Outcast Typhon input gears in outcast

[Chad08]

So I made my own home built outcast with some extra parts laying around and ebay. I bought typhon bulkheads that were factory assembled with diffs, I did take them apart to shim and put heavier fluid in. After I put the car together it started making some grinding noise under hard acceleration. Well after 2 days of thinking this over and problem solving I figured out the problem. Apparently arrma uses a higher tooth count input gear in the bulkheads of the typhon and both front and rear ring gears stripped out. I can't for the life of me understand why that would happen. I understand I was using the wrong gearing but that should only increase top speed. Help me understand this hahah.

 

[2fast4u]

Along with the different ratio, the Typhon gears are straight cut. All other 6s gears are spiral cut.

 

[olds97_lss]

Also, with a fixed size case, if the pinion is different, the ring gear would need to be different to match. Can't take a tooth from one and not add it to the other or you end up with bad mesh. If they left more slop in the case so it required excess shims, then you could get away with it. But from what I find, most of the diff cases only have enough room for a couple thin shims, which I doubt would be enough to make up the mesh needed for more/less teeth on a pinion.

That's if the cases were identical.

 

[2fast4u]

Also, with a fixed size case, if the pinion is different, the ring gear would need to be different to match. Can't take a tooth from one and not add it to the other or you end up with bad mesh. If they left more slop in the case so it required excess shims, then you could get away with it. But from what I find, most of the diff cases only have enough room for a couple thin shims, which I doubt would be enough to make up the mesh needed for more/less teeth on a pinion.

That's if the cases were identical.

You do not have to change the number of teeth on both. The tooth spacing remains the same. The diameter of the ring/crown or the pinion only becomes larger or smaller with a different # of teeth. Thus requiring different shimming to get them in the correct location in relation to each other. But yes, case size can limit what you can do.

 

[olds97_lss]

You do not have to change the number of teeth on both. The tooth spacing remains the same. The diameter of the ring/crown or the pinion only becomes larger or smaller with a different # of teeth. Thus requiring different shimming to get them in the correct location in relation to each other. But yes, case size can limit what you can do.

Yeah, I mentioned that. If the case had a wide enough margin to allow for shimming, you don't need to change both.

 

[2fast4u]

So I made my own home built outcast with some extra parts laying around and ebay. I bought typhon bulkheads that were factory assembled with diffs, I did take them apart to shim and put heavier fluid in. After I put the car together it started making some grinding noise under hard acceleration. Well after 2 days of thinking this over and problem solving I figured out the problem. Apparently arrma uses a higher tooth count input gear in the bulkheads of the typhon and both front and rear ring gears stripped out. I can't for the life of me understand why that would happen. I understand I was using the wrong gearing but that should only increase top speed. Help me understand this hahah.

This guy is nuts but maybe you will understand why your diffs failed. The larger tires/increased weight and rotating mass were most likely more than the straight cut gears wanted.

l

If the link works.

 

[Chad08]

Ahhhhhh! Thank you guys. I didn't realize those gears were straight cut in the typhon. I'm now wondering what advantages straight cut gears would give the typhon. Why wouldn't they just use the more robust spiral cut gears? Manufacturing savings?
I would have never guessed they would use different gear tooth counts and gear cut on a car that literally uses almost all the same parts as an outcast. Thank you guys for clearing that up for me.

 

[Notorious J]

Ahhhhhh! Thank you guys. I didn't realize those gears were straight cut in the typhon. I'm now wondering what advantages straight cut gears would give the typhon. Why wouldn't they just use the more robust spiral cut gears? Manufacturing savings?
I would have never guessed they would use different gear tooth counts and gear cut on a car that literally uses almost all the same parts as an outcast. Thank you guys for clearing that up for me.

I don't remember exactly which thread, but someone did explain the concept of why you would use spiral over straight in different applications. The jist was, the spiral are able to handle more load because there is a longer contact patch between the gears, thus making them better for bashing. The straight cut would be more akin to speed, and the Typhon is the most likely to be used as a track truck. Found it
https://www.arrmaforum.com/threads/mildly-modded-senton.9351/

 

[SrC]

Mismatching a spiral gear to a straight cut gear = user error.
If mismatching gears was an experiment, then maybe something was learned from it. That is fine.
Shimming means nothing if parts are not setup/matched as Arrma intended.
I surmise that if the Arrma manual was properly used as your Bible and part numbers were carefully matched, this thread would not exist.
We usually adhere to gearing recommendations, yet many forget that adding those extra large wheels impact the final drive in the end.
They are left wondering "why did this happen"?

 

[LibertyMKiii]

I don't remember exactly which thread, but someone did explain the concept of why you would use spiral over straight in different applications. The jist was, the spiral are able to handle more load because there is a longer contact patch between the gears, thus making them better for bashing. The straight cut would be more akin to speed, and the Typhon is the most likely to be used as a track truck. Found it
https://www.arrmaforum.com/threads/mildly-modded-senton.9351/

This sums it up very well.
Often race cars use straight cut gears simply because they are easier to manufacture. Overall spiral cut gears operate quieter and offer more strength. So far people have put 8s power through Typhon diffs and they seem to hold up well. I cannot see any major weakness in them as of yet. Typically it would be casting flaws of powdered metal that result in failures. Nothing beats CNC cut forged metal parts.

-Liberty

 

[SrC]

This sums it up very well.
Often race cars use straight cut gears simply because they are easier to manufacture. Overall spiral cut gears operate quieter and offer more strength. So far people have put 8s power through Typhon diffs and they seem to hold up well. I cannot see any major weakness in them as of yet. Typically it would be casting flaws of powdered metal that result in failures. Nothing beats CNC cut forged metal parts.

-Liberty

Spiral/bevel cut gears require tighter tolerances. Less room for error. They can cross-mesh and fail easier.
Spiral/bevel cut gears need to be Cnc'd. to be durable. Casting these, although much less expensive to produce, leads to tolerance issues as well as a less stronger gear.

 

[Megasty]

Spiral/bevel cut gears require tighter tolerances. Less room for error. They can cross-mesh and fail easier.
Spiral/bevel cut gears need to be Cnc'd. to be durable. Casting these, although much less expensive to produce, leads to tolerance issues as well as a less stronger gear.

Perfect case in point is the Traxxas spiral cut gears for the X-Maxx. They are indeed casted or sintered & were a huge expensive failure.

 

[LibertyMKiii]

Perfect case in point is the Traxxas spiral cut gears for the X-Maxx. They are indeed casted or sintered & were a huge expensive failure.

I was trying to avoid bashing on the X-Maxx again but differentials were my biggest disappointment with that RC.
Evidently I didn't save pictures, but I had blown up a few of those on the X-Maxx

 

[Chad08]

Well at least my mistake resulted in a very interesting learning experience about gears. Thats another reason I love this hobby.

 

[SrC]

Well at least my mistake resulted in a very interesting learning experience about gears. Thats another reason I love this hobby.

We have all been through this at some juncture in this hobby. You are not alone. It does show initiative and creativity on your part.

 

[Yonic]

So far people have put 8s power through Typhon diffs and they seem to hold up well.

It's less how of how much power the system is using, more how much torque those gears need to withstand, and what affect this is the size of the wheels, for a given speed, the smaller typhon/senton wheels rotate faster with less torque going through them, relative to the bigger trucks.

 

[LibertyMKiii]

It's less how of how much power the system is using, more how much torque those gears need to withstand, and what affect this is the size of the wheels, for a given speed, the smaller typhon/senton wheels rotate faster with less torque going through them, relative to the bigger trucks.

I completely agree that torque is ultimately the killer for differentials. For 99% of us it is landing a jump on throttle. That instant shock of traction rips the teeth right off. I might be going with something over 8s for my "Unlimited" build

 

[SrC]

I completely agree that torque is ultimately the killer for differentials. For 99% of us it is landing a jump on throttle. That instant shock of traction rips the teeth right off. I might be going with something over 8s for my "Unlimited" build

Throttle release at the moment you touch down. That's key. Let it unload before you throttle again. Its precision timing. Master that and you break less. Easier said than done.