Kristoffer_E

Hey,

I've been toying with the idea of building an rc sandrail around the Volcano driveline, and I'm curious how the rear diff will hold up. To start, I want to pull out the front driveshaft, put 2.2 sand paddles on the rear and 2.2 rib tires on the front and see what happens. Will I wreak the rear diff/drive cups putting all the power through it, instead of half, or will it be fine? To compensate for the smaller tires, I've got a Shockwave tranny that I'll install.

If all goes well, I'll try welding a proper chromoly tube chassis for it, but before I buy the tires, what do you think of the feasibility of a rwd-only volcano?

NewRageRC

My Feedback: (1)

If you're going to end up going through the trouble of fabbing a new chassis for it, I would skip the Volcano and find stronger diff, whether another brand or at least stepping up to a 1/8 scale Redcat diff. 

Dads like rc too

I'd agree
I'd agree. My Tornado diffs never gave me a problem, and I've actually used the upgraded Volcano diffs in my HPI nitro MT2 but if you want to make it bulletproof, swap in the diffs from the 1/8 scale pro series.

Kristoffer_E

Alright, fair enough. My only thought was that for ~$150 I can pick up a Tornado from the LHS and pull the driveline/engine from that, and use most the leftover parts as extras for my Volcano, as opposed to spending well over that $150 to get a SH .21 or even just another .18, tuned pipe, center tranny, rear differential, fuel tank, etc etc.

So, the most cost-effective scenario I can see besides the above leaves me buying an Earthquake or an Aftershock and gutting it, and trying to sell the extra stuff on Ebay or something. Redcats electronics are craptastic, but they should work for awhile, anyway. If you think the Volcano diff can handle the power, I'd far prefer to go that route because of cost, otherwise I'll probably look around for a used tmaxx or savage or something to get parts from.

derailed75

I would get something from the XTR line. I know you are trying to keep cost down, but get the strongest thing you can find for a good price. My Aftershock 3.5 has been a great truck for me. My engine had an airleak and I swapped in an Axial .32 spec1s, which has a ton of torque. I had to replace my front diff after about 2 tanks.
I have a question for you. Why dont you get the drive line parts you need without buying the whole truck? You can use the parts break down from Red Cats website then search for the parts on Ebay. Thats where I got my new diff from. Some dealer parted out a few trucks he had extra of. I would bet you could get it all from there for a lot less than buying a new truck.

NewRageRC

My Feedback: (1)

I see what you're saying.. if you don't have a pile of parts laying around buying a new parts car might be the way to go. But remember, electronics can be had pretty cheap. Hobbyking has receivers and servos for around $10 apiece.

nitrosportsandrunner

the center trans sends the same power to the front/rear diffs.
so pulling the front dogbone out wont put any more strain on the rear than it already gets.

It would be a different story with the aftershock/backdraft as they have a center DIFF. Lose the front center shaft and all the power goes nowhere as the center diff spins freely.

a custom (longer) chassis shouldnt be to hard to do tho.

I also feel its cheaper to buy a whole truck...and sell off anything you dont need. Or keep them around for future projects.

bpohl

You plain this being a nitro truck? If so the Volcano S30 should hold up. I have a .21 in my Volcano S30 with good grip tires on the rear adn have had no issues with the rear diff at all. I have run, I know a gallon a fuel through it. I did start to see alot of slack in the front diff between the ring and pinion and changed them as  precaution. I run this truck hard. Had very little issues. With the new shock set up the truck lands alot better.

Dads like rc too

Okay in my first response I didn't realize you needed everything to go with it, I thought you were just asking about strengthening the diffs. I'd also say go with the Tornado. The stock engine will be plenty powerful enough. Be careful with the tires though. If you put a buggy 2.2 tire on it will work fine with either the Tornado or Shockwave tranny. If you use monster truck 2.2 tires they will be taller and you'll need the gearing from the Volcano tranny which is a piece of junk. The diffs are the same in the Volcano and the Tornado, they will work fine enough for what your wanting to do. Like I think you figured out, you can buy a whole car for about $160 shipped on Ebay or spend about $120 for a compete engine with pipe and clutchbell.

NewRageRC

My Feedback: (1)

It definitely WILL put more strain on the rear diff. There are a few knuckleheads that have locked the center diff in their Subaru WRXs and removed the front drive shaft. They end up with blown up rear diffs and broken axles.

nitrosportsandrunner

1st, why would anyone want there subby to be just RWD? if you want RWD, start with that.

2nd, what happens in real cars doesnt always translate into RC models. The RC is light. The subby has lots of weight over the tires and the traction translate into strain. You will never get that kinda traction in an RC model. The tire traction will give before the diffs do.
Again, the volcano's center diff isnt open(like the subby) and the rear diff is. Thus, the rear diff is used to getting full engine power..and can always unload it to the tire with least traction.

Kristoffer_E

The rear diff will, in fact, see far more power for the reasons NewRage explained. Stock, power is being used to spin the front wheels. As a RWD vehicle, that power is still created and has to go somewhere, specifically the rear diff.

Honestly, I'm more worried about the drive cups/dogbones than the actual differential. I think I'll go run my Volcano with no front driveshaft in a parking lot for 5 or 6 tanks and see if I blow up the rear diff, and go from there. If it lives, I'll just get a tornado and tear it apart. If not, I'll find an alternative.

NewRageRC

My Feedback: (1)

Like I said, they're knuckleheads. The effect is the same, though. The argument that you'll lose traction is also true in the Subaru (that's why these drifter dorks are making their cars RWD). Before that you're adding a lot of shock to the rear diff and axles.

I think the saving grace here is the SH21. They don't have the quick onset of power like an electric.

Kristoffer_E

Well, I ran a 2 tanks with only a rear diff, and the ring and pinion are intact, as are the spider gears. So I thimk we are good in that respect.

However, the front clutch bearing failed, and needs to be replaced. By failed, I mean it was behaving like a bushing and not actually spinning at all . After 2.5 gallons of runtime and never cleaning the craptastic metal-shielded bearings, it seems many of them are also due for replacement. [link=http://www.avidrc.com/product/1/bearings/]AvidRC[/link] has fancy half-rubber half-metal shielded bearings for $1, so I think I am going to replace every bearing in the truck (diffs, outdrives, tranny, engine, clutch), and I have most of them picked out. However, I've tried to clean the engine multiple times, and I've never managed to remove the crankshaft. There is a metal collet that sits behind the flywheel that does not seem to like me, and refuses to come off. It looks like there is a brass bushing in there that is locking it into place, but I can't tell. If someone could tell me how to remove the mini-flywheel (for lack of a better term) or even what size the front and rear SH .18 bearings are, I'd be most appricitive.

Also, when I discovered the abysmal state of the bearings, I figured other stuff needed changed too. I've drained all the shock oil and cleaned all the diffs out, and now I need new stuff to put in there. Does anyone have a recommendation for a good range of shock oil wieghts? I would like to get a few and make my own opinions from there, but I don't know where to start. I think that a 35-45 weight is a good starting point for light bashing use (Little jumps, ie. <3 feet, rocks, bumpy stuff, etc)? Will the Volcano diffs hold silicone oil (I see no rubber seals), or am I stuck with grease? If silicone won't work stock, could I just seal it up with rtv silicone, and be good? Assuming I can use silicone oil, what weight should I start testing with? I hear people reccomend 3k-7k for diffs, is this good?

It seems that this project is on hold temporarily while I rebuild my poor, neglected truck. I'll be out of town for the next few weeks, so I'll see what happens that way. Finally, I'm going try to learn SolidWorks enough to model the chassis before I start brazing/welding stuff. Is there any interest in having Redcat parts drawn in SolidWorks? If no one cares, I'll just sketch the stuff I need to lay out a chassis, but if people would actually use models of diffs, trannies, etc. I could try to draw those up in some level of detail.

Let me know, especially about the SH.18 bearings or if you are interested in the CAD models.

Thanks,

Kristoffer

EDIT: someone mentioned a 1/8 diff. Would such a diff be able to work with the driveshafts from the 1/10 volcano, or are the drive cups totally different? Or, could a 1/10 drive cup be stuck on the 1/8 diff?
Also, people talk about shimming the diffs in these trucks. I never did, and mine were fine. If it were to need shimming, where would I find shims? Also, I seem to be missing 2 of the the shim-looking things that go outside the small (5x10x4) bearings on the outdrives, between the bearing and the the aluminum hex. Where could I find this part; I can't find part numbers for on any of the exploded diagrams?

NewRageRC

My Feedback: (1)

The diffs will hold oil. Since you're going 2wd I'd think you would probably want a pretty heavy weight oil in there, maybe even locking it.

Kristoffer_E

I want this to be as close to rear-engine as possible, so I'm looking at a Stampede tranny for like [link=http://www.ebay.com/itm/Traxxas-4109-Nitro-Stampede-Complete-Transmission-Slipper-Disc-Brakes-/190679529049?pt=Radio_Control_Parts_Accessories&hash=item2c6562b659]$40 on eBay[/link]. I still think I'll use Volcano suspension arms, hub carriers, steering, etc because I have tons of that stuff, but if I can shove the engine and tranny into the very back then I have room in the middle for some scale details.

However, if I flip my sh .18 sideways to work with the pede tranny, is there a header I can run that will keep the pipe pointing the right way? Or would the pipe even care if it was flipped 90 degrees? My only concern is if the pipe is perpendicular to the body, it won't be adequetely protected from a collision, ie sticking out the side.

I ran across this earlier today, and it has become my inspiration for the project: http://www.rcuniverse.com/forum/m_10..._1/key_/tm.htm

NewRageRC

My Feedback: (1)

I wouldn't think there'd be any issue with mounting the engine sideways, as long as you can find a way to drive the transmission. And since you're building your own chassis it would be easy to add some protection to your pipe however you decide to mount it.