Bracing and Straightening my Diffs!

In this video i convert the front diff to flipped arms, then brace and straighten the housings while performing an experiment. Which way is the best to weld a diff to prevent it warping?

[@noahkonstantinou3149]

Would be super interesting to see the process of how you straighten the housing

[@_Crewsy_]

I was really looking forward to seeing how that's done

[@noahkonstantinou3149]

Same

[@rockcrawler31]

I was kind of hoping the same. I recently straightened a trophy truck housing with a 3.5" x 3/8" wall thickness axle tube. Did it by securing on a huge beam and preloading in the direction it needed to go then using lots of heat/quench cycles. Is now running true

[@tdenduro8086]

Would love to see the process of straightening a diff 👌🏽

[@OzModified]

Definitely like to see how you straighten the diff

[@PeaceyThompson]

I love the detail you're going into mate. It's awesome to go through the thinking of the build and design decisions.

[@geofftuck7347]

Really keen to see the process of how you straighten the diff housings

[@markcastley65]

Would love to see the process of straightening a diff for at home builds

[@husq2100]

Great video mate, and you’ve covered a lot of what I agree with. One major issue (other than welding distortion) that I often see is the bracing/reinforcement being placed inboard of the spring points/ link mounts etc. Your rear housing was on point (end to end) but the front (for obvious reasons) was inboard. Given the input forces are at the wheel and the resistance to these is at the links, springs and bumpstops, the bracing isn’t doing much. In fact it could be introducing a greater difference in stiffness at the highest stress point which is less than ideal.

[@husq2100]

Matt will probably address this (either comment or video) but for the DIY’r if you want to straighten an axle housing after welding you’ll need the following. Centreless ground solid bar , pucks to suit carrier bearing location in diff housing (and solid bar) a steel beam (UB ) , lifting chains and at least a 10 tonne bottle jack (but a porta press is favourable) Simply chain the housing to the beam ( obviously one chain each end) and press the housing in the appropriate areas to return to straight. This will take multiple goes and moving the hydraulic jack/cylinder about as necessary.

[@Smiffbuilt]

Love the content. So much great information in a short video. Keep it up mate

[@SHOCKcustoms]

Master craftsmen. Well done

[@camdenvalleyaustralianwhit5017]

Another awesome video mate… Thank you

[@eddycalvert7138]

Awesome Matt, that’s a dreamy front housing and cool how you’ve made the flipped arms low profile to maximise uptravel!👌 Would love to get numbers on up/down travel and ride height once it’s all setup for context

[@dgs0011]

Great job. Great videos 👍 Keen to do the flipped arms on 78 series

[@robdog8807]

I’ve watched all the other 4wd boys weld in diff braces on the million dollar cars and not one of them has checked to see how straight they are .. they all probably watching matty freaking out now haha

[@farmer-jon]

I would love to see how the arms are made and brackets as well. Is there a way to get a flipped arm DIY fabrication kit to the US? Or maybe laser cut file sent to me or a trusted distributor who could cut them and ship them in the US? I have a Disco and a Classic with 80 series axles under one currently and one in a soon to be swap. I too would love to see the straightening process in long-form with all the details. It may save my rearend one day.

[@husq2100]

D2 radius arms will be longer than Toyota LC and they have big flexible bushes….

[@JackMckee-k3n]

Love the work

[@rhyswilliams695]

Nice work Matt. Makes me wonder how many bent axle housing there are out there :)

[@husq2100]

Lots. Small amounts get away with it, but more bent can definitely lead to failed wheel bearings, snapped drive flange bolts or axles.

[@jacks86australia]

Hey Matt, I'd be interested to hear your opinion on this, I recently welded up my front GU diff using a road runner kit. I followed the directions as per road runner and similar to superior. I did 50mm passes over the brace and diff pumpkin housing, I did this over 2-3 days, welding 2-3 50mm passes at a time and letting cool, I obviously tacked and fitted it all up. With the knuckles being cast I wanted to pre heat so I left the housing in the sun on a hot day and map gassed the knuckles and welded on the 8mm knuckles plates, these are opposite each side so hoped that they would counter each other out, these I welded side to side but didn't let them cool obviously as I was trying to keep the heat in with cast and then let them cool over the rest of the day gradually. I've been running the front diff for a few months, maybe putting 1-2k on the car, wheel alignment was was fine and no front axle seal leaks however I've only been in 4x4 for 200-300k of those ks. Do you find these home jobs tend to have bent housings and any issues with this process? Obviously been a home job I didn't have any way to check if the housing was bent pre or post..

[@husq2100]

The problem is the stresses are accumulative. When a weld cools, it shrinks. You might reduce this with not doing them all at once or even “back stepping” but they won’t be neutral. Peening the hot weld can help as well. I’d guess your housing is not true. But you might be lucky and it might be minimal. I’m not familiar with GU but I don’t run axle seals in the housing in my LR. A CV will allow a little more misalignment than a straight rear axle will. The other thing, are the swivel balls cast or forged? They can look very similar. Forging would be superior in strength.

[@sullysshed]

Great video Matt. I have braced housings before and used the take your time method, but I will generally only weld 25mm at a time then move around, let it cool and repeat. It looked like your stitch welds were around 75mm in the experiment you did, do you think a much shorter stitch weld would produce different results?

[@rockcrawler31]

I don't think it'd make a difference. It's not the just the "timeframe" that pulls the diff, it's the added metal of the filler wire. You just can't get around the fact that you're adding metal to the assembly in a molten form that then cools and contracts.

[@bennyjahmin3953]

How much does the flip arm change the anti dive geometry?

[@husq2100]

If you are retaining a standard arm then flipping it will do little. If you change the bush separation at axle end or the overall length of arm this would.

[@bennyjahmin3953]

@husq2100 I have played around a little with the suspension calculators but not worked out how to calculate for radius arms. I would have thought the angle of the arms would affect the anti dive characteristics. The separation of the mounts at the diff end would effect the stability under brakes and obviously flex. But for a rear triangulated 4 link the link separation at the diff housing is around 25% of tyre diameter which isn't part of anti squat calculation, more a resistance to the diff rolling under accelerations and braking. Happy to be corrected and would be even happier if someone could show how to put radius arms into a suspension calculator

[@husq2100]

@@bennyjahmin3953 I was a bit wrong. The axle end separation will absolutely affect anti squat/dive on a 3 link or 4 link because it’s the relationship between upper and lower control arms that determines the convergence points, but on a RA it is simply the chassis end pivot that would change anything . A Longer radius arm up front means less anti lift/dive. As for angle of the arm, it doesn’t matter if on top or bottom of the housing the convergence is still the same at the chassis end and the line from tyre contact still strikes through the convergence point. As for axle roll axis angle, some will argue that this changes with flipped radius arms, but I can’t see how it can give its physical attachment and attributes to and with the axle housing. I always plot my front roll axis (with RAs) from axle tube centre to centre of RA chassis bush. Regarding how to calculate RA anti lift (anti dive is a braking force and also requires brake bias in the equation) just use the 3 link calculator. Lowers will be the lower axle bush and chassis bush centres, upper will be the upper axle bush and chassis bush centres. It won’t be truly accurate for change through travel as a 3 link will have a slightly different pinion change and relationship change between upper and lower than a “fixed” RA but it will be close enough for your needs.

[@jessealadin5553]

Can you put the strait pipe in the housing before you brace it, So you don’t have to straiten it ?

[@Smiffbuilt]

It would bend that bar and you'll never get it out.

[@harisbuza8862]

Do you even sleep bro? 😴