[fordem]

First, I'm not much of a welder, so I'm looking for advice & guidance before I attempt to shave an axle - and for what it's worth, I do have a spare, I wouldn't even consider this if I didn't.

So - please correct me where I'm going wrong - the axle in this case is the rear axle on an SQ series Grand Vitara ...

The idea of shaving an axle appears to be to cut the lowest part of the housing (and diff carrier) away for increased ground clearance, and to close the resulting opening by welding plate over it - in my mind we're cutting a "flat spot" as close to the ring gear as we can safely get - I'm thinking no less than 5~6 mm - I've seen some folk do an angled portion up the back of the housing - is this an option, a requirement, or recommended?

I'm hoping to get an inch or so of additional clearance, I have not yet gotten under the vehicle to eyeball it and see what's possible, I do not know where the studs that hold the third member into the housing are, yet, I'm still at the "does this make sense" part of the thought process.

Welding - I've read and been told that welding cast iron has it's challenges, requires special rods, pre-heating of the job and controlled cool down - how do you manage this with something as large as an axle housing? Can it be done with a wire feed welder (FCAW)? Is warping likely to be an issue?

Are there any alternatives to welding? I recall KAM in the UK having an electric diff locker that required a flange to be fitted to the differential, and if my memory is correct, there were looking at using some sort of adhesive as an alternative to welding. In my mind, this part of the process is not structural, so strength is not really an issue, we're just closing a hole so that we can keep lube inside & dirt outside - it does need to be strong enough that we don't dislodge it on a rock (not too many of those where I drive), on the edge of a pot hole (lots of those), or in a mud pit.

Oh - I promise I will not be upset if you tell me I should leave it alone - everyone I've talked to on the ground has looked at me like I'm crazy, and the first question has been "what do you hope to achieve"? It seems like no one here has ever heard of it.

[Beery]

I'm not sure if you have seen my build thread but I recently done this to both my housings, there is a few photos there if you're interested. (I have some more too, if there is something in particular you want to see)

Yes, it's as simple as it sounds really - cut the bottom of the housing off and plate it over. Before pulling the housing, you will want to get a reference point to how it sits in the car, you want the cut to be parallel with the ground when complete, this will make sure you gain the maximum amount of clearance possible. 5-6mm to the ring gear is pretty safe, I only had about 2mm, but ground the infill plate only where the ring gear runs for a bit of extra insurance. I used 6mm plate as my local steel place had a handy off cut but 5mm is plenty I would say.

Making a angled portion or "ramp" on the housing is quite desirable in my opinion. One of the reasons I shaved mine was due to damage caused my rocks hitting the front of the housing (and rear), which is quite thin, (lucky to be 2mm on a sierra) so adding some strength here was a must for me. It also allows the diff to slide over things more easily and gives a nice approach angle.

I believe quite a lot can be cut off a Vitara housing, an inch should be doable, but I've never done one, so not completely sure.

The welding part is where I'm a bit confused, I don't really know anything about Vitara's but what is cast iron that needs welding? aren't they just a standard rear diff housing? (mild steel) if so, a MIG is fine, or a TIG, I'd avoid a stick just due to the fact is has to be fully sealed and it's harder to get a clean weld form my experience, but I'm no welder.

Warping is an issue, but for shaving a housing I'm not sure you could warp it bad enough to cause issues (trussing a housing on the other hand will turn it into a banana), mine didn't pull a lot but it did move enough that I decided to tension certain sections for welding - this is hard to do without an alignment bar though, as you won't be able to tell if it's moved about. ideally you want to find a junk third member/carrier to bolt in while doing the welding too, the mating flange can and will move about once the bottom is cut off, if you weld it without a centre in you could be in for some leaks/ alignment issues when installing - that would suck.

No, I don't think there is an alternative to welding. You're removing a lot of strength when you cut the bottom of the housing off, whatever you replace it with needs to be properly strong to avoid it bending, cracking, splitting the housing in half etc.

I won't tell you not to do it, I think it's one of the best/most underrated mods there is.

[fordem]

Beery wrote:

I'm not sure if you have seen my build thread but I recently done this to both my housings, there is a few photos there if you're interested. (I have some more too, if there is something in particular you want to see)

<SNIP>

The welding part is where I'm a bit confused, I don't really know anything about Vitara's but what is cast iron that needs welding? aren't they just a standard rear diff housing? (mild steel) if so, a MIG is fine, or a TIG, I'd avoid a stick just due to the fact is has to be fully sealed and it's harder to get a clean weld form my experience, but I'm no welder.

I believe your build thread was actually one of the "push factors" that made me want to do it.

Regarding the welding cast iron confusion, I made some assumptions that may be incorrect - I assumed the third member might need to be shaved, I assumed the third member was cast. This is one time I'm happy to hear that I'm wrong.

As I mention I do have a spare axle - with the exception of the brake components, it's complete from hub-to-hub, so I do have a third member that I can bolt in during the welding - I'll try to make some time this week to actually "eye ball" both the spare and the axle on the vehicle, and get a better idea of what's involved

Thanks much.

[Gwagensteve]

I’ll reply in more detail later but there’s no welding of anything other than the mild steel axlehousing.

[Beery]

cool, it's definitely worth it if you find yourself on the diff quite often.

You're correct the third member may require "shaving" but it's only the flange area that mates to the diff housing, it simply gets cut off for clearance and to match the housing cut, there's no need to fill anything in or weld it. your ring gear will be the limitation well before something like that is ever a consideration.

Here's some more pictures to hopefully make this make more sense: This is my finished cut all welded out and the bottom ground smooth on the housing side, you can see I've cut into the flange area a bit, therefore the third member will hang below this.



This next picture is showing how far the third member flange hangs down, you simply cut this off - nothing else is required. (I obviously haven't welded the plate on it here, but you get the picture)



The yellow paint pen line on the flange area is where my particular third was cut. you're reducing the sealing area a bit, but there's still lots of meat there, nothing to be worried about imo.



hope this makes more sense.

[Gwagensteve]

Beery has pretty much nailed it.

There is a LOT of gain to be had by shaving a Vitara rear axle. ~35mm or so.

[fordem]

Thanks a ton guys.

Does it make sense to fit a "drain bung" - perhaps offset to one side, rather than on the flat shaved surface?

[Beery]

Yes, I would prefer to keep the bottom flat and smooth, drain bungs get pretty beat up. I didn't add one at all - sierra third members bolt in, so you can just remove one of the bottom bolts to drain. I think vitara may be studs? You could either replace the bottom studs with bolts or add a drain bung off to the side.

[shakes]

I'm going to tack onto this as it's in my future.

I assume you still just fill the diff with oil to the filler, as overfilling will cause as many problems as it solves?

Is there any heat buildup issues on longer freeway runs ?

[Beery]

Mine is filled to the factory level, my filler plug wasn't moved. I'm not sure if overfilling would cause problems, or solve any, as I'm not sure the amount of oil lost is worth talking about and I doubt anyone has done any testing to prove otherwise.

The first trip after shaving my diffs, I put my hand on the rear diff to see how hot it had got after over an hour of highway driving and I was a bit surprised - it felt pretty hot! But then I walked over to another sierra that had just done the same drive (without the diffs shaved) and it felt the exact same, so i don't think it's an issue, I had never felt a rear diff after driving before so I didn't know what to expect

I have a few dollars (and effort!) in both my diffs, so I'm happy to check/change the oil a bit more regularly to be on the safe side.

[Beery]

Another thing I'll add - because I don't have a drain bung, I've lost the magnet that's attached to it, used to pick up any contaminants/shavings etc. I haven't bothered to research it yet, but I think i'll try find a fill/drain plug with a magnet and suitable thread to replace my fill plugs.

Adding a proper drain bung would be desirable in this regard, as it would be more effective in the bottom of the diff. If I add a magnet to the fill plug it's only going to see the oil the crown wheel throws at it while in motion, but i figure that's better then nothing. I not sure how detrimental small shavings are, i'm mainly worried about the air locker seals but I may be overthinking again...

[Gwagensteve]

Beery - Just stick a small magnet to the bottom of the inside of the housing. That's what Aisin-Warner do with the AW-4, for example. It won't move. If you're worried, glue it down with some JB weld.

Shakes- I haven't found heat to be an issue. I keep the fill level stock.

I have fitted drain plugs on the sides over the years but I've deleted it on my front axle build and have swapped the studs on the bottom two bolts of the Vitara housing for bolts so I can drain from the bolts.

[Sausager]

The drain bung is my biggest mental struggle with shaves. I have done both with and without in the past. The next one on my chopping list is a Vitara rear and I don't want a drain bung on the soon to be flat bottom.

To convert the bottom two studs to holes, I am guessing it's as simple as knocking the studs out, and then drill and tap the hole oversize?

[Gwagensteve]

I just welded a nut behind the mounting flange.

[doe2]

Hello buddy


Sent from my iPhone using Tapatalk

[vet 180]

Great thread to see what everyone has done. Love your work Beery!

If the pumkin is your lowest point a good shave is like going from 30's to 33's clearance wise. I guess that the difference between an engineerable car and something that has no chance of being legal.

Sent from my SM-N960F using Tapatalk