Thread: Reinforcing Front Diff Housing

Hi Dave! IMHO - something along the lines of this is the best option:

Turning back to the front axle, Rocky added on one of our "no hole" front upper gussets to prevent bending of the housing. This should help keep the axle straight when jumping sand dunes at Pismo Beach!

And before anyone says it, yes I know the above axle is a toyota. Marlin Crawler Formula Toyota Buildup

And this is their diff pan reinforcement (and clearancing):



The axle at the top of this image is a rover one. You can see where you could fit a nice gusset similar to the above, between the diff centre and the bump stop bracket. A very small one (about 1" long) could be welded in on the other side, but it isn't really necessary.

The breather will need to be relocated. If you ever plan to fit an MD locker, you would need to rotate the gusset to the rear to fit the actuator in. But this is probably a moot point now MD are no more...

Hopefully these images explain what I mean about the MD actuator:




it probably also explains why Mal used to reinforce inside and underneath the axle rather than on top.

Hi Dave,
The front diff housing on my 88 Rangie cracked around the bottom part of that same weld some 7 years ago during a trip down the Tanami track. When I got home I simply got under it with the welder and ran a bead of weld around the crack. The vehicle has done a LOT of work in the ensuing 7 years, including some very punishing outback trips and a lot of high country 4WDing. No further problems with the front axle. Rear axle is another story.
My advice would be to take the car to someone who can weld and get them to weld up the crack, and keep driving it. If we're on the same wavelength and you're talking about the ring of weld that holds the cover plate onto the housing, it is not going to affect the structural integrity of your axle. It's simply holding in place a piece of stamped sheet metal that keeps the oil in and the dirt out. On salisbury type axles it is bolted on. Unless of course you are stuck with excess money that you need to get rid of for no real reason
If you're anywhere near West Gippsland I'd be happy to make some time to help you out.

Originally Posted by POD

Hi Dave,
The front diff housing on my 88 Rangie cracked around the bottom part of that same weld some 7 years ago during a trip down the Tanami track. When I got home I simply got under it with the welder and ran a bead of weld around the crack. The vehicle has done a LOT of work in the ensuing 7 years, including some very punishing outback trips and a lot of high country 4WDing. No further problems with the front axle. Rear axle is another story.
My advice would be to take the car to someone who can weld and get them to weld up the crack, and keep driving it. If we're on the same wavelength and you're talking about the ring of weld that holds the cover plate onto the housing, it is not going to affect the structural integrity of your axle. It's simply holding in place a piece of stamped sheet metal that keeps the oil in and the dirt out. On salisbury type axles it is bolted on. Unless of course you are stuck with excess money that you need to get rid of for no real reason
If you're anywhere near West Gippsland I'd be happy to make some time to help you out.

The only problem is the heavy ISUZU donk is well known for bending axle housings - hence the need for reinforcement.

I have twice rewelded this join (the need to reweld it probably reflects my welding skills rather than anything else). It has now gone a couple of years without further problems.

Whether correctly or not, I attributed the original failure to twisting of the axle housing due to the previous owner fitting polyurethane bushes to the hockey sticks (now replaced). An analysis of the forces suggests that bending would not affect this weld, but twisting would do so.

With this in mind, it is difficult to see the proposed reinforcing helping, although it would undoubtedly help prevent bending - and is basically the same as reinforcing introduced on Series axles. It might even make the situation worse by preventing twisting of the housing except in the diff pan area.

John

my previous Isuzu County had a maxi front locker, and was laminated on the underside. Someone told me Mal did this in the early days when fitting a diff lock.

Bill Anderson's showed me under his Perentie mockup, the one he keeps for himself. It had a re-inforced front axle that he said was fitted to Norforce vehicles and similar.

Originally Posted by rar110

my previous Isuzu County had a maxi front locker, and was laminated on the underside. Someone told me Mal did this in the early days when fitting a diff lock.

Bill Anderson's showed me under his Perentie mockup, the one he keeps for himself. It had a re-inforced front axle that he said was fitted to Norforce vehicles and similar.

Mal reccomended laminating the front housing on all 3.9s - they are very prone to bending on them when used offroad. He told me he used to sleeve the axle tubes internally, then weld plates on the bottom. However he said he stopped tubing the inside, as it added a lot of weight in comparison to the strength gain.

hey dave, the pics that ben put up are what i was trying to explain to you the other night bit hard to try and explain over the phone though.