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Revo 3.3 Tranny Problems

Discussion in Traxxas Revo forum, started by stevoswanson.

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Unread 6-14-2008, 10:54 PM   #1
stevoswanson
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Revo 3.3 Tranny Problems

I just upgraded my revo from a 2.5R to a 3.3 and noticed my transmission wasn't shifting. I followed the engine break in requirements and still nothing. So the genius in me (sarcastic) decided to take apart the transmission on my revo to see why it wasn't shifting. After taking it apart and thinking I put it back together correctly my truck will not go forward or reverse. It seems like the engine gear spins but is not picking up the transmission. Can some one please shed some lime light on this?

Thanks



P.S. I am a newb to the whole gas powered trucks. If anyone can help me please post in newb talk as I don't understand a lot about the cars.
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Unread 6-14-2008, 11:12 PM   #2
MrClean
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Hey Stevo, I'm a newbie too. My Revo 3.3 was doing almost the same thing, read this thread and see if it helps any. http://www.rcnitrotalk.com/forum/showthread.php?t=59280
Be sure to check out Rolex's link, it has nice pics of the adjustments needed.
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Unread 6-14-2008, 11:53 PM   #3
stevoswanson
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Did this work for you. I guess I will read the instructions and see what it should be set at. If I hit the throttle and it barely moves and then stops should tighten it or loosen it more?

Any advice would be handy

Thanks
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Unread 6-15-2008, 12:02 AM   #4
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Sorry, I didn't explain that very well. The problem started with it not shifting into 2nd gear. The next time I ran the truck it would hardly move with the throttle wide open. If you still have your owners manual, look up slipper clutch in the back and it will show you what page (you can go to Traxxas web-site for the owners manual too).

I tightened mine up about 1/2 to 3/4 of a turn. Now it's hard for me to keep the front wheels on the ground, so yes it did fix my problem. It's a 8mm nut that needs to be tightened, you'll have to take the air filter off the carb to get to it. The link I posted is to the thread I started about the slipper clutch. In that thread Rolex posted a link to a site called 'rcmisbehavin' and it shows some excellent pictures and exactly how to fix this problem. It's pretty simple really and I don't know all that much about nitro cars either.

Good luck and let us know if this changes anything.
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Unread 6-15-2008, 12:07 AM   #5
stevoswanson
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I will give it a try and see where it goes from there

Thanks for the help
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Unread 6-16-2008, 9:17 AM   #6
stevoswanson
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It didn't work. It is still doing the same thing. I loosened the slipper clutch but nothing. It seems like the slipper clutch and the gear that is attached to the engine to not meet up. Is it normal for the gear on the engine to spin without me hitting the gas? For some reason I don't remember that spinning until you hit the gas.

I could have screwed up the transmission but I am putting everything back together per the instructions.

Any more help would be greatful

Thanks
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Unread 6-16-2008, 9:36 AM   #7
CharliesTheMan
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Stevo, you need to line up your gear mesh. The clutchbell will be spinning on idle, that's what the clutch is for. When adjusted properly, the clutch bell spins on idle and does not engae the clutch. When the revs are increased, it spreads the clutch shoes and grabs the clutch bell, allowing the power to be transferred to the drivetrain.

Do a quick search and learn how to line up your gear mesh. That's what the problem is if the clutch bell (metal gear attached to the motor) is not connected to the spur gear (big gear that should be touching the gear on the motor). You will need to loosen the engine mount bolts and line up the spur gear, put fresh loc-tite on everything, and tighten it back down. If the spur gear is warped at all of has teeth missing or chewed up, then replace it. You should always have a few spare spur gears on hand, especially until you learn how to properly set the mesh.

Mr clean, the advice that you gave him was good for adjusting the shift point, but that's not going to help me now. Stevo, it's a possibility when you tore down the transmission, upon assembly you installed something wrong and apparently its either binding up, or it got bound up and stripped something, or maybe there is just a piece missing or in the wrong place to keep it from working. For the shift point, I would bet you $500 that your problem had nothing to do with the transmission (at first, before you took it apart). Your problem was most likeley a tuning problem. Next time something happens, you're welcome to come on here and ask us questions to help you out. We probably could have saved you a lot of headaches. I think your truck is probably running rich. I learned this through having to figure out the same issue. WHen you truck is out of tune, even just a lil bit, the engine will not run at it's peak, and therefore will not go ahead and shift over into 2nd gear. I think you need to get some assistance in the way of illustation and parts diagrams and look over the transmission, assemble it according to the instructions, inspect all the parts while you're doing that, and get it back together. Once you get the transmission together, and get the truck back to where it was before you ever took it apart, you can start over fresh.

Do you have a temp gun? If you don't, don't run the truck again until you get one. It will help you out SOOO MUCH, as well as it might save your engine. Once you get the transmission together, come back on here and one of the veterans will help you tune it correctly. You should only have to adjust the transmission shift point by a fraction of a turn, so I'm pretty sure that you had a tuning issue if nothing was broken. If you listen to one of the tuning gurus, like Rolex, he will guide you through tuning it perfect. It's amazing the way that he can guide you through finding a tune from a tousand miles away, but you have to do EXACTLY as he says, or he won't be able to diagnose what the truck is doing and put you on the right path.

Last edited by CharliesTheMan; 6-16-2008 at 9:45 AM.
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Unread 6-16-2008, 11:11 PM   #8
stevoswanson
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Charliestheman,

Thanks for the insight. I haven't had a chance to rip the transmission apart because of a new job. I will have to get back to it within the next few nights. Right now I have the slipper clutch tightened all of the way, I figure I will have to loosen it.

If I understand your post correctly I just have to line up the slipper clutch and the gear on the engine. If I am wrong please let me know.

P.S. right now my engine is running a little rich because I just upgraded from the 2.5R to the 3.3 so once I get it going again I will lean it out and see if that helps the shifting.

Thanks for the help
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Unread 6-21-2008, 4:12 PM   #9
stevoswanson
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I found out what the problem was. It was the angle the engine was at. There are two black screws on the engine mount, one of them allows you to change the position of the engine so that the two gears meet.

I changed the slipper clutch gear assembly and have tested it and works just as new.

Thanks for all of your help
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