round the block, 40 years later! talk about turning back the clock!
They are just such a poor design. All those curves in the rails must create thin spots.
That's not cracked on a weld. It's cracked through the rail and that bracket as well.
My guess is the weld has made the steel brittle - you can see the crack at both welds. The bracket has probably cracked due to the rail flexing as a result of the cracking.
Of the dozens and dozens of these I've pulled apart or fiddled with over the years the only ones I've ever found not cracked have been vehicles with their original front springs and original size or at least original profile front tyres. Every other one I've had has been cracked and has had aftermarket lowered springs fitted at some stage. Gas shocks make them very harsh too, I've always gone for oil shocks as they don't seem to be as tough on the car.
Now it has been found, a thorough inspection, and all the corrective work can be done. A lot of work, but when finished the van will have no issue's.
"Proud To Be An Old Fart".
If you assess a HZ chassis closely you'll find extra steel welded to the lower rearmost control arm attachment bracket. GMH were probably aware of the chassis then bracket cracking and re-inforced the bracket on HZ. HZ chassis steel is also thinner than HQ-HX (or at least HX up to 6/77, later are the same as HZ I think) so maybe of a different grade? Literature says it is to make the chassis lighter.
The grade of steel must have a lot to do with the cracks growing/radiating the way they do. To press out awkward curves like the chassis has out the thickness of steel must cause the cracking. The curves would be thinner on the outside and thicker on the inside and also under tension on the outside and compression on the inside. It has to have some effect on the tensile strength.
Truck chassis don't generally crack and they are usually just two dead straight high tensile channels, not boxed. They take way more abuse and weight loading.
Holden defiantly knew there was a problem as they added those strengthening bars to the outback/country pack.
Blocker make sure that who ever welds it up has done it before and knows what they are doing. Cracks tend to come back if not done properly. Now is the only time to fix it while the chassis is out.
They also added the bars to all HZ commercials - I agree they knew it was an issue.
The cracks will need to be drilled at their ends, the chassis sat level, checked all is right as per the drawings I sent Blocker and then cracks welded with the right equipment (I think it is low hydrogen wire in a Mig?). Blocker i'd be replacing that whole lower control arm bracket, after you've ground the weld out at the cracks it'll be half removed anyway.
Nice discussion.
All is being done with by a knowledgeable chassis guy, we've discussed potential issues - this being one, and worked out plans to rectify/repair.
We will be adding the additional bars to provide some rigidity to the frame, repair the cracks and weld in some kidney plates which have been engineered for this purpose and approved by Regency (SA's vehicle inspection authority).
That's good Blocker, no more chassis drama's. Now with over 30 year's of wear and tear behind it, all the short coming's can be rectified and improved upon.
"Proud To Be An Old Fart".
There are currently 2 users browsing this thread. (0 members and 2 guests)
Posting Permissions
Reply With Quote
Bookmarks