Ok, more details on that ball diff you got!! I was planning on getting the upgrade ball diff from the Latrax rally upgrade page, but it's now discontinued. So, more details please!
hmmm just a guess but rc18 diff?
summit /mustang /stampede-2s spc lipo
Got a chance to run it with the oil shocks, so much better.
It was still a little funky, I found out why:
The front pinion was chipped and split. The car was running loud, but I though that was just a chip on the spur gear. I think it started before I did the end swap, that my have been why it didn't work so well. Or the rear spool chipped it because of the shock load.
I swapped in the ball diff in the front while I was in there. I think the car rotated better with it than the spool, but it didn't snap around like the gear diff.
The other problem I have to find a solution for is the chassis tweak. Not sure if it hit hard once or something's crooked, but it's a little annoying that the car hooks one way and pushes the other.
I also found shocks to work on a rally set-up for more clearance.
The RC18T has steel gears available, that might be worth a try. I went through a bunch of diff gears on my RC18t.
I like turtles.
I wonder if the pinion from the rc18 would fit also
Seems the pinon is a bit of a weak piont
I like turtles.
Hey i was checking out your posts. And i was wondering if u ever you found out how to make this motor fit without any problems? Post a video or pics @Geo
Last edited by Streetz Daddi; 12-25-2013 at 02:28 PM.
If you went to a ball diff those gears would work, or run the metal pinon with the other diffs. The RC18 pinions should work too, the pitch is the same. Not sure about spur gears. The RC18 uses a hex to index the gear on the center shaft instead of the cross pin that the latrax uses. I don't know if the RC18 center shaft will work, haven't tried it yet
Streetz Daddi, we're talking about the ring and pinion in the diff. 08kgraves modified the motor plate to fit a different motor in his thread, look at post #33.
thanks for the tips. I don't actually have the car yet I'm just taking down some good notes before the car comes I definitely don't want to run stock. I'm going to check out #33 because I was thinking about getting that motor.
question? Would the Traxxas VXL-3M be a good motor if I'm looking for speed and power?
So you're saying an rc18t ball diff fits in this car? And the metal pinion and diff gears are the same pitch/mod as the LaTrax stock?
I assume the aluminum versions of these ball diffs are identical measurements?
Does the ball diff in the rear really run all that different than the stock LaTrax diff? I'm uncertain which would be a smarter route:
Rc18t ball diff, or Traxxas solid axle.
I was also considering swapping out the stock 14t motor pinion gear with a 17t to give it a bit more speed... Thoughts?
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I have found using the latrax spool causes the diff pinion to span very easily on high traction surfaces
the ball diffs are by far the best choice , actually ran mine last night without a single failure with the 7.2v battery with ball diff front and rear
I will agree that the spool will transfer shock load and kill the diff pinon. I like the diff vs. the spool in the front, turns better and doesn't want to traction roll. I haven't tried one in the rear, but I would definitely not run the spool back there.
Gearing depends on where you're running it. If you have a lot of space it should be fine, I would keep an eye on motor temps though. Battery will play a big role in speed, go to 7.2v or li-po then decide if you need more gear.
I am running it with the one way driveshaft, 7.2v NiMh, and a bearing kit. It's already much better than stock, but I tinker and tweak, so I want more. My primary driving conditions are my underground parkade and blacktop. The parkade has a smooth floor, so it drifts nicely there, but it is very dusty so everything gets coated with a fine powder. I may go for oil shocks soon, but they're expensive... And I don't know how they'll handle the dust. On the blacktop, it grips a bit too much and is harder to kick it into a drift. Should I just go for ball diffs in both ends and call it a day?
As for the motor pinion, I read that someone put a 20t and it made a big speed difference but my understanding is that it comes at the expense of torque, so a 17t sounds like a happy medium.
Anyone know the shaft diameter of the stock 370 motor?
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Gearing up you will lose torque and some drift power. The speed may help on dusty surfaces, or you may just end up losing it(spin out). Ball diffs will help, but then your shocks may be holding it back. The shocks shouldn't mind the dust that much as long as you brush them off occasionally. The lack of rebuild parts is kind of annoying.
Pinions are pretty standard, anything for an rc18 or mini-t will bolt up perfect.
A little PSA for anyone that's taken apart their rally recently:
Got the aluminum shock towers and found that they are more clearly marked front and rear. The stock ones have a very small raised letter in the center that is hard to read. They are different and when they're wrong the rear end sits really low.
I just assembled and installed the ball diffs from the RC18T. Tricky procedure to assemble them, but all went well.
I didn't need to shim the diffs, they fit really snug.
I also installed the 17t pinion, took out the spacer plate from the stock motor mount and just used the slot... Can't find my file to widen the hole in the spacer...
Haven't been out to give it a good run, just in the house a bit. Also picked up another 7.2v 1200mah NiMH so I hope I can update soon!
Oh, one thing... The Traxxas sleeves that go over the dogbone cups are a hair smaller, and cause the pegs in the shafts to bind. You can't really use them on this diff. I don't know how necessary they are, but you may want to look into the sleeves for this specific diff if you go that route.
The sleeves prevent the out-drive from breaking. Not that necessary with the power and traction available, but definitely needed with more power.
The pins are a problem even with the stock set-up. The pins can move from being centered on the shaft and cause the binding. Another reason to install sleeves.
Ok, I guess I have to order the ones for that diff. If the pins could slip out, it's probably best to ensure that doesn't happen. I'd rather minimize damage
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I see that you've installed the one way drive shaft. Does this mean it only goes froward or does it only fit in one way?
Good explanation of the one way shaft Seegee, and it does only fit in one way. The shaft is called that because there is a one-way bearing in the front.
You may want to check your suspension throughout it's travel and see if the drive-shafts are are bottoming out on the dust caps on the the diffs. I noticed that the suspension was stopping before full travel because of this.
The only other explanation I have for the truing issue is the chassis seems to tweak and I'm not sure how it git rid of it.
Going up 3 teeth will do that to run time and heat. I bet it was quick though.
If you think the motor pinion/spur mesh is good I would double check the ring and pinion mesh. The diff does fit tight in the case, but there is still some play. You should still feel some tick in the mesh and if it's too large the shims that came with the diffs should help take it out.
Yeah, 17t pinion is probably too much for the stock motor. My gear mesh was a bit too tight, but it still gets the motor too hot for my liking.
So the carbon chassis showed up and after finishing and sealing the edges I figured I may as well build it up.
Only thing missing is the tuning links and I have those on the way.
Teton diff in the rear with a shim to slow it down and the metal pinion on the front with the rc18 diff, should be just about bomb proof.
I'm not as happy as I wanted to be with the chassis
The one hold down post isn't threaded enough or the screws are too long. (yes I know they are machine thread)
Doesn't matter that much to me because it'll end up modified to hold the lipo that doesn't currently fit.
So what does fit? Short singe cell height packs. It was hard to get the stock Teton pack to fit, I imagine it wouldn't without loosening the battery posts. The problem is the old fat end caps that are used on that pack, newer skinny sticks fit fine. The tray is wider, the Traxxas lipo is actually kind of loose, not sure that'll help with drive-shaft clearance.
I built it up with new core components, bulkheads, spur housing. Still the most frustrating part is there, chassis tweak. Not sure what to do about it or where it's coming from.
Or perhaps I'm imaging it, so I'll ask question.
Anyone else notice their Rally/Teton turning harder one way than the other?
Yea this turning better one way than the others puzzles me. I can do donuts one way but the other maybe a 4' circle. Thought maybe the left and right side weight difference caused it.
thanks you very much GeoVW72!
So the rc18 old ball diffs work with the latrax? If they do, will i have to do any chassis modifications or will they just drop in once i assemble them?
They just drop in. You may need to shim things depending on your setup, but I didn't need any.
does it compatible with lipo 30c 7.4v 5000mah?
Good afternoon. It's been a few months from the last post. Hope it's still monitored.
Was getting bored on these cold rainy weekends. Went to find something indoors to do. Found a local track that is running these rally cars. Looks impressive. So, I'm sure I'll be getting one soon and do the usual bearings and oil shocks. I have plenty rc18 diffs and it's good to see that is an option. My question is what type of tires are most running for good traction. They race on a wooden track painted. What options are available for tires for this rally car?
Awesome build dude, I'm insanely jealous of your 3d printer
Good afternoon. Great thread. BTW, Does the rc18 pinion on the drive shaft work on the latrax shaft?
Agree. Well I am going to try the RC 18 nylon gears for a while and see how it works. I do not plan on running this vehicle brushless for its only for stock racing.