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WMD Big Blue

mess1ah1

Active Member
Messages
83
To start off the rebuild of the WMD Big Blue, I’m tearing into the modded differentials. Years and years ago, I built these diffs and then bashed the hell out of them. They held up great. All the internals are Hot Bodies machined steel. No slippage wear and no broken teeth, so that’s a plus.

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mess1ah1

Active Member
Messages
83
The plus to these Vorza diff cups was the ability to use the bigger bearing on the non-ring gear side of the diff. You can see in the measurement pics the difference in the size of the OD for the stock cup and the Vorza cup. This was the sole reason for this mod. 97A478D6-2D5D-4198-B467-B34AEA9AD148.jpeg DF279337-D4C0-407A-99AF-B274AA44596B.jpeg 7974708F-0E28-48C2-B0F9-748D22D23171.jpeg FC2C5108-5471-47DA-9574-16757121A472.jpeg
 

olds97_lss

Well-Known Member
Messages
2,456
Location
Dekalb, IL 60115
So that steel insert in the vorza cup isn't molded into the cup?

That bearing blowing out is still an issue for my with my savage's. I just try to keep an eye on it. Any idea of the savage internals fit inside that cup?
 

mess1ah1

Active Member
Messages
83
Upon inspection of the inside of the Vorza cup, I noticed some wear from the bevel gear shaft. Over time it wobbled and wore a little bit. Kinda to be expected I suppose. In any case, I can’t put back together with that defect because it’ll only get worse and cause some real damage.

5BDAC348-A8BA-4874-B5C0-F734431A6F19.jpeg 3C76C20B-15FC-41F3-9947-2BF54A8C47C7.jpeg

So I’m going to go back to the stock aluminium diff cups. But, I’m going to turn down the end so it’ll take the bigger bearing. That will negate the need to use the Vorza cups.
 

mess1ah1

Active Member
Messages
83
So that steel insert in the vorza cup isn't molded into the cup?

That bearing blowing out is still an issue for my with my savage's. I just try to keep an eye on it. Any idea of the savage internals fit inside that cup?
It’s just press fit and uses seals. The Savage internals fit just fine. I used Hot Bodies because they were machined not sintered.
 

mess1ah1

Active Member
Messages
83
Here’s a comparison shot of the two cups inside. On the Vorza cup, the bevel gear shaft just sits inside the smaller groove, unlike the aluminum cup, where it sits in a small tab that then slides into the larger groove. This is, I’m assuming, why there was wobble over time.

88A33705-EF41-4B2B-90EC-CC82A6EB4793.jpeg
 

olds97_lss

Well-Known Member
Messages
2,456
Location
Dekalb, IL 60115
Maybe see if the LST2/XL cup will work. The latest one they had was plastic but had steel inserts. Pretty sure it used the same sized bearings on both sides.

I have some arrma ones laying around... not sure I have a savage diff out of a truck though to try and install the internals in it. They also have a metal insert for the output and uses blocks on the ends of the pins.

No clue why HPI went the route they did. I wonder if turning down the aluminum cup will be a good idea. Will make that output boss pretty thin and likely to crack. Would have made more sense if they just did what you had with the HB output, but used the blocks like they did in the alloy one for the x-pins. Then you get the best of both worlds.
 

mess1ah1

Active Member
Messages
83
No clue why HPI went the route they did. I wonder if turning down the aluminum cup will be a good idea. Will make that output boss pretty thin and likely to crack.
It won’t make it any thinner than the Vorza one. It’ll be the same ID and OD. And what do I have to lose, really. I’m not going to use those cups with the thin bearing so...
 

olds97_lss

Well-Known Member
Messages
2,456
Location
Dekalb, IL 60115
Guessing the forsa one is sintered steel or machined steel whereas the other one appears to be cast aluminum. So, may be likely to crack on you.
 

mess1ah1

Active Member
Messages
83
Guessing the forsa one is sintered steel or machined steel whereas the other one appears to be cast aluminum. So, may be likely to crack on you.
🤷‍♂️ Like I said. Nothing to lose really. The cups are sitting wasted right now. Have been for about 8 years. I’d be really surprised if taking 2mm off the OD affects the structural integrity of the aluminum that much. The bearing is a tight fit on the outside and the output is a tight fit on the inside. There is virtually no wobble that could create a cracking issue. So, we shall see.
 

mess1ah1

Active Member
Messages
83
So I went ahead and took some material off the bearing seat OD of a set of the XL aluminum diff cups. Worked perfect and is exactly the dimensions of the Vorza cups. Nice.

DF298ABE-58BC-45CA-895D-CA62E132A258.jpeg

Bearing seated nicely:

6631C828-87D0-499B-9076-FB05D3780CBF.jpeg

Old thin-band bearing on un-modified diff for reference:

0A16DC16-9865-4580-9519-071D2699BAB6.jpeg

Un-modded on left, Vorza, modded:

0C68B53E-7773-44E7-8335-F84A8D97A0CD.jpeg
 

lokky

Active Member
Messages
118
Hope the modded HPI diff case is as strong as the Vorza diff, is the Vorza diff insert made from steel vs the aluminium HPI diff?
 

mess1ah1

Active Member
Messages
83
Hope the modded HPI diff case is as strong as the Vorza diff, is the Vorza diff insert made from steel vs the aluminium HPI diff?
The insert is steel. I imagine it’s probably sintered though. The aluminum cup should be stronger than the plastic cup. No chance of internal wobble/wear.
 

mess1ah1

Active Member
Messages
83
Giving the Hellfire towers a go on this rebuild. A bit of grinding on the bulkheads clears the way to mount them. Also cleaned off the lower arm holes on the towers because I don’t need them.

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SavageXL85

Active Member
Messages
70
Wonder how that diff cup will hold up ...seems like it will good idea too to run the bigger bearing...can you cut mine down?!?!? Haha
 

mess1ah1

Active Member
Messages
83
Had to make a replacement bushing for one of the front uprights because it has disappeared... Prototyped it in aluminum and will make the final from steel. The Hellfire towers turned out great.

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mess1ah1

Active Member
Messages
83
De-anodized a bunch of parts to get rid of the purple. Coat of aluminum primer and then hit it with some metallic red. The spacers behind the Vorza hexes I did in gun metal. 108979CA-9950-46CF-8EB8-F34CC9A6FB99.jpeg 45B9581D-2BC1-457C-9371-BAB21AB6461E.jpeg
 
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