Cracked Diff housing just outside the Hangers 2016 D Max

The vehicle has had a GVM upgrade and is fiited with ARB old man emu suspension. Is an extra cab with box on the back (vehicle is in my profile pic). In regards to weight, with the big trips we do we are maxed out and generally we utilise the public weighbridge to ensure the GVM is not exceeded.
Tyres are standard 265 70 R17 with original rims.
Tyre pressure was reduced to 28psi.
Gut feel then is a combination of weight, tyre pressure and corrugation / speed.

Just asking the question to see if there was anything inherently wrong with the vehicle model that i did not know about.

GVM increase with standard running gear wonder why they only done half of the job axel and brakes should be included as well maybe even chassis strengthening drive shaft etc. It's an expensive mistake to make getting amatures without engineering what is required first.

Unfortunately lots of people are subject to getting caught out by these off the shelf cheap upgrades.

Tezza.
If you wash the area to see the extent of cracking on both sides and then have the cracks welded and a strengthening web welded above and the 1/3 circle tube plating underneath welded to near the back plate and extending inward to, past and inward, of the spring hanger/ U Bolt points it will provide much greater integrity for a heavy load. No welds around the circumference of the tube, only along the tube. You may have to bend/ reform the lower sides of then U bolts to cater for any additional thickness of the underside strengthening tube.

The cracks are on the outside of the spring pads, not the inside. Anyone who jacks up a vehicle via the diff housing should be nail gunned to the garage wall or similar punitive treatment.

Don't know if it's still the case but Toyota used to show the diff as a rear jacking point on the Prado.

Opps been doing it since 1985 without issues and always placed axel stands under there as well to support the weight when working on vehicles what can happen doing this that we need to be wary of thanks.

Also most mechanics and tyre oulets use trolly jacks under diffs

Guess it depends on the situation/jack etc Batt's. At home with a trolley jack and stands is very different to out bush with a skinny topped windup/hydraulic. Is there also an issue of strength/stress involved with a trolley jack on the diff for a minute or two?

Like to see someone change a tyre on a 4wd using a bottle jack off the chassis or body safely anywhere. Not sure the time factor would play any part had vehicles on stands for weeks .

If you check a vehicle manual for a solid axel jacking position you may find some or maybe all manufacturers disagrees with RMD I wonder why that is ? Not sure where he got his info from or if it's his own idea he come up with.
The GQ patrol manual has pics to show the jacking position under the axel.

Think he was talking specifically diff, not axle housing, which is often a recommended jack point along with chassis rails. I've jacked on the diff (with trolley and stands) many times when I wanted to rotate wheels. Jack and diff are only weight-bearing for a minute or two while I position the stands but his comment did get me thinking.

While it may seem ok, there are two common differential housings, Banjo and Salisbury. The Banjo is a steel unit construction which is integrally welded with the axle tubes. The Salisbury however, has two tubes jammed into a cast differential housing and plug welded in a couple of spots. If you wish to SEE & OBSERVE what the axle housing does by jacking under the differential, place a straight edge across from spring to spring and Mark a line above it in the centre on the diff housing. Now with your over GVM load above, simply jack up under the differential and see what moves. The stress on both axle types is high and is possibly the reason why some Salisbury types have broken welds at the tube entry to the cast housing. I wonder why???????? Still want to jack it up under the diff? I might in an emergency but not as a matter of normality.

EDIT . If you unnoticeably bend the rear axle housing by jacking a loaded vehicle under the diff and BEND IT, you now have the centre line of outer bearings and diff action not in line anymore. That then !Dan's due to the off centre of the drive axles, they will then fatigue and break the splined end off the drive axle OR the outer end will fatigue and fracture. Very similar to running a LandCruiser with loose rear bearings. The axle breaks off the stud flange. Still want to jack up under the diff?

I have Salisbury diffs in the front and rear of my 4wd and always jack under the diffs when needed and never had an issue.

Think I'll stick to what the vehicle manufacturer recommends which is what I have been doing for the past 34yrs regardless of the load. Still I wonder how you jack a 4wd up to change a tyre or pack the wheels if your hung up on a rock etc in the real world.

Batts
Jacking up under the axle tube is what you would normally do, that is what you do isn't it? That is normal and ok. Just jacking centrally under the diff with the centre of the axle subjected to a heavily loaded vehicle is a bit unwise. You wouldn't be jacking up the vehicle out in the bush or when bogged by placing the jack under the diff anyway.
I don't jack under diffs because with a Nissan station wagon I towed a ute on a tandem. The heavy load on wheels made the axle diff centre area bent and lower than the wheel bearings. Result, Negative camber on both back wheels. That was only because of the leverage effect of the wheel around the leaf spring on both sides. If jacked in the middle under diff, the forces to bend the axle tubes at the either side of the salisbury diff would be greatly increased, principle of levers applies there. I straightened it by tying down the axle tube ends and jacking under the Salisbury diff.
When a banjo diff is bent it is hardly noticeable as the bend is not localized as with a Salisbury. Just because people have not had problems or haven't noticed anything doesn't mean it isn't present. They simply find later the spline end or the flange end breaks off and then don't relate it to a bent housing or axle tubes. One thing I had to do during my apprenticeship was make half moon discs which fitted into the bearing area of Salisbury diffs and centred plugs at the wheel bearing ends. Either a visual or tight wire was used to then check all centres were in line. If not, the axle then had to be pressed to make them in line. Nice job to do.

Trolley jack under the diff centre if it allows the vehicle to raise up evenly or tubes if not and bottle jack just under tube.

I wonder if the axel rating is reduced when off road like tow bar ratings are because of the extra stress on them.

Batts - Almost certainly the case. The military reduce off-road axle loadings to 50% of on-highway loadings - and for good reason.

Cheers, Ron.

Tezza

You may be very aware of load, but in no way does a GVM upgrade do anything but provide MORE weight onto the rear axle than the vehicle was designed to tolerate. Yes hard running will have had an effect but you haven't supplied any info about the situation of ride height and running chassis to axle safety clearance or shock absorbers. If others under similar weight have survived and your ride height clearances are reduced there would be a higher risk of breakages especially if the suspension closes up to the max at regular intervals with a heavy load.

Tezza - "GVM upgrade to 3250". There's your problem, right there.

The current Hi Ride D-Max is rated at 3050kg maximum GVM - and as far as I understand, all the "GVM upgrades" are merely heavier springs and shocks - which makes even the current model D-Max overloaded with a 3250kg GVM upgrade - which exceeds the manufacturers maximum permissible total load rating.

As your D-Max is the earlier model with the lighter capacity rear axle, it appears your original maximum GVM would have been 190kg less than the current model, making your original factory GVM, 2860kg.

I fail to understand how your "GVM upgrade" supplier could rate your vehicle to 3250kg, when there is no way Isuzu would approve this level of weight-carrying.

Any engineering operation worth their salt, that is providing GVM upgrades, should be reinforcing the rear axle housing with trusses, to enable the housing to withstand the greater weight - and never exceeding the manufacturers recommended maximum GVM.

Interestingly, the D-Max GVM is not the capacity of the axles added together.

The front axle of the current D-Max is rated at 1350kg, and the rear is rated at 1870kg. Added together, this would make 3220kg.

But Isuzu say the maximum GVM is 3050kg - so it's very obvious it's a mistake to add front and rear axle ratings together to come up with the GVM.

A little more research shows you're actually not alone. Scroll down the following article to the comments, and find the one by Darryl Cross - who has had a D-Max housing fracture after a GVM upgrade - and Isuzu will not even look at his problem.

He provides a contact number if you wish to discuss the problem with him.

D-Max gets a GVM upgrade

What is a little concerning is the comments at the bottom of the article by Aaron Schubert (who wrote the article about his D-Max upgrade) - that Lovells and Pedders are "upgrading" the D-Max front and rear axles with their GVM upgrade kits.

I'd be interested to know how these two companies can offer "upgraded" front and rear axles, that produces a result, that exceeds the manufacturers maximum GVM - without factory permission - which Isuzu will obviously, NOT give to anyone.

A local engineers report approving the GVM upgrade to a level exceeding the manufacturers maximum GVM, is totally and utterly worthless, without factory approval.

MY18 Isuzu D-Max - full specifications

Cheers, Ron.

I am unaware of any GVM upgrade mobs who change the front ball joints to a larger unit to cater for over maximum GVM stated by the maker. Are the front wheel bearings also upgraded somehow?
Same for rear axles, apart from the strength of the axle tube which is the limiting factor here, the bearings are not changed for larger capacity loads either.
At Factory GVM and beyond, ie, supposedly upgraded, the axle tube has to be flexing more than the factory rating causes, ie, causing material compression at the site. I hazard a guess the cracks are just along the spring pad welds where sudden section change is present. The MIG welds may also be slightly undercut into the axle tube surface which WILL definitely cause localized stress and cracking if excessive flex is present.
If nothing is out of alignment, have the cracks welded, Isuzu welded onto the tube too, and also have support webs/gussets welded to the area, plus a long 1/4 arc tubular section welded from near the wheel bearings to half way to the diff. That will provide increased strength and reduce flex with minimal weight addition. You may not have to change the axle assembly at all.
If the vertical plane of both rear wheels is not parallel, best to check that accurately, then either bending to straight before repair or axle housing replacement is needed.

Thanks Bazooka, interesting read..........
Definitely some key learnings from this

Oh look. Airbags!

RHS wheel? Tank and missing wheel shows it is the LHS. Those airbags don't have a large bump rubber, if any, built in, and so any closure of suspension will cause immense sudden stress onto the axle/s, beyond their limit with a heavily laden vehicle.

Note the important words...."heavily laden vehicle"

Overloading....the root of all evil! (and I should know because I'm an expert at it!)

Mind you I do try and toughen the diff housing these days. This was the very first 79 series diff extension prototype that Multidrive Technologies ever did. For what ever reason, strengthening of the diff was neglected. This has since been replaced with the current Multidrive billet axle and custom strengthened rear diff housing...no issues!)

My thinking back at that time with a crack right around the housing just inside the mounting plate was "Thank god for Robin Matthews" :-)

We were having a feed at well 9 few weeks back, when the Dmax was carted past our group with LHS rear wheel missing.

Didn't take a lot of notice as we were having an issue with one of the canopies mounts. Just assumed it was a Triton until corrected by a companion.

Bob

Here is the video from the crew that were traveling with it.
https://youtu.be/Q8G7WDB9QZM

That spring pack is a lot thicker than standard. Looks like a GVM upgrade spring but the ute doesn't look that heavy. Unless all the excess baggage was removed to put it on the trailer. Be interested in the story. Was he towing?

Dont know if they were towing but guessing not.

Think I might buy a old VW beetle, might take all year to get there..BUT!!.

That spring looks flat, which indicates it is heavily loaded, unless the spring shackle has been used to tie the vehicle to the trailer.

Macca.

Ivan - Is that a L/Cruiser 70 series front axle?
It could have already done quite a substantial amount of kays, and been a bit tired.

Cheers, Ron.

Don't you just align and reweld those bits back together?

RMD A bush fix to limp home would be done that way .lol


Have seen it done on a mack truck with a snapped rear housing out at Moree NSW.