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Can I Have an official Mammoth ST thread?

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Can I Have an official Mammoth ST thread?

Old 12-22-2006, 07:31 PM
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Default RE: Can I Have an official Mammoth ST thread?

ssj2, do you have a link or part number to those upgraded spider gear diffs? They are still sealed right? so you can run diff oils? My brother fried both diffs, ring and pinion in both are toast. might as well spend the money on a good set while he is buying parts so he doesn't have to worry again.
Old 12-22-2006, 08:45 PM
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Default RE: Can I Have an official Mammoth ST thread?

The upgraded diffs are just going to be the actual gears, and such so it's not a sealed unit.
First off is a thread from the Global Hobby forums about suggestions of what diff oils to use: http://globalservices.globalhobby.co...ic.php?t=19543
Next, here's the links for everything you should need:
Diff Outdrives (2)-http://www.hobbypeople.net/gallery/149893.asp
Spider Diffs (3)-http://www.hobbypeople.net/gallery/149895.asp
Center Diff Outdrives-http://www.hobbypeople.net/gallery/149891.asp
That's based off of what I saw on the XTM forums and it's from somebody who actually did the conversion. In case you were interested, here's the links for the center diff and clutch bell you're gonna need:
Center Diff: http://www.hobbypeople.net/gallery/149794.asp
One-Speed Clutch Bell (what I have and what most other people get, the 14T or 15T usually): http://www.hobbypeople.net/gallery/149580.asp
Here's the search page I got in case you were interested in a clutch bell with more teeth: http://www.hobbypeople.net/guru/hps_760746559.asp
Hopefully, I'm not missing anything, if I am, lemme know and I'll be on it right away. Good luck and this should help.
Old 12-23-2006, 10:14 AM
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Default RE: Can I Have an official Mammoth ST thread?

thanks ssj2. I do have a few questions though.

You said they aren't sealed but in those links i see o-rings so they are sealed right? I mean thats what that link to the xtm site is about, what oil to run in the sealed diffs.

Why are there (3) sets of the spider gears? (1) set for the center diff?

I don't need to change the diff outdrives that run from the diffs to the wheels?
Old 12-23-2006, 11:10 AM
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Default RE: Can I Have an official Mammoth ST thread?

When I was looking at it, I was a little leery on that too. By sealed, I thought you meant the whole unit being sealed, with the plastic covering and everything. In that case all you would do is have to put it onto the truck w/o opening the diffs. It's not like that, my bad for misunderstanding you. However, since everything is sold as a kit to replace the stock diffs, how can it be a sealed system? By sealed, I would assume that you aren't able to open it, i.e. rivets instead of screws. But I think I can sort it all out. First of all, here's a link to a guy that did the whole transfer to the spider diffs, pics are included:
http://globalservices.globalhobby.co...ic.php?t=19727
Abiding from that information, I see that the first link that I gave you is the drive cup that will be coming out (from the left and right side) of the differential. That's why you need two, because there's a total of 4 drive cups that will be replaced. The drive cups attached to the wheel are left alone, so are the ones that lead right out of the front of each differential.
The second link, I believe that you would only need 2 of the bevel diffs. With the center diff link that I gave you, there are no gears found inside of the solid yellow piece that's visible. The only thing that the center diff does is transfer power from the engine to the drive shafts.
About the third link, since you have the center diff I do, I really don't think you'll need to replace the brake output joints. To me, it looks as if Valve has a totally different center differential setup, he may have used one from another truck. Then you'll be getting into a whole lotta money.
Do not quote me on any of this information, it's kind of confusing and I think if you need a more in-detail explanation that I can't give to you over RCU, then call XTM Customer Service. I think all of the stuff I said is alright, but it's how I'm interpreting the situation; I haven't replaced to the spider diffs so I'm just going off of topics and pics in the Global Hobby forum. Oh yeah, if I had replaced the diffs then I would be able to tell you but I've never been there so that's why I'm saying your best bet would be to check the info by calling XTM Customer Service. The number is located inside the truck's manual so I hope this helped some and good luck! Feel free to ask any further questions and I'll answer them to the best of my ability.
Old 12-23-2006, 10:07 PM
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Default RE: Can I Have an official Mammoth ST thread?

Thanks for the reply. I'm sure I'll find out what I need to upgade, I was just trying to learn some stuff before jumping into it. It's actually my brothers truck but he wants to upgrade. I'll look into and find out some info and let you know!
Old 12-23-2006, 10:20 PM
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Default RE: Can I Have an official Mammoth ST thread?

Sounds good to me, from what I've heard it's a really worthy investment for those diffs. They're better quality and they should definitely last longer. Keep me posted on what's up! Good luck and happy holidays!
Old 12-23-2006, 10:29 PM
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Default RE: Can I Have an official Mammoth ST thread?

will do! I forgot to mention what I meant about the diffs being sealed. I didn't mean sealed as in the diffs not being able to come apart. I meant that the diffs are sealed with Orings so that you can run oil inside of them to change the diffs action.

Anyways, he tore the front diff apart and said the ring and pinion look ok, he said he took apart the center gears too but he isn't sure what to look for. I asked if he seen any metal shavings and he said no so that is good. He did say one of the cups was loose. I'll have to look at it tomorrow sometime and see what it looks like.

I'm sure he is going to the single speed and probably upgrading spider gears. I'll snag some pics when the upgrades come!
Old 12-23-2006, 10:39 PM
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Default RE: Can I Have an official Mammoth ST thread?

Sounds good to me, you know where to post when everything is done.
Old 12-24-2006, 06:15 AM
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Default RE: Can I Have an official Mammoth ST thread?

well i am currently rebuilding mine with some pro parts and gonna put my beloved dadders stg II sts .30 in it...just waiting to get a hold of a jp-2 or jp-3 exhaust..should be shortly after christmas....gonna experiment with jammin x1-cr hubs...can't wait...
Old 12-24-2006, 01:17 PM
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Default RE: Can I Have an official Mammoth ST thread?

Wise idea NewKid, I saw you talk about all this on the XTM forums too. Hope everything works out for ya!
Old 12-27-2006, 12:44 AM
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Default RE: Can I Have an official Mammoth ST thread?

here is my st i just got the engine single gear in

NEW

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Old 12-27-2006, 12:49 AM
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Default RE: Can I Have an official Mammoth ST thread?


Old 12-27-2006, 08:29 AM
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Default RE: Can I Have an official Mammoth ST thread?

ssj2,

Well I went over to my brothers place and looked over his truck. The 2 speed is trashed but the diffs are actually in good shape. Turns out that the front diff was slipping because the outdrive set screw came undone and was turning on the shaft. The rear end wasn't getting power becuase the outdrive setscrew on the 2 speed came out and was spinning on the 2 speed shaft. The spurs had a few spots that were chunked though.

Anyways. I did a lot of research on what to do with those spider gears. He bought 3 sets because he also put spider gears inside his center diff. Then he bought new outdrives that run to each wheel and new outdrives for the center diff. I'm not sure what my brother is gonna do about the diffs. He doesn't really want to drop the coin on the spider gear upgrade yet. all the gears are fine so I think he might stick with the planetary gears. I was trying to get him to at least get the spider gears for the center diff since that take the brunt of the hits. He isn't sure yet. I think he is gonna order parts early next week. I'll snag some pics of it going back together.
Old 12-27-2006, 11:45 AM
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Default RE: Can I Have an official Mammoth ST thread?

At least you didn't trash the diffs, I think I may have the same problem with my ST. Once you get the center diff, if anything happens with the front differential, the whole truck is useless. It just revs when you apply throttle. That's what got me really pissed off... I did talk to my dad about the spider diffs and he thought that there wasn't a spider gear in the center diff. I told him there was, but he came up with this song & dance that I fell for. [] I've also had to replace the drive cups, try not to floor the truck from a dead stop to prevent that. If you think of the power to weight ratio, in that case, it's pretty harsh on the truck. I totally see your bro's point of view with not wanting to spend the money, exactly my reason too. I dished out so much on upgrades for my truck, and then when I really need something, you second guess yourself. If the center diff is where you're getting the most trouble, definitely upgrade it, then hopefully it's "problem solved" from there. I look forward to seeing the pics and I wish you all the best of luck with your truck! Keep me posted!
Old 12-27-2006, 12:47 PM
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Default RE: Can I Have an official Mammoth ST thread?

no 1 likes my picks[][][][][][][][][][][:@][:@][:@][:@][:@][:@][:@][&o]












lol
Old 12-27-2006, 01:12 PM
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Default RE: Can I Have an official Mammoth ST thread?

rcboy, i'm diggin the pics! Sorry I just glanced at them and didn't really feel like replying... my bad! what do you think of the truck?

ssj2, The center diff comes with planateries. I told him to get the center diff and put spider gears in it. That way the center diff is bomb proof. then upgrade diffs as needed. I'll post pics with what he ends up doing. I'll pass on the info about taking it easy off the line.
Old 12-27-2006, 04:21 PM
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Default RE: Can I Have an official Mammoth ST thread?

Yeah, the going off the line thing is really something I surpassed. But if you break it all down it does make sense. Especially considering I run the XTM .28. With the .21 he may not have as much trouble as he would with a bigger engine. The center diff w/spider gears=an awesome idea. Good luck and I'm waiting for the pics!
Old 12-30-2006, 08:52 PM
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Default RE: Can I Have an official Mammoth ST thread?

finished break-in of the Ofna Force 32 in my mammoth ST today. Definite improvement over the 24.7. I'm running a 2spd with a 12/17t clutchbell and it burns all 4 off the line and then some...when it hits 2nd it's like you hit the afterburners . There's enough torque here that I'm likely going to get a 14/19 bell. I'm also pleased that it burns about the same amount of gas that my 24.7 did. I base that off the fact that it runs about the same amount of time on a full tank (290cc tank). Before break-in I had concerns about it being a gas guzzler.

what a fun truggy
Old 12-31-2006, 07:27 AM
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Default RE: Can I Have an official Mammoth ST thread?

those ofna .32 are suprisingly powerful for what they are...if tuned correctly...well the rebuild should be done soon just need some more hub bearings because the ones i have are shot and then i'll install the hubs, motor, and fire her up...can't wait..ss i saw you selling your mammoth what you leaning towards? or just need the cash?
Old 12-31-2006, 10:49 AM
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I take it we're gonna get some vids on here posted soon of the Ofna .32 in the mammoth ST... [:-]
Old 01-01-2007, 02:46 PM
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Default RE: Can I Have an official Mammoth ST thread?

im runnin 17/65 to much torqe!!!!!!!!!!!!!!!!!!!!!
Old 01-06-2007, 08:01 PM
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Default RE: Can I Have an official Mammoth ST thread?

Ok guys I have run into some problems. My brother got the parts in for his truck so I went over there to help him put the truck together.

Everything went great accept for the first thing I started on. I wanted to change over the 2 speed clutch bell to the single speed clutchbell. Here is my problem.









As you can see, after I put the clutch bell on the pilot shaft was sticking out. After you put the retaining screw in there is WAY to much play on the clutch bell. Is there supposed to be a spacer or something there? I looked in the manual and it looked like there was some type of spacer in the exploded view but there was not a spacer used on the 2 speed when I took it apart. Any ideas?

We ended up putting the diffs back together stock. All the gears looked fine, I think the outdrive setscrews came loose and were the cause of the slipping.

For the center diff he got the spider gears so I put all that together and we ran 10,000 weight in that. We ended up putting 3,000 weight in the rear and 7,000 weight in the front. I read a couple places some guys using close to this set so it'll be a good starting point. It'll be a few days until the truck is all back together though. Here are some pics of the center diff assembly.











Old 01-06-2007, 08:37 PM
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Default RE: Can I Have an official Mammoth ST thread?

Me, me, me! I know this! This is the exact problem I had when I converted to the one-speed clutch bell also. First off, nice differentials, they're a great investment. Your bro won't regret it at all, I guarantee it. About the clutch bell though, I just put a washer in there. There's supposed to be a very small amount of play with that clutch bell against the shaft, so to close that empty space, use a washer with the same diameter as the shaft and the thickness enough so there's a tiny bit of play in the entire clutch bell. Check the "play" side to side and up and down. I spent about 45 minutes downstairs looking through my dad's washers, I finally found one, I do not have the direct dimensions of it though. I ran into the exact same problem, funny. If you think about it, the only reason this problem comes up is because with the 2 speed the clutch bell took up a greater area over the shaft. You've now cut that space in "half" with the single speed clutch bell, so I would just use a washer. It will take a sh%^ load of shims to do what you want. Any questions, ask.
Old 01-06-2007, 09:21 PM
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Default RE: Can I Have an official Mammoth ST thread?

I totally understand why people get the center differential, but I'm still hung up on the 2spd. I just love the shifting and top end
Of course, it works for me because I'm not into big jump.
Old 01-06-2007, 09:23 PM
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Default RE: Can I Have an official Mammoth ST thread?

If you were into jumping or worried about stripping gears, you would feel that same way all of us with the single speed do. I gotta hand it to you though, I like the 2 speed too, I just didn't wanna wreck it and have to replace it all.

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